WP_View_Config_Data::merge_list_by_identity( array $current, array $incoming ): array
- Since
- 7.1.0
- Source
wp-includes/class-wp-view-config-data.php:676
Description
A member of the incoming list whose identity matches one already present merges into it in place, keeping its position; an unmatched member is appended to the end, except a literal null, which carries no identity and holds nothing to merge and so is dropped. An appended member has no existing leaf for a nested null to delete (the same rationale as set()), so its nulls are stripped rather than stored. A matched member's contents merge recursively with the same rules (merge_properties), so the identity-aware merge applies at any nesting level: each key named by the patch is substituted while the others are left intact, and a list nested inside a member merges by identity just like the list it lives in.
Compatibility
- WordPress
- since 7.1.0
- PHP
- 7.4–8.6-dev
- 6.7.7
- 6.8.8
- 6.9.7
- 7.0.4
- 7.1.0
Present in 1 of the 5 tracked releases, added in 7.1.0, and compiles on PHP 7.4 through 8.6-dev.
Parameters
$currentarray- The current list.
$incomingarray- The incoming list.
Return value
array- The merged list.
Performance profile
How much work a call to WP_View_Config_Data::merge_list_by_identity() 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
- Scaling
- Scales with input
- Instructions
- 6–7
- Plugin surface
- None
- Called by
- 1
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 44.
Nothing here hands control to plugin code.
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 WP_View_Config_Data::merge_list_by_identity() can have, taken from its control-flow graph on PHP 8.5.
| When | Instructions | Calls it makes |
|---|---|---|
| always | 6–7 | none |
Across PHP versions
Compiles the same on PHP 7.4, 8.1, 8.2, 8.3, 8.4, 8.5 and 8.6-dev: 44 instructions, 6–7 executed per call, 8 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 · 3
- WP_View_Config_Data::list_item_identity()Resolves the identity used to match a list member against another.
- WP_View_Config_Data::strip_nulls()Recursively drops every property whose value is `null` from a value.
- WP_View_Config_Data::merge_properties()Merges an incoming value into the current one, recursing by value shape.
Used by · 1
- WP_View_Config_Data::merge_properties()Merges an incoming value into the current one, recursing by value shape.
Source code
private function merge_list_by_identity( array $current, array $incoming ) { $result = $current; foreach ( $incoming as $item ) { // A null member carries no identity and holds nothing to merge, // so it is dropped rather than appended as a literal null. if ( null === $item ) { continue; } $identity = $this->list_item_identity( $item ); // Find the index of the existing member with the same identity, if any. // If there's none, append the incoming member to the end of the list. $index = null; if ( null !== $identity ) { foreach ( $result as $i => $existing ) { if ( $this->list_item_identity( $existing ) === $identity ) { $index = $i; break; } } } if ( null === $index ) { // An appended member has no existing leaf for a nested null to // delete, so nulls are dropped rather than stored. $result[] = $this->strip_nulls( $item ); continue; } // Otherwise, merge the incoming member into the existing one in place. $result[ $index ] = $this->merge_properties( $result[ $index ], $item, false ); } return $result; }Changelog
Introduced in 7.1.0.
Signature, return type and hooks compared across 1 parsed release.
About this page
- Parsed data
- Generated from the wordpress-develop 7.1.0 tag, from
src/wp-includes/class-wp-view-config-data.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.