Redesign of the Evaluation System

MathPad/MPParsedOperator.m

@@ -0,0 +1,54 @@
+//
+//  MPParsedOperator.m
+//  MathPad
+//
+//  Created by Kim Wittenburg on 13.09.14.
+//  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
+//
+
+#import "MPParsedOperator.h"
+
+@interface MPParsedOperator ()
+@property (nonatomic) NSRange range;
+@property (nonatomic) NSUInteger numberOfOperators;
+@property (nonatomic, strong) NSDecimalNumber *multiplicator;
+@end
+
+@implementation MPParsedOperator
+
+- (instancetype)initWithRange:(NSRange)range
+                     inString:(NSString *)string
+{
+    self = [super init];
+    if (self) {
+        _range = range;
+        if (range.location == NSNotFound) {
+            _multiplicator = [NSDecimalNumber one];
+            _numberOfOperators = 0;
+        } else {
+            NSString *stringValue = [string substringWithRange:range];
+            NSString *operators = [[stringValue componentsSeparatedByCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] componentsJoinedByString:@""];
+            NSInteger multiplicator = 1;
+            for (NSUInteger characterIndex = 0; characterIndex < operators.length; characterIndex++) {
+                if ([[operators substringWithRange:NSMakeRange(characterIndex, 1)] isEqualToString:@"-"]) {
+                    multiplicator *= -1;
+                }
+            }
+            _multiplicator = [[NSDecimalNumber alloc] initWithInteger:multiplicator];
+            _numberOfOperators = operators.length;
+        }
+    }
+    return self;
+}
+
+- (BOOL)exists
+{
+    return self.range.location != NSNotFound;
+}
+
+- (NSDecimalNumber *)evaluateWithError:(MPParseError *__autoreleasing *)error
+{
+    return self.multiplicator;
+}
+
+@end