traverse_and_serialize_block( array $block, callable $pre_callback = null, callable $post_callback = null ): string
- Since
- 6.4.0
- Source
wp-includes/blocks.php:1875
Description
Recursively traverses the block and its inner blocks and applies the two callbacks provided as arguments, the first one before serializing the block, and the second one after serializing it.
If either callback returns a string value, it will be prepended and appended to the serialized block markup, respectively.
The callbacks will receive a reference to the current block as their first argument, so that they can also modify it, and the current block's parent block as second argument. Finally, the $pre_callback receives the previous block, whereas the $post_callback receives the next block as third argument.
Serialized blocks are returned including comment delimiters, and with all attributes serialized.
This function should be used when there is a need to modify the saved block, or to inject markup into the return value. Prefer serialize_block when preparing a block to be saved to post content.
This function is meant for internal use only.
Compatibility
- WordPress
- since 6.4.0
- 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
$blockarray- An associative array of a single parsed block object. See WP_Block_Parser_Block.
$pre_callbackcallableoptional- Callback to run on each block in the tree before it is traversed and serialized.
It is called with the following arguments: &$block, $parent_block, $previous_block.
Its string return value will be prepended to the serialized block markup.Default:null $post_callbackcallableoptional- Callback to run on each block in the tree after it is traversed and serialized.
It is called with the following arguments: &$block, $parent_block, $next_block.
Its string return value will be appended to the serialized block markup.Default:null
Return value
string- Serialized block markup.
Performance profile
How much work a call to traverse_and_serialize_block() 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
- Light
- Scaling
- Scales with input
- Instructions
- 21–24
- Plugin surface
- None
- Called by
- 2
Touches nothing outside its own arguments.
The body loops, so the work grows with what you pass in.
Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 85.
Nothing here hands control to plugin code.
2 places 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 traverse_and_serialize_block() can have, taken from its control-flow graph on PHP 8.5.
| When | Instructions | Calls it makes |
|---|---|---|
| always | 21–24 | get_comment_delimited_block_content() |
Across PHP versions
Compiles the same on PHP 7.4, 8.1, 8.2, 8.3, 8.4, 8.5 and 8.6-dev: 85 instructions, 21–24 executed per call, 9 branches. The work does not change between versions.
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 · 2
- traverse_and_serialize_block()Traverses a parsed block tree and applies callbacks before and after serializing it.
- get_comment_delimited_block_content()Returns the content of a block, including comment delimiters.
Used by · 2
- traverse_and_serialize_block()Traverses a parsed block tree and applies callbacks before and after serializing it.
- traverse_and_serialize_blocks()Given an array of parsed block trees, applies callbacks before and after serializing them and returns their concatenated output.
Source code
function traverse_and_serialize_block( $block, $pre_callback = null, $post_callback = null ) { $block_content = ''; $block_index = 0; foreach ( $block['innerContent'] as $chunk ) { if ( is_string( $chunk ) ) { $block_content .= $chunk; } else { $inner_block = $block['innerBlocks'][ $block_index ]; if ( is_callable( $pre_callback ) ) { $prev = 0 === $block_index ? null : $block['innerBlocks'][ $block_index - 1 ]; $block_content .= call_user_func_array( $pre_callback, array( &$inner_block, &$block, $prev ) ); } if ( is_callable( $post_callback ) ) { $next = count( $block['innerBlocks'] ) - 1 === $block_index ? null : $block['innerBlocks'][ $block_index + 1 ]; $post_markup = call_user_func_array( $post_callback, array( &$inner_block, &$block, $next ) ); } $block_content .= traverse_and_serialize_block( $inner_block, $pre_callback, $post_callback ); $block_content .= $post_markup ?? ''; ++$block_index; } } if ( ! is_array( $block['attrs'] ) ) { $block['attrs'] = array(); } return get_comment_delimited_block_content( $block['blockName'], $block['attrs'], $block_content );}Changelog
Introduced in 6.4.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
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. - Corrections
- Something wrong on this page? Report it and it gets fixed in the next regeneration.