Tokenizer Functions

Introduction

The tokenizer functions provide an interface to the PHP tokenizer embedded in the Zend Engine. Using these functions you may write your own PHP source analyzing or modification tools without having to deal with the language specification at the lexical level.

Requirements

No external libraries are needed to build this extension.

Installation

Beginning with PHP 4.3.0 these functions are enabled by default. For older versions you have to configure and compile PHP with --enable-tokenizer. You can disable tokenizer support with --disable-tokenizer.

The windows version of PHP has built in support for this extension. You do not need to load any additional extension in order to use these functions.

Note:

Built-in support for tokenizer is available as of PHP 4.3.0.

Predefined Constants

When the extension has either been compiled into PHP or dynamically loaded at runtime, the tokens listed in Appendix S, List of Parser Tokens are defined as constants.

Examples

Here is a simple example PHP scripts using the tokenizer that will read in a PHP file, strip all comments from the source and print the pure code only.

Example 2558. Strip comments with the tokenizer

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<?php
/*

 * T_ML_COMMENT does not exist in PHP 5.

 * The following three lines define it in order to

 * preserve backwards compatibility.

 *

 * The next two lines define the PHP 5 only T_DOC_COMMENT,

 * which we will mask as T_ML_COMMENT for PHP 4.

 */
if (!defined('T_ML_COMMENT')) {

    define('T_ML_COMMENT', T_COMMENT);

} else {

    define('T_DOC_COMMENT', T_ML_COMMENT);

}

$source = file_get_contents('example.php');
$tokens = token_get_all($source);


foreach ($tokens as $token) {

    if (is_string($token)) {

        // simple 1-character token

        echo $token;

    } else {

        // token array

        list($id, $text) = $token;


        switch ($id) { 

            case T_COMMENT: 

            case T_ML_COMMENT: // we've defined this

            case T_DOC_COMMENT: // and this

                // no action on comments

                break;


            default:

                // anything else -> output "as is"

                echo $text;

                break;

        }

    }

}
?>

Table of Contents

token_get_all — Split given source into PHP tokens
token_name — Get the symbolic name of a given PHP token

Code Examples / Notes » ref.tokenizer

lists

The tokenizer functions are quite powerful. For example, you can retrieve all of the methods in a given class using an algorithm like: for each token: if token is T_FUNCTION then start buffer if buffer is started then add the current string to the buffer if token is ( stop buffer And the great thing is that the class methods will have the right case, so it's a good way to get around the limitations with get_class_methods returning lowercase method names. Also since using a similar algorithm you can read the arguments of a function you can implement Reflections-like functionality into PHP4. Finally you can use it as a simpler method of extracting Javadoc out of a class file to generate documentation. The util/MethodTable.php class in AMFPHP (http://www.amfphp.org) uses the tokenizer functions to create a method table with all of the arguments, a description, return type, etc. and from that method table it can generate ActionScript that matches the PHP, but it could also be fitted to generate JavaScript, documentation files, or basically anything you put your mind to. I can also see that this could be the base for a class -> WSDL file generator.