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README.md

PHP Expression Language

The purpose of this library is to provide a common base for an PHP Expression Language.

This is not really a creative library since it burrows almost all the code from the great JMSSecurityExtraBundle which already defines more or less such a base for a powerful EL (Expression Language).

The idea is to take this code outside of the Johannes's bundle and to standardize it.

Simple usage

$compiler = new ExpressionCompiler();
$evaluator = eval($compiler->compileExpression(new Expression("date.format(format)")));

$context = array(
    'date' => new \DateTime(),
    'format' => 'Y',
);
$result = $evaluator($context);

echo $result; // 2013

Adding a custom function compiler

The isNumber() function expression:

  1. First you need to create a compiler for your function

    <?php
    
    namespace My\Expression\Compiler\Func;
    
    use Pel\Expression\Compiler\Func\FunctionCompilerInterface;
    use Pel\Expression\ExpressionCompiler;
    use Pel\Expression\Ast\FunctionExpression;
    use Pel\Exception\RuntimeException;
    
    class IsNumberFunctionCompiler implements FunctionCompilerInterface
    {
        public function getName()
        {
            return 'isNumber';
        }
    
        public function compilePreconditions(ExpressionCompiler $compiler, FunctionExpression $function)
        {
            if (1 !== count($function->args)) {
                throw new RuntimeException(sprintf('The isNumber() function expects exactly one argument, but got "%s".', var_export($function->args, true)));
            }
        }
    
        public function compile(ExpressionCompiler $compiler, FunctionExpression $function)
        {
            $compiler
                ->write("is_numeric(")
                ->compileInternal($function->args[0])
                ->write(")")
            ;
        }
    }
  2. Next, after having instanciated the ExpressionCompiler, you just need to register your custom function compiler

    <?php
    
    $compiler = new ExpressionCompiler();
    $compiler->addFunctionCompiler(new IsNumberFunctionCompiler());
    
    $evaluator = eval($compiler->compileExpression(new Expression("isNumber('1234')")));
    var_dump(call_user_func($evaluator, array()));
    // bool(true)
    
    $evaluator = eval($compiler->compileExpression(new Expression("isNumber('1234abc')")));
    var_dump(call_user_func($evaluator, array()));
    // bool(false)

License

This bundle is under the MIT license. See the complete license in library:

LICENSE

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