Fundamental Redesign of Evaluation
This commit is contained in:
Kim Wittenburg
416
MathPad/MPExpressionParser.m
Normal file
416
MathPad/MPExpressionParser.m
Normal file
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//
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// MPExpressionParser.m
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// MathPad
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//
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// Created by Kim Wittenburg on 16.11.14.
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// Copyright (c) 2014 Kim Wittenburg. All rights reserved.
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//
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#import "MPExpressionParser.h"
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#import "MPExpression.h"
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#import "MPTokenStream.h"
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#import "MPTerm.h"
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#import "MPToken.h"
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#import "MPSumTerm.h"
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#import "MPProductTerm.h"
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#import "MPFactorialTerm.h"
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#import "MPElementaryFunctionTerm.h"
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#import "MPFunctionTerm.h"
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#import "MPPowerTerm.h"
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#import "MPNegatedTerm.h"
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#import "MPNumber.h"
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#import "MPVariable.h"
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#import "MPFactorialTerm.h"
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#define success() state = 0
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#define fail() state = -1
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@interface MPExpressionParser ()
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@property (nonatomic, strong) NSArray *tokens;
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@property (nonatomic) NSUInteger currentTokenIndex;
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@property (nonatomic, strong) NSMutableArray *errors;
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@property (nonatomic, strong) NSMutableArray *summands;
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@property (nonatomic) BOOL summandNegative;
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@property (nonatomic, strong) NSMutableArray *factors;
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@property (nonatomic) BOOL factorNegative;
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@property (nonatomic, strong) NSMutableArray *functionStack;
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@property (nonatomic, strong) NSMutableArray *valueGroup;
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@property (nonatomic, strong) MPTerm *value;
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@property (nonatomic) NSUInteger errorTokenIndex;
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@end
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@implementation MPExpressionParser
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- (instancetype)initWithExpression:(MPExpression *)expression
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{
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self = [super init];
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if (self) {
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_tokens = [expression allItemsInReferenceFrame:MPTokenReferenceFrame];
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_expression = expression;
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}
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return self;
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}
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- (MPParsedExpression *)parse:(NSArray *__autoreleasing *)errors
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{
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return [self parseExpectingVariableDefinition:NO
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errors:errors];
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}
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- (MPParsedExpression *)parseExpectingVariableDefinition:(BOOL)flag
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errors:(NSArray *__autoreleasing *)errors
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{
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MPParsedExpression *result = [[MPParsedExpression alloc] init];
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self.currentTokenIndex = 0;
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BOOL hasVariableDefinition = NO;
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NSString *variableName = nil;
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[self skipWhitespaces];
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if (self.currentToken.tokenType == MPVariableToken) {
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variableName = self.currentToken.stringValue;
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[self nextToken];
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[self skipWhitespaces];
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if (self.currentToken.tokenType == MPEqualsToken) {
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[self nextToken];
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hasVariableDefinition = YES;
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}
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}
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if (flag && hasVariableDefinition) {
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result.definedVariable = variableName;
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} else if (flag) {
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[self addErrorWithCode:3 localizedDescription:NSLocalizedString(@"Expected Variable Definition.", nil)];
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if (errors) {
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*errors = self.errors;
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}
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return nil;
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} else if (hasVariableDefinition) {
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[self addErrorWithCode:4 localizedDescription:NSLocalizedString(@"Unexpected Variable Definition.", nil)];
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if (errors) {
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*errors = self.errors;
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}
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return nil;
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} else {
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self.currentTokenIndex = 0;
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}
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[self skipWhitespaces];
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if (self.currentTokenIndex >= self.tokens.count) {
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[self addErrorWithCode:5 localizedDescription:NSLocalizedString(@"Empty Expression.", nil)];
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if (errors) {
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*errors = self.errors;
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}
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return nil;
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}
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[self runParserMachine];
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if ([self errorOccured]) {
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if (errors) {
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*errors = self.errors;
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}
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return nil;
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}
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result.term = [[MPSumTerm alloc] initWithSummands:self.summands];
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return result;
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}
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- (void)runParserMachine
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{
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NSInteger state = 1;
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NSInteger backtraceState = 0;
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NSUInteger backtraceTokenIndex = self.currentTokenIndex;
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BOOL alternateRoute = NO;
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while (state != 0) {
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switch (state) {
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case -1:
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state = backtraceState;
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self.currentTokenIndex = backtraceTokenIndex;
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alternateRoute = YES;
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break;
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case 1:
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[self skipWhitespaces];
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if (self.currentToken.tokenType == MPOperatorListToken) {
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self.factorNegative = [self parseOperatorList:self.currentToken];
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[self nextToken];
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state = 2;
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} else {
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self.factorNegative = NO;
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state = 2;
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}
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break;
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case 2:
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[self skipWhitespaces];
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if (self.currentToken.tokenType == MPElementaryFunctionToken) {
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[self.functionStack addObject:self.currentToken.stringValue];
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[self nextToken];
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state = 2;
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} else {
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state = 3;
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}
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break;
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case 3:
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[self skipWhitespaces];
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if (self.currentToken.tokenType == MPGenericFunctionToken) {
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NSArray *errors;
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self.value = [[MPFunctionTerm alloc] initWithFunction:(MPFunction *)self.currentToken
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errors:&errors];
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if (!self.value) {
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[self.errors addObjectsFromArray:errors];
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}
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[self nextToken];
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[self runSuffixMachine];
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if (self.value) {
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[self.valueGroup addObject:self.value];
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}
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state = 6;
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} else {
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state = 4;
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}
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break;
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case 4:
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if (self.currentToken.tokenType == MPNumberToken) {
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self.value = [[MPNumber alloc] initWithNumber:[self parseNumber:self.currentToken]];
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[self nextToken];
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[self runSuffixMachine];
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[self.valueGroup addObject:self.value];
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state = 5;
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} else if (self.currentToken.tokenType == MPVariableToken) {
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self.value = [[MPVariable alloc] initWithVariableName:[self parseVariable:self.currentToken]];
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[self nextToken];
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[self runSuffixMachine];
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[self.valueGroup addObject:self.value];
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state = 5;
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} else {
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self.errorTokenIndex = self.currentTokenIndex;
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fail();
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}
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break;
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case 5:
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if (alternateRoute) {
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alternateRoute = NO;
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state = 6;
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} else {
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backtraceState = 5;
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backtraceTokenIndex = self.currentTokenIndex;
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state = 4;
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}
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break;
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case 6:
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[self collapseFactor];
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[self skipWhitespaces];
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backtraceState = 6;
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backtraceTokenIndex = self.currentTokenIndex;
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if (!alternateRoute && self.currentToken.tokenType == MPOperatorListToken) {
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[self collapseSummand];
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self.summandNegative = [self parseOperatorList:self.currentToken];
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[self nextToken];
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state = 1;
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} else {
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state = 7;
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}
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break;
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case 7:
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if (alternateRoute) {
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[self collapseSummand];
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alternateRoute = NO;
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success();
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} else {
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backtraceState = 7;
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backtraceTokenIndex = self.currentTokenIndex;
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state = 8;
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}
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break;
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case 8:
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[self skipWhitespaces];
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if (self.currentToken.tokenType == MPMultiplicationSymbolToken) {
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[self nextToken];
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state = 1;
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} else {
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state = 1;
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}
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break;
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default:
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// Should never get here
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break;
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}
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}
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}
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- (void)skipWhitespaces
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{
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while ([self currentToken] != nil && [self currentToken].tokenType == MPWhitespaceToken) {
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[self nextToken];
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}
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}
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- (id<MPToken>)currentToken
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{
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if (self.currentTokenIndex >= self.tokens.count) {
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return nil;
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}
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return self.tokens[self.currentTokenIndex];
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}
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- (void)nextToken
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{
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self.currentTokenIndex++;
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}
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- (NSMutableArray *)errors
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{
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if (!_errors) {
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_errors = [[NSMutableArray alloc] init];
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}
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return _errors;
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}
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- (NSMutableArray *)summands
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{
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if (!_summands) {
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_summands = [[NSMutableArray alloc] init];
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}
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return _summands;
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}
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- (NSMutableArray *)factors
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{
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if (!_factors) {
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_factors = [[NSMutableArray alloc] init];
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}
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return _factors;
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}
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- (NSMutableArray *)functionStack
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{
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if (!_functionStack) {
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_functionStack = [[NSMutableArray alloc] init];
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}
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return _functionStack;
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}
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- (NSMutableArray *)valueGroup
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{
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if (!_valueGroup) {
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_valueGroup = [[NSMutableArray alloc] init];
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}
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return _valueGroup;
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}
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- (BOOL)parseOperatorList:(id<MPToken>)token // Returns YES if list is overall negative
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{
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NSString *operatorString = [[token.stringValue stringByReplacingOccurrencesOfString:@" " withString:@""]
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stringByReplacingOccurrencesOfString:@"+" withString:@""];
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return (operatorString.length & 1) == 1;
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}
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- (NSDecimalNumber *)parseNumber:(id<MPToken>)token
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{
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return [NSDecimalNumber decimalNumberWithString:token.stringValue
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locale:[NSLocale currentLocale]];
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}
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- (NSString *)parseVariable:(id<MPToken>)token
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{
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return token.stringValue;
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}
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- (void)collapseSummand
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{
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if (self.factors.count > 0) {
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MPTerm *summand = [[MPProductTerm alloc] initWithFactors:self.factors];
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if (self.summandNegative) {
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summand = [[MPNegatedTerm alloc] initWithTerm:summand];
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}
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[self.summands addObject:summand];
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}
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self.factors = nil;
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self.summandNegative = NO;
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}
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- (void)collapseFactor
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{
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if (self.valueGroup.count > 0) {
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MPTerm *factor = [[MPProductTerm alloc] initWithFactors:self.valueGroup];
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for (NSInteger index = self.functionStack.count - 1; index >= 0; index--) {
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factor = [[MPElementaryFunctionTerm alloc] initWithFunctionIdentifier:self.functionStack[index]
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term:factor];
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}
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if (self.factorNegative) {
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factor = [[MPNegatedTerm alloc] initWithTerm:factor];
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}
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[self.factors addObject:factor];
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}
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self.valueGroup = nil;
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self.functionStack = nil;
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self.factorNegative = NO;
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}
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- (void)runSuffixMachine
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{
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BOOL checkMore = YES;
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while (checkMore) {
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if (self.currentToken.tokenType == MPFactorialToken) {
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[self nextToken];
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if (self.value) {
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MPFactorialTerm *term = [[MPFactorialTerm alloc] initWithTerm:self.value];
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self.value = term;
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}
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} else if (self.currentToken.tokenType == MPPowerToken) {
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[self nextToken];
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if (self.value) {
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NSArray *errors;
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MPPowerTerm *term = [[MPPowerTerm alloc] initWithFunction:(MPFunction *)self.currentToken errors:&errors];
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if (!term) {
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[self.errors addObjectsFromArray:errors];
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}
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term.baseTerm = self.value;
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self.value = term;
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}
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} else {
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checkMore = NO;
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}
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}
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}
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- (void)addErrorWithCode:(NSInteger)code
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localizedDescription:(NSString *)description
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{
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NSInteger errorIndex = [self.expression convertIndex:self.errorTokenIndex
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fromReferenceFrame:MPTokenReferenceFrame
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toReferenceFrame:MPSymbolReferenceFrame];
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[self.errors addObject:[NSError errorWithDomain:MPMathKitErrorDomain
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code:code
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userInfo:@{NSLocalizedDescriptionKey: description,
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MPPathToExpressionKey: self.expression.indexPath,
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MPErrorIndexKey: @(errorIndex)}]];
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}
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- (BOOL)errorOccured
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{
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[self skipWhitespaces];
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if (self.currentTokenIndex < self.tokens.count) {
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if (self.errorTokenIndex >= self.tokens.count) {
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[self addErrorWithCode:0 localizedDescription:NSLocalizedString(@"Unexpected end. Expected Value.", nil)];
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} else {
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[self addErrorWithCode:1 localizedDescription:NSLocalizedString(@"Unexpected Symbol. Expected Value", nil)];
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}
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}
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return self.errors.count > 0;
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}
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@end
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