Cleaned Code & Fixed Some Errors

MathPad/MPEvaluationContext.h

@@ -20,8 +20,6 @@
 
 - (BOOL)defineVariable:(NSString *)variable
                  value:(NSDecimalNumber *)value;
-- (BOOL)redefineVariable:(NSString *)variable
-                   value:(NSDecimalNumber *)value;
 - (void)undefineVariable:(NSString *)variable;
 
 - (NSDecimalNumber *)valueForVariable:(NSString *)variable;

MathPad/MPEvaluationContext.m

@@ -53,6 +53,7 @@ static MPEvaluationContext *sharedContext;
 - (BOOL)defineVariable:(NSString *)variable
                  value:(NSDecimalNumber *)value
 {
+    [self undefineVariable:variable];
     if ([self isVariableDefined:variable]) {
         return NO;
     }
@@ -61,14 +62,6 @@ static MPEvaluationContext *sharedContext;
     return YES;
 }
 
-- (BOOL)redefineVariable:(NSString *)variable
-                   value:(NSDecimalNumber *)value
-{
-    [self undefineVariable:variable];
-    return [self defineVariable:variable
-                          value:value];
-}
-
 - (void)undefineVariable:(NSString *)variable
 {
     NSMutableDictionary *currentBindings = self.stack.lastObject;

MathPad/MPExpression.h

@@ -490,7 +490,7 @@ typedef NS_ENUM(NSUInteger, MPReferenceFrame) {
                 is restored. That basically means that subsequent strings are
                 joined and empty strings removed. After restoring integrity the
                 receiver sends a @c
-                -didChangeElementsInIndexedRangePath:replacementLength: to
+                -changedElementsInIndexedRangePath:replacementLength: to
                 itself. For more information see the documentation on that
                 method.
  
@@ -509,6 +509,30 @@ typedef NS_ENUM(NSUInteger, MPReferenceFrame) {
                withElements:(NSArray *)elements;
 
 
+/*!
+    @method     changedElementsInRangePath:replacementLength:
+    @brief      Called after the receiver has been mutated.
+ 
+    @discussion This method does nothing more than notify it's parent that it has
+                been mutated at the receiver's index. If you need to know about
+                changes in an expression you should override this method instead
+                of @c -replaceSymbolsInRange:withElements: because this method
+                gives you information about the number of elements changed during
+                the mutation.
+ 
+    @param      rangePath
+                The range path at which the receiver was changed starting at the
+                receiver. The range addressed by @c rangePath is expressed in the
+                element reference frame.
+ 
+    @param      replacementLength
+                The number of elements replacing the elements specified by @c
+                rangePath (also specified in the element reference frame).
+ */
+- (void)changedElementsInRangePath:(MPRangePath *)rangePath
+                 replacementLength:(NSUInteger)replacementLength;
+
+
 /*!
     @method     subexpressionFromIndex:referenceFrame:
     @brief      Creates an expression from the items in the receiver from the
@@ -651,36 +675,6 @@ typedef NS_ENUM(NSUInteger, MPReferenceFrame) {
 - (MPParsedExpression *)parseExpectingVariable:(BOOL)flag
                                         errors:(NSArray *__autoreleasing *)errors;
 
-
-#pragma mark Notifications
-/*!
- @methodgroup Notifications
- */
-
-
-/*!
-    @method     didChangeElementsInRangePath:replacementLength:
-    @brief      Called after the receiver has been mutated.
- 
-    @discussion This method does nothing more than notify it's parent that it has
-                been mutated at the receiver's index. If you need to know about
-                changes in an expression you should override this method instead
-                of @c -replaceSymbolsInRange:withElements: because this method
-                gives you information about the number of elements changed during
-                the mutation.
- 
-    @param      rangePath
-                The range path at which the receiver was changed starting at the
-                receiver. The range addressed by @c rangePath is expressed in the
-                element reference frame.
- 
-    @param      replacementLength
-                The number of elements replacing the elements specified by @c
-                rangePath (also specified in the element reference frame).
- */
-- (void)didChangeElementsInRangePath:(MPRangePath *)rangePath
-                   replacementLength:(NSUInteger)replacementLength;
-
 @end
 
 

MathPad/MPExpression.m

@@ -561,7 +561,7 @@ NSString *const MPIllegalElementExceptionElementKey = @"MPIllegalElementExceptio
     }
 
     [self fixElements];
-    [self didChangeElementsInRangePath:[[MPRangePath alloc] initWithRange:_editedRange]
+    [self changedElementsInRangePath:[[MPRangePath alloc] initWithRange:_editedRange]
                      replacementLength:_replacementLength];
 }
 
@@ -592,6 +592,16 @@ NSString *const MPIllegalElementExceptionElementKey = @"MPIllegalElementExceptio
 }
 
 
+- (void)changedElementsInRangePath:(MPRangePath *)rangePath
+                 replacementLength:(NSUInteger)replacementLength
+{
+    NSUInteger selfIndex = [self.parent indexOfChild:self];
+    MPRangePath *newPath = MPMakeRangePath([rangePath.location indexPathByPreceedingIndex:selfIndex], rangePath.length);
+    [self.parent didChangeElementsInRangePath:newPath
+                            replacementLength:replacementLength];
+}
+
+
 - (MPExpression *)subexpressionFromIndex:(NSUInteger)from
                           referenceFrame:(MPReferenceFrame)referenceFrame
 {
@@ -661,19 +671,6 @@ NSString *const MPIllegalElementExceptionElementKey = @"MPIllegalElementExceptio
 }
 
 
-#pragma mark Notifications
-
-
-- (void)didChangeElementsInRangePath:(MPRangePath *)rangePath
-                   replacementLength:(NSUInteger)replacementLength
-{
-    NSUInteger selfIndex = [self.parent indexOfChild:self];
-    MPRangePath *newPath = MPMakeRangePath([rangePath.location indexPathByPreceedingIndex:selfIndex], rangePath.length);
-    [self.parent didChangeElementsInRangePath:newPath
-                            replacementLength:replacementLength];
-}
-
-
 #pragma mark Basic NSObject Methods
 
 

MathPad/MPExpressionStorage.h

@@ -15,8 +15,6 @@
 
 @interface MPExpressionStorage : MPExpression
 
-- (instancetype)initWithElements:(NSArray *)elements;
-
 @property (nonatomic, weak) MPExpressionView *expressionView; // Do not set
 @property (nonatomic, strong) MPExpressionLayout *rootLayout;
 

MathPad/MPExpressionStorage.m

@@ -35,10 +35,10 @@
 {
     _expressionView = expressionView;
     self.rootLayout = [[MPExpressionLayout alloc] initWithExpression:self parent:nil];
-    self.rootLayout.flipped = expressionView.isFlipped;
+    self.rootLayout.flipped = expressionView.flipped;
 }
 
-- (void)didChangeElementsInRangePath:(MPRangePath *)rangePath
+- (void)changedElementsInRangePath:(MPRangePath *)rangePath
                    replacementLength:(NSUInteger)replacementLength
 {
     if (rangePath.location.length == 0) {

MathPad/MPFractionTerm.m

@@ -14,16 +14,18 @@
 
 - (NSDecimalNumber *)doEvaluation:(NSError *__autoreleasing *)error
 {
-    NSDecimalNumber *nominator = [[self expressionAtIndex:0] evaluate:error];
+    MPEvaluateExpression(nominator, 0);
-    if (!nominator) {
+    MPEvaluateExpression(denominator, 1);
+    if ([denominator isEqualToNumber:@0]) {
+        if (error) {
+            *error = [NSError errorWithDomain:MPMathKitErrorDomain
+                                         code:100
+                                     userInfo:@{NSLocalizedDescriptionKey: NSLocalizedString(@"Division by zero.", nil)}];
+        }
         return nil;
+    } else {
+        return [nominator decimalNumberByDividingBy:denominator];
     }
-    NSDecimalNumber *denominator = [[self expressionAtIndex:1] evaluate:error];
-    if (!denominator) {
-        return nil;
-    }
-#warning Division by zero ahead
-    return [nominator decimalNumberByDividingBy:denominator];
 }
 
 @end

MathPad/MPFunction.m

@@ -121,7 +121,7 @@
 {
     NSUInteger selfIndex = [self.parent indexOfElement:self];
     MPRangePath *newPath = MPMakeRangePath([rangePath.location indexPathByPreceedingIndex:selfIndex], rangePath.length);
-    [self.parent didChangeElementsInRangePath:newPath
+    [self.parent changedElementsInRangePath:newPath
                             replacementLength:replacementLength];
 }
 

MathPad/MPFunctionTerm.h

@@ -8,6 +8,8 @@
 
 #import "MPTerm.h"
 
+#define MPEvaluateExpression(var, index) NSDecimalNumber *var = [[self expressionAtIndex:index] evaluate:error]; if (var == nil) return nil
+
 
 
 @class MPFunctionTerm, MPFunction, MPParsedExpression;

MathPad/MPPowerTerm.m

@@ -13,14 +13,9 @@
 
 - (NSDecimalNumber *)doEvaluation:(NSError *__autoreleasing *)error
 {
-    NSDecimalNumber *exponent = [[self expressionAtIndex:0] evaluate:error];
+    MPEvaluateExpression(exponent, 0);
-    if (!exponent) {
-        return nil;
-    }
     NSDecimalNumber *base = [self.baseTerm evaluate:error];
-    if (!base) {
+    ReturnNilIfNil(base);
-        return nil;
-    }
     if ([base isEqualToNumber:@(0)] && [exponent isEqualToNumber:@(0)]) {
         // The C pow function returns 1 for pow(0, 0). Mathematically this should be undefined.
         if (error) {

MathPad/MPSumFunctionTerm.m

@@ -15,23 +15,21 @@
 - (NSDecimalNumber *)doEvaluation:(NSError *__autoreleasing *)error
 {
     MPParsedExpression *startExpression = [self expressionAtIndex:0];
-    MPParsedExpression *targetExpression = [self expressionAtIndex:1];
     MPParsedExpression *sumExpression = [self expressionAtIndex:2];
     
     NSDecimalNumber *start = [startExpression evaluate:error];
-    NSDecimalNumber *target = [targetExpression evaluate:error];
+    ReturnNilIfNil(start);
+    MPEvaluateExpression(target, 1);
     NSDecimalNumber *value = [NSDecimalNumber zero];
     
     for (NSDecimalNumber *current = start;
          [current compare:target] <= 0;
          current = [current decimalNumberByAdding:[[NSDecimalNumber alloc] initWithInteger:1]]) {
-        if (![self redefineVariable:startExpression.definedVariable value:current error:error]) {
+        if (![self defineVariable:startExpression.definedVariable value:current error:error]) {
             return nil;
         }
         NSDecimalNumber *currentValue = [sumExpression evaluate:error];
-        if (!currentValue) {
+        ReturnNilIfNil(currentValue);
-            return nil;
-        }
         value = [value decimalNumberByAdding:currentValue];
     }
     return value;

MathPad/MPTerm.h

@@ -6,6 +6,9 @@
 //  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
 //
 
+#define ReturnIfNil(test, value) if (test == nil) return value
+#define ReturnNilIfNil(test) if (test == nil) return nil
+
 
 @class MPTerm;
 
@@ -18,9 +21,6 @@
 - (BOOL)defineVariable:(NSString *)variableName
                  value:(NSDecimalNumber *)value
                  error:(NSError *__autoreleasing *)error;
-- (BOOL)redefineVariable:(NSString *)variableName
-                   value:(NSDecimalNumber *)value
-                   error:(NSError *__autoreleasing *)error;
 - (NSDecimalNumber *)valueForVariable:(NSString *)variableName
                                 error:(NSError *__autoreleasing *)error;
 - (void)undefineVariable:(NSString *)variableName; // Should rarely be needed, defined variables are automatically undefined at the end of evaluation.

MathPad/MPTerm.m

@@ -45,23 +45,6 @@
     return couldDefineVariable;
 }
 
-- (BOOL)redefineVariable:(NSString *)variableName
-                   value:(NSDecimalNumber *)value
-                   error:(NSError *__autoreleasing *)error
-{
-    BOOL couldDefineVariable = [[MPEvaluationContext sharedContext] redefineVariable:variableName
-                                                                               value:value];
-    if (!couldDefineVariable) {
-        if (error) {
-            NSString *localizedDescription = [NSString stringWithFormat:NSLocalizedString(@"Redifinition of variable \"%@\".", nil), variableName];
-            *error = [NSError errorWithDomain:MPMathKitErrorDomain
-                                         code:100
-                                     userInfo:@{NSLocalizedDescriptionKey: localizedDescription}];
-        }
-    }
-    return couldDefineVariable;
-}
-
 - (NSDecimalNumber *)valueForVariable:(NSString *)variableName
                                 error:(NSError *__autoreleasing *)error
 {