Common Text Transformation Library: hello

Template class cttl::input implements concept of the user input text. It instantiates a copy of std::basic_string and data structures that support substrings. The actual string type can be specified as a template parameter; the default type is std::string. The input object stores user text and becomes parent of all nodes and edges associated with this particular input. Template class cttl::node encapsulates the concept of a logical position inside the input. Internally, the node relies on the identity vector model. A pair of nodes defines cttl::edge, a template class that represents CTTL substrings.

The following program demonstrates interaction between instances of cttl input, node, and edge classes. The nodes insert text at their current positions. The edge objects are constructed from pairs of existing nodes. Edges encapsulate access to underlying substrings that program can access and modify:

// sample code: hello_world.cpp

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

int main()
{
    using cttl::input;
    using cttl::node;
    using cttl::edge;

    // at the beginning, input text is empty:
    input<> inp;

    // create chain of nodes for "hello, world!" as follows:
    //                            H    RSW    BE
    node<> H( new_node( inp ) );
    node<> R( new_node( inp ) );
    node<> S( new_node( inp ) );
    node<> W( new_node( inp ) );
    node<> B( new_node( inp ) );
    node<> E( new_node( inp ) );

    // construct edges from nodes
    edge<> hello( H, R );
    edge<> rest( R, S );
    edge<> space( S, W );
    edge<> world( W, B );
    edge<> exclaim( B, E );

    // assign text to edges:
    hello = "hello";
    rest = ",";
    space = " ";
    world = "world";
    exclaim = "!";

    // show results:
    std::cout << inp.text() << std::endl;
    std::cout << std::endl;

    // modify substrings:
    hello.first.insert_stay( "<GREETING>" );
    hello.second.insert_go( "</GREETING>" );
    rest = "<REST/>";
    space = "<WHITESPACE/>";
    world.first.insert_stay( "<SCOPE>" );
    world.second.insert_go( "</SCOPE>" );
    exclaim = "<EXCLAMATION/>";

    // show results:
    std::cout << hello.text() << std::endl;
    std::cout << rest.text() << std::endl;
    std::cout << space.text() << std::endl;
    std::cout << world.text() << std::endl;
    std::cout << exclaim.text() << std::endl;

    return 0;
}

hello, world!

<GREETING>hello</GREETING>
<REST/>
<WHITESPACE/>
<SCOPE>world</SCOPE>
<EXCLAMATION/>

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