Added Lots of Documentation

Added some nice to haves
Improved and Unified General Code Layout

MathPad/MPDocument.m

@@ -8,9 +8,11 @@
 
 #import "MPDocument.h"
 
-#import "MPParsedExpression.h"
 
-@implementation MPDocument
+
+@implementation MPDocument {
+    MPExpression *loadedExpression;
+}
 
 - (id)init
 {
@@ -21,46 +23,47 @@
     return self;
 }
 
+
 - (NSString *)windowNibName
 {
-    // Override returning the nib file name of the document
-    // If you need to use a subclass of NSWindowController or if your document supports multiple NSWindowControllers, you should remove this method and override -makeWindowControllers instead.
     return @"MPDocument";
 }
 
+
 - (void)windowControllerDidLoadNib:(NSWindowController *)aController
 {
     [super windowControllerDidLoadNib:aController];
     self.expressionView.target = self;
     self.expressionView.action = @selector(evaluateExpression:);
-    // Add any code here that needs to be executed once the windowController has loaded the document's window.
+    if (loadedExpression) {
+        [self.expressionView.expressionStorage appendElements:[loadedExpression allItemsInReferenceFrame:MPElementReferenceFrame]];
+    }
 }
 
+
 + (BOOL)autosavesInPlace
 {
     return YES;
 }
 
+
 - (NSData *)dataOfType:(NSString *)typeName error:(NSError **)outError
 {
-    // Insert code here to write your document to data of the specified type. If outError != NULL, ensure that you create and set an appropriate error when returning nil.
-    // You can also choose to override -fileWrapperOfType:error:, -writeToURL:ofType:error:, or -writeToURL:ofType:forSaveOperation:originalContentsURL:error: instead.
-    NSException *exception = [NSException exceptionWithName:@"UnimplementedMethod" reason:[NSString stringWithFormat:@"%@ is unimplemented", NSStringFromSelector(_cmd)] userInfo:nil];
-    @throw exception;
-    return nil;
+    return [NSKeyedArchiver archivedDataWithRootObject:self.expressionView.expressionStorage];
 }
 
+
 - (BOOL)readFromData:(NSData *)data ofType:(NSString *)typeName error:(NSError **)outError
 {
-    // Insert code here to read your document from the given data of the specified type. If outError != NULL, ensure that you create and set an appropriate error when returning NO.
-    // You can also choose to override -readFromFileWrapper:ofType:error: or -readFromURL:ofType:error: instead.
-    // If you override either of these, you should also override -isEntireFileLoaded to return NO if the contents are lazily loaded.
-    NSException *exception = [NSException exceptionWithName:@"UnimplementedMethod" reason:[NSString stringWithFormat:@"%@ is unimplemented", NSStringFromSelector(_cmd)] userInfo:nil];
-    @throw exception;
+    MPExpression *expression = [NSKeyedUnarchiver unarchiveObjectWithData:data];
+    loadedExpression = expression;
     return YES;
 }
 
+
 #pragma mark Actions
+
+
 - (IBAction)evaluateExpression:(id)sender {
     NSArray *errors;
     MPParsedExpression *parsedExpression = [self.expressionView.expressionStorage parse:&errors];
@@ -74,4 +77,5 @@
     self.resultLabel.stringValue = result != nil ? [result descriptionWithLocale:[NSLocale currentLocale]] : @"";
 }
 
+
 @end