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make_before_block_visitor( array $hooked_blocks, WP_Block_Template|WP_Post|array $context, callable $callback = 'insert_hooked_blocks' ): callable

Since
6.4.0, 6.5.0
Source
wp-includes/blocks.php:1601
Returns a function that injects the theme attribute into, and hooked blocks before, a given block.

Description

The returned function can be used as $pre_callback argument to traverse_and_serialize_block(s), where it will inject the theme attribute into all Template Part blocks, and prepend the markup for any blocks hooked before the given block and as its parent's first_child, respectively.

This function is meant for internal use only.

Compatibility

WordPress
since 6.5.0
PHP
7.4–8.6-dev
  • 6.7.7
  • 6.8.8
  • 6.9.7
  • 7.0.4
  • 7.1.0

Present in every tracked release (6.7.7 to 7.1.0), and compiles on PHP 7.4 through 8.6-dev.

Parameters

$hooked_blocksarray
An array of blocks hooked to another given block.
$contextWP_Block_Template|WP_Post|array
A block template, template part, post object, or pattern that the blocks belong to.
$callbackcallableoptional
A function that will be called for each block to generate the markup for a given list of blocks that are hooked to it.
Default: 'insert_hooked_blocks'.Default: 'insert_hooked_blocks'

Return value

callable
A function that returns the serialized markup for the given block, including the markup for any hooked blocks before it.

Performance profile

How much work a call to make_before_block_visitor() does, and what it touches: the algorithmic scaling, the Zend instruction count per call across PHP versions, the hooks it hands control to, and the core code that calls it. Measured from the compiled opcodes, not a stopwatch, so every number is identical on any machine running the same PHP version, and every function in core is ranked by cost.

Cost class
Trivial

Touches nothing outside its own arguments.

Scaling
Constant

No loop in the body: the same number of instructions runs whatever you pass in.

Instructions
21–31

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 39.

Plugin surface
None

Nothing here hands control to plugin code.

Called by
1

1 place in core call this, so the cost is paid more often than your own code shows.

What one call costs · 1 distinct outcome

One number would be a lie: the work depends on which branch runs. These are every distinct cost make_before_block_visitor() can have, taken from its control-flow graph on PHP 8.5.

WhenInstructionsCalls it makes
always21–31_inject_theme_attribute_in_template_part_block()

Across PHP versions

PHPCompiledExecutedBranchesNotes
8.6-dev3921–312
8.53921–312
8.43921–312
8.33921–312
8.23921–312
8.13921–3122 more instructions than PHP 7.4
7.43720–292

An instruction is not a fixed amount of time, so a matching count is not necessarily the same speed; what it rules out is a difference in the work itself.

Uses · 1

Used by · 1

Source code

function make_before_block_visitor( $hooked_blocks, $context, $callback = 'insert_hooked_blocks' ) {	/**	 * Injects hooked blocks before the given block, injects the `theme` attribute into Template Part blocks, and returns the serialized markup.	 *	 * If the current block is a Template Part block, inject the `theme` attribute.	 * Furthermore, prepend the markup for any blocks hooked `before` the given block and as its parent's	 * `first_child`, respectively, to the serialized markup for the given block.	 *	 * @param array $block        The block to inject the theme attribute into, and hooked blocks before. Passed by reference.	 * @param array $parent_block The parent block of the given block. Passed by reference. Default null.	 * @param array $prev         The previous sibling block of the given block. Default null.	 * @return string The serialized markup for the given block, with the markup for any hooked blocks prepended to it.	 */	return function ( &$block, &$parent_block = null, $prev = null ) use ( $hooked_blocks, $context, $callback ) {		_inject_theme_attribute_in_template_part_block( $block ); 		$markup = ''; 		if ( $parent_block && ! $prev ) {			// Candidate for first-child insertion.			$markup .= call_user_func_array(				$callback,				array( &$parent_block, 'first_child', $hooked_blocks, $context )			);		} 		$markup .= call_user_func_array(			$callback,			array( &$block, 'before', $hooked_blocks, $context )		); 		return $markup;	};}

Changelog

Introduced in 6.4.0. Unchanged from 6.7.7 through 7.1.0.

  1. 6.7.7
  2. 6.8.8
  3. 6.9.7
  4. 7.0.4
  5. 7.1.0

Signature, return type and hooks compared across 5 parsed releases.

6.5.0
Added $callback argument.from the docblock
6.4.0
Introduced.from the docblock

About this page

Parsed data
Generated from the wordpress-develop 7.1.0 tag, from src/wp-includes/blocks.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.
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