Common Text Transformation Library: edge

Demonstrates cttl::edge_replace function object class. The program replaces words (substrings) inside input text.

// sample code: edge_functors.cpp
// demonstrates cttl::edge_replace class.

//#define NDEBUG    // must appear before assert.h is included to stop assertions from being compiled 
//#define CTTL_TRACE_EVERYTHING

#include <iostream>
#include "cttl/cttl.h"
#include "cttl/edge_functors.h"

using namespace cttl;

struct parser {
    std::vector< edge<> > word_edges;

    // semantic actions:
    size_t accumulate_words( const_edge<>& edge_ )
    {
        // remember each word that was found:
        word_edges.push_back( new_edge( edge_ ) );
        return edge_.second.offset();
    }
};

template< typename ParserT >
struct lexer : public ParserT {

    size_t start( const_edge< policy_space<> >& universe_ )
    {
        return (
                +( isalpha & rule( *this, &ParserT::accumulate_words ) )
        ).match( universe_ )
        ;
    }
};


int main(int argc, char* argv[])
{
    if ( argc == 1 ) {
        std::cout
            << "Usage: on command the line, enter some words to process, for example,"
            << std::endl
            << '\t'
            << argv[ 0 ]
            << " abc def ghi"
            << std::endl
            ;

        return 1;
    }

    // construct input string from the command line arguments:
    input<> inp( &argv[ 1 ], ' ' );

    // construct universe to be parsed:
    const_edge< policy_space<> > universe( new_edge( inp ) );

    // construct the parser:
    lexer< parser > word_parser;

    // count words:
    if ( word_parser.start( universe ) != std::string::npos ) {
        std::cout << "Input: " << inp.text() << std::endl;

        // Replace words with word marker:
        std::for_each(
            word_parser.word_edges.begin(),
            word_parser.word_edges.end(),
            edge_replace<>( "<WORD/>" )
            );

        std::cout << "Output: " << inp.text() << std::endl;

    } else {
        std::cout << "*** parser failed ***" << std::endl;
        return 1;
    }

    return 0;
}

Input: one two three
Output: <WORD/> <WORD/> <WORD/>

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