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# CLIX. 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.

See also the appendix about tokens.

# 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: Builtin support for tokenizer is available with 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 Q 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 1. Strip comments with the tokenizer

`<?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;
}
}
}
?>`

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