WP_Theme_JSON::prepend_to_selector( string $selector, string $to_prepend ): string
- Since
- 6.3.0
- Source
wp-includes/class-wp-theme-json.php:1537
Description
Given the compounded $selector "h1, h2, h3" and the $to_prepend selector ".some-class " the result will be ".some-class h1, .some-class h2, .some-class h3".
Compatibility
- WordPress
- since 6.3.0
- 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
$selectorstring- Original selector.
$to_prependstring- Selector to prepend.
Return value
string- The new selector.
Performance profile
How much work a call to WP_Theme_JSON::prepend_to_selector() does, and what it touches: the algorithmic scaling, the Zend instruction count per call across PHP versions, the hooks it hands control to, and the core code that calls it. Measured from the compiled opcodes, not a stopwatch, so every number is identical on any machine running the same PHP version, and every function in core is ranked by cost.
- Cost class
- Light
- Scaling
- Scales with input
- Instructions
- 7–21
- Plugin surface
- None
- Called by
- 0
Touches nothing outside its own arguments.
The body loops, so the work grows with what you pass in.
Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 34.
Nothing here hands control to plugin code.
Nothing in core calls this; the cost is only what you spend yourself.
What one call costs · 3 distinct outcomes
One number would be a lie: the work depends on which branch runs. These are every distinct cost WP_Theme_JSON::prepend_to_selector() can have, taken from its control-flow graph on PHP 8.5.
| When | Instructions | Calls it makes |
|---|---|---|
!$selector | 7 | none |
$selector | 17 | strcspn() |
$selector | 20–21 | strcspn(), ::split_selector_list() |
Across PHP versions
| PHP | Compiled | Executed | Branches | Notes |
|---|---|---|---|---|
| 8.6-dev | 34 | 7–21 | 4 | |
| 8.5 | 34 | 7–21 | 4 | |
| 8.4 | 34 | 7–21 | 4 | 15 fewer instructions than PHP 8.3 |
| 8.3 | 49 | 13–27 | 4 | |
| 8.2 | 49 | 13–27 | 4 | |
| 8.1 | 49 | 13–27 | 4 | |
| 7.4 | 49 | 13–27 | 4 |
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
- str_contains()Polyfill for `str_contains()` function added in PHP 8.0.
- static::split_selector_list()
Source code
protected static function prepend_to_selector( $selector, $to_prepend ) { if ( ! str_contains( $selector, ',' ) ) { return $to_prepend . trim( $selector, " \t\n" ); } /** * Check for an opportunity to skip the more-costly selector splitting. * This should be possible if there are no comments, strings, functions, * URLs, escapes, or comment declaration openers (CDOs). * * Note that this means the fast-path will not apply for selectors like * the following incomplete list: * * - `[class ~= "wide"]` * - `.wp-block:is(.is-style-a, .is-style-b)` * - `:nth-child(1)` * * These syntax forms all present opportunities where a comma may not * separate selectors. If none of the start characters are present, * there should be no way for a comma to mean anything other than a * comma token. The exception are syntax errors, which are not handled here. * * @see https://www.w3.org/TR/css-syntax-3/#parse-comma-separated-list-of-component-values */ if ( strlen( $selector ) === strcspn( $selector, '/\'"(<\\' ) ) { return $to_prepend . preg_replace( '~[ \t\n]*,[ \t\n]*~', ", {$to_prepend}", trim( $selector, " \t\n" ) ); } $new_selectors = array(); $selectors = static::split_selector_list( $selector ); foreach ( $selectors as $sel ) { $new_selectors[] = $to_prepend . $sel; } return implode( ', ', $new_selectors ); }Changelog
Introduced in 6.3.0. 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/class-wp-theme-json.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.