59 lines
1.5 KiB
Objective-C
59 lines
1.5 KiB
Objective-C
//
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// MPOperatorChain.m
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// MathPad
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//
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// Created by Kim Wittenburg on 11.10.14.
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// Copyright (c) 2014 Kim Wittenburg. All rights reserved.
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//
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#import "MPOperatorChain.h"
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@implementation MPOperatorChain
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- (id)init
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{
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self = [super init];
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if (self) {
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}
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return self;
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}
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- (instancetype)initWithTokenStream:(MPTokenStream *)tokenStream
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{
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self = [self init];
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if (self) {
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[tokenStream beginIgnoringWhitespaceTokens];
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MPToken *currentToken = tokenStream.currentToken;
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if (currentToken.tokenType != MPOperatorListToken) {
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@throw [NSException exceptionWithName:NSInternalInconsistencyException reason:@"Expected Operators" userInfo:nil];
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}
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NSString *operatorString = currentToken.stringValue;
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operatorString = [[operatorString componentsSeparatedByString:@" "] componentsJoinedByString:@""];
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_negating = NO;
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_numberOfOperators = operatorString.length;
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for (NSUInteger index = 0; index < _numberOfOperators; index++) {
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if ([[operatorString substringWithRange:NSMakeRange(index, 1)] isEqualToString:@"-"]) {
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_negating = !_negating;
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}
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}
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[tokenStream currentTokenConsumed];
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[tokenStream endIgnoringOrAcceptingWhitespaceTokens];
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}
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return self;
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}
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- (BOOL)validate:(NSError *__autoreleasing *)error
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{
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return YES;
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}
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- (NSDecimalNumber *)evaluate
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{
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return self.negating ? [[NSDecimalNumber alloc] initWithInteger:-1] : [NSDecimalNumber one];
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}
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@end
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