Implemented Expression Evaluation/Parsing with Proper Error Handling

MathPad/MPParseError.m

@@ -2,7 +2,7 @@
 //  MPParseError.m
 //  MathPad
 //
-//  Created by Kim Wittenburg on 06.09.14.
+//  Created by Kim Wittenburg on 08.09.14.
 //  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
 //
 
@@ -10,19 +10,29 @@
 
 @implementation MPParseError
 
-- (instancetype)initWithErrorIndex:(NSUInteger)errorIndex errorMessageKey:(NSString *)errorMessageKey
+- (instancetype)initWithErrorRange:(NSRange)errorRange errorMessageKey:(NSString *)key
 {
     self = [super init];
     if (self) {
-        _errorIndex = errorIndex;
-        _localizedErrorMessage = NSLocalizedString(errorMessageKey, nil);
+        _errorRange = errorRange;
+        _localizedErrorMessage = NSLocalizedString(key, nil);
+    }
+    return self;
+}
+
+- (instancetype)initWithErrorRange:(NSRange)errorRange localizederrorMessage:(NSString *)errorMessage
+{
+    self = [super init];
+    if (self) {
+        _errorRange = errorRange;
+        _localizedErrorMessage = errorMessage;
     }
     return self;
 }
 
 - (NSString *)description
 {
-    return [NSString stringWithFormat:@"MPParseError<at=%ld message=\"%@\">", self.errorIndex, self.localizedErrorMessage];
+    return [NSString stringWithFormat:@"MPParseError<at=(%ld, %ld) message=\"%@\">", self.errorRange.location, self.errorRange.length, self.localizedErrorMessage];
 }
 
 @end