force_balance_tags( string $text )

Balances tags of string using a modified stack.


Description Description


Parameters Parameters

$text

(string) (Required) Text to be balanced.


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Return Return

(string) Balanced text.


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Source Source

File: wp-includes/formatting.php

function force_balance_tags( $text ) {
	$tagstack  = array();
	$stacksize = 0;
	$tagqueue  = '';
	$newtext   = '';
	// Known single-entity/self-closing tags
	$single_tags = array( 'area', 'base', 'basefont', 'br', 'col', 'command', 'embed', 'frame', 'hr', 'img', 'input', 'isindex', 'link', 'meta', 'param', 'source' );
	// Tags that can be immediately nested within themselves
	$nestable_tags = array( 'blockquote', 'div', 'object', 'q', 'span' );

	// WP bug fix for comments - in case you REALLY meant to type '< !--'
	$text = str_replace( '< !--', '<    !--', $text );
	// WP bug fix for LOVE <3 (and other situations with '<' before a number)
	$text = preg_replace( '#<([0-9]{1})#', '&lt;$1', $text );

	while ( preg_match( '/<(\/?[\w:]*)\s*([^>]*)>/', $text, $regex ) ) {
		$newtext .= $tagqueue;

		$i = strpos( $text, $regex[0] );
		$l = strlen( $regex[0] );

		// clear the shifter
		$tagqueue = '';
		// Pop or Push
		if ( isset( $regex[1][0] ) && '/' == $regex[1][0] ) { // End Tag
			$tag = strtolower( substr( $regex[1], 1 ) );
			// if too many closing tags
			if ( $stacksize <= 0 ) {
				$tag = '';
				// or close to be safe $tag = '/' . $tag;

				// if stacktop value = tag close value then pop
			} elseif ( $tagstack[ $stacksize - 1 ] == $tag ) { // found closing tag
				$tag = '</' . $tag . '>'; // Close Tag
				// Pop
				array_pop( $tagstack );
				$stacksize--;
			} else { // closing tag not at top, search for it
				for ( $j = $stacksize - 1; $j >= 0; $j-- ) {
					if ( $tagstack[ $j ] == $tag ) {
						// add tag to tagqueue
						for ( $k = $stacksize - 1; $k >= $j; $k-- ) {
							$tagqueue .= '</' . array_pop( $tagstack ) . '>';
							$stacksize--;
						}
						break;
					}
				}
				$tag = '';
			}
		} else { // Begin Tag
			$tag = strtolower( $regex[1] );

			// Tag Cleaning

			// If it's an empty tag "< >", do nothing
			if ( '' == $tag ) {
				// do nothing
			} elseif ( substr( $regex[2], -1 ) == '/' ) { // ElseIf it presents itself as a self-closing tag...
				// ...but it isn't a known single-entity self-closing tag, then don't let it be treated as such and
				// immediately close it with a closing tag (the tag will encapsulate no text as a result)
				if ( ! in_array( $tag, $single_tags ) ) {
					$regex[2] = trim( substr( $regex[2], 0, -1 ) ) . "></$tag";
				}
			} elseif ( in_array( $tag, $single_tags ) ) { // ElseIf it's a known single-entity tag but it doesn't close itself, do so
				$regex[2] .= '/';
			} else { // Else it's not a single-entity tag
				// If the top of the stack is the same as the tag we want to push, close previous tag
				if ( $stacksize > 0 && ! in_array( $tag, $nestable_tags ) && $tagstack[ $stacksize - 1 ] == $tag ) {
					$tagqueue = '</' . array_pop( $tagstack ) . '>';
					$stacksize--;
				}
				$stacksize = array_push( $tagstack, $tag );
			}

			// Attributes
			$attributes = $regex[2];
			if ( ! empty( $attributes ) && $attributes[0] != '>' ) {
				$attributes = ' ' . $attributes;
			}

			$tag = '<' . $tag . $attributes . '>';
			//If already queuing a close tag, then put this tag on, too
			if ( ! empty( $tagqueue ) ) {
				$tagqueue .= $tag;
				$tag       = '';
			}
		}
		$newtext .= substr( $text, 0, $i ) . $tag;
		$text     = substr( $text, $i + $l );
	}

	// Clear Tag Queue
	$newtext .= $tagqueue;

	// Add Remaining text
	$newtext .= $text;

	// Empty Stack
	while ( $x = array_pop( $tagstack ) ) {
		$newtext .= '</' . $x . '>'; // Add remaining tags to close
	}

	// WP fix for the bug with HTML comments
	$newtext = str_replace( '< !--', '<!--', $newtext );
	$newtext = str_replace( '<    !--', '< !--', $newtext );

	return $newtext;
}

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Changelog Changelog

Changelog
Version Description
2.0.4 Introduced.


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User Contributed Notes User Contributed Notes

  1. Skip to note 1 content
    Contributed by Codex

    Basic Usage

    <?php force_balance_tags( $text ) ?>
    

    This function is used in the short post excerpt list, to prevent unmatched elements. For example, it makes

    <div><b>This is an excerpt. <!--more--> and this is more text... </b></div>
    

    not break, when the html after the more tag is cut off.

    <div><b>This is an excerpt. 
    

    should be changed to:

    <div><b>This is an excerpt. </b></div>
    

    by the force_balance_tags function.

  2. Skip to note 2 content
    Contributed by Codex

    Basic Usage

    <?php force_balance_tags( $text ) ?>
    

    This function is used in the short post excerpt list, to prevent unmatched elements.
    For example, it makes

    This is an excerpt. and this is more text...

    not break, when the html after the more tag is cut off.

    This is an excerpt.

    should be changed to:

    This is an excerpt.

    by the force_balance_tags function.

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