Common Text Transformation Library http://cttl.sourceforge.net/

Lexeme symbol(false)

• Category:

  • Stop symbol (always fails.)

  • Token width: N/A (stop symbol)

• Format:

  • 
        symbol( false )
    
    

    Shorthand notation:

    
        false
    
    

• Algorithm:

  • The symbol(false) lexeme always fails, this is a stop symbol.

• Space sensitivity:

  • N/A

• Searchability:

  • N/A

• Usage example:

  • 
    #define CTTL_TRACE_EVERYTHING
    #include "cttl/cttl.h"
    
    using namespace cttl;
    
    int main()
    {
        std::string inp = "XYZ";
        const_edge<> substring( inp );
        const_edge<> token = substring;
    
        size_t result = (
            token( entity( isdigit ) )
            |
            false // shorthand for 'symbol(false)' lexeme
        ).match( substring );
    
        assert( result == std::string::npos );
    
        return 0;
    }
    
    

• Trace output format:

  • The trace symbol of symbol(false) lexeme is digit zero: '0'. The above example generates the following trace:

    
        ---------------------@XYZ?{|            0-3
        ---------------------@XYZ? {e           0-3
                                    :3:1
        ~~~~~~~~~~~~~~~~~~~~~~~~@~  $           0-3     FAIL isdigit
        ~~~~~~~~~~~~~~~~~~~~~~~~@~  e3          0-3     FAIL
                                   }
        ~~~~~~~~~~~~~~~~~~~~~~~~@~ 0            0-3     FAIL
        ~~~~~~~~~~~~~~~~~~~~~~~~@~ |            0-3     FAIL
                                  }
    
    

   

Copyright © 1997-2009 Igor Kholodov mailto:cttl@users.sourceforge.net.

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