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Merge pull request #277 from PHPCSStandards/universal/new-nodoublenegative-sniff
✨ New `Universal.CodeAnalysis.NoDoubleNegative` sniff
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‎Universal/Docs/CodeAnalysis/NoDoubleNegativeStandard.xml

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<?xml version="1.0"?>
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<documentation xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:noNamespaceSchemaLocation="https://phpcsstandards.github.io/PHPCSDevTools/phpcsdocs.xsd"
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title="No Double Negative"
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>
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<standard>
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<![CDATA[
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Detects double negation in code, which is effectively the same as a boolean cast, but with a much higher cognitive load.
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]]>
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</standard>
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<code_comparison>
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<code title="Valid: using singular negation or a boolean cast.">
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<![CDATA[
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$var = $a && <em>!</em> $b;
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if(<em>(bool)</em> callMe($a)) {}
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]]>
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</code>
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<code title="Invalid: using double negation (or more).">
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<![CDATA[
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$var = $a && <em>! !</em> $b;
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if(<em>! ! !</em> callMe($a)) {}
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]]>
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</code>
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</code_comparison>
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</documentation>

‎Universal/Sniffs/CodeAnalysis/NoDoubleNegativeSniff.php

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<?php
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/**
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* PHPCSExtra, a collection of sniffs and standards for use with PHP_CodeSniffer.
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*
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* @package PHPCSExtra
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* @copyright 2023 PHPCSExtra Contributors
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* @license https://opensource.org/licenses/LGPL-3.0 LGPL3
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* @link https://github.com/PHPCSStandards/PHPCSExtra
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*/
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namespace PHPCSExtra\Universal\Sniffs\CodeAnalysis;
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use PHP_CodeSniffer\Files\File;
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use PHP_CodeSniffer\Sniffs\Sniff;
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use PHP_CodeSniffer\Util\Tokens;
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use PHPCSUtils\BackCompat\BCFile;
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use PHPCSUtils\Utils\GetTokensAsString;
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use PHPCSUtils\Utils\Parentheses;
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/**
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* Detects double negation in code, which is effectively the same as a boolean cast,
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* but with a much higher cognitive load.
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*
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* The sniff will only autofix if the precedence change from boolean not to boolean cast
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* will not cause a behavioural change (as it would with instanceof).
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*
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* @since 1.2.0
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*/
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final class NoDoubleNegativeSniff implements Sniff
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{
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/**
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* Operators with lower precedence than the not-operator.
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*
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* Used to determine when to stop searching for `instanceof`.
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*
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* @since 1.2.0
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*
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* @var array<int|string, int|string>
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*/
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private $operatorsWithLowerPrecedence;
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/**
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* Returns an array of tokens this test wants to listen for.
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*
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* @since 1.2.0
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*
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* @return array<int|string>
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*/
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public function register()
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{
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// Collect all the operators only once.
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$this->operatorsWithLowerPrecedence = Tokens::$assignmentTokens;
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$this->operatorsWithLowerPrecedence += Tokens::$booleanOperators;
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$this->operatorsWithLowerPrecedence += Tokens::$comparisonTokens;
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$this->operatorsWithLowerPrecedence += Tokens::$operators;
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$this->operatorsWithLowerPrecedence[\T_INLINE_THEN] = \T_INLINE_THEN;
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$this->operatorsWithLowerPrecedence[\T_INLINE_ELSE] = \T_INLINE_ELSE;
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return [\T_BOOLEAN_NOT];
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}
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/**
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* Processes this test, when one of its tokens is encountered.
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*
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* @since 1.2.0
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*
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* @param \PHP_CodeSniffer\Files\File $phpcsFile The file being scanned.
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* @param int $stackPtr The position of the current token
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* in the stack passed in $tokens.
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*
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* @return int|void Integer stack pointer to skip forward or void to continue
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* normal file processing.
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*/
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public function process(File $phpcsFile, $stackPtr)
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{
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$tokens = $phpcsFile->getTokens();
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$notCount = 1;
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$lastNot = $stackPtr;
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for ($afterNot = ($stackPtr + 1); $afterNot < $phpcsFile->numTokens; $afterNot++) {
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if (isset(Tokens::$emptyTokens[$tokens[$afterNot]['code']])) {
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continue;
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}
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if ($tokens[$afterNot]['code'] === \T_BOOLEAN_NOT) {
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$lastNot = $afterNot;
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++$notCount;
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continue;
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}
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break;
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}
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if ($notCount === 1) {
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// Singular unary not-operator. Nothing to do.
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return;
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}
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$found = \trim(GetTokensAsString::compact($phpcsFile, $stackPtr, $lastNot));
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$data = [$found];
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if (($notCount % 2) === 1) {
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/*
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* Oh dear... silly code time, found a triple negative (or other uneven number),
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* this should just be a singular not-operator.
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*/
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$fix = $phpcsFile->addFixableError(
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'Triple negative (or more) detected. Use a singular not (!) operator instead. Found: %s',
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$stackPtr,
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'FoundTriple',
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$data
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);
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if ($fix === true) {
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$phpcsFile->fixer->beginChangeset();
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$this->removeNotAndTrailingSpaces($phpcsFile, $stackPtr, $lastNot);
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$phpcsFile->fixer->endChangeset();
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}
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// Only throw one error, even if there are more than two not-operators.
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return $lastNot;
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}
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/*
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* Found a double negative, which should be a boolean cast.
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*/
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$fixable = true;
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/*
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* If whatever is being "cast" is within parentheses, we're good.
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* If not, we need to prevent creating a change in behaviour
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* when what follows is an `$x instanceof ...` expression, as
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* the "instanceof" operator is right between a boolean cast
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* and the ! operator precedence-wise.
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*
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* Note: this only applies to double negative, not triple negative.
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*
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* @link https://www.php.net/language.operators.precedence
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*/
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if ($tokens[$afterNot]['code'] !== \T_OPEN_PARENTHESIS) {
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$end = Parentheses::getLastCloser($phpcsFile, $stackPtr);
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if ($end === false) {
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$end = BCFile::findEndOfStatement($phpcsFile, $stackPtr);
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}
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for ($nextRelevant = $afterNot; $nextRelevant < $end; $nextRelevant++) {
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if (isset(Tokens::$emptyTokens[$tokens[$nextRelevant]['code']])) {
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continue;
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}
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if ($tokens[$nextRelevant]['code'] === \T_INSTANCEOF) {
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$fixable = false;
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break;
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}
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if (isset($this->operatorsWithLowerPrecedence[$tokens[$nextRelevant]['code']])) {
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// The expression the `!` belongs to has ended.
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break;
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}
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// Skip over anything within some form of brackets.
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if (isset($tokens[$nextRelevant]['scope_closer'])
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&& ($nextRelevant === $tokens[$nextRelevant]['scope_opener']
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|| $nextRelevant === $tokens[$nextRelevant]['scope_condition'])
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) {
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$nextRelevant = $tokens[$nextRelevant]['scope_closer'];
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continue;
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}
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if (isset($tokens[$nextRelevant]['bracket_opener'], $tokens[$nextRelevant]['bracket_closer'])
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&& $nextRelevant === $tokens[$nextRelevant]['bracket_opener']
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) {
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$nextRelevant = $tokens[$nextRelevant]['bracket_closer'];
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continue;
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}
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if ($tokens[$nextRelevant]['code'] === \T_OPEN_PARENTHESIS
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&& isset($tokens[$nextRelevant]['parenthesis_closer'])
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) {
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$nextRelevant = $tokens[$nextRelevant]['parenthesis_closer'];
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continue;
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}
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// Skip over attributes (just in case).
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if ($tokens[$nextRelevant]['code'] === \T_ATTRIBUTE
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&& isset($tokens[$nextRelevant]['attribute_closer'])
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) {
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$nextRelevant = $tokens[$nextRelevant]['attribute_closer'];
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continue;
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}
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}
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}
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$error = 'Double negative detected. Use a (bool) cast %s instead. Found: %s';
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$code = 'FoundDouble';
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$data = [
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'',
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$found,
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];
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if ($fixable === false) {
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$code = 'FoundDoubleWithInstanceof';
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$data[0] = 'and parentheses around the instanceof expression';
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// Don't auto-fix in combination with instanceof.
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$phpcsFile->addError($error, $stackPtr, $code, $data);
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// Only throw one error, even if there are more than two not-operators.
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return $lastNot;
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}
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$fix = $phpcsFile->addFixableError($error, $stackPtr, $code, $data);
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if ($fix === true) {
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$phpcsFile->fixer->beginChangeset();
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$this->removeNotAndTrailingSpaces($phpcsFile, $stackPtr, $lastNot);
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$phpcsFile->fixer->replaceToken($lastNot, '(bool)');
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$phpcsFile->fixer->endChangeset();
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}
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// Only throw one error, even if there are more than two not-operators.
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return $lastNot;
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}
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/**
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* Remove boolean not-operators and trailing whitespace after those,
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* but don't remove comments or trailing whitespace after comments.
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*
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* @since 1.2.0
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*
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* @param \PHP_CodeSniffer\Files\File $phpcsFile The file being scanned.
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* @param int $stackPtr The position of the current token
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* in the stack passed in $tokens.
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* @param int $lastNot The position of the last boolean not token
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* in the chain.
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*
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* @return void
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*/
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private function removeNotAndTrailingSpaces(File $phpcsFile, $stackPtr, $lastNot)
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{
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$tokens = $phpcsFile->getTokens();
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$ignore = false;
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for ($i = $stackPtr; $i < $lastNot; $i++) {
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if (isset(Tokens::$commentTokens[$tokens[$i]['code']])) {
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// Ignore comments and whitespace after comments.
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$ignore = true;
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continue;
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}
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if ($tokens[$i]['code'] === \T_WHITESPACE && $ignore === false) {
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$phpcsFile->fixer->replaceToken($i, '');
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continue;
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}
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if ($tokens[$i]['code'] === \T_BOOLEAN_NOT) {
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$ignore = false;
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$phpcsFile->fixer->replaceToken($i, '');
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}
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}
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}
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}

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