Internal Redesign:

- Combined MPExpression and MPMutableExpression
- Abstracted children of MPExpression into MPExpressionElement protocol
- Abstracted most of MPExpressionLayout and MPFunctionLayout into common superclass MPLayout

MathPad.xcodeproj/project.pbxproj

@@ -9,20 +9,20 @@
 /* Begin PBXBuildFile section */
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 		3B0F69AC1902A82C00817707 /* MPExpressionTests.m in Sources */ = {isa = PBXBuildFile; fileRef = 3B0F69AB1902A82C00817707 /* MPExpressionTests.m */; };
-		3B0F69AD1902AD2200817707 /* MPExpression.m in Sources */ = {isa = PBXBuildFile; fileRef = 3B87E3581900857C00259938 /* MPExpression.m */; };
 		3B0F69AE1902AD2800817707 /* MPException.m in Sources */ = {isa = PBXBuildFile; fileRef = 3B0F69A819028C6000817707 /* MPException.m */; };
 		3B0F69B01902AD2E00817707 /* MPFunction.m in Sources */ = {isa = PBXBuildFile; fileRef = 3B87E35F19009D5F00259938 /* MPFunction.m */; };
+		3B528D10199417E10054DB5F /* MPExpressionLayout.m in Sources */ = {isa = PBXBuildFile; fileRef = 3B528D0F199417E10054DB5F /* MPExpressionLayout.m */; };
+		3B528D13199417E90054DB5F /* MPFunctionLayout.m in Sources */ = {isa = PBXBuildFile; fileRef = 3B528D12199417E90054DB5F /* MPFunctionLayout.m */; };
+		3B528D1619941F5B0054DB5F /* MPExpressionLayout.m in Sources */ = {isa = PBXBuildFile; fileRef = 3B528D0F199417E10054DB5F /* MPExpressionLayout.m */; };
+		3B528D1819941F5B0054DB5F /* MPFunctionLayout.m in Sources */ = {isa = PBXBuildFile; fileRef = 3B528D12199417E90054DB5F /* MPFunctionLayout.m */; };
+		3B53AD5F1997E0FB00C925C4 /* MPExpression.m in Sources */ = {isa = PBXBuildFile; fileRef = 3BFAC38E1997B61300B3EF67 /* MPExpression.m */; };
+		3B688D9919982DF50006B4AB /* MPLayout.m in Sources */ = {isa = PBXBuildFile; fileRef = 3B688D9819982DF50006B4AB /* MPLayout.m */; };
 		3B87E3561900856F00259938 /* MPExpressionView.m in Sources */ = {isa = PBXBuildFile; fileRef = 3B87E3551900856F00259938 /* MPExpressionView.m */; };
-		3B87E3591900857C00259938 /* MPExpression.m in Sources */ = {isa = PBXBuildFile; fileRef = 3B87E3581900857C00259938 /* MPExpression.m */; };
 		3B87E36019009D5F00259938 /* MPFunction.m in Sources */ = {isa = PBXBuildFile; fileRef = 3B87E35F19009D5F00259938 /* MPFunction.m */; };
 		3BB09EB21905DE500080A5ED /* MPExpressionStorage.m in Sources */ = {isa = PBXBuildFile; fileRef = 3BB09EB11905DE500080A5ED /* MPExpressionStorage.m */; };
 		3BB09EC91906FD830080A5ED /* MPSumFunction.m in Sources */ = {isa = PBXBuildFile; fileRef = 3BB09EC81906FD830080A5ED /* MPSumFunction.m */; };
-		3BB09ED0190713F00080A5ED /* MPExpressionLayout.m in Sources */ = {isa = PBXBuildFile; fileRef = 3BB09ECF190713F00080A5ED /* MPExpressionLayout.m */; };
+		3BB09EDE190728220080A5ED /* NSIndexPath+MPAdditions.m in Sources */ = {isa = PBXBuildFile; fileRef = 3BB09EDD190728220080A5ED /* NSIndexPath+MPAdditions.m */; };
-		3BB09ED3190713FC0080A5ED /* MPFunctionLayout.m in Sources */ = {isa = PBXBuildFile; fileRef = 3BB09ED2190713FC0080A5ED /* MPFunctionLayout.m */; };
-		3BB09EDE190728220080A5ED /* NSIndexPath+MPReverseIndexPath.m in Sources */ = {isa = PBXBuildFile; fileRef = 3BB09EDD190728220080A5ED /* NSIndexPath+MPReverseIndexPath.m */; };
 		3BB09EE1190736160080A5ED /* MPSumFunctionLayout.m in Sources */ = {isa = PBXBuildFile; fileRef = 3BB09EE0190736160080A5ED /* MPSumFunctionLayout.m */; };
-		3BBBA358190327B700824E74 /* MPMutableExpressionTests.m in Sources */ = {isa = PBXBuildFile; fileRef = 3BBBA357190327B700824E74 /* MPMutableExpressionTests.m */; };
-		3BBBA35D1903F8A700824E74 /* NSObject+MPStringTest.m in Sources */ = {isa = PBXBuildFile; fileRef = 3BBBA35C1903F8A700824E74 /* NSObject+MPStringTest.m */; };
 		3BBBA35E1903FD3600824E74 /* MPRangePath.m in Sources */ = {isa = PBXBuildFile; fileRef = 3B87E35C1900933200259938 /* MPRangePath.m */; };
 		3BBBA35F1903FD3600824E74 /* MPRangePath.m in Sources */ = {isa = PBXBuildFile; fileRef = 3B87E35C1900933200259938 /* MPRangePath.m */; };
 		3BBBA3951905704200824E74 /* MPRangeTests.m in Sources */ = {isa = PBXBuildFile; fileRef = 3BBBA3941905704200824E74 /* MPRangeTests.m */; };
@@ -37,7 +37,8 @@
 		3BF9979118DE623E009CF6C4 /* XCTest.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 3BF9979018DE623E009CF6C4 /* XCTest.framework */; };
 		3BF9979218DE623E009CF6C4 /* Cocoa.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 3BF9976E18DE623E009CF6C4 /* Cocoa.framework */; };
 		3BF9979A18DE623E009CF6C4 /* InfoPlist.strings in Resources */ = {isa = PBXBuildFile; fileRef = 3BF9979818DE623E009CF6C4 /* InfoPlist.strings */; };
-		3BFCFF491905AAF30001FE33 /* NSTextStorage+MPSetContents.m in Sources */ = {isa = PBXBuildFile; fileRef = 3BFCFF481905AAF30001FE33 /* NSTextStorage+MPSetContents.m */; };
+		3BFAC38F1997B61300B3EF67 /* MPExpression.m in Sources */ = {isa = PBXBuildFile; fileRef = 3BFAC38E1997B61300B3EF67 /* MPExpression.m */; };
+		3BFAC39C1997BC7600B3EF67 /* NSString+MPExpressionElement.m in Sources */ = {isa = PBXBuildFile; fileRef = 3BFAC39B1997BC7600B3EF67 /* NSString+MPExpressionElement.m */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXContainerItemProxy section */
@@ -54,10 +55,14 @@
 		3B0F69A719028BC600817707 /* MPException.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = MPException.h; sourceTree = "<group>"; };
 		3B0F69A819028C6000817707 /* MPException.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = MPException.m; sourceTree = "<group>"; };
 		3B0F69AB1902A82C00817707 /* MPExpressionTests.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = MPExpressionTests.m; sourceTree = "<group>"; };
+		3B528D0D199417740054DB5F /* MPLayout.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = MPLayout.h; sourceTree = "<group>"; };
+		3B528D0E199417E10054DB5F /* MPExpressionLayout.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = MPExpressionLayout.h; sourceTree = "<group>"; };
+		3B528D0F199417E10054DB5F /* MPExpressionLayout.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = MPExpressionLayout.m; sourceTree = "<group>"; };
+		3B528D11199417E90054DB5F /* MPFunctionLayout.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = MPFunctionLayout.h; sourceTree = "<group>"; };
+		3B528D12199417E90054DB5F /* MPFunctionLayout.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = MPFunctionLayout.m; sourceTree = "<group>"; };
+		3B688D9819982DF50006B4AB /* MPLayout.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = MPLayout.m; sourceTree = "<group>"; };
 		3B87E3541900856F00259938 /* MPExpressionView.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = MPExpressionView.h; sourceTree = "<group>"; };
 		3B87E3551900856F00259938 /* MPExpressionView.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = MPExpressionView.m; sourceTree = "<group>"; };
-		3B87E3571900857C00259938 /* MPExpression.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = MPExpression.h; sourceTree = "<group>"; };
-		3B87E3581900857C00259938 /* MPExpression.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = MPExpression.m; sourceTree = "<group>"; };
 		3B87E35B1900933200259938 /* MPRangePath.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = MPRangePath.h; sourceTree = "<group>"; };
 		3B87E35C1900933200259938 /* MPRangePath.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = MPRangePath.m; sourceTree = "<group>"; };
 		3B87E35E19009D5F00259938 /* MPFunction.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = MPFunction.h; sourceTree = "<group>"; };
@@ -66,18 +71,11 @@
 		3BB09EB11905DE500080A5ED /* MPExpressionStorage.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = MPExpressionStorage.m; sourceTree = "<group>"; };
 		3BB09EC71906FD830080A5ED /* MPSumFunction.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = MPSumFunction.h; sourceTree = "<group>"; };
 		3BB09EC81906FD830080A5ED /* MPSumFunction.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = MPSumFunction.m; sourceTree = "<group>"; };
-		3BB09ECE190713F00080A5ED /* MPExpressionLayout.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = MPExpressionLayout.h; sourceTree = "<group>"; };
+		3BB09EDC190728220080A5ED /* NSIndexPath+MPAdditions.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = "NSIndexPath+MPAdditions.h"; sourceTree = "<group>"; };
-		3BB09ECF190713F00080A5ED /* MPExpressionLayout.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = MPExpressionLayout.m; sourceTree = "<group>"; };
+		3BB09EDD190728220080A5ED /* NSIndexPath+MPAdditions.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = "NSIndexPath+MPAdditions.m"; sourceTree = "<group>"; };
-		3BB09ED1190713FC0080A5ED /* MPFunctionLayout.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = MPFunctionLayout.h; sourceTree = "<group>"; };
-		3BB09ED2190713FC0080A5ED /* MPFunctionLayout.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = MPFunctionLayout.m; sourceTree = "<group>"; };
-		3BB09EDC190728220080A5ED /* NSIndexPath+MPReverseIndexPath.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = "NSIndexPath+MPReverseIndexPath.h"; sourceTree = "<group>"; };
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-		3BBBA357190327B700824E74 /* MPMutableExpressionTests.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = MPMutableExpressionTests.m; sourceTree = "<group>"; };
 		3BBBA3591903EA9B00824E74 /* MPModel.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = MPModel.h; sourceTree = "<group>"; };
-		3BBBA35B1903F8A700824E74 /* NSObject+MPStringTest.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = "NSObject+MPStringTest.h"; sourceTree = "<group>"; };
-		3BBBA35C1903F8A700824E74 /* NSObject+MPStringTest.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = "NSObject+MPStringTest.m"; sourceTree = "<group>"; };
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 		3BBBA3941905704200824E74 /* MPRangeTests.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = MPRangeTests.m; sourceTree = "<group>"; };
 		3BF9976B18DE623E009CF6C4 /* MathPad.app */ = {isa = PBXFileReference; explicitFileType = wrapper.application; includeInIndex = 0; path = MathPad.app; sourceTree = BUILT_PRODUCTS_DIR; };
@@ -99,8 +97,11 @@
 		3BF9979018DE623E009CF6C4 /* XCTest.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = XCTest.framework; path = Library/Frameworks/XCTest.framework; sourceTree = DEVELOPER_DIR; };
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-		3BFCFF471905AAF30001FE33 /* NSTextStorage+MPSetContents.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = "NSTextStorage+MPSetContents.h"; sourceTree = "<group>"; };
+		3BFAC38D1997B61300B3EF67 /* MPExpression.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = MPExpression.h; sourceTree = "<group>"; };
-		3BFCFF481905AAF30001FE33 /* NSTextStorage+MPSetContents.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = "NSTextStorage+MPSetContents.m"; sourceTree = "<group>"; };
+		3BFAC38E1997B61300B3EF67 /* MPExpression.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = MPExpression.m; sourceTree = "<group>"; };
+		3BFAC3961997B67400B3EF67 /* MPExpressionElement.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = MPExpressionElement.h; sourceTree = "<group>"; };
+		3BFAC39A1997BC7600B3EF67 /* NSString+MPExpressionElement.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = "NSString+MPExpressionElement.h"; sourceTree = "<group>"; };
+		3BFAC39B1997BC7600B3EF67 /* NSString+MPExpressionElement.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = "NSString+MPExpressionElement.m"; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -127,14 +128,18 @@
 		3B87E350190082B300259938 /* Model */ = {
 			isa = PBXGroup;
 			children = (
-				3BBBA35A1903F89100824E74 /* Categories */,
 				3BBBA3591903EA9B00824E74 /* MPModel.h */,
-				3B87E3571900857C00259938 /* MPExpression.h */,
+				3BFAC38D1997B61300B3EF67 /* MPExpression.h */,
-				3B87E3581900857C00259938 /* MPExpression.m */,
+				3BFAC38E1997B61300B3EF67 /* MPExpression.m */,
+				3BFAC3961997B67400B3EF67 /* MPExpressionElement.h */,
 				3B87E35E19009D5F00259938 /* MPFunction.h */,
 				3B87E35F19009D5F00259938 /* MPFunction.m */,
+				3BFAC39A1997BC7600B3EF67 /* NSString+MPExpressionElement.h */,
+				3BFAC39B1997BC7600B3EF67 /* NSString+MPExpressionElement.m */,
 				3B87E35B1900933200259938 /* MPRangePath.h */,
 				3B87E35C1900933200259938 /* MPRangePath.m */,
+				3BB09EDC190728220080A5ED /* NSIndexPath+MPAdditions.h */,
+				3BB09EDD190728220080A5ED /* NSIndexPath+MPAdditions.m */,
 				3B0F69A719028BC600817707 /* MPException.h */,
 				3B0F69A819028C6000817707 /* MPException.m */,
 				3BB09EBC1905EF210080A5ED /* Functions */,
@@ -194,10 +199,12 @@
 		3BB09ED819071C270080A5ED /* Private */ = {
 			isa = PBXGroup;
 			children = (
-				3BB09ECE190713F00080A5ED /* MPExpressionLayout.h */,
+				3B528D0D199417740054DB5F /* MPLayout.h */,
-				3BB09ECF190713F00080A5ED /* MPExpressionLayout.m */,
+				3B688D9819982DF50006B4AB /* MPLayout.m */,
-				3BB09ED1190713FC0080A5ED /* MPFunctionLayout.h */,
+				3B528D0E199417E10054DB5F /* MPExpressionLayout.h */,
-				3BB09ED2190713FC0080A5ED /* MPFunctionLayout.m */,
+				3B528D0F199417E10054DB5F /* MPExpressionLayout.m */,
+				3B528D11199417E90054DB5F /* MPFunctionLayout.h */,
+				3B528D12199417E90054DB5F /* MPFunctionLayout.m */,
 			);
 			name = Private;
 			sourceTree = "<group>";
@@ -211,19 +218,6 @@
 			name = "Function Layouts";
 			sourceTree = "<group>";
 		};
-		3BBBA35A1903F89100824E74 /* Categories */ = {
-			isa = PBXGroup;
-			children = (
-				3BBBA35B1903F8A700824E74 /* NSObject+MPStringTest.h */,
-				3BBBA35C1903F8A700824E74 /* NSObject+MPStringTest.m */,
-				3BFCFF471905AAF30001FE33 /* NSTextStorage+MPSetContents.h */,
-				3BFCFF481905AAF30001FE33 /* NSTextStorage+MPSetContents.m */,
-				3BB09EDC190728220080A5ED /* NSIndexPath+MPReverseIndexPath.h */,
-				3BB09EDD190728220080A5ED /* NSIndexPath+MPReverseIndexPath.m */,
-			);
-			name = Categories;
-			sourceTree = "<group>";
-		};
 		3BF9976218DE623E009CF6C4 = {
 			isa = PBXGroup;
 			children = (
@@ -292,7 +286,6 @@
 			isa = PBXGroup;
 			children = (
 				3B0F69AB1902A82C00817707 /* MPExpressionTests.m */,
-				3BBBA357190327B700824E74 /* MPMutableExpressionTests.m */,
 				3BBBA3941905704200824E74 /* MPRangeTests.m */,
 				3BF9979618DE623E009CF6C4 /* Supporting Files */,
 			);
@@ -408,17 +401,17 @@
 			isa = PBXSourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
+				3B688D9919982DF50006B4AB /* MPLayout.m in Sources */,
 				3BB09EE1190736160080A5ED /* MPSumFunctionLayout.m in Sources */,
 				3B87E3561900856F00259938 /* MPExpressionView.m in Sources */,
-				3BFCFF491905AAF30001FE33 /* NSTextStorage+MPSetContents.m in Sources */,
 				3BB09EC91906FD830080A5ED /* MPSumFunction.m in Sources */,
 				3BB09EB21905DE500080A5ED /* MPExpressionStorage.m in Sources */,
 				3BF9977B18DE623E009CF6C4 /* main.m in Sources */,
-				3B87E3591900857C00259938 /* MPExpression.m in Sources */,
+				3BFAC38F1997B61300B3EF67 /* MPExpression.m in Sources */,
-				3BB09ED3190713FC0080A5ED /* MPFunctionLayout.m in Sources */,
+				3BFAC39C1997BC7600B3EF67 /* NSString+MPExpressionElement.m in Sources */,
-				3BB09ED0190713F00080A5ED /* MPExpressionLayout.m in Sources */,
+				3B528D10199417E10054DB5F /* MPExpressionLayout.m in Sources */,
-				3BBBA35D1903F8A700824E74 /* NSObject+MPStringTest.m in Sources */,
+				3B528D13199417E90054DB5F /* MPFunctionLayout.m in Sources */,
-				3BB09EDE190728220080A5ED /* NSIndexPath+MPReverseIndexPath.m in Sources */,
+				3BB09EDE190728220080A5ED /* NSIndexPath+MPAdditions.m in Sources */,
 				3B87E36019009D5F00259938 /* MPFunction.m in Sources */,
 				3B0F69A919028C6000817707 /* MPException.m in Sources */,
 				3BBBA35E1903FD3600824E74 /* MPRangePath.m in Sources */,
@@ -430,13 +423,14 @@
 			isa = PBXSourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
-				3BBBA358190327B700824E74 /* MPMutableExpressionTests.m in Sources */,
+				3B528D1619941F5B0054DB5F /* MPExpressionLayout.m in Sources */,
+				3B528D1819941F5B0054DB5F /* MPFunctionLayout.m in Sources */,
 				3B0F69AE1902AD2800817707 /* MPException.m in Sources */,
 				3B0F69AC1902A82C00817707 /* MPExpressionTests.m in Sources */,
 				3BBBA3951905704200824E74 /* MPRangeTests.m in Sources */,
 				3B0F69B01902AD2E00817707 /* MPFunction.m in Sources */,
+				3B53AD5F1997E0FB00C925C4 /* MPExpression.m in Sources */,
 				3BBBA35F1903FD3600824E74 /* MPRangePath.m in Sources */,
-				3B0F69AD1902AD2200817707 /* MPExpression.m in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};

MathPad/Base.lproj/MPDocument.xib

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8" standalone="no"?>
-<document type="com.apple.InterfaceBuilder3.Cocoa.XIB" version="3.0" toolsVersion="5056" systemVersion="13C1021" targetRuntime="MacOSX.Cocoa" propertyAccessControl="none" useAutolayout="YES">
+<document type="com.apple.InterfaceBuilder3.Cocoa.XIB" version="3.0" toolsVersion="5056" systemVersion="13E28" targetRuntime="MacOSX.Cocoa" propertyAccessControl="none" useAutolayout="YES">
     <dependencies>
         <plugIn identifier="com.apple.InterfaceBuilder.CocoaPlugin" version="5056"/>
     </dependencies>
@@ -7,7 +7,6 @@
         <customObject id="-2" userLabel="File's Owner" customClass="MPDocument">
             <connections>
                 <outlet property="resultExpressionView" destination="lcd-Ip-jjR" id="1NN-l5-30k"/>
-                <outlet property="termExpressionView" destination="fqc-IQ-ceJ" id="br9-0u-qYk"/>
                 <outlet property="window" destination="xOd-HO-29H" id="JIz-fz-R2o"/>
             </connections>
         </customObject>
@@ -17,22 +16,18 @@
             <windowStyleMask key="styleMask" titled="YES" closable="YES" miniaturizable="YES" resizable="YES"/>
             <windowPositionMask key="initialPositionMask" leftStrut="YES" rightStrut="YES" topStrut="YES" bottomStrut="YES"/>
             <rect key="contentRect" x="133" y="235" width="507" height="240"/>
-            <rect key="screenRect" x="0.0" y="0.0" width="1920" height="1080"/>
+            <rect key="screenRect" x="0.0" y="0.0" width="1920" height="1178"/>
             <value key="minSize" type="size" width="94" height="86"/>
             <view key="contentView" id="gIp-Ho-8D9">
                 <rect key="frame" x="0.0" y="0.0" width="507" height="240"/>
                 <autoresizingMask key="autoresizingMask"/>
                 <subviews>
-                    <customView translatesAutoresizingMaskIntoConstraints="NO" id="fqc-IQ-ceJ" customClass="MPExpressionView">
+                    <customView translatesAutoresizingMaskIntoConstraints="NO" id="lcd-Ip-jjR" customClass="MPExpressionView">
                         <rect key="frame" x="20" y="124" width="467" height="96"/>
                         <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMinY="YES"/>
                     </customView>
-                    <customView translatesAutoresizingMaskIntoConstraints="NO" id="lcd-Ip-jjR" customClass="MPExpressionView">
+                    <button verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="IMg-L0-qdu">
-                        <rect key="frame" x="20" y="20" width="467" height="96"/>
+                        <rect key="frame" x="209" y="13" width="88" height="32"/>
-                        <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMinY="YES"/>
-                    </customView>
-                    <button verticalHuggingPriority="750" fixedFrame="YES" translatesAutoresizingMaskIntoConstraints="NO" id="IMg-L0-qdu">
-                        <rect key="frame" x="405" y="-7" width="88" height="32"/>
                         <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMinY="YES"/>
                         <buttonCell key="cell" type="push" title="Change" bezelStyle="rounded" alignment="center" borderStyle="border" imageScaling="proportionallyDown" inset="2" id="Xxz-j2-fsI">
                             <behavior key="behavior" pushIn="YES" lightByBackground="YES" lightByGray="YES"/>
@@ -44,14 +39,12 @@
                     </button>
                 </subviews>
                 <constraints>
-                    <constraint firstItem="lcd-Ip-jjR" firstAttribute="top" secondItem="fqc-IQ-ceJ" secondAttribute="bottom" constant="8" symbolic="YES" id="GTC-QI-4wc"/>
+                    <constraint firstAttribute="trailing" secondItem="lcd-Ip-jjR" secondAttribute="trailing" constant="20" symbolic="YES" id="3tX-J3-Wte"/>
-                    <constraint firstItem="fqc-IQ-ceJ" firstAttribute="trailing" secondItem="lcd-Ip-jjR" secondAttribute="trailing" id="Pth-4c-GNR"/>
+                    <constraint firstItem="IMg-L0-qdu" firstAttribute="top" secondItem="lcd-Ip-jjR" secondAttribute="bottom" constant="83" id="62S-rU-IWO"/>
-                    <constraint firstAttribute="bottom" secondItem="lcd-Ip-jjR" secondAttribute="bottom" constant="20" symbolic="YES" id="VNk-bs-YOH"/>
+                    <constraint firstItem="lcd-Ip-jjR" firstAttribute="leading" secondItem="gIp-Ho-8D9" secondAttribute="leading" constant="20" symbolic="YES" id="XN3-k3-tOU"/>
-                    <constraint firstAttribute="trailing" secondItem="fqc-IQ-ceJ" secondAttribute="trailing" constant="20" symbolic="YES" id="fER-QH-XqN"/>
+                    <constraint firstItem="lcd-Ip-jjR" firstAttribute="top" secondItem="gIp-Ho-8D9" secondAttribute="top" constant="20" symbolic="YES" id="gqS-BG-xpS"/>
-                    <constraint firstItem="fqc-IQ-ceJ" firstAttribute="top" secondItem="gIp-Ho-8D9" secondAttribute="top" constant="20" symbolic="YES" id="kpD-MX-yOS"/>
+                    <constraint firstItem="IMg-L0-qdu" firstAttribute="centerX" secondItem="lcd-Ip-jjR" secondAttribute="centerX" id="sCM-Pj-4wd"/>
-                    <constraint firstItem="fqc-IQ-ceJ" firstAttribute="leading" secondItem="gIp-Ho-8D9" secondAttribute="leading" constant="20" symbolic="YES" id="to2-nb-CUV"/>
+                    <constraint firstAttribute="bottom" secondItem="IMg-L0-qdu" secondAttribute="bottom" constant="20" symbolic="YES" id="tNe-R6-QlG"/>
-                    <constraint firstItem="fqc-IQ-ceJ" firstAttribute="leading" secondItem="lcd-Ip-jjR" secondAttribute="leading" id="xJa-Qd-Ytg"/>
-                    <constraint firstItem="lcd-Ip-jjR" firstAttribute="top" secondItem="gIp-Ho-8D9" secondAttribute="top" constant="124" id="xrY-1x-QCm"/>
                 </constraints>
             </view>
             <connections>

MathPad/MPDocument.m

@@ -59,9 +59,9 @@
 }
 
 #pragma mark Actions
-
 - (IBAction)changeExpression:(id)sender {
-    [self.resultExpressionView.expressionStorage insertString:@"abc" atIndex:6];
+    [self.resultExpressionView.expressionStorage insertElement:@"abc" atLocation:6];
+    self.resultExpressionView.needsDisplay = YES;
 }
 
 @end

MathPad/MPException.h

@@ -9,7 +9,7 @@
 #ifndef MathPad_MPException_h
 #define MathPad_MPException_h
 
-extern NSString *MPIllegalSymbolException;
+extern NSString *MPIllegalElementException;
-extern NSString *MPIllegalSymbolExceptionSymbolKey;
+extern NSString *MPIllegalElementExceptionElementKey;
 
 #endif

MathPad/MPException.m

@@ -8,5 +8,5 @@
 
 #import "MPException.h"
 
-NSString *MPIllegalSymbolException = @"MPIllegalSymbolException";
+NSString *MPIllegalElementException = @"MPIllegalSymbolException";
-NSString *MPIllegalSymbolExceptionSymbolKey = @"MPIllegalSymbolExceptionSymbolKey";
+NSString *MPIllegalElementExceptionElementKey = @"MPIllegalSymbolExceptionSymbolKey";

MathPad/MPExpression.h

@@ -2,124 +2,82 @@
 //  MPExpression.h
 //  MathPad
 //
-//  Created by Kim Wittenburg on 17.04.14.
+//  Created by Kim Wittenburg on 10.08.14.
 //  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
 //
 
+@import Foundation;
+#import "NSString+MPExpressionElement.h"
+
 @class MPExpression, MPFunction, MPRangePath;
+@protocol MPExpressionElement;
 
-extern NSString *MPAdditionOperator;
+@interface MPExpression : NSObject <NSCopying, NSCoding>
-extern NSString *MPSubtractionOperator;
-extern NSString *MPMultiplicationOperator;
-extern NSString *MPDivisionOperator;
-
-@interface MPExpression : NSObject <NSCopying, NSMutableCopying, NSCoding>
 
 #pragma mark Creation Methods
-
+- (instancetype)init; // Convenience
-- (instancetype)initWithSymbols:(NSArray *)symbols;
+- (instancetype)initWithElement:(id<MPExpressionElement>)element; // Convenience
+- (instancetype)initWithElements:(NSArray *)elements; // Designated Initializer
 
 #pragma mark Working With the Expression Tree
+@property (nonatomic, weak) MPFunction *parent; // Set automatically, nil for root expression
 
-@property (nonatomic, weak) MPFunction *parent; // Documentation: Do not set, may be nil
+- (void)fixElements; // Called automatically, removes empty elements, joins subsequent strings
-
-- (void)fixSymbols;
 
 #pragma mark Primitive Methods
-
+- (NSUInteger)length;
-- (NSUInteger)numberOfSymbols;
+- (NSUInteger)numberOfElements;
-- (id)symbolAtIndex:(NSUInteger)index; // Either an NSString or a MPFunction (which can be mutated)
+- (id<MPExpressionElement>)elementAtIndex:(NSUInteger)index;
+- (NSArray *)elementsInRange:(NSRange)range;
+- (NSUInteger)indexOfElement:(id<MPExpressionElement>)element;
+- (void)replaceElementsInRange:(NSRange)range withElements:(NSArray *)elements;
+// TODO: - (NSUInteger)indexOfElementAtLocation:(NSUInteger)location;
 
 - (double)doubleValue; // Evaluates Expression
 
+#pragma mark Notifications
+// All notification methods should create a new rangePath with the receiver's index added to the beginning of the path and then ascend the message to it's parent
+// TODO: More notifications
+- (void)didChangeElementsInRangePath:(MPRangePath *)rangePath
+                   replacementLength:(NSUInteger)replacementLength;
+
+#pragma mark Basic NSObject Methods
+- (BOOL)isEqualToExpression:(MPExpression *)anExpression;
+
+- (NSString *)description;
+- (NSUInteger)hash;
+
 @end
 
-@interface MPExpression (MPExpressionExtensionMethods)
+@interface MPExpression (MPExpressionExtension)
-
-+ (NSArray *)operators;
-
-#pragma mark Creation Methods
-
-- (id)init;
-- (instancetype)initWithString:(NSString *)aString;
-- (instancetype)initWithFunction:(MPFunction *)aFunction;
-
-+ (instancetype)expression;
-+ (instancetype)expressionWithString:(NSString *)aString;
-+ (instancetype)expressionWithFunction:(MPFunction *)aFunction;
-+ (instancetype)expressionWithSymbols:(NSArray *)symbols;
 
 #pragma mark Working With the Expression Tree
-
+- (id)elementAtIndexPath:(NSIndexPath *)indexPath; // Returns an MPExpression or id<MPExpressionElement>
-- (NSUInteger)indexOfSymbol:(id)symbol;
+- (NSArray *)elementsInRangePath:(MPRangePath *)rangePath;
-- (id)symbolAtIndexPath:(NSIndexPath *)indexPath; // May also return MPExpression
 
 #pragma mark Working With Expressions
 
-- (NSUInteger)length;
+- (MPExpression *)subexpressionFromLocation:(NSUInteger)from;
-
+- (MPExpression *)subexpressionToLocation:(NSUInteger)to;
-- (MPExpression *)subexpressionFromIndex:(NSUInteger)from;
-- (MPExpression *)subexpressionToIndex:(NSUInteger)to;
 - (MPExpression *)subexpressionWithRange:(NSRange)range;
 
-- (BOOL)isEqualToExpression:(MPExpression *)anExpression;
 
-- (MPExpression *)expressionByAppendingString:(NSString *)aString;
+#pragma mark Mutating Expressions
-- (MPExpression *)expressionByAppendingFunction:(MPFunction *)aFunction;
+- (void)appendElement:(id<MPExpressionElement>)anElement;
-- (MPExpression *)expressionByAppendingExpression:(MPExpression *)anExpression;
+- (void)appendElements:(NSArray *)elements;
-- (MPExpression *)expressionByAppendingSymbols:(NSArray *)symbols;
+
+- (void)insertElement:(id<MPExpressionElement>)anElement atLocation:(NSUInteger)index;
+- (void)insertElements:(NSArray *)elements atLocation:(NSUInteger)index;
+
+- (void)deleteElementsInRange:(NSRange)range;
 
 #pragma mark Evaluating Expressions
-
 - (float)floatValue;
 - (int)intValue;
 - (NSInteger)integerValue;
 - (long long)longLongValue;
 
-#pragma mark Querying an Expression's Contents
+#pragma mark Querying Expressions
-
+- (NSArray *)elements;
-- (NSArray *)symbols;
-
-- (NSString *)description;
-
-- (NSUInteger)hash;
-
-@end
-
-@interface MPExpression (MPChangeNotificationExtension)
-
-- (void)symbolsChangedInRangePath:(MPRangePath *)rangePath replacementLength:(NSUInteger)length;
-
-@end
-
-@interface MPMutableExpression : MPExpression
-
-- (void)replaceSymbolsInRange:(NSRange)range
-                  withSymbols:(NSArray *)symbols;
-
-@end
-
-@interface MPMutableExpression (MPMutableExpressionExtensionMethods)
-
-- (void)insertString:(NSString *)aString
-             atIndex:(NSUInteger)loc;
-- (void)insertFunction:(MPFunction *)aFunction
-               atIndex:(NSUInteger)loc;
-- (void)insertExpression:(MPExpression *)anExpression
-                 atIndex:(NSUInteger)loc;
-- (void)insertSymbols:(NSArray *)symbols
-              atIndex:(NSUInteger)loc;
-
-- (void)deleteSymbolsInRange:(NSRange)range;
-
-- (void)appendString:(NSString *)aString;
-- (void)appendFunction:(MPFunction *)aFunction;
-- (void)appendExpression:(MPExpression *)anExpression;
-- (void)appendSymbols:(NSArray *)symbols;
-
-- (void)setString:(NSString *)aString;
-- (void)setFunction:(MPFunction *)aFunction;
-- (void)setExpression:(MPExpression *)anExpression;
-- (void)setSymbols:(NSArray *)symbols;
 
 @end

MathPad/MPExpression.m

@@ -2,88 +2,228 @@
 //  MPExpression.m
 //  MathPad
 //
-//  Created by Kim Wittenburg on 17.04.14.
+//  Created by Kim Wittenburg on 10.08.14.
 //  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
 //
 
 #import "MPExpression.h"
 #import "MPFunction.h"
-#import "MPException.h"
 #import "MPRangePath.h"
 
-#import "NSObject+MPStringTest.h"
+#import "NSIndexPath+MPAdditions.h"
-#import "NSIndexPath+MPReverseIndexPath.h"
+#import "MPException.h"
 
-NSString *MPAdditionOperator = @"+";
+@interface MPExpression ()
-NSString *MPSubtractionOperator = @"-";
+@property (readonly, nonatomic, strong) NSMutableArray *elements;
-NSString *MPMultiplicationOperator = @"*";
+@end
-NSString *MPDivisionOperator = @"/";
 
 @interface MPExpression (MPExpressionPrivate)
 
-- (NSInteger)lengthOfSymbol:(id)symbol;
+- (void)validateElements:(NSArray *)elements;
-- (void)validateSymbols:(NSArray *)symbols;
+- (BOOL)splitElementsAtLocation:(NSUInteger)location
-- (void)getSplitOffset:(out NSUInteger *)offset
+                 insertionIndex:(out NSUInteger *)insertionIndex;
-       inSymbolAtIndex:(out NSUInteger *)symbolIndex
+- (NSUInteger)calculateSplitOffsetForSplitLocation:(NSUInteger)location
-      forSplitLocation:(NSUInteger)loc;
+                                  inElementAtIndex:(out NSUInteger *)elementIndex;
+
+@end
+
+@implementation MPExpression (MPExpressionPrivate)
+
+- (void)validateElements:(NSArray *)elements
+{
+    for (id element in elements) {
+        if (![element conformsToProtocol:@protocol(MPExpressionElement)]) {
+            @throw [NSException exceptionWithName:MPIllegalElementException
+                                           reason:@"Elements must conform to the MPExpressionElement protocol."
+                                         userInfo:@{MPIllegalElementExceptionElementKey: element}];
+        }
+    }
+}
+
+- (BOOL)splitElementsAtLocation:(NSUInteger)location
+                 insertionIndex:(out NSUInteger *)insertionIndex
+{
+    if (location == 0) {
+        *insertionIndex = 0;
+        return NO;
+    }
+    NSUInteger splitElementIndex;
+    NSUInteger splitOffset = [self calculateSplitOffsetForSplitLocation:location
+                                                       inElementAtIndex:&splitElementIndex];
+    id<MPExpressionElement> splitElement = self.elements[splitElementIndex];
+    if (splitOffset == splitElement.length) {
+        splitOffset = 0;
+        splitElementIndex++;
+    }
+    if (splitOffset != 0) {
+        NSString *stringElement = (NSString *)splitElement;
+        NSString *leftPart = [stringElement substringToIndex:splitOffset];
+        NSString *rightPart = [stringElement substringFromIndex:splitOffset];
+        [self.elements replaceObjectsInRange:NSMakeRange(splitElementIndex, 1)
+                        withObjectsFromArray:@[leftPart, rightPart]];
+        ++splitElementIndex;
+    }
+    *insertionIndex = splitElementIndex;
+    return splitOffset != 0;
+}
+
+- (NSUInteger)calculateSplitOffsetForSplitLocation:(NSUInteger)location
+                                  inElementAtIndex:(out NSUInteger *)elementIndex
+{
+    NSUInteger length = 0;
+    NSUInteger index = 0;
+    NSUInteger elementLength = 0;
+    for (id<MPExpressionElement> element in self.elements) {
+        elementLength = element.length;
+        length += elementLength;
+        if (length >= location) {
+            break;
+        }
+        ++index;
+    }
+    *elementIndex = index;
+    return elementLength - (length - location);
+}
 
 @end
 
 @implementation MPExpression {
-    @package
+    NSUInteger _cachedLength;
-    __strong NSArray *_symbols;
+    NSRange editedRange;
-    NSInteger _length;
+    NSRange replacementRange;
 }
 
-#pragma mark Creation Methods
+@synthesize elements = _elements;
 
-- (instancetype)initWithSymbols:(NSArray *)symbols
+#pragma mark Creation Methods
+- (instancetype)init
+{
+    return [self initWithElements:@[]];
+}
+
+- (instancetype)initWithElement:(id<MPExpressionElement>)element
+{
+    return [self initWithElements:@[element]];
+}
+
+- (instancetype)initWithElements:(NSArray *)elements
 {
-    [self validateSymbols:symbols];
     self = [super init];
     if (self) {
-        _symbols = [[NSArray alloc] initWithArray:symbols
+        _cachedLength = 0;
+        _elements = [[NSMutableArray alloc] initWithCapacity:elements.count];
+        _elements = [[NSMutableArray alloc] initWithArray:elements
                                                 copyItems:YES];
-        [self fixSymbols];
+        [self fixElements];
     }
     return self;
 }
 
 #pragma mark Working With the Expression Tree
-
+- (void)fixElements
-- (void)fixSymbols
 {
-    NSMutableArray *mutableSymbols = [_symbols mutableCopy];
+    for (NSUInteger index = 0; index < self.elements.count; index++) {
-    for (NSInteger index = 0; index < mutableSymbols.count; index++) {
+        id<MPExpressionElement> next = index+1 < self.elements.count ? self.elements[index+1] :nil;
-        id next = index+1 < mutableSymbols.count ? mutableSymbols[index+1] : nil;
+        id<MPExpressionElement> current = self.elements[index];
-        id current = mutableSymbols[index];
         if ([current isString]) {
-            if ([current length] == 0) {
+            if (current.length == 0) {
-                [mutableSymbols removeObjectAtIndex:index];
+                [self.elements removeObjectAtIndex:index];
-                index--;
+                if (index < replacementRange.location) {
+                    replacementRange.location--;
+                } else if (index < NSMaxRange(replacementRange)-1) {
+                    replacementRange.length--;
+                } else if (index == NSMaxRange(replacementRange)) {
+                    editedRange.length++;
+                }
+                --index;
             } else if ([next isString]) {
                 NSString *new = [NSString stringWithFormat:@"%@%@", current, next];
-                [mutableSymbols replaceObjectAtIndex:index withObject:new];
+                [self.elements replaceObjectsInRange:NSMakeRange(index, 2)
-                [mutableSymbols removeObjectAtIndex:index+1];
+                                withObjectsFromArray:@[new]];
-                index--;
+                if (index < replacementRange.location) {
+                    replacementRange.location--;
+                } else if (index < NSMaxRange(replacementRange)-1) {
+                    replacementRange.length--;
+                } else if (index == NSMaxRange(replacementRange)-1) {
+                    editedRange.length++;
+                }
+                --index;
             }
         } else {
             [(MPFunction *)current setParent:self];
         }
     }
-    _symbols = [mutableSymbols copy];
 }
 
 #pragma mark Primitive Methods
-
+- (NSUInteger)length
-- (NSUInteger)numberOfSymbols
 {
-    return [_symbols count];
+    if (_cachedLength == 0) {
+        for (id<MPExpressionElement> element in self.elements) {
+            _cachedLength += element.length;
+        }
+    }
+    return _cachedLength;
 }
 
-- (id)symbolAtIndex:(NSUInteger)index
+- (NSUInteger)numberOfElements
 {
-    return _symbols[index];
+    return self.elements.count;
+}
+
+- (id<MPExpressionElement>)elementAtIndex:(NSUInteger)index
+{
+    return self.elements[index];
+}
+
+- (NSArray *)elementsInRange:(NSRange)range
+{
+    return [self.elements subarrayWithRange:range];
+}
+
+- (NSUInteger)indexOfElement:(id<MPExpressionElement>)element
+{
+    return [self.elements indexOfObject:element];
+}
+
+- (void)replaceElementsInRange:(NSRange)range
+                  withElements:(NSArray *)elements
+{
+    if (NSMaxRange(range) > self.length) {
+        @throw [NSException exceptionWithName:NSRangeException
+                                       reason:@"Range out of bounds of expression"
+                                     userInfo:nil];
+    }
+    [self validateElements:elements];
+    
+    // Locate the position, split the elements
+    NSUInteger startIndex;
+    BOOL didSplitStart = NO;
+    if ([self numberOfElements] == 0) {
+        startIndex = 0;
+    } else {
+        didSplitStart = [self splitElementsAtLocation:range.location
+                                       insertionIndex:&startIndex];
+    }
+    NSUInteger endIndex;
+    BOOL didSplitEnd = [self splitElementsAtLocation:NSMaxRange(range)
+                                      insertionIndex:&endIndex];
+    
+    // Perform the replacement
+    NSArray *newElements = [[NSArray alloc] initWithArray:elements
+                                                copyItems:YES];
+    [self.elements replaceObjectsInRange:NSMakeRange(startIndex, endIndex-startIndex)
+                    withObjectsFromArray:newElements];
+    
+    
+    _cachedLength = 0;
+    NSUInteger editingStart = startIndex - (didSplitStart?1:0);
+    NSUInteger editingLength = endIndex - startIndex + (didSplitStart?1:0) + (didSplitEnd?1:0);
+    editedRange = NSMakeRange(editingStart, editingLength);
+    replacementRange = NSMakeRange(startIndex, elements.count);
+    [self fixElements];
+    MPRangePath *changePath = [[MPRangePath alloc] initWithRange:editedRange];
+    [self didChangeElementsInRangePath:changePath replacementLength:replacementRange.length];
 }
 
 - (double)doubleValue
@@ -92,218 +232,18 @@ NSString *MPDivisionOperator = @"/";
     return 0;
 }
 
-#pragma mark - NSCopying
+#pragma mark Notifications
-
+- (void)didChangeElementsInRangePath:(MPRangePath *)rangePath
-- (id)copyWithZone:(NSZone *)zone
+                   replacementLength:(NSUInteger)replacementLength
 {
-    MPExpression *copy = [[MPExpression allocWithZone:zone] initWithSymbols:_symbols];
+    NSUInteger selfIndex = [self.parent indexOfChild:self];
-    return copy;
+    MPRangePath *newPath = rangePath.copy;
+    newPath.location = [newPath.location indexPathByPreceedingIndex:selfIndex];
+    [self.parent didChangeElementsInRangePath:newPath
+                            replacementLength:replacementLength];
 }
 
-#pragma mark - NSMutableCopying
+#pragma mark Basic NSObject Methods
-
-- (id)mutableCopyWithZone:(NSZone *)zone
-{
-    MPMutableExpression *mutableCopy = [[MPMutableExpression allocWithZone:zone] initWithSymbols:_symbols];
-    return mutableCopy;
-}
-
-#pragma mark - NSCoding
-
-- (id)initWithCoder:(NSCoder *)aDecoder
-{
-    // TODO: Test Coding
-    return [self initWithSymbols:[aDecoder decodeObject]];
-}
-
-- (void)encodeWithCoder:(NSCoder *)aCoder
-{
-    [aCoder encodeObject:_symbols];
-}
-
-@end
-
-@implementation MPExpression (MPExpressionPrivate)
-
-- (NSInteger)lengthOfSymbol:(id)symbol
-{
-    if ([symbol isString]) {
-        return [symbol length];
-    }
-    return 1;
-}
-
-- (void)validateSymbols:(NSArray *)symbols
-{
-    for (id symbol in symbols) {
-        if (!([symbol isString]
-              || [symbol isKindOfClass:[MPFunction class]])) {
-            @throw [NSException exceptionWithName:MPIllegalSymbolException
-                                           reason:@"Only NSString and MPFunction objects are valid symbols."
-                                         userInfo:@{MPIllegalSymbolExceptionSymbolKey: symbol}];
-        }
-    }
-}
-
-- (void)getSplitOffset:(out NSUInteger *)offset
-       inSymbolAtIndex:(out NSUInteger *)symbolIndex
-      forSplitLocation:(NSUInteger)loc
-{
-    NSUInteger length = 0;
-    NSUInteger index = 0;
-    NSUInteger symbolLength = 0;
-    for (id symbol in _symbols) {
-        symbolLength = [self lengthOfSymbol:symbol];
-        length += symbolLength;
-        if (length >= loc) {
-            break;
-        }
-        index++;
-    }
-    *offset = symbolLength - (length - loc);
-    *symbolIndex = index;
-}
-
-@end
-
-@implementation MPExpression (MPExpressionExtensionMethods)
-
-+ (NSArray *)operators
-{
-    return @[MPAdditionOperator, MPSubtractionOperator, MPMultiplicationOperator, MPDivisionOperator];
-}
-
-#pragma mark Creation Methods
-
-- (instancetype)init
-{
-    return [self initWithSymbols:@[]];
-}
-
-- (instancetype)initWithString:(NSString *)aString
-{
-    return [self initWithSymbols:@[aString]];
-}
-
-- (instancetype)initWithFunction:(MPFunction *)aFunction
-{
-    return [self initWithSymbols:@[aFunction]];
-}
-
-+ (instancetype)expression
-{
-    return [[self alloc] init];
-}
-
-+ (instancetype)expressionWithString:(NSString *)aString
-{
-    return [[self alloc] initWithString:aString];
-}
-
-+ (instancetype)expressionWithFunction:(MPFunction *)aFunction
-{
-    return [[self alloc] initWithFunction:aFunction];
-}
-
-+ (instancetype)expressionWithSymbols:(NSArray *)symbols
-{
-    return [[self alloc] initWithSymbols:symbols];
-}
-
-#pragma mark Working With the Expression Tree
-
-- (NSUInteger)indexOfSymbol:(id)symbol
-{
-    return [_symbols indexOfObject:symbol];
-}
-
-- (id)symbolAtIndexPath:(NSIndexPath *)indexPath
-{
-    if (indexPath.length == 0) {
-        return self;
-    }
-    id symbol = [self symbolAtIndex:[indexPath indexAtPosition:0]];
-    if (indexPath.length == 1) {
-        return symbol;
-    }
-    if ([symbol isKindOfClass:[MPFunction class]]) {
-        return [symbol symbolAtIndexPath:[indexPath indexPathByRemovingFirstIndex]];
-    }
-    return nil;
-}
-
-#pragma mark Working With Expressions
-
-- (NSUInteger)length
-{
-    if (_length == 0) {
-        for (id symbol in _symbols) {
-            _length += [self lengthOfSymbol:symbol];
-        }
-    }
-    return _length;
-}
-
-- (MPExpression *)subexpressionFromIndex:(NSUInteger)from
-{
-    return [self subexpressionWithRange:NSMakeRange(from, [self length] - from)];
-}
-
-- (MPExpression *)subexpressionToIndex:(NSUInteger)to
-{
-    return [self subexpressionWithRange:NSMakeRange(0, to)];
-}
-
-- (MPExpression *)subexpressionWithRange:(NSRange)range
-{
-    if (NSMaxRange(range) > self.length) {
-        @throw [NSException exceptionWithName:NSRangeException
-                                       reason:@"Range outside bounds of expression."
-                                     userInfo:nil];
-    }
-    if (range.location == self.length || NSMaxRange(range) == 0 || range.length == 0) {
-        // Speed this up
-        return [[MPExpression alloc] init];
-    }
-    NSUInteger startOffset;
-    NSUInteger startSymbolIndex;
-    [self getSplitOffset:&startOffset
-         inSymbolAtIndex:&startSymbolIndex
-        forSplitLocation:range.location];
-    id startSymbol = _symbols[startSymbolIndex];
-    if (startOffset == [self lengthOfSymbol:startSymbol]) {
-        startOffset = 0;
-        startSymbolIndex++;
-        startSymbol = _symbols[startSymbolIndex];
-    } else if ([startSymbol isString]) {
-        startSymbol = [startSymbol substringFromIndex:startOffset];
-    }
-    NSUInteger endOffset;
-    NSUInteger endSymbolIndex;
-    [self getSplitOffset:&endOffset
-         inSymbolAtIndex:&endSymbolIndex
-        forSplitLocation:NSMaxRange(range)];
-    id endSymbol = _symbols[endSymbolIndex];
-    if ([endSymbol isString]) {
-        endSymbol = [endSymbol substringToIndex:endOffset];
-        
-    }
-    
-    NSMutableArray *symbols = [[NSMutableArray alloc] initWithCapacity:endSymbolIndex-startSymbolIndex+1];
-    [symbols addObject:startSymbol];
-    if (endSymbolIndex > startSymbolIndex + 1) {
-        NSInteger restLength = endSymbolIndex - startSymbolIndex - 1;
-        [symbols addObjectsFromArray:[_symbols subarrayWithRange:NSMakeRange(startSymbolIndex+1, restLength)]];
-    }
-    if (endSymbolIndex > startSymbolIndex) {
-        [symbols addObject:endSymbol];
-    } else if (endSymbolIndex == startSymbolIndex && [startSymbol isString]) {
-        NSString *result = [_symbols[startSymbolIndex] substringWithRange:NSMakeRange(startOffset, endOffset-startOffset)];
-        [symbols replaceObjectAtIndex:0
-                           withObject:result];
-    }
-    return [[MPExpression alloc] initWithSymbols:symbols];
-}
 
 - (BOOL)isEqual:(id)object
 {
@@ -321,32 +261,141 @@ NSString *MPDivisionOperator = @"/";
 
 - (BOOL)isEqualToExpression:(MPExpression *)anExpression
 {
-    // TODO: Use ->_symbols or .symbols
+    return [self.elements isEqualToArray:anExpression.elements];
-    return [_symbols isEqualToArray:anExpression->_symbols];
 }
 
-- (MPExpression *)expressionByAppendingString:(NSString *)aString
+- (NSString *)description
 {
-    return [self expressionByAppendingSymbols:@[aString]];
+    NSMutableString *description = [[NSMutableString alloc] init];
+    NSUInteger index = 0;
+    for (id element in self.elements) {
+        if ([element isString]) {
+            NSMutableString *correctedSymbol = [[element stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] mutableCopy];
+            // Prefix operator
+            if (element != self.elements[0]) {
+                unichar prefix = [correctedSymbol characterAtIndex:0];
+                if ([[NSCharacterSet decimalDigitCharacterSet] characterIsMember:prefix]) {
+                    [correctedSymbol insertString:@"*"
+                                          atIndex:0];
+                }
+            }
+            // Suffix operator
+            if (element != [self.elements lastObject]) {
+                unichar suffix = [correctedSymbol characterAtIndex:correctedSymbol.length-1];
+                if ([[NSCharacterSet decimalDigitCharacterSet] characterIsMember:suffix]) {
+                    [correctedSymbol appendString:@"*"];
+                }
+            }
+            [description appendString:correctedSymbol];
+        } else if (index > 0 && [self.elements[index-1] isKindOfClass:[MPFunction class]]) {
+            [description appendFormat:@"*%@", [element description]];
+        } else {
+            [description appendString:[element description]];
+        }
+        index++;
+    }
+    return description;
 }
 
-- (MPExpression *)expressionByAppendingFunction:(MPFunction *)aFunction
+- (NSUInteger)hash
 {
-    return [self expressionByAppendingSymbols:@[aFunction]];
+    return [self.elements hash];
 }
 
-- (MPExpression *)expressionByAppendingExpression:(MPExpression *)anExpression
+#pragma mark - NSCopying
+- (id)copyWithZone:(NSZone *)zone
 {
-    return [self expressionByAppendingSymbols:anExpression.symbols];
+    MPExpression *copy = [[MPExpression allocWithZone:zone] initWithElements:self.elements];
+    return copy;
 }
 
-- (MPExpression *)expressionByAppendingSymbols:(NSArray *)symbols
+#pragma mark - NSCoding
+- (id)initWithCoder:(NSCoder *)aDecoder
 {
-    return [[MPExpression alloc] initWithSymbols:[_symbols arrayByAddingObjectsFromArray:symbols]];
+    // TODO: Test Coding
+    return [self initWithElements:[aDecoder decodeObject]];
+}
+
+- (void)encodeWithCoder:(NSCoder *)aCoder
+{
+    [aCoder encodeObject:self.elements];
+}
+
+@end
+
+@implementation MPExpression (MPExpressionExtension)
+
+#pragma mark Working With the Expression Tree
+- (id)elementAtIndexPath:(NSIndexPath *)indexPath
+{
+    if (indexPath.length == 0) {
+        return self;
+    }
+    id<MPExpressionElement> element = [self elementAtIndex:[indexPath indexAtPosition:0]];
+    if (indexPath.length == 1) {
+        return element;
+    }
+    if ([element isFunction]) {
+        return [(MPFunction *)element elementAtIndexPath:[indexPath indexPathByRemovingLastIndex]];
+    }
+    return nil;
+}
+
+- (NSArray *)elementsInRangePath:(MPRangePath *)rangePath
+{
+    MPExpression *targetExpression = [self elementAtIndexPath:[rangePath.location indexPathByRemovingLastIndex]];
+    return [targetExpression elementsInRange:rangePath.rangeAtLastIndex];
+}
+
+#pragma mark Working With Expressions
+- (MPExpression *)subexpressionFromLocation:(NSUInteger)from
+{
+    return [self subexpressionWithRange:NSMakeRange(from, self.length - from)];
+}
+
+- (MPExpression *)subexpressionToLocation:(NSUInteger)to
+{
+    return [self subexpressionWithRange:NSMakeRange(0, to)];
+}
+
+- (MPExpression *)subexpressionWithRange:(NSRange)range
+{
+    MPExpression *subexpression = [self copy];
+    NSRange preceedingRange = NSMakeRange(0, range.location);
+    NSUInteger firstOut = NSMaxRange(range);
+    NSRange exceedingRange = NSMakeRange(firstOut, self.length-firstOut);
+    [subexpression deleteElementsInRange:exceedingRange];
+    [subexpression deleteElementsInRange:preceedingRange];
+    return subexpression;
+}
+
+#pragma mark Mutating Expressions
+- (void)appendElement:(id<MPExpressionElement>)anElement
+{
+    [self appendElements:@[anElement]];
+}
+
+- (void)appendElements:(NSArray *)elements
+{
+    [self replaceElementsInRange:NSMakeRange(self.length, 0) withElements:elements];
+}
+
+- (void)insertElement:(id<MPExpressionElement>)anElement atLocation:(NSUInteger)index
+{
+    [self insertElements:@[anElement] atLocation:index];
+}
+
+- (void)insertElements:(NSArray *)elements atLocation:(NSUInteger)index
+{
+    [self replaceElementsInRange:NSMakeRange(index, 0) withElements:elements];
+}
+
+- (void)deleteElementsInRange:(NSRange)range
+{
+    [self replaceElementsInRange:range withElements:@[]];
 }
 
 #pragma mark Evaluating Expressions
-
 - (float)floatValue
 {
     return (float)[self doubleValue];
@@ -367,290 +416,4 @@ NSString *MPDivisionOperator = @"/";
     return (long long)[self doubleValue];
 }
 
-#pragma mark Querying an Expression's Contents
-
-- (NSArray *)symbols
-{
-    // _symbols is immutable so it is ok to just return it instead of making a copy
-    return _symbols;
-}
-
-- (NSString *)description
-{
-    NSMutableString *description = [[NSMutableString alloc] init];
-    NSUInteger index = 0;
-    for (id symbol in _symbols) {
-        if ([symbol isString]) {
-            NSMutableString *correctedSymbol = [[symbol stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] mutableCopy];
-            // Prefix operator
-            if (symbol != _symbols[0]) {
-                unichar prefix = [correctedSymbol characterAtIndex:0];
-                if ([[NSCharacterSet decimalDigitCharacterSet] characterIsMember:prefix]) {
-                    [correctedSymbol insertString:@"*"
-                                          atIndex:0];
-                }
-            }
-            // Suffix operator
-            if (symbol != [_symbols lastObject]) {
-                unichar suffix = [correctedSymbol characterAtIndex:correctedSymbol.length-1];
-                if ([[NSCharacterSet decimalDigitCharacterSet] characterIsMember:suffix]) {
-                    [correctedSymbol appendString:@"*"];
-                }
-            }
-            [description appendString:correctedSymbol];
-        } else if (index > 0 && [_symbols[index-1] isKindOfClass:[MPFunction class]]) {
-            [description appendFormat:@"*%@", [symbol description]];
-        } else {
-            [description appendString:[symbol description]];
-        }
-        index++;
-    }
-    return description;
-}
-
-- (NSUInteger)hash
-{
-    return [_symbols hash];
-}
-
-@end
-
-@implementation MPExpression (MPChangeNotificationExtension)
-
-- (void)symbolsChangedInRangePath:(MPRangePath *)rangePath replacementLength:(NSUInteger)length
-{
-    if (!self.parent) {
-        return;
-    }
-    NSUInteger selfIndex = [self.parent indexOfChild:self];
-    NSIndexPath *newLocation = [rangePath.location indexPathByPrecedingIndex:selfIndex];
-    MPRangePath *newPath = [[MPRangePath alloc] initWithLocation:newLocation length:rangePath.length];
-    [self.parent symbolsChangedInRangePath:newPath replacementLength:length];
-}
-
-@end
-
-@implementation MPMutableExpression {
-    NSRange editedRange;
-    NSRange replacementRange;
-}
-
-- (instancetype)initWithSymbols:(NSArray *)symbols
-{
-    [self validateSymbols:symbols];
-    self = [super initWithSymbols:nil];
-    if (self) {
-        editedRange = NSMakeRange(0, 0);
-        replacementRange = NSMakeRange(0, 0);
-        _symbols = [[NSMutableArray alloc] initWithArray:symbols
-                                               copyItems:YES];
-        [self fixSymbols];
-    }
-    return self;
-}
-
-- (void)fixSymbols
-{
-    NSMutableArray *mutableSymbols = (NSMutableArray *)_symbols;
-    for (NSInteger index = 0; index < mutableSymbols.count; index++) {
-        id next = index+1 < mutableSymbols.count ? mutableSymbols[index+1] : nil;
-        id current = mutableSymbols[index];
-        if ([current isString]) {
-            if ([current length] == 0) {
-                [mutableSymbols removeObjectAtIndex:index];
-                if (index < replacementRange.location) {
-                    replacementRange.location--;
-                } else if (index < NSMaxRange(replacementRange)-1) {
-                    replacementRange.length--;
-                } else if (index == NSMaxRange(replacementRange)) {
-                    editedRange.length++;
-                }
-                index--;
-            } else if ([next isString]) {
-                NSString *new = [NSString stringWithFormat:@"%@%@", current, next];
-                [mutableSymbols replaceObjectAtIndex:index withObject:new];
-                [mutableSymbols removeObjectAtIndex:index+1];
-                if (index < replacementRange.location) {
-                    replacementRange.location--;
-                } else if (index < NSMaxRange(replacementRange)-1) {
-                    replacementRange.length--;
-                } else if (index == NSMaxRange(replacementRange)-1) {
-                    editedRange.length++;
-                }
-                index--;
-            }
-        } else {
-            [(MPFunction *)current setParent:self];
-        }
-    }
-}
-
-- (NSArray *)symbols
-{
-    // Return an immutable array:
-    return [_symbols copy];
-}
-
-- (void)replaceSymbolsInRange:(NSRange)range
-                  withSymbols:(NSArray *)symbols
-{
-    if (NSMaxRange(range) > self.length) {
-        @throw [NSException exceptionWithName:NSRangeException
-                                       reason:@"Range out of bounds of expression."
-                                     userInfo:nil];
-    }
-    [self validateSymbols:symbols];
-    
-    // Locate the position, split the symbols
-    NSUInteger startIndex;
-    BOOL didSplitStart = NO;
-    if ([self numberOfSymbols] == 0) {
-        startIndex = 0;
-    } else {
-        [self splitSymbolsAtLocation:range.location
-                      insertionIndex:&startIndex
-                            didSplit:&didSplitStart];
-    }
-    
-    // Perform the deletion
-    NSUInteger endIndex;
-    BOOL didSplitEnd = NO;
-    [self splitSymbolsAtLocation:NSMaxRange(range)
-                  insertionIndex:&endIndex
-                        didSplit:&didSplitEnd];
-    if (range.length > 0) {
-        NSMutableIndexSet *indexes = [[NSMutableIndexSet alloc] init];
-        for (NSUInteger index = startIndex; index < endIndex; index++) {
-            [indexes addIndex:index];
-        }
-        // TODO: Replace with removeObjectsInRange:
-        [(NSMutableArray *)_symbols removeObjectsAtIndexes:indexes];
-    }
-    
-    // Perform the insertion
-    if (symbols.count > 0) {
-        NSArray *newSymbols = [[NSArray alloc] initWithArray:symbols copyItems:YES];
-        [(NSMutableArray *)_symbols replaceObjectsInRange:NSMakeRange(startIndex, 0)
-                                     withObjectsFromArray:newSymbols];
-    }
-    
-    // Invalidate length and revalidate structure
-    _length = 0;
-    NSUInteger editingStart = startIndex - (didSplitStart?1:0);
-    NSUInteger editingLength = endIndex - startIndex + (didSplitStart?1:0) + (didSplitEnd?1:0);
-    editedRange = NSMakeRange(editingStart, editingLength);
-    replacementRange = NSMakeRange(startIndex, symbols.count);
-    [self fixSymbols];
-    MPRangePath *changePath = [[MPRangePath alloc] initWithRange:editedRange];
-    [self symbolsChangedInRangePath:changePath replacementLength:replacementRange.length];
-}
-
-- (void)splitSymbolsAtLocation:(NSUInteger)loc
-                insertionIndex:(out NSUInteger *)insertionIndex
-                      didSplit:(out BOOL *)flag;
-{
-    NSUInteger splitSymbolIndex;
-    NSUInteger splitOffset;
-    [self getSplitOffset:&splitOffset
-         inSymbolAtIndex:&splitSymbolIndex
-        forSplitLocation:loc];
-    id splitSymbol = _symbols[splitSymbolIndex];
-    NSInteger splitSymbolLength = [self lengthOfSymbol:splitSymbol];
-    if (splitOffset == splitSymbolLength) {
-        splitOffset = 0;
-        splitSymbolIndex++;
-    }
-    if (splitOffset != 0) {
-        NSString *leftPart = [splitSymbol substringToIndex:splitOffset];
-        NSString *rightPart = [splitSymbol substringFromIndex:splitOffset];
-        [(NSMutableArray *)_symbols replaceObjectAtIndex:splitSymbolIndex
-                                              withObject:leftPart];
-        splitSymbolIndex++;
-        [(NSMutableArray *)_symbols insertObject:rightPart
-                                         atIndex:splitSymbolIndex];
-    }
-    *flag = splitOffset != 0;
-    *insertionIndex = splitSymbolIndex;
-}
-
-@end
-
-@implementation MPMutableExpression (MPMutableExpressionExtensionMethods)
-
-- (void)insertString:(NSString *)aString
-             atIndex:(NSUInteger)loc
-{
-    [self insertSymbols:@[aString]
-                atIndex:loc];
-}
-
-- (void)insertFunction:(MPFunction *)aFunction
-               atIndex:(NSUInteger)loc
-{
-    [self insertSymbols:@[aFunction]
-                atIndex:loc];
-}
-
-- (void)insertExpression:(MPExpression *)anExpression
-                 atIndex:(NSUInteger)loc
-{
-    [self insertSymbols:anExpression.symbols
-                atIndex:loc];
-}
-
-- (void)insertSymbols:(NSArray *)symbols
-              atIndex:(NSUInteger)loc
-{
-    [self replaceSymbolsInRange:NSMakeRange(loc, 0)
-                    withSymbols:symbols];
-}
-
-- (void)deleteSymbolsInRange:(NSRange)range
-{
-    [self replaceSymbolsInRange:range
-                    withSymbols:@[]];
-}
-
-- (void)appendString:(NSString *)aString
-{
-    [self appendSymbols:@[aString]];
-}
-
-- (void)appendFunction:(MPFunction *)aFunction
-{
-    [self appendSymbols:@[aFunction]];
-}
-
-- (void)appendExpression:(MPExpression *)anExpression
-{
-    [self appendSymbols:anExpression.symbols];
-}
-
-- (void)appendSymbols:(NSArray *)symbols
-{
-    [self replaceSymbolsInRange:NSMakeRange(self.length, 0)
-                    withSymbols:symbols];
-}
-
-- (void)setString:(NSString *)aString
-{
-    [self setSymbols:@[aString]];
-}
-
-- (void)setFunction:(MPFunction *)aFunction
-{
-    [self setSymbols:@[aFunction]];
-}
-
-- (void)setExpression:(MPExpression *)anExpression
-{
-    [self setSymbols:anExpression.symbols];
-}
-
-- (void)setSymbols:(NSArray *)symbols
-{
-    [self replaceSymbolsInRange:NSMakeRange(0, self.length)
-                    withSymbols:symbols];
-}
-
 @end

MathPad/MPExpressionElement.h

@@ -0,0 +1,24 @@
+//
+//  MPExpressionElement.h
+//  MathPad
+//
+//  Created by Kim Wittenburg on 10.08.14.
+//  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
+//
+
+@import Foundation;
+
+@protocol MPExpressionElement <NSObject, NSCoding>
+
+- (BOOL)isString;
+- (BOOL)isFunction;
+
+- (NSUInteger)length;
+
+- (double)doubleValue;
+- (float)floatValue;
+- (int)intValue;
+- (NSInteger)integerValue;
+- (long long)longLongValue;
+
+@end

MathPad/MPExpressionLayout.h

@@ -2,64 +2,18 @@
 //  MPExpressionLayout.h
 //  MathPad
 //
-//  Created by Kim Wittenburg on 22.04.14.
+//  Created by Kim Wittenburg on 07.08.14.
 //  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
 //
 
-#import <Foundation/Foundation.h>
+@import Cocoa;
+#import "MPLayout.h"
+#import "MPExpression.h"
 
-@class MPExpressionLayout, MPFunctionLayout, MPExpressionStorage, MPExpressionView, MPExpression;
+@interface MPExpressionLayout : MPLayout
 
-@interface MPExpressionLayout : NSObject {
+- (instancetype)initRootLayoutWithExpressionStorage:(MPExpressionStorage *)expressionStorage;
-    BOOL _valid;
-    NSSize _cachedSize;
-    NSMutableArray *_symbolCache;
-}
 
-#pragma mark Creation Methods
+@property (readonly, nonatomic, weak) MPExpression *expression; // Convenience
-
-// -init not supported
-- (id)initRootLayoutWithExpressionStorage:(MPExpressionStorage *)expressionStorage;
-- (id)initWithExpressionPath:(NSIndexPath *)expressionPath
-                      parent:(MPFunctionLayout *)parent;
-
-#pragma mark Properties
-
-@property (readonly, nonatomic, weak) MPFunctionLayout *parent;
-
-@property (readonly, nonatomic, weak) MPExpressionStorage *expressionStorage;
-@property (readonly, nonatomic, strong) NSIndexPath *expressionPath;
-
-@property (nonatomic, weak) MPExpressionView *expressionView;
-
-- (MPExpression *)expression; // Convenience
-- (NSLayoutManager *)layoutManager;
-- (NSTextContainer *)textContainer;
-- (NSTextStorage *)textStorage;
-
-#pragma mark Cache Methods
-
-- (void)invalidate;
-- (void)editedExpressionInRange:(NSRange)range
-              replacementLength:(NSUInteger)length;
-
-- (BOOL)hasCacheForSymbolAtIndex:(NSUInteger)index;
-- (MPFunctionLayout *)functionLayoutForFunctionAtIndex:(NSUInteger)index;
-- (NSSize)cachedSizeForSymbolAtIndex:(NSUInteger)index;
-- (void)cacheSize:(NSSize)size forSymbolAtIndex:(NSUInteger)index;
-
-#pragma mark Sizes Calculation Methods
-
-- (NSSize)sizeForAllSymbols;
-- (NSSize)sizeForSymbolAtIndex:(NSUInteger)index;
-- (NSSize)sizeForSymbolsInRange:(NSRange)range;
-
-#pragma mark Drawing Methods
-
-- (void)drawSymbolAtIndex:(NSUInteger)index
-                  atPoint:(NSPoint)point;
-- (void)drawSymbolsInRange:(NSRange)range
-                   atPoint:(NSPoint)point;
-- (void)drawAllSymbolsAtPoint:(NSPoint)point;
 
 @end

MathPad/MPExpressionLayout.m

@@ -2,45 +2,69 @@
 //  MPExpressionLayout.m
 //  MathPad
 //
-//  Created by Kim Wittenburg on 22.04.14.
+//  Created by Kim Wittenburg on 07.08.14.
 //  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
 //
 
 #import "MPExpressionLayout.h"
-#import "MPExpressionStorage.h"
 #import "MPFunctionLayout.h"
-#import "MPModel.h"
+
-#import "MPExpressionView.h"
+@interface MPExpressionLayout (MPPathGeneration)
+
+- (NSBezierPath *)bezierPathForChildAtIndex:(NSUInteger)index;
+- (NSBezierPath *)generateBezierPathForString:(NSString *)aString;
+
+
+@end
+
+@implementation MPExpressionLayout (MPPathGeneration)
+
+- (NSBezierPath *)bezierPathForChildAtIndex:(NSUInteger)index
+{
+    id symbol = [self.expression elementAtIndex:index];
+    if ([symbol isString]) {
+        return [self cachableObjectForIndex:index
+                                  generator:^id{
+            return [self generateBezierPathForString:symbol];
+        }];
+    } else {
+        MPLayout *layout = [self childLayoutAtIndex:index];
+        return layout.bezierPath;
+    }
+}
+
+- (NSBezierPath *)generateBezierPathForString:(NSString *)aString
+{
+    NSAttributedString *text = [[NSAttributedString alloc] initWithString:aString
+                                                               attributes:@{NSFontAttributeName: [NSFont fontWithName:@"Lucida Grande" size:18.0]}];
+    self.textStorage.attributedString = text;
+    NSRange glyphRange = [self.layoutManager glyphRangeForTextContainer:self.textContainer];
+    NSGlyph glyphs[glyphRange.length+1];
+    NSUInteger actualGlyphCount = [self.layoutManager getGlyphs:glyphs
+                                                          range:glyphRange];
+    NSBezierPath *path = [NSBezierPath bezierPath];
+    [path moveToPoint:NSZeroPoint];
+    [path appendBezierPathWithGlyphs:glyphs
+                               count:actualGlyphCount
+                              inFont:[NSFont fontWithName:@"Lucida Grande" size:18.0]];
+    return path;
+}
+
+@end
 
 @implementation MPExpressionLayout
 
 # pragma mark Creation Methods
-
 - (instancetype)initRootLayoutWithExpressionStorage:(MPExpressionStorage *)expressionStorage
 {
     self = [super init];
     if (self) {
-        _symbolCache = [[NSMutableArray alloc] init];
         _expressionStorage = expressionStorage;
-        _expressionPath = [[NSIndexPath alloc] init];
-    }
-    return self;
-}
-
-- (instancetype)initWithExpressionPath:(NSIndexPath *)expressionPath
-                                parent:(MPFunctionLayout *)parent
-{
-    self = [super init];
-    if (self) {
-        _symbolCache = [[NSMutableArray alloc] init];
-        _expressionPath = expressionPath;
-        _parent = parent;
     }
     return self;
 }
 
 #pragma mark Properties
-
 @synthesize expressionStorage = _expressionStorage;
 - (MPExpressionStorage *)expressionStorage
 {
@@ -52,172 +76,50 @@
 
 - (MPExpression *)expression
 {
-    return [self.expressionStorage symbolAtIndexPath:self.expressionPath];
+    return [self.expressionStorage elementAtIndexPath:self.path];
-}
-
-- (NSLayoutManager *)layoutManager
-{
-    return self.expressionStorage.layoutManager;
-}
-
-- (NSTextContainer *)textContainer
-{
-    return self.expressionStorage.textContainer;
-}
-
-- (NSTextStorage *)textStorage
-{
-    return self.expressionStorage.textStorage;
 }
 
 #pragma mark Cache Methods
-
+- (MPLayout *)childLayoutAtIndex:(NSUInteger)index
-// TODO: Return nil from caching with illegal index
-
-- (void)invalidate
 {
-    _valid = NO;
+    id cachedObject = [self cachableObjectForIndex:index generator:^id{
-    [self.parent invalidate];
+        NSIndexPath *indexPath = [self.path indexPathByAddingIndex:index];
-    [self.expressionView setNeedsDisplay:YES];
+        MPFunctionLayout *layout = [MPFunctionLayout functionLayoutForFunctionAtIndexPath:indexPath
-}
+                                                                                   parent:self];
-
+        return layout;
-- (void)editedExpressionInRange:(NSRange)range replacementLength:(NSUInteger)length
+    }];
-{
+    if ([cachedObject isKindOfClass:[NSBezierPath class]]) {
-    // TODO: New symbols may also be inserted in the middle or at the beginning
-    NSInteger changeInLength = length - range.length;
-    while (_symbolCache.count < (self.expression.numberOfSymbols + changeInLength)) {
-        [_symbolCache addObject:[NSNull null]];
-    }
-    NSMutableArray *newPlaceholders = [[NSMutableArray alloc] initWithCapacity:length];
-    while (newPlaceholders.count < length) {
-        [newPlaceholders addObject:[NSNull null]];
-    }
-    [_symbolCache replaceObjectsInRange:range withObjectsFromArray:newPlaceholders];
-    [self invalidate];
-}
-
-- (BOOL)hasCacheForSymbolAtIndex:(NSUInteger)index
-{
-    if (index >= _symbolCache.count) {
-        return NO;
-    }
-    return _symbolCache[index] != [NSNull null];
-}
-
-- (MPFunctionLayout *)functionLayoutForFunctionAtIndex:(NSUInteger)index;
-{
-    if ([self hasCacheForSymbolAtIndex:index]) {
-        id cacheObject = _symbolCache[index];
-        if ([cacheObject isKindOfClass:[NSValue class]]) {
         return nil;
     }
-        return cacheObject;
+    return cachedObject;
-    }
-     MPFunctionLayout *layout = [MPFunctionLayout functionLayoutForFunctionAtIndexPath:[self.expressionPath indexPathByAddingIndex:index] parent:self];
-    while (index >= _symbolCache.count) {
-        [_symbolCache addObject:[NSNull null]];
-    }
-    _symbolCache[index] = layout;
-    return layout;
 }
 
-- (NSSize)cachedSizeForSymbolAtIndex:(NSUInteger)index
+- (NSSize)sizeForChildAtIndex:(NSUInteger)index
 {
-    id cachedSymbol = _symbolCache[index];
+    id symbol = [self.expression elementAtIndex:index];
-    if ([cachedSymbol isKindOfClass:[NSValue class]]) {
-        return [cachedSymbol sizeValue];
-    }
-    return [(MPFunctionLayout *)cachedSymbol sizeOfFunction];
-}
-
-- (void)cacheSize:(NSSize)size forSymbolAtIndex:(NSUInteger)index
-{
-    while (index >= _symbolCache.count) {
-        [_symbolCache addObject:[NSNull null]];
-    }
-    _symbolCache[index] = [NSValue valueWithSize:size];
-}
-
-#pragma mark Size Calculation Methods
-
-- (NSSize)sizeForAllSymbols
-{
-    if (!_valid) {
-        _cachedSize = [self sizeForSymbolsInRange:NSMakeRange(0, self.expression.numberOfSymbols)];
-        _valid = YES;
-    }
-    return _cachedSize;
-}
-
-- (NSSize)sizeForSymbolsInRange:(NSRange)range
-{
-    NSSize size = NSMakeSize(0, 0);
-    for (NSUInteger index = range.location; index < NSMaxRange(range); index++) {
-        NSSize symbolSize = [self sizeForSymbolAtIndex:index];
-        size.width += symbolSize.width;
-        size.height = MAX(size.height, symbolSize.height);
-    }
-    return size;
-}
-
-- (NSSize)sizeForSymbolAtIndex:(NSUInteger)index
-{
-    if ([self hasCacheForSymbolAtIndex:index]) {
-        return [self cachedSizeForSymbolAtIndex:index];
-    }
-    id symbol = [self.expression symbolAtIndex:index];
     if ([symbol isString]) {
-        [self.textStorage setString:symbol];
+        return [self bezierPathForChildAtIndex:index].bounds.size;
-        NSRange glyphRange = [self.layoutManager glyphRangeForTextContainer:self.textContainer];
-        NSSize symbolSize = [self.layoutManager boundingRectForGlyphRange:glyphRange
-                                                          inTextContainer:self.textContainer].size;
-        [self cacheSize:symbolSize
-       forSymbolAtIndex:index];
-
-        return symbolSize;
     } else {
-        MPFunctionLayout *layout = [self functionLayoutForFunctionAtIndex:index];
+        return [self childLayoutAtIndex:index].size;
-        return [layout sizeOfFunction];
     }
 }
 
 #pragma mark Drawing Methods
-
+- (NSBezierPath *)generateBezierPath
-- (void)drawSymbolAtIndex:(NSUInteger)index
-                  atPoint:(NSPoint)point
 {
-    id symbol = [self.expression symbolAtIndex:index];
+    NSBezierPath *fullPath = [NSBezierPath bezierPath];
-    // point.x = point.y = 0;
+    [fullPath moveToPoint:NSZeroPoint];
-    NSLog(@"draw Symbol: %@ at Point: (x: %f, y: %f)", symbol, point.x, point.y);
+    NSUInteger x = 0;
-    if ([symbol isString]) {
+    for (NSInteger index = 0; index < self.expression.numberOfElements; ++index) {
-        [self.textStorage setString:symbol];
+        NSAffineTransform *transform = [NSAffineTransform transform];
-        NSRange glyphRange = [self.layoutManager glyphRangeForTextContainer:self.textContainer];
+        // TODO: Translate by the right amount
-        [self.layoutManager drawGlyphsForGlyphRange:glyphRange
+        [transform translateXBy:x yBy:0];
-                                            atPoint:point];
+        NSBezierPath *path = [self bezierPathForChildAtIndex:index].copy;
-    } else {
+        [path transformUsingAffineTransform:transform];
-        MPFunctionLayout *layout = [self functionLayoutForFunctionAtIndex:index];
+        [fullPath appendBezierPath:path];
-        NSLog(@"layout: %@, index: %ld", layout, index);
+        x += path.bounds.size.width;
-        [layout drawFunctionAtPoint:point];
     }
-}
+    return fullPath;
-
-- (void)drawSymbolsInRange:(NSRange)range
-                   atPoint:(NSPoint)point
-{
-    NSSize overallSize = [self sizeForSymbolsInRange:range];
-    CGFloat x = point.x;
-    for (NSUInteger index = range.location; index < NSMaxRange(range); index++) {
-        NSSize symbolSize = [self sizeForSymbolAtIndex:index];
-        CGFloat dy = (overallSize.height - symbolSize.height) / 2;
-        [self drawSymbolAtIndex:index
-                        atPoint:NSMakePoint(x, point.y + dy)];
-        x += symbolSize.width;
-    }
-}
-
-- (void)drawAllSymbolsAtPoint:(NSPoint)point
-{
-    [self drawSymbolsInRange:NSMakeRange(0, [self.expression numberOfSymbols]) atPoint:point];
 }
 
 @end

MathPad/MPExpressionStorage.h

@@ -10,9 +10,9 @@
 
 @class MPExpressionStorage, MPExpressionLayout;
 
-@interface MPExpressionStorage : MPMutableExpression
+@interface MPExpressionStorage : MPExpression
 
-@property (nonatomic, strong) MPExpressionLayout *expressionLayout;
+@property (nonatomic, strong) MPExpressionLayout *rootLayout;
 
 - (NSLayoutManager *)layoutManager;
 - (NSTextContainer *)textContainer;

MathPad/MPExpressionStorage.m

@@ -19,11 +19,11 @@
 
 @implementation MPExpressionStorage
 
-- (instancetype)initWithSymbols:(NSArray *)symbols
+- (instancetype)initWithElements:(NSArray *)elements
 {
-    self = [super initWithSymbols:symbols];
+    self = [super initWithElements:elements];
     if (self) {
-        _expressionLayout = [[MPExpressionLayout alloc] initRootLayoutWithExpressionStorage:self];
+        _rootLayout = [[MPExpressionLayout alloc] initRootLayoutWithExpressionStorage:self];
     }
     return self;
 }
@@ -59,24 +59,17 @@
     }
 }
 
-- (void)symbolsChangedInRangePath:(MPRangePath *)rangePath replacementLength:(NSUInteger)length
+- (void)didChangeElementsInRangePath:(MPRangePath *)rangePath
+                   replacementLength:(NSUInteger)replacementLength
 {
     if (rangePath.location.length == 0) {
         return;
     }
-    id current = self.expressionLayout;
+    MPLayout *current = self.rootLayout;
-    for (NSUInteger position = 1; position < rangePath.location.length-1; position++) {
+    for (NSUInteger index = 1; index < rangePath.location.length-1; index++) {
-        if ([current isKindOfClass:[MPExpressionLayout class]]) {
+        current = [current childLayoutAtIndex:index];
-            current = [(MPExpressionLayout *)current functionLayoutForFunctionAtIndex:position];
-        } else {
-            current = [(MPFunctionLayout *)current expressionLayoutForChildAtIndex:position];
-        }
-    }
-    if ([current isKindOfClass:[MPExpressionLayout class]]) {
-        [(MPExpressionLayout *)current editedExpressionInRange:rangePath.rangeAtLastIndex replacementLength:length];
-    } else {
-        [(MPFunctionLayout *)current editedChildAtIndex:[rangePath.location indexAtPosition:rangePath.location.length-1]];
     }
+    [current clearCacheInRange:rangePath.rangeAtLastIndex replacementLength:replacementLength];
 }
 
 @end

MathPad/MPExpressionView.h

@@ -21,7 +21,6 @@
 #pragma mark Properties
 
 @property (readonly, nonatomic, strong) MPExpressionStorage *expressionStorage;
-- (MPExpressionLayout *)expressionLayout; // Convenience Method
 
 @property (nonatomic, getter = isEditable) BOOL editable;
 @property (nonatomic, strong) MPRangePath *selection;

MathPad/MPExpressionView.m

@@ -7,13 +7,15 @@
 //
 
 #import "MPExpressionView.h"
-#import "MPExpressionLayout.h"
 #import "MPExpressionStorage.h"
-
+#import "MPExpressionLayout.h"
-#import "NSObject+MPStringTest.h"
 
 #import "MPSumFunction.h"
 
+@interface MPExpressionView (MPCursor)
+@property (nonatomic, strong) NSTimer *cursorTimer;
+@end
+
 @implementation MPExpressionView
 
 #pragma mark Creation Methods
@@ -47,23 +49,20 @@
 
 - (void)initializeObjects
 {
-    MPExpressionStorage *expressionStorage = [[MPExpressionStorage alloc] initWithSymbols:@[@"12 345", [[MPSumFunction alloc] init], [[MPSumFunction alloc] init]]];
+    MPExpressionStorage *expressionStorage = [[MPExpressionStorage alloc] initWithElements:@[@"12345", [[MPSumFunction alloc] init], [[MPSumFunction alloc] init]]];
     _expressionStorage = expressionStorage;
-    [self.expressionLayout setExpressionView:self];
 }
 
 #pragma mark Properties
 
-- (void)setExpressionStorage:(MPExpressionStorage *)expressionStorage
+- (BOOL)isFlipped
 {
-    [_expressionStorage.expressionLayout setExpressionView:nil];
+    return NO;
-    _expressionStorage = expressionStorage;
-    [_expressionStorage.expressionLayout setExpressionView:self];
 }
 
-- (MPExpressionLayout *)expressionLayout
+- (void)setExpressionStorage:(MPExpressionStorage *)expressionStorage
 {
-    return self.expressionStorage.expressionLayout;
+    _expressionStorage = expressionStorage;
 }
 
 #pragma mark Drawing Methods
@@ -74,11 +73,10 @@
     [[NSColor whiteColor] set];
     NSRectFill(self.bounds);
     [[NSColor blackColor] set];
-    NSSize expressionSize = [self.expressionLayout sizeForAllSymbols];
+    NSSize expressionSize = [self.expressionStorage.rootLayout size];
     CGFloat y = (self.bounds.size.height - expressionSize.height) / 2;
-    NSLog(@"%f", self.bounds.origin.y);
     NSPoint point = NSMakePoint(self.bounds.origin.x, self.bounds.origin.y + y);
-    [self.expressionLayout drawAllSymbolsAtPoint:point];
+    [self.expressionStorage.rootLayout drawAtPoint:point];
 }
 
 @end

MathPad/MPFunction.h

@@ -6,58 +6,47 @@
 //  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
 //
 
+@import Foundation;
+#import "MPExpressionElement.h"
+
 @class MPFunction, MPExpression, MPRangePath;
 
-@interface MPFunction : NSObject <NSCopying, NSCoding>
+@interface MPFunction : NSObject <NSCoding, NSCopying, MPExpressionElement>
 
 #pragma mark Creation Methods
 
 - (instancetype)init;
 
-#pragma mark Working With the Expression Tree
+#pragma mark Properties
+// Subclasses should define accessor properties for all sub expressions, which, in the setter, should send didChangeElementAtRangePath:replacementLength: to self with a replacement length of 1.
 
+#pragma mark Working With the Expression Tree
 @property (nonatomic, weak) MPExpression *parent; // Documentation: Do not set
 
-- (NSUInteger)numberOfChildren;
+- (NSUInteger)numberOfChildren; // Override
-- (MPExpression *)childAtIndex:(NSUInteger)index;
+- (MPExpression *)childAtIndex:(NSUInteger)index; // Override
 - (void)setChild:(MPExpression *)child
-         atIndex:(NSUInteger)index;
+         atIndex:(NSUInteger)index; // Override
-
-#pragma mark Evaluating Functions
-
-- (double)doubleValue;
-
-#pragma mark Working With Functions
-
-- (BOOL)isEqualToFunction:(MPFunction *)aFunction;
-
-@end
-
-@interface MPFunction (MPFunctionExtensionMethods)
-
-#pragma mark Working With the Expression Tree
 
 // May be overridden for performance improvements
-- (NSArray *)children;
+- (NSArray *)children; // Indexes must equal the ones from the native methods
 - (NSUInteger)indexOfChild:(MPExpression *)child;
 
-- (id)symbolAtIndexPath:(NSIndexPath *)indexPath;
+- (id)elementAtIndexPath:(NSIndexPath *)indexPath;
 
 #pragma mark Evaluating Functions
+- (double)doubleValue; // Override
 
-- (float)floatValue;
+#pragma mark Messages
-- (int)intValue;
+- (void)didChangeElementsInRangePath:(MPRangePath *)rangePath
-- (NSInteger)integerValue;
+                   replacementLength:(NSUInteger)replacementLength;
-- (long long)longLongValue;
+- (void)didChangeChild:(MPExpression *)child;
+- (void)didChangeChildAtIndex:(NSUInteger)index;
 
-- (NSString *)description;
+#pragma mark Working With Functions
+- (BOOL)isEqualToFunction:(MPFunction *)aFunction; // Override
 
-- (NSUInteger)hash;
+- (NSString *)description; // Should be overridden
-
+- (NSUInteger)hash;// Override
-@end
-
-@interface MPFunction (MPDisplayExtension)
-
-- (void)symbolsChangedInRangePath:(MPRangePath *)rangePath replacementLength:(NSUInteger)length;
 
 @end

MathPad/MPFunction.m

@@ -10,12 +10,11 @@
 #import "MPExpression.h"
 #import "MPRangePath.h"
 
-#import "NSIndexPath+MPReverseIndexPath.h"
+#import "NSIndexPath+MPAdditions.h"
 
 @implementation MPFunction
 
 #pragma mark Creation Methods
-
 - (instancetype)init
 {
     self = [super init];
@@ -25,7 +24,6 @@
 }
 
 #pragma mark Working With the Expression Tree
-
 - (NSUInteger)numberOfChildren
 {
     return 0;
@@ -38,63 +36,10 @@
 
 - (void)setChild:(MPExpression *)child
          atIndex:(NSUInteger)index
-{}
-
-#pragma mark Evaluating Functions
-
-- (double)doubleValue
 {
-    return 0;
+    [self didChangeChildAtIndex:index];
 }
 
-#pragma mark Working With Functions
-
-- (BOOL)isEqual:(id)object
-{
-    if (self == object) {
-        return YES;
-    }
-    if (object == nil) {
-        return NO;
-    }
-    if (![object isKindOfClass:[MPFunction class]]) {
-        return NO;
-    }
-    return [self isEqualToFunction:(MPFunction *)object];
-}
-
-- (BOOL)isEqualToFunction:(MPFunction *)aFunction
-{
-    return [aFunction isMemberOfClass:[MPFunction class]] && [self isMemberOfClass:[MPFunction class]];
-}
-
-#pragma mark - NSCopying
-
-- (id)copyWithZone:(NSZone *)zone
-{
-    return [[MPFunction allocWithZone:zone] init];
-}
-
-#pragma mark - NSCoding
-
-- (id)initWithCoder:(NSCoder *)aDecoder
-{
-    self = [super init];
-    if (self) {
-        
-    }
-    return self;
-}
-
-- (void)encodeWithCoder:(NSCoder *)aCoder
-{}
-
-@end
-
-@implementation MPFunction (MPFunctionExtensionMethods)
-
-#pragma mark Working With the Expression Tree
-
 - (NSArray *)children
 {
     NSUInteger childCount = [self numberOfChildren];
@@ -116,16 +61,115 @@
     return NSNotFound;
 }
 
-- (id)symbolAtIndexPath:(NSIndexPath *)indexPath
+- (id)elementAtIndexPath:(NSIndexPath *)indexPath
 {
     if (indexPath.length == 0) {
         return self;
     }
     MPExpression *child = [self childAtIndex:[indexPath indexAtPosition:0]];
-    return [child symbolAtIndexPath:[indexPath indexPathByRemovingFirstIndex]];
+    return [child elementAtIndexPath:[indexPath indexPathByRemovingFirstIndex]];
 }
 
 #pragma mark Evaluating Functions
+- (double)doubleValue
+{
+    return 0;
+}
+
+#pragma mark Notifications
+- (void)didChangeElementsInRangePath:(MPRangePath *)rangePath
+                   replacementLength:(NSUInteger)replacementLength
+{
+    NSUInteger selfIndex = [self.parent indexOfElement:self];
+    MPRangePath *newPath = rangePath.copy;
+    newPath.location = [newPath.location indexPathByPreceedingIndex:selfIndex];
+    [self.parent didChangeElementsInRangePath:newPath
+                            replacementLength:replacementLength];
+}
+
+- (void)didChangeChild:(MPExpression *)child
+{
+    [self didChangeChildAtIndex:[self indexOfChild:child]];
+}
+
+- (void)didChangeChildAtIndex:(NSUInteger)index
+{
+    MPRangePath *path = [[MPRangePath alloc] initWithRange:NSMakeRange(index, 1)];
+    [self didChangeElementsInRangePath:path
+                     replacementLength:1];
+}
+
+#pragma mark Working With Functions
+- (BOOL)isEqual:(id)object
+{
+    if (self == object) {
+        return YES;
+    }
+    if (object == nil) {
+        return NO;
+    }
+    if (![object isKindOfClass:[MPFunction class]]) {
+        return NO;
+    }
+    return [self isEqualToFunction:(MPFunction *)object];
+}
+
+- (BOOL)isEqualToFunction:(MPFunction *)aFunction
+{
+    return [aFunction isMemberOfClass:[MPFunction class]] && [self isMemberOfClass:[MPFunction class]];
+}
+
+- (NSString *)description
+{
+    return @"[]";
+}
+
+- (NSUInteger)hash
+{
+    return 0;
+}
+
+#pragma mark - NSCopying
+- (id)copyWithZone:(NSZone *)zone
+{
+    return [[MPFunction allocWithZone:zone] init];
+}
+
+#pragma mark - NSCoding
+- (id)initWithCoder:(NSCoder *)aDecoder
+{
+    self = [super init];
+    if (self) {
+        NSArray *children = [aDecoder decodeObject];
+        NSInteger index = 0;
+        for (MPExpression *child in children) {
+            [self setChild:child atIndex:index];
+            ++index;
+        }
+    }
+    return self;
+}
+
+- (void)encodeWithCoder:(NSCoder *)aCoder
+{
+    [aCoder encodeObject:self.children];
+}
+
+#pragma mark - MPExpressionElement
+- (BOOL)isString
+{
+    return NO;
+}
+
+- (BOOL)isFunction
+{
+    return YES;
+}
+
+- (NSUInteger)length
+{
+    return 1;
+}
 
 - (float)floatValue
 {
@@ -147,26 +191,4 @@
     return (long long)[self doubleValue];
 }
 
-- (NSString *)description
-{
-    return @"[]";
-}
-
-- (NSUInteger)hash
-{
-    return 0;
-}
-
-@end
-
-@implementation MPFunction (MPDisplayExtension)
-
-- (void)symbolsChangedInRangePath:(MPRangePath *)rangePath replacementLength:(NSUInteger)length
-{
-    NSUInteger index = [self.parent indexOfSymbol:self];
-    NSIndexPath *newLocation = [rangePath.location indexPathByPrecedingIndex:index];
-    MPRangePath *newRangePath = [[MPRangePath alloc] initWithLocation:newLocation length:rangePath.length];
-    [self.parent symbolsChangedInRangePath:newRangePath replacementLength:length];
-}
-
 @end

MathPad/MPFunctionLayout.h

@@ -2,56 +2,30 @@
 //  MPFunctionLayout.h
 //  MathPad
 //
-//  Created by Kim Wittenburg on 22.04.14.
+//  Created by Kim Wittenburg on 07.08.14.
 //  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
 //
 
-#import <Foundation/Foundation.h>
+@import Cocoa;
+#import "MPLayout.h"
 
-@class MPFunctionLayout, MPExpressionLayout, MPExpressionStorage, MPFunction;
+@interface MPFunctionLayout : MPLayout
 
-@interface MPFunctionLayout : NSObject {
++ (MPFunctionLayout *)functionLayoutForFunctionAtIndexPath:(NSIndexPath *)path
-    @protected
-    BOOL _valid;
-    NSSize _cachedSize;
-    NSMutableArray *_childCache;
-}
-
-#pragma mark Creation Methods
-
-+ (instancetype)functionLayoutForFunctionAtIndexPath:(NSIndexPath *)functionPath
                                                     parent:(MPExpressionLayout *)parent;
 
-- (id)initWithFunctionPath:(NSIndexPath *)functionPath
+@property (readonly, nonatomic, weak) MPFunction *function; // Convenience
-                    parent:(MPExpressionLayout *)parent;
+
-
+@end
-#pragma mark Properties
+
-
+@interface MPFunctionLayout (MPSubclassOverride)
-@property (readonly, nonatomic, weak) MPExpressionLayout *parent;
+
-
+// Should also implement accessor method for special function type:
-@property (readonly, nonatomic, strong) NSIndexPath *functionPath;
+// - (MPCustomFunction *)customFunction
-
+// {
-- (MPExpressionStorage *)expressionStorage;
+//      return (MPCustomFunction *)self.function;
-- (MPFunction *)function; // Convenience
+// }
-- (NSLayoutManager *)layoutManager;
+
-- (NSTextContainer *)textContainer;
+- (NSBezierPath *)generateBezierPath;
-- (NSTextStorage *)textStorage;
-
-#pragma mark Cache Methods
-
-- (void)invalidate;
-- (void)editedChildAtIndex:(NSUInteger)index;
-
-- (BOOL)hasCacheForChildAtIndex:(NSUInteger)index;
-- (MPExpressionLayout *)expressionLayoutForChildAtIndex:(NSUInteger)index;
-
-#pragma mark Size Calculation Methods
-
-- (NSSize)sizeOfFunction;
-- (NSSize)calculateSize;
-
-#pragma mark Drawing Methods
-
-- (void)drawFunctionAtPoint:(NSPoint)point;
 
 @end

MathPad/MPFunctionLayout.m

@@ -2,14 +2,13 @@
 //  MPFunctionLayout.m
 //  MathPad
 //
-//  Created by Kim Wittenburg on 22.04.14.
+//  Created by Kim Wittenburg on 07.08.14.
 //  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
 //
 
 #import "MPFunctionLayout.h"
-#import "MPExpressionLayout.h"
-#import "MPExpressionStorage.h"
 #import "MPFunction.h"
+#import "MPExpressionLayout.h"
 
 #import "MPSumFunction.h"
 #import "MPSumFunctionLayout.h"
@@ -17,114 +16,43 @@
 @implementation MPFunctionLayout
 
 #pragma mark Creation Methods
-
++ (MPFunctionLayout *)functionLayoutForFunctionAtIndexPath:(NSIndexPath *)path
-+ (instancetype)functionLayoutForFunctionAtIndexPath:(NSIndexPath *)functionPath
                                                     parent:(MPExpressionLayout *)parent
 {
-    MPFunction *function = [parent.expressionStorage symbolAtIndexPath:functionPath];
+    MPFunction *function = [parent.expressionStorage elementAtIndexPath:path];
     Class class = [function class];
     if (class == [MPSumFunction class]) {
-        return [[MPSumFunctionLayout alloc] initWithFunctionPath:functionPath parent:parent];
+        return [[MPSumFunctionLayout alloc] initWithPath:path parent:parent];
     }
-    return nil;
+    return [[self alloc] initWithPath:path parent:parent];
-}
-
-- (id)initWithFunctionPath:(NSIndexPath *)functionPath
-                    parent:(MPExpressionLayout *)parent
-{
-    self = [super init];
-    if (self) {
-        _functionPath = functionPath;
-        _parent = parent;
-        _childCache = [[NSMutableArray alloc] init];
-    }
-    return self;
 }
 
 #pragma mark Properties
-
-- (MPExpressionStorage *)expressionStorage
-{
-    return self.parent.expressionStorage;
-}
-
 - (MPFunction *)function
 {
-    return [self.expressionStorage symbolAtIndexPath:self.functionPath];
+    return [self.expressionStorage elementAtIndexPath:self.path];
-}
-
-- (NSLayoutManager *)layoutManager
-{
-    return self.expressionStorage.layoutManager;
-}
-
-- (NSTextContainer *)textContainer
-{
-    return self.expressionStorage.textContainer;
-}
-
-- (NSTextStorage *)textStorage
-{
-    return self.expressionStorage.textStorage;
 }
 
 #pragma mark Cache Methods
-
+- (MPLayout *)childLayoutAtIndex:(NSUInteger)index
-- (void)invalidate
 {
-    _valid = NO;
+    return [self cachableObjectForIndex:index generator:^id{
-    [self.parent invalidate];
+        NSIndexPath *childPath = [self.path indexPathByAddingIndex:index];
+        MPExpressionLayout *layout = [[MPExpressionLayout alloc] initWithPath:childPath
+                                                                       parent:self];
+        return layout;
+    }];
 }
 
-- (void)editedChildAtIndex:(NSUInteger)index
+- (NSSize)sizeForChildAtIndex:(NSUInteger)index
 {
-    if ([self hasCacheForChildAtIndex:index]) {
+    MPLayout *childLayout = [self childLayoutAtIndex:index];
-        _childCache[index] = [NSNull null];
+    return [childLayout size];
-    }
-    [self invalidate];
 }
 
-- (BOOL)hasCacheForChildAtIndex:(NSUInteger)index
+- (NSBezierPath *)generateBezierPath
-{
-    if (index >= _childCache.count) {
-        return NO;
-    }
-    return _childCache[index] != [NSNull null];
-}
-
-- (MPExpressionLayout *)expressionLayoutForChildAtIndex:(NSUInteger)index
-{
-    if ([self hasCacheForChildAtIndex:index]) {
-        return _childCache[index];
-    }
-    while (index >= _childCache.count) {
-        [_childCache addObject:[NSNull null]];
-    }
-    MPExpressionLayout *expressionLayout = [[MPExpressionLayout alloc] initWithExpressionPath:[self.functionPath indexPathByAddingIndex:index] parent:self];
-    _childCache[index] = expressionLayout;
-    return expressionLayout;
-}
-
-#pragma mark Size Calculation Methods
-
-- (NSSize)sizeOfFunction
-{
-    if (!_valid) {
-        _cachedSize = [self calculateSize];
-        _valid = YES;
-    }
-    return _cachedSize;
-}
-
-- (NSSize)calculateSize
-{
-    return NSMakeSize(0, 0);
-}
-
-#pragma mark Drawing Methods
-
-- (void)drawFunctionAtPoint:(NSPoint)point
 {
+    return [NSBezierPath bezierPath];
 }
 
 @end

MathPad/MPLayout.h

@@ -0,0 +1,56 @@
+//
+//  MPDrawable.h
+//  MathPad
+//
+//  Created by Kim Wittenburg on 07.08.14.
+//  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
+//
+
+@import Cocoa;
+#import "MPExpressionStorage.h"
+
+#define MPNull [NSNull null]
+
+@interface MPLayout : NSObject
+
+#pragma mark Creation Methods
+- (instancetype)init;
+- (instancetype)initWithPath:(NSIndexPath *)path
+                      parent:(MPLayout *)parent;
+
+#pragma mark Text System Objects
+@property (readonly, nonatomic, weak) MPExpressionStorage *expressionStorage;
+@property (readonly, nonatomic, weak) NSLayoutManager *layoutManager;
+@property (readonly, nonatomic, weak) NSTextContainer *textContainer;
+@property (readonly, nonatomic, weak) NSTextStorage *textStorage;
+
+#pragma mark Cache Tree
+@property (readonly, nonatomic, weak) MPLayout *parent;
+@property (readonly, nonatomic, strong) NSIndexPath *path;
+
+#pragma mark Cache Methods
+// Querying Caches
+- (id)cachableObjectForIndex:(NSUInteger)index
+                   generator:(id(^)())generator;
+
+// Clearing Caches
+- (void)clearCacheInRange:(NSRange)range
+        replacementLength:(NSUInteger)replacementLength;
+- (void)invalidate;
+
+#pragma mark Calculation and Drawing Methods
+// @property (nonatomic) BOOL usesSmallSize;
+- (NSSize)size;
+
+- (NSBezierPath *)bezierPath;
+- (NSBezierPath *)bezierPathAtOrigin:(NSPoint)point;
+
+- (void)drawAtPoint:(NSPoint)point;
+
+@end
+
+@interface MPLayout (MPSubclassImplement)
+- (MPLayout *)childLayoutAtIndex:(NSUInteger)index; // To be implemented
+- (NSSize)sizeForChildAtIndex:(NSUInteger)index; // To be implemented
+- (NSBezierPath *)generateBezierPath; // To be implemented
+@end

MathPad/MPLayout.m

@@ -0,0 +1,159 @@
+//
+//  MPLayout.m
+//  MathPad
+//
+//  Created by Kim Wittenburg on 11.08.14.
+//  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
+//
+
+#import "MPLayout.h"
+
+@interface MPLayout ()
+
+// Querying Caches
+- (BOOL)hasCacheForElementAtIndex:(NSUInteger)index;
+
+// Storing Caches
+- (void)cacheObject:(id)anObject
+  forElementAtIndex:(NSUInteger)index;
+- (void)ensureCacheSizeForIndex:(NSUInteger)index;
+
+@end
+
+@implementation MPLayout {
+    NSMutableArray *_cache;
+    NSBezierPath *_cachedPath;
+}
+
+#pragma mark Creation Methods
+- (id)init
+{
+    self = [super init];
+    if (self) {
+        _cache = [[NSMutableArray alloc] init];
+        _cachedPath = nil;
+        _path = [[NSIndexPath alloc] init];
+    }
+    return self;
+}
+
+- (id)initWithPath:(NSIndexPath *)path
+            parent:(MPLayout *)parent
+{
+    self = [self init];
+    if (self) {
+        _path = path;
+        _parent = parent;
+    }
+    return self;
+}
+
+#pragma Text System Objects
+- (MPExpressionStorage *)expressionStorage
+{
+    return self.parent.expressionStorage;
+}
+
+- (NSLayoutManager *)layoutManager
+{
+    return self.expressionStorage.layoutManager;
+}
+
+- (NSTextContainer *)textContainer
+{
+    return self.expressionStorage.textContainer;
+}
+
+- (NSTextStorage *)textStorage
+{
+    return self.expressionStorage.textStorage;
+}
+
+#pragma mark Cache Tree
+// Querying Caches
+- (BOOL)hasCacheForElementAtIndex:(NSUInteger)index
+{
+    if (index >= _cache.count) {
+        return NO;
+    }
+    return _cache[index] != MPNull;
+}
+
+- (id)cachableObjectForIndex:(NSUInteger)index
+                   generator:(id (^)())generator
+{
+    if ([self hasCacheForElementAtIndex:index]) {
+        return _cache[index];
+    }
+    id object = generator();
+    [self cacheObject:object
+    forElementAtIndex:index];
+    return object;
+}
+
+// Storing Caches
+- (void)cacheObject:(id)anObject
+  forElementAtIndex:(NSUInteger)index
+{
+    [self ensureCacheSizeForIndex:index];
+    _cache[index] = anObject;
+}
+
+- (void)ensureCacheSizeForIndex:(NSUInteger)index
+{
+    while (index >= _cache.count) {
+        [_cache addObject:MPNull];
+    }
+}
+
+// Clearing Caches
+- (void)clearCacheInRange:(NSRange)range
+        replacementLength:(NSUInteger)replacementLength
+{
+    NSMutableArray *placeholders = [[NSMutableArray alloc] initWithCapacity:replacementLength];
+    while (placeholders.count < replacementLength) {
+        [placeholders addObject:MPNull];
+    }
+    [_cache replaceObjectsInRange:range
+             withObjectsFromArray:placeholders];
+    [self invalidate];
+}
+
+- (void)invalidate
+{
+    _cachedPath = nil;
+    [self.parent invalidate];
+}
+
+#pragma mark Calculation Methods
+- (NSSize)size
+{
+    return self.bezierPath.bounds.size;
+}
+
+- (NSBezierPath *)bezierPath
+{
+    if (!_cachedPath) {
+        _cachedPath = [self generateBezierPath];
+    }
+    return _cachedPath;
+}
+
+- (NSBezierPath *)bezierPathAtOrigin:(NSPoint)point
+{
+    NSAffineTransform *transform = [NSAffineTransform transform];
+    [transform translateXBy:point.x
+                        yBy:point.y];
+    NSBezierPath *path = [NSBezierPath bezierPath];
+    [path appendBezierPath:self.bezierPath];
+    [path transformUsingAffineTransform:transform];
+    return path;
+}
+
+- (void)drawAtPoint:(NSPoint)point
+{
+    NSBezierPath *path = [self bezierPathAtOrigin:point];
+    [path fill];
+}
+
+@end

MathPad/MPModel.h

@@ -18,8 +18,6 @@
 #import "MPFunction.h"
 #import "MPRangePath.h"
 
-#import "NSObject+MPStringTest.h"
+#import "NSIndexPath+MPAdditions.h"
-#import "NSTextStorage+MPSetContents.h"
-#import "NSIndexPath+MPReverseIndexPath.h"
 
 #endif

MathPad/MPRangePath.h

@@ -6,8 +6,12 @@
 //  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
 //
 
+@import Foundation;
+
 #import "MPExpression.h"
 
+@class MPRangePath, MPExpression;
+
 @interface MPRangePath : NSObject <NSCopying, NSCoding>
 
 #pragma mark Creation Methods

MathPad/MPRangePath.m

@@ -7,6 +7,7 @@
 //
 
 #import "MPRangePath.h"
+#import "MPExpression.h"
 
 @implementation MPRangePath
 
@@ -143,7 +144,7 @@
 
 - (MPExpression *)subexpressionWithRangePath:(MPRangePath *)aRangePath
 {
-    MPExpression *targetExpression = [self symbolAtIndexPath:[aRangePath.location indexPathByRemovingLastIndex]];
+    MPExpression *targetExpression = [self elementAtIndexPath:[aRangePath.location indexPathByRemovingLastIndex]];
     if (![targetExpression isKindOfClass:[MPExpression class]]) {
         return nil;
     }

MathPad/MPSumFunction.h

@@ -6,6 +6,7 @@
 //  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
 //
 
+@import Foundation;
 #import "MPFunction.h"
 
 @class MPSumFunction, MPExpression;

MathPad/MPSumFunction.m

@@ -12,7 +12,6 @@
 @implementation MPSumFunction
 
 #pragma mark Creation Methods
-
 - (instancetype)init
 {
     self = [super init];
@@ -27,8 +26,32 @@
     return self;
 }
 
-#pragma mark Working With the Expression Tree
+#pragma mark Properties
+- (void)setStartExpression:(MPExpression *)startExpression
+{
+    _startExpression.parent = nil;
+    _startExpression = startExpression;
+    _startExpression.parent = self;
+    [self didChangeChildAtIndex:0];
+}
 
+- (void)setTargetExpression:(MPExpression *)targetExpression
+{
+    _targetExpression.parent = nil;
+    _targetExpression = targetExpression;
+    _targetExpression.parent = self;
+    [self didChangeChildAtIndex:1];
+}
+
+- (void)setSumExpression:(MPExpression *)sumExpression
+{
+    _sumExpression.parent = nil;
+    _sumExpression = sumExpression;
+    _sumExpression.parent = self;
+    [self didChangeChildAtIndex:2];
+}
+
+#pragma mark Working With the Expression Tree
 - (NSUInteger)numberOfChildren
 {
     return 3;
@@ -48,36 +71,32 @@
     }
 }
 
-- (NSArray *)children
-{
-    return @[self.startExpression, self.targetExpression, self.sumExpression];
-}
-
 - (void)setChild:(MPExpression *)child
          atIndex:(NSUInteger)index
 {
     switch (index) {
             // TODO: Copy child?
         case 0:
-            self.startExpression.parent = nil;
             self.startExpression = child;
             break;
         case 1:
-            self.targetExpression.parent = nil;
             self.targetExpression = child;
             break;
         case 2:
-            self.sumExpression.parent = nil;
             self.sumExpression = child;
             break;
         default:
             return;
     }
-    child.parent = self;
+    [self didChangeChildAtIndex:index];
+}
+
+- (NSArray *)children
+{
+    return @[self.startExpression, self.targetExpression, self.sumExpression];
 }
 
 #pragma mark Evaluating Functions
-
 - (double)doubleValue
 {
 #warning Implementation
@@ -85,7 +104,6 @@
 }
 
 #pragma mark Working With Functions
-
 - (BOOL)isEqualToFunction:(MPFunction *)aFunction
 {
     if (![aFunction isKindOfClass:[MPSumFunction class]]) {
@@ -106,8 +124,13 @@
     return [NSString stringWithFormat:@"Sum(From: %@; To: %@; Using: %@)", self.startExpression, self.targetExpression, self.sumExpression];
 }
 
-#pragma mark - NSCopying
+- (NSUInteger)hash
+{
+#warning Unimplemented Method
+    return [super hash];
+}
 
+#pragma mark - NSCopying
 - (id)copyWithZone:(NSZone *)zone
 {
     MPSumFunction *copy = [[MPSumFunction allocWithZone:zone] init];

MathPad/MPSumFunctionLayout.m

@@ -16,20 +16,21 @@
     return (MPSumFunction *)self.function;
 }
 
-- (NSSize)calculateSize
+- (NSBezierPath *)generateBezierPath
 {
-    NSAttributedString *text = [[NSAttributedString alloc] initWithString:@"∑" attributes:@{NSFontAttributeName: [NSFont fontWithName:@"HelveticaNeue" size:50.0]}];
+    NSAttributedString *text = [[NSAttributedString alloc] initWithString:@"∑"
-    [self.textStorage setAttributedString:text];
+                                                               attributes:@{NSFontAttributeName: [NSFont fontWithName:@"Lucida Grande" size:18.0]}];
+    self.textStorage.attributedString = text;
     NSRange glyphRange = [self.layoutManager glyphRangeForTextContainer:self.textContainer];
-    return [self.layoutManager boundingRectForGlyphRange:glyphRange inTextContainer:self.textContainer].size;
+    NSGlyph glyphs[glyphRange.length+1];
-}
+    NSUInteger actualGylphCount = [self.layoutManager getGlyphs:glyphs
-
+                                                          range:glyphRange];
-- (void)drawFunctionAtPoint:(NSPoint)point
+    NSBezierPath *path = [NSBezierPath bezierPath];
-{
+    [path moveToPoint:NSZeroPoint];
-    NSAttributedString *text = [[NSAttributedString alloc] initWithString:@"∑" attributes:@{NSFontAttributeName: [NSFont fontWithName:@"HelveticaNeue" size:50.0]}];
+    [path appendBezierPathWithGlyphs:glyphs
-    [self.textStorage setAttributedString:text];
+                               count:actualGylphCount
-    NSRange glyphRange = [self.layoutManager glyphRangeForTextContainer:self.textContainer];
+                              inFont:[NSFont fontWithName:@"Lucida Grande" size:18.0]];
-    [self.layoutManager drawGlyphsForGlyphRange:glyphRange atPoint:point];
+    return path;
 }
 
 @end

MathPad/NSIndexPath+MPAdditions.h

@@ -0,0 +1,30 @@
+//
+//  NSIndexPath+MPRemoveFirstIndex.h
+//  MathPad
+//
+//  Created by Kim Wittenburg on 23.04.14.
+//  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
+//
+
+@import Foundation;
+
+@interface NSIndexPath (MPAdditions)
+
+/*!
+ @method indexPathByRemovingFirstIndex
+ @brief Provides an index path with the indexes in the receiving index path, excluding the first one.
+ @discussion Returns an empty NSIndexPath instance if the receiving index path’s length is 1 or less.
+ @return A new index path with the receiving index path’s indexes, excluding the first one.
+ */
+- (NSIndexPath *)indexPathByRemovingFirstIndex;
+
+/*!
+ @method indexPathByPreceedingIndex:
+ @brief Provides an index path with the given index followed by the indexes of the receiver.
+ @discussion If the receiver does not contain any indexes the given index is the only index contained in the returned index path.
+ @param index The index new index preceeding all others
+ @return A new index path with all the receiver's indexes preceeded by @c index.
+ */
+- (NSIndexPath *)indexPathByPreceedingIndex:(NSUInteger)index;
+
+@end

MathPad/NSIndexPath+MPAdditions.m

@@ -0,0 +1,37 @@
+//
+//  NSIndexPath+MPRemoveFirstIndex.m
+//  MathPad
+//
+//  Created by Kim Wittenburg on 23.04.14.
+//  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
+//
+
+#import "NSIndexPath+MPAdditions.h"
+
+@implementation NSIndexPath (MPAdditions)
+
+- (NSIndexPath *)indexPathByRemovingFirstIndex
+{
+    if (self.length <= 1) {
+        return [[NSIndexPath alloc] init];
+    }
+    NSUInteger indexes[self.length];
+    [self getIndexes:indexes];
+    NSUInteger newIndexes[self.length-1];
+    for (NSUInteger i = 0; i < self.length-1; i++) {
+        newIndexes[i] = indexes[i+1];
+    }
+    return [[NSIndexPath alloc] initWithIndexes:newIndexes length:self.length-1];
+}
+
+- (NSIndexPath *)indexPathByPreceedingIndex:(NSUInteger)index
+{
+    NSUInteger newIndexes[self.length+1];
+    newIndexes[0] = index;
+    for (NSUInteger i = 0; i < self.length; i++) {
+        newIndexes[i+1] = [self indexAtPosition:i];
+    }
+    return [[NSIndexPath alloc] initWithIndexes:newIndexes length:self.length+1];
+}
+
+@end

MathPad/NSString+MPExpressionElement.h

@@ -0,0 +1,14 @@
+//
+//  NSString+MPExpressionElement.h
+//  MathPad
+//
+//  Created by Kim Wittenburg on 10.08.14.
+//  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
+//
+
+@import Foundation;
+#import "MPExpressionElement.h"
+
+@interface NSString (MPExpressionElement) <MPExpressionElement>
+
+@end

MathPad/NSString+MPExpressionElement.m

@@ -0,0 +1,49 @@
+//
+//  NSString+MPExpressionElement.m
+//  MathPad
+//
+//  Created by Kim Wittenburg on 10.08.14.
+//  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
+//
+
+#import "NSString+MPExpressionElement.h"
+
+@implementation NSString (MPExpressionElement)
+
+- (BOOL)isString
+{
+    return YES;
+}
+
+- (BOOL)isFunction
+{
+    return NO;
+}
+
+- (double)doubleValue
+{
+#warning Unimplemented Method
+    return 0;
+}
+
+- (float)floatValue
+{
+    return (float)[self doubleValue];
+}
+
+- (int)intValue
+{
+    return (int)[self doubleValue];
+}
+
+- (NSInteger)integerValue
+{
+    return (NSInteger)[self doubleValue];
+}
+
+- (long long)longLongValue
+{
+    return (long long)[self doubleValue];
+}
+
+@end

MathPadTests/MPExpressionTests.m

@@ -20,119 +20,119 @@
 - (void)testInitialization {
     // Test empty expression
     MPExpression *testExpression = [[MPExpression alloc] init];
-    XCTAssertEqual([testExpression numberOfSymbols], 0);
+    XCTAssertEqual(testExpression.numberOfElements, 0);
 
     // Test expression with string
-    testExpression = [[MPExpression alloc] initWithString:@"1234+5678"];
+    testExpression = [[MPExpression alloc] initWithElement:@"1234+5678"];
-    XCTAssertEqual([testExpression numberOfSymbols], 1);
+    XCTAssertEqual(testExpression.numberOfElements, 1);
-    XCTAssertEqualObjects([testExpression symbolAtIndex:0], @"1234+5678");
+    XCTAssertEqualObjects([testExpression elementAtIndex:0], @"1234+5678");
     
     // Test expression with function
-    testExpression = [[MPExpression alloc] initWithFunction:[[MPFunction alloc] init]];
+    testExpression = [[MPExpression alloc] initWithElement:[[MPFunction alloc] init]];
-    XCTAssertEqual([testExpression numberOfSymbols], 1);
+    XCTAssertEqual([testExpression numberOfElements], 1);
-    XCTAssertEqualObjects([testExpression symbolAtIndex:0], [[MPFunction alloc] init]);
+    XCTAssertEqualObjects([testExpression elementAtIndex:0], [[MPFunction alloc] init]);
     
-    testExpression = [[MPExpression alloc] initWithSymbols:@[@"1234", [[MPFunction alloc] init], @"17", [[MPFunction alloc] init]]];
+    testExpression = [[MPExpression alloc] initWithElements:@[@"1234", [[MPFunction alloc] init], @"17", [[MPFunction alloc] init]]];
-    XCTAssertEqual([testExpression numberOfSymbols], 4);
+    XCTAssertEqual([testExpression numberOfElements], 4);
-    XCTAssertEqualObjects([testExpression symbolAtIndex:2], @"17");
+    XCTAssertEqualObjects([testExpression elementAtIndex:2], @"17");
     
     // Test expression with subsequent strings
-    testExpression = [[MPExpression alloc] initWithSymbols:@[@"1234", @"5678"]];
+    testExpression = [[MPExpression alloc] initWithElements:@[@"1234", @"5678"]];
-    XCTAssertEqual([testExpression numberOfSymbols], 1);
+    XCTAssertEqual([testExpression numberOfElements], 1);
-    XCTAssertEqualObjects([testExpression symbolAtIndex:0], @"12345678");
+    XCTAssertEqualObjects([testExpression elementAtIndex:0], @"12345678");
     
     // Test expression with only empty string
-    testExpression = [[MPExpression alloc] initWithString:@""];
+    testExpression = [[MPExpression alloc] initWithElement:@""];
-    XCTAssertEqual([testExpression numberOfSymbols], 0);
+    XCTAssertEqual([testExpression numberOfElements], 0);
 }
 
 - (void)testSubexpressions {
-    MPExpression *testExpression = [MPExpression expressionWithSymbols:@[@"1234", [[MPFunction alloc] init], @"17", [[MPFunction alloc] init]]];
+    MPExpression *testExpression = [[MPExpression alloc] initWithElements:@[@"1234", [[MPFunction alloc] init], @"17", [[MPFunction alloc] init]]];
     
     /********** subexpressionFromIndex: **********/
     // Test with start index at front
-    MPExpression *subexpression = [testExpression subexpressionFromIndex:0];
+    MPExpression *subexpression = [testExpression subexpressionFromLocation:0];
-    XCTAssertEqual([subexpression numberOfSymbols], 4);
+    XCTAssertEqual([subexpression numberOfElements], 4);
-    XCTAssertEqualObjects([subexpression symbolAtIndex:0], @"1234");
+    XCTAssertEqualObjects([subexpression elementAtIndex:0], @"1234");
     
-    // Test with start index in first symbol
+    // Test with start index in first element
-    subexpression = [testExpression subexpressionFromIndex:2];
+    subexpression = [testExpression subexpressionFromLocation:2];
-    XCTAssertEqual([subexpression numberOfSymbols], 4);
+    XCTAssertEqual([subexpression numberOfElements], 4);
-    XCTAssertEqualObjects([subexpression symbolAtIndex:0], @"34");
+    XCTAssertEqualObjects([subexpression elementAtIndex:0], @"34");
     
-    // Test with start index in middle symbol starting with a literal
+    // Test with start index in middle element starting with a literal
-    subexpression = [testExpression subexpressionFromIndex:6];
+    subexpression = [testExpression subexpressionFromLocation:6];
-    XCTAssertEqual([subexpression numberOfSymbols], 2);
+    XCTAssertEqual([subexpression numberOfElements], 2);
-    XCTAssertEqualObjects([subexpression symbolAtIndex:0], @"7");
+    XCTAssertEqualObjects([subexpression elementAtIndex:0], @"7");
     
-    // Test with start index in middle symbol starting with a function
+    // Test with start index in middle element starting with a function
-    subexpression = [testExpression subexpressionFromIndex:4];
+    subexpression = [testExpression subexpressionFromLocation:4];
-    XCTAssertEqual([subexpression numberOfSymbols], 3);
+    XCTAssertEqual([subexpression numberOfElements], 3);
-    XCTAssertEqualObjects([subexpression symbolAtIndex:0], [[MPFunction alloc] init]);
+    XCTAssertEqualObjects([subexpression elementAtIndex:0], [[MPFunction alloc] init]);
     
-    // Test with start index in last symbol
+    // Test with start index in last element
-    subexpression = [testExpression subexpressionFromIndex:7];
+    subexpression = [testExpression subexpressionFromLocation:7];
-    XCTAssertEqual([subexpression numberOfSymbols], 1);
+    XCTAssertEqual([subexpression numberOfElements], 1);
-    XCTAssertEqualObjects([subexpression symbolAtIndex:0], [[MPFunction alloc] init]);
+    XCTAssertEqualObjects([subexpression elementAtIndex:0], [[MPFunction alloc] init]);
     
     // Test with start index at end
-    subexpression = [testExpression subexpressionFromIndex:8];
+    subexpression = [testExpression subexpressionFromLocation:8];
-    XCTAssertEqual([subexpression numberOfSymbols], 0);
+    XCTAssertEqual([subexpression numberOfElements], 0);
     
     /********** subexpressionToIndex: **********/
     // Test with end index at front
-    subexpression = [testExpression subexpressionToIndex:0];
+    subexpression = [testExpression subexpressionToLocation:0];
-    XCTAssertEqual([subexpression numberOfSymbols], 0);
+    XCTAssertEqual([subexpression numberOfElements], 0);
 
-    // Test with end index in first symbol
+    // Test with end index in first Element
-    subexpression = [testExpression subexpressionToIndex:2];
+    subexpression = [testExpression subexpressionToLocation:2];
-    XCTAssertEqual([subexpression numberOfSymbols], 1);
+    XCTAssertEqual([subexpression numberOfElements], 1);
-    XCTAssertEqualObjects([subexpression symbolAtIndex:0], @"12");
+    XCTAssertEqualObjects([subexpression elementAtIndex:0], @"12");
     
-    // Test with end index in middle symbol ending with a literal
+    // Test with end index in middle Element ending with a literal
-    subexpression = [testExpression subexpressionToIndex:6];
+    subexpression = [testExpression subexpressionToLocation:6];
-    XCTAssertEqual([subexpression numberOfSymbols], 3);
+    XCTAssertEqual([subexpression numberOfElements], 3);
-    XCTAssertEqualObjects([subexpression symbolAtIndex:2], @"1");
+    XCTAssertEqualObjects([subexpression elementAtIndex:2], @"1");
     
-    // Test with end index in middle symbol ending with a function
+    // Test with end index in middle Element ending with a function
-    subexpression = [testExpression subexpressionToIndex:5];
+    subexpression = [testExpression subexpressionToLocation:5];
-    XCTAssertEqual([subexpression numberOfSymbols], 2);
+    XCTAssertEqual([subexpression numberOfElements], 2);
-    XCTAssertEqualObjects([subexpression symbolAtIndex:1], [[MPFunction alloc] init]);
+    XCTAssertEqualObjects([subexpression elementAtIndex:1], [[MPFunction alloc] init]);
     
     // Test with end index at end
-    subexpression = [testExpression subexpressionToIndex:8];
+    subexpression = [testExpression subexpressionToLocation:8];
-    XCTAssertEqual([subexpression numberOfSymbols], 4);
+    XCTAssertEqual([subexpression numberOfElements], 4);
-    XCTAssertEqualObjects([subexpression symbolAtIndex:3], [[MPFunction alloc] init]);
+    XCTAssertEqualObjects([subexpression elementAtIndex:3], [[MPFunction alloc] init]);
     
     /********** subexpressionWithRange: **********/
     // Test with empty range
     subexpression = [testExpression subexpressionWithRange:NSMakeRange(4, 0)];
-    XCTAssertEqual([subexpression numberOfSymbols], 0);
+    XCTAssertEqual([subexpression numberOfElements], 0);
     
-    // Test with start and end in first symbol
+    // Test with start and end in first element
     subexpression = [testExpression subexpressionWithRange:NSMakeRange(1, 2)];
-    XCTAssertEqual([subexpression numberOfSymbols], 1);
+    XCTAssertEqual([subexpression numberOfElements], 1);
-    XCTAssertEqualObjects([subexpression symbolAtIndex:0], @"23");
+    XCTAssertEqualObjects([subexpression elementAtIndex:0], @"23");
     
     // Test with start in first and end in middle after function
     subexpression = [testExpression subexpressionWithRange:NSMakeRange(2, 3)];
-    XCTAssertEqual([subexpression numberOfSymbols], 2);
+    XCTAssertEqual([subexpression numberOfElements], 2);
-    XCTAssertEqualObjects([subexpression symbolAtIndex:0], @"34");
+    XCTAssertEqualObjects([subexpression elementAtIndex:0], @"34");
-    XCTAssertEqualObjects([subexpression symbolAtIndex:1], [[MPFunction alloc] init]);
+    XCTAssertEqualObjects([subexpression elementAtIndex:1], [[MPFunction alloc] init]);
     
     // Test with start in first and end in middle after literal
     subexpression = [testExpression subexpressionWithRange:NSMakeRange(2, 4)];
-    XCTAssertEqual([subexpression numberOfSymbols], 3);
+    XCTAssertEqual([subexpression numberOfElements], 3);
-    XCTAssertEqualObjects([subexpression symbolAtIndex:0], @"34");
+    XCTAssertEqualObjects([subexpression elementAtIndex:0], @"34");
-    XCTAssertEqualObjects([subexpression symbolAtIndex:2], @"1");
+    XCTAssertEqualObjects([subexpression elementAtIndex:2], @"1");
 }
 
 - (void)testSubexpressionsIllegalRange {
-    MPExpression *testExpression = [MPExpression expressionWithSymbols:@[@"1234", [[MPFunction alloc] init], @"17", [[MPFunction alloc] init]]];
+    MPExpression *testExpression = [[MPExpression alloc] initWithElements:@[@"1234", [[MPFunction alloc] init], @"17", [[MPFunction alloc] init]]];
     
     // Test with start index beyond end
     @try {
-        [testExpression subexpressionFromIndex:10];
+        [testExpression subexpressionFromLocation:10];
         XCTFail(@"Should have raised an exception.");
     }
     @catch (NSException *exception) {}
@@ -146,11 +146,11 @@
 }
 
 - (void)testEqualExpressions {
-    MPExpression *expression1 = [[MPExpression alloc] initWithString:@"123"];
+    MPExpression *expression1 = [[MPExpression alloc] initWithElement:@"123"];
-    MPExpression *expression2 = [[MPExpression alloc] initWithString:@"1234"];
+    MPExpression *expression2 = [[MPExpression alloc] initWithElement:@"1234"];
-    MPExpression *expression3 = [[MPExpression alloc] initWithFunction:[[MPFunction alloc] init]];
+    MPExpression *expression3 = [[MPExpression alloc] initWithElement:[[MPFunction alloc] init]];
-    MPExpression *expression4 = [[MPExpression alloc] initWithSymbols:@[[[MPFunction alloc] init], @"123"]];
+    MPExpression *expression4 = [[MPExpression alloc] initWithElements:@[[[MPFunction alloc] init], @"123"]];
-    MPExpression *expression5 = [[MPExpression alloc] initWithSymbols:@[[[MPFunction alloc] init], @"123"]];
+    MPExpression *expression5 = [[MPExpression alloc] initWithElements:@[[[MPFunction alloc] init], @"123"]];
     
     XCTAssertNotEqualObjects(expression1, expression2);
     XCTAssertNotEqualObjects(expression1, expression3);
@@ -159,68 +159,83 @@
     XCTAssertEqualObjects(expression4, expression5);
 }
 
-- (void)testAppendSymbols {
-    MPExpression *expression1 = [[MPExpression alloc] initWithString:@"123"];
-    MPExpression *expression2 = [expression1 expressionByAppendingFunction:[[MPFunction alloc] init]];
-    MPExpression *expression3 = [[MPExpression alloc] initWithSymbols:@[@"123", [[MPFunction alloc] init]]];
-    
-    XCTAssertEqualObjects(expression2, expression3);
-}
-
 - (void)testDescription {
     // Test Simple Expressions
-    MPExpression *testExpression = [[MPExpression alloc] initWithString:@"1234"];
+    MPExpression *testExpression = [[MPExpression alloc] initWithElement:@"1234"];
     XCTAssertEqualObjects([testExpression description], @"1234");
     
-    testExpression = [[MPExpression alloc] initWithFunction:[[MPFunction alloc] init]];
+    testExpression = [[MPExpression alloc] initWithElement:[[MPFunction alloc] init]];
     XCTAssertEqualObjects([testExpression description], @"[]");
     
     // Test function after literal without explicit operator
-    testExpression = [[MPExpression alloc] initWithSymbols:@[@"123", [[MPFunction alloc] init]]];
+    testExpression = [[MPExpression alloc] initWithElements:@[@"123", [[MPFunction alloc] init]]];
     XCTAssertEqualObjects([testExpression description], @"123*[]");
     
     // Test function after literal with explicit operator
-    testExpression = [[MPExpression alloc] initWithSymbols:@[@"123+", [[MPFunction alloc] init]]];
+    testExpression = [[MPExpression alloc] initWithElements:@[@"123+", [[MPFunction alloc] init]]];
     XCTAssertEqualObjects([testExpression description], @"123+[]");
     
     // Test literal after function without explicit operator
-    testExpression = [[MPExpression alloc] initWithSymbols:@[[[MPFunction alloc] init], @"123"]];
+    testExpression = [[MPExpression alloc] initWithElements:@[[[MPFunction alloc] init], @"123"]];
     XCTAssertEqualObjects([testExpression description], @"[]*123");
     
     // Test literal after function with explicit operator
-    testExpression = [[MPExpression alloc] initWithSymbols:@[[[MPFunction alloc] init], @"-123"]];
+    testExpression = [[MPExpression alloc] initWithElements:@[[[MPFunction alloc] init], @"-123"]];
     XCTAssertEqualObjects([testExpression description], @"[]-123");
     
     // Test function after function without explicit operator
-    testExpression = [[MPExpression alloc] initWithSymbols:@[[[MPFunction alloc] init], [[MPFunction alloc] init]]];
+    testExpression = [[MPExpression alloc] initWithElements:@[[[MPFunction alloc] init], [[MPFunction alloc] init]]];
     XCTAssertEqualObjects([testExpression description], @"[]*[]");
     
     // Test function after function with explicit operator
-    testExpression = [[MPExpression alloc] initWithSymbols:@[[[MPFunction alloc] init], @"-", [[MPFunction alloc] init]]];
+    testExpression = [[MPExpression alloc] initWithElements:@[[[MPFunction alloc] init], @"-", [[MPFunction alloc] init]]];
     XCTAssertEqualObjects([testExpression description], @"[]-[]");
     
     
     // Test whitespaces in literal
-    testExpression = [[MPExpression alloc] initWithSymbols:@[@" 123 + ", [[MPFunction alloc] init]]];
+    testExpression = [[MPExpression alloc] initWithElements:@[@" 123 + ", [[MPFunction alloc] init]]];
     XCTAssertEqualObjects([testExpression description], @"123 +[]");
 }
 
 - (void)testCopying {
-    MPExpression *baseExpression = [[MPExpression alloc] initWithFunction:[[MPFunction alloc] init]];
+    MPExpression *baseExpression = [[MPExpression alloc] initWithElement:[[MPFunction alloc] init]];
     MPExpression *copy = [baseExpression copy];
     
+    XCTAssertEqual(baseExpression.numberOfElements, copy.numberOfElements);
     XCTAssertNotEqual(copy, baseExpression);
-    XCTAssertNotEqual([baseExpression symbolAtIndex:0], [copy symbolAtIndex:0]);
+    XCTAssertNotEqual([baseExpression elementAtIndex:0], [copy elementAtIndex:0]);
+    XCTAssertEqualObjects(baseExpression, copy);
 }
 
-- (void)testMutableCopying {
+- (void)testMutating {
-    MPExpression *baseExpression = [[MPExpression alloc] initWithString:@"123"];
+    MPExpression *testExpression = [[MPExpression alloc] initWithElements:@[@"1234", [[MPFunction alloc] init], @"5678", [[MPFunction alloc] init]]];
-    MPMutableExpression *expression1 = [baseExpression mutableCopy];
-    [expression1 appendFunction:[[MPFunction alloc] init]];
-    MPExpression *expression2 = [[MPExpression alloc] initWithSymbols:@[@"123", [[MPFunction alloc] init]]];
     
-    XCTAssertEqualObjects(expression1, expression2);
+    [testExpression appendElement:@"90"];
-    XCTAssertNotEqualObjects(baseExpression, expression1);
+    XCTAssertEqual([testExpression numberOfElements], 5);
+    // 1234 [] 5678 [] 90
+    
+    [testExpression deleteElementsInRange:NSMakeRange(2, 4)];
+    XCTAssertEqual([testExpression numberOfElements], 3);
+    // 12678 [] 90
+    
+    [testExpression insertElement:[[MPFunction alloc] init]
+                       atLocation:2];
+    XCTAssertEqual([testExpression numberOfElements], 5);
+    // 12 [] 678 [] 90
+    
+    [testExpression replaceElementsInRange:NSMakeRange(2, 5)
+                              withElements:@[[[MPFunction alloc] init]]];
+    XCTAssertEqual([testExpression numberOfElements], 3);
+    // 12 [] 90
+}
+
+- (void)testInvalidMutatingRange {
+    @try {
+        MPExpression *testExpression = [[MPExpression alloc] initWithElements:@[@"1234", [[MPFunction alloc] init], @"5678", [[MPFunction alloc] init]]];
+        [testExpression deleteElementsInRange:NSMakeRange(5, 17)];
+        XCTFail(@"Should have raised an exception");
+    }
+    @catch (NSException *exception) {}
 }
 
 // TODO: Test evaluating expressions