Hoa is a modular, extensible and structured set of PHP libraries. Moreover, Hoa aims at being a bridge between industrial and research worlds.
This library provides tools around mathemetical operations.
With Composer, to include this library into your
dependencies, you need to require
hoa/math:
{
"require": {
"hoa/math": "~1.0"
}
}Please, read the website to get more informations about how to install.
We propose a quick overview of one feature: evaluation of arithmetical expressions.
The hoa://Library/Math/Arithmetic.pp describes the form of an arithmetical
expression. Therefore, we will use the classical workflow when manipulating a
grammar, that involves the Hoa\Compiler
library and the
Hoa\Math\Visitor\Arithmetic class.
// 1. Load the compiler.
$compiler = Hoa\Compiler\Llk::load(
new Hoa\File\Read('hoa://Library/Math/Arithmetic.pp')
);
// 2. Load the visitor, aka the “evaluator”.
$visitor = new Hoa\Math\Visitor\Arithmetic();
// 3. Declare the expression.
$expression = '1 / 2 / 3 + 4 * (5 * 2 - 6) * PI / avg(7, 8, 9)';
// 4. Parse the expression.
$ast = $compiler->parse($expression);
// 5. Evaluate.
var_dump(
$visitor->visit($ast)
);
/**
* Will output:
* float(6.4498519738463)
*/
// Bonus. Print the AST of the expression.
$dump = new Hoa\Compiler\Visitor\Dump();
echo $dump->visit($ast);
/**
* Will output:
* > #addition
* > > #division
* > > > token(number, 1)
* > > > #division
* > > > > token(number, 2)
* > > > > token(number, 3)
* > > #multiplication
* > > > token(number, 4)
* > > > #multiplication
* > > > > #group
* > > > > > #substraction
* > > > > > > #multiplication
* > > > > > > > token(number, 5)
* > > > > > > > token(number, 2)
* > > > > > > token(number, 6)
* > > > > #division
* > > > > > token(constant, PI)
* > > > > > #function
* > > > > > > token(id, avg)
* > > > > > > token(number, 7)
* > > > > > > token(number, 8)
* > > > > > > token(number, 9)
*/We can add functions and constants on the visitor, thanks to the addFunction
and addConstant methods. Thus, we will add the rand function (with 2
parameters) and the ANSWER constant, set to 42:
$visitor->addFunction('rand', function ($min, $max) {
return mt_rand($min, $max);
});
$visitor->addConstant('ANSWER', 42);
$expression = 'rand(ANSWER / 2, ANSWER * 2)'
var_dump(
$visitor->visit($compiler->parse($expression))
);
/**
* Could output:
* int(53)
*/Different documentations can be found on the website: http://hoa-project.net/.
Hoa is under the New BSD License (BSD-3-Clause). Please, see
LICENSE.