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LoopVariableReuseVisitor.php
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LoopVariableReuseVisitor.php
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<?php
declare(strict_types=1);
namespace Phan\Plugin\Internal;
use ast;
use ast\Node;
use Phan\Language\Context;
use Phan\Language\Element\Variable;
use Phan\PluginV3\PluginAwarePostAnalysisVisitor;
use function array_intersect_key;
use function count;
use function in_array;
use function is_string;
/**
* This visitor implements the checks for reuse of loop variables.
*/
class LoopVariableReuseVisitor extends PluginAwarePostAnalysisVisitor
{
// A plugin's visitors should not override visit() unless they need to.
/**
* @var list<Node> set by plugin framework
* @suppress PhanReadOnlyProtectedProperty
*/
protected $parent_node_list;
/**
* @override checks for reuse of variables in a node of kind ast\AST_FOREACH
*/
public function visitForeach(Node $node): Context
{
$this->findVariableReuse($this->extractLoopVariablesOfForeach($node));
return $this->context;
}
/**
* Extract "loop variables" of foreach loops.
*
* @return array<string|int,Node>
*/
public function extractLoopVariablesOfForeach(Node $node): array
{
return $this->extractVariables($node->children['key']) + $this->extractVariables($node->children['value']);
}
/**
* @override checks for reuse of variables in a node of kind ast\AST_FOR
*/
public function visitFor(Node $node): Context
{
$this->findVariableReuse($this->extractLoopVariablesOfFor($node));
return $this->context;
}
/**
* Extract "loop variables" of for loops.
*
* @param Node $node a node of kind ast\AST_FOR
* @return array<string|int,Node>
*/
public function extractLoopVariablesOfFor(Node $node): array
{
$directions = RedundantConditionLoopCheck::extractComparisonDirections($node->children['cond']) +
RedundantConditionLoopCheck::extractIncrementDirections($this->code_base, $this->context, $node->children['loop']);
if (!$directions) {
return [];
}
$variables = self::extractVariables($node->children['cond']) + self::extractVariables($node->children['loop']);
return array_intersect_key($variables, $directions);
}
/**
* @override checks for reuse of variables in a node of kind ast\AST_WHILE
*/
public function visitWhile(Node $node): Context
{
$this->findVariableReuse($this->extractLoopVariablesOfWhile($node));
return $this->context;
}
/**
* Extract "loop variables" of while loops.
*
* @param Node $node a node of kind ast\AST_WHILE
* @return array<string|int,Node>
*/
public function extractLoopVariablesOfWhile(Node $node): array
{
$directions = RedundantConditionLoopCheck::extractComparisonDirections($node->children['cond']);
if (!$directions) {
return [];
}
return array_intersect_key(self::extractVariables($node->children['cond']), $directions);
}
/**
* @param array<string|int,Node> $variables
*/
private function findVariableReuse(array $variables): void
{
if (!$variables) {
return;
}
for ($i = count($this->parent_node_list) - 1; $i >= 0; $i--) {
$parent_node = $this->parent_node_list[$i];
$outer_variables = [];
switch ($parent_node->kind) {
case ast\AST_FOREACH:
$outer_variables = $this->extractLoopVariablesOfForeach($parent_node);
break;
case ast\AST_FOR:
$outer_variables = $this->extractLoopVariablesOfFor($parent_node);
break;
case ast\AST_WHILE:
$outer_variables = $this->extractLoopVariablesOfWhile($parent_node);
break;
case ast\AST_FUNC_DECL:
case ast\AST_CLOSURE:
case ast\AST_ARROW_FUNC:
case ast\AST_METHOD:
case ast\AST_CLASS:
return;
default:
continue 2;
}
$common_outer_variables = array_intersect_key($outer_variables, $variables);
if ($common_outer_variables) {
$this->warnCommonOuterVariables($variables, $common_outer_variables);
return;
}
}
}
/**
* @param array<string|int,Node> $variables
* @param array<string|int,Node> $common_outer_variables
*/
private function warnCommonOuterVariables(array $variables, array $common_outer_variables): void
{
foreach ($common_outer_variables as $variable_name => $node) {
$inner_node = $variables[$variable_name];
$this->emitPluginIssue(
$this->code_base,
(clone $this->context)->withLineNumberStart($inner_node->lineno),
'PhanPluginLoopVariableReuse',
'Variable ${VARIABLE} used in loop was also used in an outer loop on line {LINE}',
[$variable_name, $node->lineno]
);
}
}
/**
* @param Node|string|int|float|null $node
* @return array<int|string,Node> a list of all variable nodes in this foreach
*/
public function extractVariables($node): array
{
if (!$node instanceof Node) {
return [];
}
switch ($node->kind) {
case ast\AST_VAR:
if ($node->kind === ast\AST_VAR) {
$var_name = $node->children['name'];
if (is_string($var_name)) {
if (in_array($var_name, ['this', '_'], true) || Variable::isHardcodedVariableInScopeWithName($var_name, $this->context->isInGlobalScope())) {
return [];
}
return [$var_name => $node];
}
}
break;
// Kinds of nodes we don't bother checking
case ast\AST_STATIC_PROP:
case ast\AST_PROP:
// Kinds of declarations creating a new scope.
case ast\AST_FUNC_DECL:
case ast\AST_CLOSURE:
case ast\AST_ARROW_FUNC:
case ast\AST_METHOD:
case ast\AST_CLASS:
// FUNC_DECL and METHOD are probably unreachable.
return [];
}
$result = [];
foreach ($node->children as $child_node) {
$result += $this->extractVariables($child_node);
}
return $result;
}
}

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LoopVariableReuseVisitor.php (6 KB)

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