PHP Expression

PHP Expression Language

Description

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.

Code Quality Rank: L4

Programming language: PHP

License: MIT License

Tags: Miscellaneous     Expressions     Expression     Expression Language     El    

README

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