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<?php |
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namespace ABlocks\Classes; |
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|
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if ( ! defined( 'ABSPATH' ) ) { |
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exit; |
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} |
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|
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/** |
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* Deduplicate generated per-instance CSS by merging rules that share an |
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* identical declaration body into a single grouped selector |
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* (`.a{X} .b{X}` -> `.a,.b{X}`). |
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* |
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* Safety: aBlocks generates per-instance CSS under a unique |
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* `.ablocks-block-{id}` wrapper, so almost every selector is globally unique |
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* and therefore cascade-independent (nothing else in the sheet targets those |
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* elements). We ONLY merge rules whose selector is globally unique, and we emit |
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* each merged group at the position of its first member — rules with a |
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* duplicated selector (which could carry cascade order) and @media blocks are |
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* left exactly in place. Runs on every generation (it produces byte-for-byte |
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* equivalent styling); disable via the `ablocks/perf/dedupe_css` filter. |
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*/ |
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class CssDedupe { |
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|
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public static function process( $css ) { |
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$css = (string) $css; |
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if ( '' === trim( $css ) ) { |
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return $css; |
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} |
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return self::dedupe_scope( $css ); |
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} |
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|
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/** |
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* Dedupe one scope (the whole sheet, or the inside of an @media block). |
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* @media/at-rule segments are passed through (their inner rules are deduped |
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* recursively) and never merged with top-level rules. |
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*/ |
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private static function dedupe_scope( $css ) { |
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$segments = self::parse( $css ); |
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|
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// Frequency of each selector among mergeable (non-at) rules. |
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$freq = []; |
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foreach ( $segments as $s ) { |
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if ( 'rule' === $s['type'] ) { |
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$freq[ $s['sel'] ] = ( $freq[ $s['sel'] ] ?? 0 ) + 1; |
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} |
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} |
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|
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// Group unique-selector rules by identical body; remember first position. |
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$groups = []; |
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foreach ( $segments as $i => $s ) { |
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if ( 'rule' === $s['type'] && 1 === $freq[ $s['sel'] ] && '' !== $s['body'] ) { |
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if ( ! isset( $groups[ $s['body'] ] ) ) { |
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$groups[ $s['body'] ] = [ 'sels' => [], 'first' => $i ]; |
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} |
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$groups[ $s['body'] ]['sels'][] = $s['sel']; |
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} |
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} |
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|
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$out = ''; |
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foreach ( $segments as $i => $s ) { |
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if ( 'at' === $s['type'] ) { |
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$out .= self::dedupe_at_rule( $s['raw'] ); |
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continue; |
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} |
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$mergeable = ( 1 === $freq[ $s['sel'] ] && '' !== $s['body'] ); |
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if ( $mergeable ) { |
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$group = $groups[ $s['body'] ]; |
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if ( $group['first'] === $i ) { |
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$out .= implode( ',', $group['sels'] ) . '{' . $s['body'] . '}'; |
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} |
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// Non-first members are folded into the group above — skip. |
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} else { |
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$out .= $s['raw']; |
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} |
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} |
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return $out; |
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} |
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|
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/** |
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* Recurse into an @media/@supports block's body; leave keyframes/font-face |
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* untouched (order/steps matter). |
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*/ |
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private static function dedupe_at_rule( $raw ) { |
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$open = strpos( $raw, '{' ); |
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if ( false === $open ) { |
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return $raw; |
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} |
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$prelude = substr( $raw, 0, $open ); |
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if ( 0 !== stripos( ltrim( $prelude ), '@media' ) && 0 !== stripos( ltrim( $prelude ), '@supports' ) ) { |
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return $raw; // @keyframes, @font-face, etc. |
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} |
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$inner = substr( $raw, $open + 1, strrpos( $raw, '}' ) - $open - 1 ); |
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return $prelude . '{' . self::dedupe_scope( $inner ) . '}'; |
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} |
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|
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/** |
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* Parse CSS into ordered segments respecting brace depth. Each segment is |
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* either ['type'=>'rule','sel'=>..,'body'=>..,'raw'=>..] or |
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* ['type'=>'at','raw'=>..] for at-rules (prelude starts with '@'). |
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*/ |
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private static function parse( $css ) { |
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$segments = []; |
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$len = strlen( $css ); |
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$i = 0; |
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$buffer = ''; |
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|
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while ( $i < $len ) { |
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$char = $css[ $i ]; |
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$buffer .= $char; |
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|
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if ( '{' === $char ) { |
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$prelude = substr( $buffer, 0, -1 ); |
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$depth = 1; |
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$i++; |
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while ( $i < $len && $depth > 0 ) { |
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$c = $css[ $i ]; |
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$buffer .= $c; |
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if ( '{' === $c ) { |
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$depth++; |
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} elseif ( '}' === $c ) { |
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$depth--; |
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} |
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$i++; |
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} |
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$sel = trim( $prelude ); |
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if ( '' !== $sel && '@' === $sel[0] ) { |
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$segments[] = [ 'type' => 'at', 'raw' => $buffer ]; |
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} else { |
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$body = trim( substr( $buffer, strlen( $prelude ) + 1, -1 ) ); |
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$segments[] = [ 'type' => 'rule', 'sel' => $sel, 'body' => $body, 'raw' => $buffer ]; |
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} |
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$buffer = ''; |
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continue; |
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} |
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$i++; |
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} |
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if ( '' !== trim( $buffer ) ) { |
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$segments[] = [ 'type' => 'at', 'raw' => $buffer ]; // stray text, pass through |
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} |
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return $segments; |
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} |
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} |
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|
