59 lines
1.7 KiB
PHP
59 lines
1.7 KiB
PHP
<?php
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namespace Phabel\Plugin;
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use Phabel\Context;
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use Phabel\Plugin;
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use PhpParser\Node;
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use PhpParser\Node\Expr\BinaryOp\Concat;
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use PhpParser\Node\Scalar\String_;
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use SplQueue;
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/**
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* Optimizes concatenation of multiple strings.
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*/
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class StringConcatOptimizer extends Plugin
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{
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private function enqueue(Concat $concat, SplQueue $queue)
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{
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if ($concat->left instanceof Concat) {
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$this->enqueue($concat->left, $queue);
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} else {
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$queue->enqueue($concat->left);
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}
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if ($concat->right instanceof Concat) {
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$this->enqueue($concat->right, $queue);
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} else {
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$queue->enqueue($concat->right);
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}
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}
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public function enter(Concat $concat, Context $ctx): ?Node
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{
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if ($ctx->parents->top() instanceof Concat) {
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return;
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}
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$concatQueue = new SplQueue;
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$this->enqueue($concat, $concatQueue);
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$newQueue = new SplQueue;
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$prevNode = $concatQueue->dequeue();
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while ($node = $concatQueue->dequeue()) {
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if ($node instanceof String_ && $prevNode instanceof String_) {
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$prevNode = new String_($prevNode->value.$node->value);
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} else {
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$newQueue->enqueue($prevNode);
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$prevNode = $node;
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}
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}
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$newQueue->enqueue($prevNode);
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if ($newQueue->count() === 1) {
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return $newQueue->dequeue();
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}
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$concat = new Concat($newQueue->dequeue(), $newQueue->dequeue());
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while ($node = $newQueue->dequeue()) {
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$concat = new Concat($concat, $newQueue->dequeue());
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}
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return $concat;
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}
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}
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