141 lines
3.0 KiB
Objective-C
141 lines
3.0 KiB
Objective-C
//
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// MPTokenStream.m
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// MathPad
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//
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// Created by Kim Wittenburg on 20.09.14.
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// Copyright (c) 2014 Kim Wittenburg. All rights reserved.
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//
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#import "MPTokenStream.h"
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#import "MPToken.h"
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@interface MPTokenStream ()
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@property (nonatomic, copy) NSArray *tokens;
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@property (nonatomic) NSUInteger currentTokenIndex;
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@property (nonatomic) NSUInteger eofLocation;
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@property (nonatomic) BOOL *whitespaceStates;
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@property (nonatomic) NSUInteger maxWhitespaceIgnores;
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@property (nonatomic) NSUInteger currentWhitespaceIgnoreState;
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- (void)pushWhitespaceState:(BOOL)state;
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@end
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@implementation MPTokenStream
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- (instancetype)initWithTokens:(NSArray *)tokens
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{
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self = [super init];
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if (self) {
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self.tokens = tokens;
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self.whitespaceStates = malloc(10 * sizeof(BOOL));
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self.maxWhitespaceIgnores = 10;
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self.currentWhitespaceIgnoreState = 0;
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[self beginAcceptingWhitespaceTokens];
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_currentTokenIndex = 0;
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if (tokens.count > 0) {
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self.eofLocation = NSMaxRange([tokens.lastObject range]);
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} else {
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self.eofLocation = 0;
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}
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}
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return self;
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}
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- (void)beginAcceptingWhitespaceTokens
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{
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[self pushWhitespaceState:YES];
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}
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- (void)beginIgnoringWhitespaceTokens
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{
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[self pushWhitespaceState:NO];
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}
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- (void)pushWhitespaceState:(BOOL)state
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{
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self.currentWhitespaceIgnoreState++;
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if (self.currentWhitespaceIgnoreState >= self.maxWhitespaceIgnores) {
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self.maxWhitespaceIgnores += 10;
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BOOL *reallocatedWhitespaceIgnores = realloc(self.whitespaceStates, self.maxWhitespaceIgnores);
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if (reallocatedWhitespaceIgnores) {
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self.whitespaceStates = reallocatedWhitespaceIgnores;
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} else {
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@throw [NSException exceptionWithName:NSInternalInconsistencyException reason:@"Realloc Failed" userInfo:nil];
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}
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}
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self.whitespaceStates[self.currentWhitespaceIgnoreState] = state;
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}
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- (void)endIgnoringOrAcceptingWhitespaceTokens
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{
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self.currentWhitespaceIgnoreState--;
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}
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- (void)skipWhitespaces
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{
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if (self.whitespaceStates[self.currentWhitespaceIgnoreState]) {
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return;
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}
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while (_currentTokenIndex < self.tokens.count) {
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MPToken *token = self.tokens[_currentTokenIndex];
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if (token.tokenType != MPWhitespaceToken) {
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return;
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}
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_currentTokenIndex++;
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}
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}
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- (BOOL)hasMoreTokens
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{
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[self skipWhitespaces];
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return _currentTokenIndex < self.tokens.count;
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}
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- (id<MPToken>)currentToken
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{
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[self skipWhitespaces];
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if (_currentTokenIndex >= _tokens.count) {
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return nil;
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}
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return _tokens[_currentTokenIndex];
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}
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- (id<MPToken>)peekNextToken
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{
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NSUInteger currentTokenIndex = _currentTokenIndex;
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[self currentTokenConsumed]; // Pretend the current token has been consumed
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id<MPToken> token = [self currentToken];
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_currentTokenIndex = currentTokenIndex; // Undo the lookahead
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return token;
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}
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- (void)currentTokenConsumed
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{
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[self currentToken];
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++_currentTokenIndex;
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}
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- (void)dealloc
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{
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free(self.whitespaceStates);
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}
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@end
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