373 lines
10 KiB
PHP
373 lines
10 KiB
PHP
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<?php
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namespace staabm\SideEffectsDetector;
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final class SideEffectsDetector {
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/**
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* @var array<int>
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*/
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private array $scopePollutingTokens = [
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T_CLASS,
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T_FUNCTION,
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T_NEW,
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T_EVAL,
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T_GLOBAL,
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T_GOTO,
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T_HALT_COMPILER,
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T_INCLUDE,
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T_INCLUDE_ONCE,
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T_REQUIRE,
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T_REQUIRE_ONCE,
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T_THROW,
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T_UNSET,
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T_UNSET_CAST
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];
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private const PROCESS_EXIT_TOKENS = [
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T_EXIT
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];
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private const OUTPUT_TOKENS = [
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T_PRINT,
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T_ECHO,
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T_INLINE_HTML
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];
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private const SCOPE_POLLUTING_FUNCTIONS = [
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'putenv',
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'setlocale',
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'class_exists',
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'ini_set',
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];
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private const STANDARD_OUTPUT_FUNCTIONS = [
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'printf',
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'vprintf'
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];
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private const INPUT_OUTPUT_FUNCTIONS = [
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'fopen',
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'file_get_contents',
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'file_put_contents',
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'fwrite',
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'fputs',
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'fread',
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'unlink'
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];
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/**
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* @var array<string, array{'hasSideEffects': bool}>
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*/
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private array $functionMetadata;
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public function __construct() {
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$functionMeta = require __DIR__ . '/functionMetadata.php';
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if (!is_array($functionMeta)) {
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throw new \RuntimeException('Invalid function metadata');
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}
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$this->functionMetadata = $functionMeta;
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if (defined('T_ENUM')) {
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$this->scopePollutingTokens[] = T_ENUM;
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}
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}
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/**
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* @api
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*
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* @return array<SideEffect::*>
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*/
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public function getSideEffects(string $code): array {
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$tokens = token_get_all($code);
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$sideEffects = [];
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for ($i = 0; $i < count($tokens); $i++) {
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$token = $tokens[$i];
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if (!is_array($token)) {
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continue;
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}
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if ($this->isAnonymousFunction($tokens, $i)) {
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continue;
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}
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if (in_array($token[0], self::OUTPUT_TOKENS, true)) {
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$sideEffects[] = SideEffect::STANDARD_OUTPUT;
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continue;
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}
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if (in_array($token[0], self::PROCESS_EXIT_TOKENS, true)) {
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$sideEffects[] = SideEffect::PROCESS_EXIT;
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continue;
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}
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if (in_array($token[0], $this->scopePollutingTokens, true)) {
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$sideEffects[] = SideEffect::SCOPE_POLLUTION;
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$i++;
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if (in_array($token[0], [T_FUNCTION, T_CLASS], true)) {
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$this->consumeWhitespaces($tokens, $i);
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}
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// consume function/class-name
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if (
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!array_key_exists($i, $tokens)
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|| !is_array($tokens[$i])
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|| $tokens[$i][0] !== T_STRING
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) {
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continue;
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}
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$i++;
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continue;
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}
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$functionCall = $this->getFunctionCall($tokens, $i);
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if ($functionCall !== null) {
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$callSideEffect = $this->getFunctionCallSideEffect($functionCall);
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if ($callSideEffect !== null) {
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$sideEffects[] = $callSideEffect;
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}
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continue;
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}
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$methodCall = $this->getMethodCall($tokens, $i);
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if ($methodCall !== null) {
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$sideEffects[] = SideEffect::MAYBE;
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continue;
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}
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$propertyAccess = $this->getPropertyAccess($tokens, $i);
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if ($propertyAccess !== null) {
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$sideEffects[] = SideEffect::SCOPE_POLLUTION;
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continue;
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}
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if ($this->isNonLocalVariable($tokens, $i)) {
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$sideEffects[] = SideEffect::SCOPE_POLLUTION;
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continue;
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}
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}
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return array_values(array_unique($sideEffects));
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}
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/**
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* @return SideEffect::*|null
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*/
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private function getFunctionCallSideEffect(string $functionName): ?string { // @phpstan-ignore return.unusedType
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if (in_array($functionName, self::STANDARD_OUTPUT_FUNCTIONS, true)) {
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return SideEffect::STANDARD_OUTPUT;
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}
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if (in_array($functionName, self::INPUT_OUTPUT_FUNCTIONS, true)) {
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return SideEffect::INPUT_OUTPUT;
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}
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if (in_array($functionName, self::SCOPE_POLLUTING_FUNCTIONS, true)) {
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return SideEffect::SCOPE_POLLUTION;
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}
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if (array_key_exists($functionName, $this->functionMetadata)) {
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if ($this->functionMetadata[$functionName]['hasSideEffects'] === true) {
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return SideEffect::UNKNOWN_CLASS;
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}
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} else {
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try {
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$reflectionFunction = new \ReflectionFunction($functionName);
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$returnType = $reflectionFunction->getReturnType();
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if ($returnType === null) {
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return SideEffect::MAYBE; // no reflection information -> we don't know
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}
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if ((string)$returnType === 'void') {
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return SideEffect::UNKNOWN_CLASS; // functions with void return type must have side-effects
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}
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} catch (\ReflectionException $e) {
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return SideEffect::MAYBE; // function does not exist -> we don't know
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}
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}
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return null;
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}
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/**
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* @param array<int, array{0:int,1:string,2:int}|string|int> $tokens
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*/
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private function getFunctionCall(array $tokens, int $index): ?string {
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if (
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!array_key_exists($index, $tokens)
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|| !is_array($tokens[$index])
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|| $tokens[$index][0] !== T_STRING
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) {
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return null;
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}
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$functionName = $tokens[$index][1];
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$index++;
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$this->consumeWhitespaces($tokens, $index);
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if (
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array_key_exists($index, $tokens)
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&& $tokens[$index] === '('
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) {
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return $functionName;
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}
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return null;
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}
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/**
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* @param array<int, array{0:int,1:string,2:int}|string|int> $tokens
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*/
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private function getMethodCall(array $tokens, int $index): ?string {
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if (
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!array_key_exists($index, $tokens)
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|| !is_array($tokens[$index])
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|| !in_array($tokens[$index][0], [T_VARIABLE, T_STRING], true)
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) {
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return null;
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}
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$callee = $tokens[$index][1];
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$index++;
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$this->consumeWhitespaces($tokens, $index);
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if (
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!array_key_exists($index, $tokens)
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|| !is_array($tokens[$index])
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|| !in_array($tokens[$index][0], [T_OBJECT_OPERATOR , T_DOUBLE_COLON ], true)
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) {
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return null;
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}
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$operator = $tokens[$index][1];
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$index++;
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$this->consumeWhitespaces($tokens, $index);
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if (
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!array_key_exists($index, $tokens)
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|| !is_array($tokens[$index])
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|| !in_array($tokens[$index][0], [T_STRING], true)
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) {
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return null;
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}
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$method = $tokens[$index][1];
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$index++;
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$this->consumeWhitespaces($tokens, $index);
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if (
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array_key_exists($index, $tokens)
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&& $tokens[$index] !== '('
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) {
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return null;
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}
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return $callee . $operator . $method;
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}
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/**
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* @param array<int, array{0:int,1:string,2:int}|string|int> $tokens
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*/
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private function getPropertyAccess(array $tokens, int $index): ?string {
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if (
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!array_key_exists($index, $tokens)
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|| !is_array($tokens[$index])
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|| !in_array($tokens[$index][0], [T_VARIABLE, T_STRING], true)
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) {
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return null;
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}
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$objectOrClass = $tokens[$index][1];
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$index++;
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$this->consumeWhitespaces($tokens, $index);
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if (
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!array_key_exists($index, $tokens)
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|| !is_array($tokens[$index])
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|| !in_array($tokens[$index][0], [T_OBJECT_OPERATOR , T_DOUBLE_COLON ], true)
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) {
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return null;
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}
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$operator = $tokens[$index][1];
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$index++;
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$this->consumeWhitespaces($tokens, $index);
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if (
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!array_key_exists($index, $tokens)
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|| !is_array($tokens[$index])
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|| !in_array($tokens[$index][0], [T_STRING, T_VARIABLE], true)
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) {
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return null;
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}
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$propName = $tokens[$index][1];
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return $objectOrClass . $operator . $propName;
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}
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/**
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* @param array<int, array{0:int,1:string,2:int}|string|int> $tokens
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*/
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private function isAnonymousFunction(array $tokens, int $index): bool
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{
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if (
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!array_key_exists($index, $tokens)
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|| !is_array($tokens[$index])
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|| $tokens[$index][0] !== T_FUNCTION
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) {
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return false;
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}
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$index++;
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$this->consumeWhitespaces($tokens, $index);
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if (
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array_key_exists($index, $tokens)
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&& $tokens[$index] === '('
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) {
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return true;
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}
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return false;
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}
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/**
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* @param array<int, array{0:int,1:string,2:int}|string|int> $tokens
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*/
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private function isNonLocalVariable(array $tokens, int $index): bool
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{
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if (
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array_key_exists($index, $tokens)
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&& is_array($tokens[$index])
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&& $tokens[$index][0] === T_VARIABLE
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) {
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if (
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in_array(
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$tokens[$index][1],
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[
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'$this',
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'$GLOBALS', '$_SERVER', '$_GET', '$_POST', '$_FILES', '$_COOKIE', '$_SESSION', '$_REQUEST', '$_ENV',
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],
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true)
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) {
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return true;
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}
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}
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return false;
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}
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/**
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* @param array<int, array{0:int,1:string,2:int}|string|int> $tokens
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*/
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private function consumeWhitespaces(array $tokens, int &$index): void {
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while (
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array_key_exists($index, $tokens)
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&& is_array($tokens[$index])
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&& $tokens[$index][0] === T_WHITESPACE
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) {
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$index++;
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}
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}
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}
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