145 lines
4.1 KiB
PHP
145 lines
4.1 KiB
PHP
<?php
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namespace Phabel\Plugin;
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use Phabel\Plugin;
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use PhpParser\Node;
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use PhpParser\Node\Expr\Array_;
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use PhpParser\Node\Expr\ArrayDimFetch;
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use PhpParser\Node\Expr\Assign;
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use PhpParser\Node\Expr\Isset_;
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use PhpParser\Node\Expr\Variable;
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use PhpParser\Node\FunctionLike;
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use PhpParser\Node\Identifier;
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use PhpParser\Node\Param;
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use PhpParser\Node\Stmt\If_;
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use PhpParser\Node\Stmt\Return_;
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use PhpParser\Node\Stmt\Static_;
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use PhpParser\Node\Stmt\StaticVar;
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use SplStack;
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/**
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* Enable memoization of results based on a parameter.
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*
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* @author Daniil Gentili <daniil@daniil.it>
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* @license MIT
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*/
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class Memoization
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{
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/**
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* Stack of cache objects for current function.
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*
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* @var SplStack<null|ArrayDimFetch>
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*/
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private SplStack $cache;
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/**
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* Stack of stmts to prepend for current function.
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*
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* @var SplStack<Node[]>
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*/
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private SplStack $stmts;
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/**
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* Constructor function.
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*/
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public function __construct()
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{
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$this->cache = new SplStack;
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$this->stmts = new SplStack;
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}
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/**
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* Enter functions.
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*
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* @param FunctionLike $node Function
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*
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* @return void
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*/
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public function enterFunctionLike(FunctionLike $node): void
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{
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if (!\preg_match_all('/@memoize \$([\w\d_]+)/', (string) ($node->getDocComment() ?? ''), $matches)) {
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$this->cache->push(null);
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$this->stmts->push([]);
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return;
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}
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if ($node->getReturnType() instanceof Identifier && $node->getReturnType()->name === 'void') {
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throw new \RuntimeException('Cannot memoize void function');
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}
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/** @var Node[] */
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$toPrepend = [];
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/** @var string[] */
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$memoizeParams = $matches[1];
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/** @var array<string, Param> */
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$params = [];
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foreach ($node->getParams() as $param) {
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if (!$param->var instanceof Variable) {
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continue;
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}
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$params[$param->var->name] = $param;
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}
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/** @var Variable[] */
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$memoizeVars = [];
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foreach ($memoizeParams as $memoizeVar) {
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if (!isset($params[$memoizeVar])) {
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throw new \RuntimeException('Cannot find memoization parameter $'.$memoizeVar);
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}
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$memoizeParam = $params[$memoizeVar];
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if ($memoizeParam->type === null) {
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throw new \RuntimeException('Cannot memoize by untyped parameter $'.$memoizeVar);
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}
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if ($memoizeParam->type instanceof Identifier) {
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if ($memoizeParam->type->name === 'array') {
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throw new \RuntimeException('Cannot memoize by array parameter $'.$memoizeVar);
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}
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if (\in_array($memoizeParam->type->name, ['string', 'int', 'float', 'bool'])) {
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$memoizeVars[] = $memoizeParam->var;
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continue;
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}
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}
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$toPrepend []= Plugin::assign(
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$variable = new Variable($memoizeParam->var->name.'___memo'),
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Plugin::call('spl_object_hash', $memoizeParam->var)
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);
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$memoizeVars []= $variable;
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}
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$toPrepend []= new Static_([new StaticVar($cache = new Variable('memoizeCache'), new Array_())]);
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foreach ($memoizeVars as $var) {
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$cache = new ArrayDimFetch($cache, $var);
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}
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$toPrepend []= new If_(new Isset_([$cache]), [new Return_($cache)]);
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$this->cache->push($cache);
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$this->stmts->push($toPrepend);
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}
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/**
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* Leave function.
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*
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* @param FunctionLike $fun Function
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*
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* @return void
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*/
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public function leaveFunctionLike(FunctionLike $fun): void
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{
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$this->cache->pop();
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$fun->stmts = \array_merge($this->stmts->pop(), $fun->stmts);
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}
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/**
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* Enter return expression.
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*
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* @param Return_ $return Return expression
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*
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* @return void
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*/
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public function enterReturn(Return_ $return)
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{
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if ($this->cache->top()) {
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$return->expr = new Assign($this->cache->top(), $return->expr);
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}
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}
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}
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