pi's parser

gistfile1.txt

- (BOOL)tokeniser:(CPTokeniser *)tokeniser shouldConsumeToken:(CPToken *)token
{
    return YES;
}

- (NSArray *)tokeniser:(CPTokeniser *)tokeniser willProduceToken:(CPToken *)token
{
    if ([token isKindOfClass:[CPWhiteSpaceToken class]] || [[token name] isEqualToString:@"Comment"])
    {
        return [NSArray array];
    }
    return [NSArray arrayWithObject:token];
}

- (id)parse:(NSString *)input
{
    CPTokeniser *tokeniser = [[[CPTokeniser alloc] init] autorelease];
    [tokeniser addTokenRecogniser:[CPNumberRecogniser numberRecogniser]];
    [tokeniser addTokenRecogniser:[CPWhiteSpaceRecogniser whiteSpaceRecogniser]];
    [tokeniser addTokenRecogniser:[CPQuotedRecogniser quotedRecogniserWithStartQuote:@"\"" endQuote:@"\"" escapeSequence:@"\\" name:@"String"]];
    [tokeniser addTokenRecogniser:[CPKeywordRecogniser recogniserForKeyword:@":"]];
    [tokeniser addTokenRecogniser:[CPKeywordRecogniser recogniserForKeyword:@"="]];
    [tokeniser addTokenRecogniser:[CPKeywordRecogniser recogniserForKeyword:@"{"]];
    [tokeniser addTokenRecogniser:[CPKeywordRecogniser recogniserForKeyword:@"}"]];
    [tokeniser addTokenRecogniser:[CPKeywordRecogniser recogniserForKeyword:@"theme"]];
    [tokeniser addTokenRecogniser:[CPKeywordRecogniser recogniserForKeyword:@"comment"]];
    [tokeniser addTokenRecogniser:[CPKeywordRecogniser recogniserForKeyword:@"presets"]];
    [tokeniser addTokenRecogniser:[CPIdentifierRecogniser identifierRecogniser]];
    
    [tokeniser setDelegate:self];
    CPTokenStream *tokenStream = [tokeniser tokenise:input];
    
    NSString *grammar = @"TuningSystems ::= <TuningSystem> <TuningSystems> | ;"
                        @"TuningSystem  ::= <Theme> <Comment> <Presets>;"
                        @"Theme         ::= \"theme\" \":\" \"String\";"
                        @"Comment       ::= \"comment\" \":\" \"String\";"
                        @"Presets       ::= \"presets\" \"{\" <PresetBlock> \"}\";"
                        @"PresetBlock   ::= <Preset> <PresetBlock> | ;"
                        @"Preset        ::= \"Identifier\" \"=\" \"Number\";";
    CPGrammar *g = [CPGrammar grammarWithStart:@"TuningSystems" backusNaurForm:grammar];
    CPParser parser = [CPParser parserWithGrammar:g];
    [parser setDelegate:self];
    return [parser parse:tokenStream];
}