<?php
/*
* This file is part of Psy Shell.
*
* (c) 2012-2020 Justin Hileman
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/
namespace Psy\CodeCleaner;
use PhpParser\Node;
use PhpParser\Node\Expr;
use PhpParser\Node\Expr\Exit_;
use PhpParser\Node\Stmt;
use PhpParser\Node\Stmt\Break_;
use PhpParser\Node\Stmt\Expression;
use PhpParser\Node\Stmt\If_;
use PhpParser\Node\Stmt\Namespace_;
use PhpParser\Node\Stmt\Return_;
use PhpParser\Node\Stmt\Switch_;
/**
* Add an implicit "return" to the last statement, provided it can be returned.
*/
class ImplicitReturnPass extends CodeCleanerPass
{
/**
* @param array $nodes
*
* @return array
*/
public function beforeTraverse(array $nodes)
{
return $this->addImplicitReturn($nodes);
}
/**
* @param array $nodes
*
* @return array
*/
private function addImplicitReturn(array $nodes)
{
// If nodes is empty, it can't have a return value.
if (empty($nodes)) {
return [new Return_(NoReturnValue::create())];
}
$last = \end($nodes);
// Special case a few types of statements to add an implicit return
// value (even though they technically don't have any return value)
// because showing a return value in these instances is useful and not
// very surprising.
if ($last instanceof If_) {
$last->stmts = $this->addImplicitReturn($last->stmts);
foreach ($last->elseifs as $elseif) {
$elseif->stmts = $this->addImplicitReturn($elseif->stmts);
}
if ($last->else) {
$last->else->stmts = $this->addImplicitReturn($last->else->stmts);
}
} elseif ($last instanceof Switch_) {
foreach ($last->cases as $case) {
// only add an implicit return to cases which end in break
$caseLast = \end($case->stmts);
if ($caseLast instanceof Break_) {
$case->stmts = $this->addImplicitReturn(\array_slice($case->stmts, 0, -1));
$case->stmts[] = $caseLast;
}
}
} elseif ($last instanceof Expr && !($last instanceof Exit_)) {
// @codeCoverageIgnoreStart
$nodes[\count($nodes) - 1] = new Return_($last, [
'startLine' => $last->getLine(),
'endLine' => $last->getLine(),
]);
// @codeCoverageIgnoreEnd
} elseif ($last instanceof Expression && !($last->expr instanceof Exit_)) {
// For PHP Parser 4.x
$nodes[\count($nodes) - 1] = new Return_($last->expr, [
'startLine' => $last->getLine(),
'endLine' => $last->getLine(),
]);
} elseif ($last instanceof Namespace_) {
$last->stmts = $this->addImplicitReturn($last->stmts);
}
// Return a "no return value" for all non-expression statements, so that
// PsySH can suppress the `null` that `eval()` returns otherwise.
//
// Note that statements special cased above (if/elseif/else, switch)
// _might_ implicitly return a value before this catch-all return is
// reached.
//
// We're not adding a fallback return after namespace statements,
// because code outside namespace statements doesn't really work, and
// there's already an implicit return in the namespace statement anyway.
if (self::isNonExpressionStmt($last)) {
$nodes[] = new Return_(NoReturnValue::create());
}
return $nodes;
}
/**
* Check whether a given node is a non-expression statement.
*
* As of PHP Parser 4.x, Expressions are now instances of Stmt as well, so
* we'll exclude them here.
*
* @param Node $node
*
* @return bool
*/
private static function isNonExpressionStmt(Node $node)
{
return $node instanceof Stmt &&
!$node instanceof Expression &&
!$node instanceof Return_ &&
!$node instanceof Namespace_;
}
}