[boost] [spirit][xpressive][memory] A new regex library: TPL

From: shiwei xu (xushiweizh_at_[hidden])
Date: 2008-05-28 21:43:22

TPL is short for "Text Processing Library". It is a spirit/xpressive like
library.

I used spirit/xpressive. But the codes based on spirit or xpressive was
compiled slowly.

Here are some hints of TPL:

* It is simple.
* It will always be compiled fast.
* It is based on Boost-Memory (still is a sandbox library).

Here is an example of TPL:

#include <stack>
#include <tpl/RegExp.h>
#include <tpl/ext/Calculator.h>
#include <cmath>

using namespace tpl;

void calculate2()
{
    typedef SimpleImplementation impl;

    // ---- define rules ----

    impl::Allocator alloc;

    std::stack<double> stk;

    impl::Grammar::Var rFactor;

    impl::Grammar rMul( alloc, '*' + rFactor/calc<std::multiplies>(stk) );
    impl::Grammar rDiv( alloc, '/' + rFactor/calc<std::divides>(stk) );
    impl::Grammar rTerm( alloc, rFactor + *(rMul | rDiv) );

    impl::Grammar rAdd( alloc, '+' + rTerm/calc<std::plus>(stk) );
    impl::Grammar rSub( alloc, '-' + rTerm/calc<std::minus>(stk) );
    impl::Grammar rExpr( alloc, rTerm + *(rAdd | rSub) );

    impl::Rule rFun( alloc, "sin"/calc(stk, sin) | "cos"/calc(stk, cos) |
"pow"/calc(stk, pow) );

    rFactor.assign( alloc,
        real()/assign(stk) |
        '-' + rFactor/calc<std::negate>(stk) |
        '(' + rExpr + ')' |
        (gr(c_symbol()) + '(' + rExpr % ',' + ')')/(gr(rFun) + '(') |
        '+' + rFactor );

    // ---- do match ----

    for (;;)
    {
        std::string strExp;
        std::cout << "input an expression (q to quit): ";
        if (!std::getline(std::cin, strExp) || strExp == "q") {
            std::cout << '\n';
            break;
        }

        try {
            while ( !stk.empty() )
                stk.pop();
            if ( !impl::match(strExp.c_str(), rExpr + eos(), skipws(),
alloc) )
                std::cout << ">>> ERROR: invalid expression!\n";
            else
                std::cout << stk.top() << '\n';
        }
        catch (const std::logic_error& e) {
            std::cout << ">>> ERROR: " << e.what() << '\n';
        }
    }
}

// -------------------------------------------------------------------------

If you are interested in TPL, you can check out its source code from SVN:

svn checkout http://libtpl.googlecode.com/svn/trunk/