118 lines
2.7 KiB
Objective-C
118 lines
2.7 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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@implementation MPTokenStream {
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NSUInteger _currentTokenIndex;
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NSUInteger eofLocation;
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BOOL *whitespaceIgnores;
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NSUInteger maxWhitespaceIgnores;
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NSUInteger currentWhitespaceState;
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}
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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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whitespaceIgnores = malloc(10 * sizeof(BOOL));
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maxWhitespaceIgnores = 10;
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currentWhitespaceState = 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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eofLocation = NSMaxRange([tokens.lastObject range]);
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} else {
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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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currentWhitespaceState++;
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if (currentWhitespaceState >= maxWhitespaceIgnores) {
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maxWhitespaceIgnores += 10;
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BOOL *reallocatedWhitespaceIgnores = realloc(whitespaceIgnores, maxWhitespaceIgnores);
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if (reallocatedWhitespaceIgnores) {
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whitespaceIgnores = 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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whitespaceIgnores[currentWhitespaceState] = state;
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}
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- (void)endIgnoringOrAcceptingWhitespaceTokens
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{
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currentWhitespaceState--;
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}
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- (void)skipWhitespaces
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{
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if (whitespaceIgnores[currentWhitespaceState]) {
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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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[self currentTokenConsumed];
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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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- (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 [[MPToken alloc] initEOFTokenAtLocation:eofLocation];
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}
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return _tokens[_currentTokenIndex];
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}
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- (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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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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++_currentTokenIndex;
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}
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- (void)dealloc
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{
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free(whitespaceIgnores);
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}
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@end
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