=== Introduction ===

CalcPHP is a math expression calculator write in PHP. 

I write it just for fun and programming language implement study purpose.

It define and implement a small language to do calculation works.

You can use it as a command line tool like :

    $ php CalcPHP.php
    CalcPHP command line interface V1.0
    > 1.
    result: 1.000000 (0.000102 sec)
    > 1 + 2.
    result: 3.000000 (0.000133 sec)
    > 1 + 2 * 3.
    result: 7.000000 (0.000426 sec)
    > 1 + 2 * 3 / 4.
    result: 2.500000 (0.000357 sec)
    > (1 + 2) * (3 / 4).
    result: 2.250000 (0.000329 sec)
    > a = 1, b = 2, c = 3, (a + b) / c.
    result: 1.000000 (0.000782 sec)
    > add = fun(a, b) -> a + b end.
    result: 1.000000 (0.000448 sec)
    > add(10, 20).
    result: 30.000000 (0.000431 sec)
    > exit

And you can embed CalcPHP in your app by include "CalcPHP.php", and use it like:

    //create global state
    $state = new CalcState();

    //create a parser
    $parser = new CalcParser($code, $state);

    //parse code as AST
    $doc = $parser->Parse();

    //execute AST and get result
    $result = $doc->Exec();