Given an array of parsed block trees, applies callbacks before and after serializing them and returns their concatenated output.
Description
Recursively traverses the blocks and their inner blocks and applies the two callbacks provided as arguments, the first one before serializing a block, and the second one after serializing.
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 blocks, or to inject markup into the return value. Prefer serialize_blocks when preparing blocks to be saved to post content.
This function is meant for internal use only.
See also
Parameters
$blocksarray[]required- An array of parsed blocks. 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
Source
function traverse_and_serialize_blocks( $blocks, $pre_callback = null, $post_callback = null ) {
$result = '';
$parent_block = null; // At the top level, there is no parent block to pass to the callbacks; yet the callbacks expect a reference.
foreach ( $blocks as $index => $block ) {
if ( is_callable( $pre_callback ) ) {
$prev = 0 === $index
? null
: $blocks[ $index - 1 ];
$result .= call_user_func_array(
$pre_callback,
array( &$block, &$parent_block, $prev )
);
}
if ( is_callable( $post_callback ) ) {
$next = count( $blocks ) - 1 === $index
? null
: $blocks[ $index + 1 ];
$post_markup = call_user_func_array(
$post_callback,
array( &$block, &$parent_block, $next )
);
}
$result .= traverse_and_serialize_block( $block, $pre_callback, $post_callback );
$result .= isset( $post_markup ) ? $post_markup : '';
}
return $result;
}
Changelog
| Version | Description |
|---|---|
| 6.4.0 | Introduced. |
User Contributed Notes
You must log in before being able to contribute a note or feedback.