<?php
/**
* @package s9e\TextFormatter
* @copyright Copyright (c) 2010-2022 The s9e authors
* @license http://www.opensource.org/licenses/mit-license.php The MIT License
*/
namespace s9e\TextFormatter\Configurator\Helpers;
use DOMAttr;
use DOMDocument;
use DOMText;
use DOMXPath;
abstract class TemplateModifier
{
/**
* XSL namespace
*/
const XMLNS_XSL = 'http://www.w3.org/1999/XSL/Transform';
/**
* Replace parts of a template that match given regexp
*
* Treats attribute values as plain text. Replacements within XPath expression is unsupported.
* The callback must return an array with two elements. The first must be either of 'expression',
* 'literal' or 'passthrough', and the second element depends on the first.
*
* - 'expression' indicates that the replacement must be treated as an XPath expression such as
* '@foo', which must be passed as the second element.
*
* - 'literal' indicates a literal (plain text) replacement, passed as its second element.
*
* - 'passthrough' indicates that the replacement should the tag's content. It works differently
* whether it is inside an attribute's value or a text node. Within an attribute's value, the
* replacement will be the text content of the tag. Within a text node, the replacement
* becomes an <xsl:apply-templates/> node. A second optional argument can be passed to be used
* as its @select node-set.
*
* @param string $template Original template
* @param string $regexp Regexp for matching parts that need replacement
* @param callable $fn Callback used to get the replacement
* @return string Processed template
*/
public static function replaceTokens($template, $regexp, $fn)
{
$dom = TemplateLoader::load($template);
$xpath = new DOMXPath($dom);
foreach ($xpath->query('//@*') as $attribute)
{
self::replaceTokensInAttribute($attribute, $regexp, $fn);
}
foreach ($xpath->query('//text()') as $node)
{
self::replaceTokensInText($node, $regexp, $fn);
}
return TemplateLoader::save($dom);
}
/**
* Create a node that implements given replacement strategy
*
* @param DOMDocument $dom
* @param array $replacement
* @return DOMNode
*/
protected static function createReplacementNode(DOMDocument $dom, array $replacement)
{
if ($replacement[0] === 'expression')
{
$newNode = $dom->createElementNS(self::XMLNS_XSL, 'xsl:value-of');
$newNode->setAttribute('select', $replacement[1]);
}
elseif ($replacement[0] === 'passthrough')
{
$newNode = $dom->createElementNS(self::XMLNS_XSL, 'xsl:apply-templates');
if (isset($replacement[1]))
{
$newNode->setAttribute('select', $replacement[1]);
}
}
else
{
$newNode = $dom->createTextNode($replacement[1]);
}
return $newNode;
}
/**
* Replace parts of an attribute that match given regexp
*
* @param DOMAttr $attribute Attribute
* @param string $regexp Regexp for matching parts that need replacement
* @param callable $fn Callback used to get the replacement
* @return void
*/
protected static function replaceTokensInAttribute(DOMAttr $attribute, $regexp, $fn)
{
$attrValue = preg_replace_callback(
$regexp,
function ($m) use ($fn, $attribute)
{
$replacement = $fn($m, $attribute);
if ($replacement[0] === 'expression' || $replacement[0] === 'passthrough')
{
// Use the node's text content as the default expression
$replacement[] = '.';
return '{' . $replacement[1] . '}';
}
else
{
return $replacement[1];
}
},
$attribute->value
);
$attribute->value = htmlspecialchars($attrValue, ENT_COMPAT, 'UTF-8');
}
/**
* Replace parts of a text node that match given regexp
*
* @param DOMText $node Text node
* @param string $regexp Regexp for matching parts that need replacement
* @param callable $fn Callback used to get the replacement
* @return void
*/
protected static function replaceTokensInText(DOMText $node, $regexp, $fn)
{
// Grab the node's parent so that we can rebuild the text with added variables right
// before the node, using DOM's insertBefore(). Technically, it would make more sense
// to create a document fragment, append nodes then replace the node with the fragment
// but it leads to namespace redeclarations, which looks ugly
$parentNode = $node->parentNode;
$dom = $node->ownerDocument;
preg_match_all($regexp, $node->textContent, $matches, PREG_SET_ORDER | PREG_OFFSET_CAPTURE);
$lastPos = 0;
foreach ($matches as $m)
{
$pos = $m[0][1];
// Catch-up to current position
$text = substr($node->textContent, $lastPos, $pos - $lastPos);
$parentNode->insertBefore($dom->createTextNode($text), $node);
$lastPos = $pos + strlen($m[0][0]);
// Get the replacement for this token
$replacement = $fn(array_column($m, 0), $node);
$newNode = self::createReplacementNode($dom, $replacement);
$parentNode->insertBefore($newNode, $node);
}
// Append the rest of the text
$text = substr($node->textContent, $lastPos);
$parentNode->insertBefore($dom->createTextNode($text), $node);
// Now remove the old text node
$parentNode->removeChild($node);
}
}