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PhantasmVisitor.php
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PhantasmVisitor.php
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<?php
declare(strict_types=1);
namespace Phan\Plugin\Internal\PhantasmPlugin;
use ast;
use ast\Node;
use Exception;
use Phan\AST\ASTReverter;
use Phan\AST\ContextNode;
use Phan\Language\Context;
use Phan\PluginV3\PluginAwarePostAnalysisVisitor;
use function in_array;
use function strtolower;
/**
* Replaces expressions with simplified expressions using Phan's information about the entire codebase.
*/
final class PhantasmVisitor extends PluginAwarePostAnalysisVisitor
{
/**
* Visits a node of kind ast\AST_CLASS_CONST to replace the class constant with its value, in cases where it would help performance.
*
* For example, opcache can't optimize away the code or check for `if (ADifferentClass::DEBUG) { ... }`, because the class is in a different file.
* @suppress PhanUndeclaredProperty
*/
public function visitClassConst(Node $node): void
{
if (!isset($node->tolerant_ast_node)) {
return;
}
if (!self::isOptimizableClassNameReference($node->children['class'])) {
return;
}
// CLI::printToStderr("TODO: Support " . ASTReverter::toShortString($node) . "\n");
try {
$constant = (new ContextNode(
$this->code_base,
$this->context,
$node
))->getClassConst();
} catch (Exception $_) {
// Swallow any other types of exceptions. We'll log the errors
// elsewhere.
return;
}
if ($constant->isPHPInternal()) {
// Don't optimize stubs for php constants or the values of php constants
return;
}
$original_node = $constant->getNodeForValue();
if ($original_node === null) {
return;
}
if (!$constant->isPublic()) {
// For now, only optimize uses of public class constants.
return;
}
// @phan-suppress-next-line PhanPartialTypeMismatchArgument
if (!$this->isSafeNodeToSubstitute($constant->getContext(), $original_node)) {
return;
}
$class_fqsen = $constant->getClassFQSEN();
if ($this->code_base->hasClassWithFQSEN($class_fqsen->withAlternateId(1))) {
// Give up on copies of the class.
return;
}
// CLI::printToStderr("TODO: Replace {$constant} with " . ASTReverter::toShortString($constant->getNodeForValue()) . "\n");
// TODO: If the original tolerant_ast_node had no parenthesis, omit the parenthesis here.
$node->tolerant_ast_node->string_replacement = ' /* ' . ASTReverter::toShortString($node) . ' */ (' . ASTReverter::toShortString($original_node) . ')';
}
/**
* Check if the value node of a constant can be safely substituted in other files
* @param Node|string|float|int|null $value_node
*/
public function isSafeNodeToSubstitute(Context $context, $value_node): bool
{
if (!$value_node instanceof Node) {
// TODO: floats might lose precision when converted back to strings by phantasm. Use the original expression based on the parent node?
return \is_int($value_node) || \is_string($value_node); // not null
}
// TODO: Guard against infinite recursion if AST_CLASS_CONST gets supported
switch ($value_node->kind) {
/* TODO: Convert class references to fully qualified class references in the output
case ast\AST_CLASS_CONST:
$name_node = $value_node->children['name'];
if ($name_node instanceof Node && $name_node->kind === ast\AST_NAME) {
if (!self::isSafeNodeToSubstitute($name_node)) {
return false;
}
}
return false;
*/
case ast\AST_CONST:
return $this->isSafeNodeToSubstitute($context, $value_node->children['name']);
case ast\AST_NAME:
// TODO: Support other constants, convert those to fully qualified form before substituting
// @phan-suppress-next-line PhanPartialTypeMismatchArgumentInternal
return \in_array(strtolower($value_node->children['name']), ['true', 'false', 'null'], true);
case ast\AST_UNARY_OP:
case ast\AST_BINARY_OP:
foreach ($value_node->children as $c) {
if (!self::isSafeNodeToSubstitute($context, $c)) {
return false;
}
}
}
return false;
}
/**
* Check if the reference to a class name can be optimized.
* @param Node|string|int|float $node
*/
public static function isOptimizableClassNameReference($node): bool
{
if (!$node instanceof Node || $node->kind !== ast\AST_NAME) {
return false;
}
// Closures can be rebound. For now, treat references to self:: as unsafe to optimize
// @phan-suppress-next-line PhanPartialTypeMismatchArgumentInternal
return !in_array(strtolower($node->children['name']), ['self', 'static', 'parent'], true);
}
}

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PhantasmVisitor.php (5 KB)

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