126 lines
3.2 KiB
Objective-C
126 lines
3.2 KiB
Objective-C
//
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// MPExpressionTree.m
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// MathPad
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//
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// Created by Kim Wittenburg on 09.10.14.
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// Copyright (c) 2014 Kim Wittenburg. All rights reserved.
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//
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#import "MPExpressionTree.h"
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#import "MPSummand.h"
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#import "MPTokenStream.h"
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#import "MPToken.h"
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#import "MPExpression.h"
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@implementation MPExpressionTree {
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NSMutableArray *_summands;
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}
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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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_summands = [[NSMutableArray alloc] init];
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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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self.definedVariable = nil;
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if (tokenStream.currentToken.tokenType == MPVariableToken) {
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if (tokenStream.peekNextToken.tokenType == MPEqualsToken) {
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self.definedVariable = tokenStream.currentToken.stringValue;
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[tokenStream currentTokenConsumed];
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[tokenStream currentTokenConsumed];
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}
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}
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while ([tokenStream hasMoreTokens]) {
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[_summands addObject:[[MPSummand alloc] initWithTokenStream:tokenStream]];
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}
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[tokenStream endIgnoringOrAcceptingWhitespaceTokens];
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}
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return self;
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}
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- (NSArray *)summands
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{
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return _summands;
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}
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- (BOOL)validate:(NSError *__autoreleasing *)error
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{
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return [self validateExpectingVariableDefinition:NO
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error:error];
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}
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- (BOOL)validateExpectingVariableDefinition:(BOOL)flag
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error:(NSError *__autoreleasing *)error
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{
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if (flag) {
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if (!self.definedVariable) {
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if (error) {
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*error = MPParseError(1,
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NSLocalizedString(@"Expected Variable Definition.", @"Error message. This is displayed when an expected variable definition was not found."),
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nil);
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}
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return NO;
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}
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} else {
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if (self.definedVariable) {
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if (error) {
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*error = MPParseError(2,
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NSLocalizedString(@"Unexpected Variable Definition.", @"Error message. This is displayed when no variable definition was expected but one was found."),
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nil);
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}
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return NO;
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}
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}
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if (_summands.count == 0) {
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if (error) {
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*error = MPParseError(3,
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NSLocalizedString(@"Empty Expression.", @"Error message. This is displayed when the user tried to evaluate an empty expression."),
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nil);
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}
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return NO;
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}
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for (MPSummand *summand in _summands) {
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if (![summand validate:error]) {
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return NO;
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}
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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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NSDecimalNumber *value = [NSDecimalNumber zero];
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for (MPSummand *summand in _summands) {
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NSDecimalNumber *currentValue = [summand evaluate];
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if ([currentValue isEqualToNumber:[NSDecimalNumber notANumber]]) {
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value = currentValue;
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break;
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}
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value = [value decimalNumberByAdding:currentValue];
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}
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return value;
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}
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@end
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