WordPress/Sniffs/PHP/YodaConditionsSniff.php
public function process_token( $stackPtr ) {

		$start = $this->phpcsFile->findPrevious( $this->condition_start_tokens, $stackPtr, null, false, null, true );

		$needs_yoda = false;

		// Note: going backwards!
		for ( $i = $stackPtr; $i > $start; $i-- ) {

			// Ignore whitespace.
			if ( isset( Tokens::$emptyTokens[ $this->tokens[ $i ]['code'] ] ) ) {
				continue;
			}

			// If this is a variable or array, we've seen all we need to see.
			if ( \T_VARIABLE === $this->tokens[ $i ]['code']
				|| \T_CLOSE_SQUARE_BRACKET === $this->tokens[ $i ]['code']
			) {
				$needs_yoda = true;
				break;
			}

			// If this is a function call or something, we are OK.
			if ( \T_CLOSE_PARENTHESIS === $this->tokens[ $i ]['code'] ) {
				return;
			}
		}

		if ( ! $needs_yoda ) {
			return;
		}

		// Check if this is a var to var comparison, e.g.: if ( $var1 == $var2 ).
		$next_non_empty = $this->phpcsFile->findNext( Tokens::$emptyTokens, ( $stackPtr + 1 ), null, true );

		if ( isset( Tokens::$castTokens[ $this->tokens[ $next_non_empty ]['code'] ] ) ) {
			$next_non_empty = $this->phpcsFile->findNext( Tokens::$emptyTokens, ( $next_non_empty + 1 ), null, true );
		}

		if ( \in_array( $this->tokens[ $next_non_empty ]['code'], array( \T_SELF, \T_PARENT, \T_STATIC ), true ) ) {
			$next_non_empty = $this->phpcsFile->findNext(
				array_merge( Tokens::$emptyTokens, array( \T_DOUBLE_COLON ) ),
				( $next_non_empty + 1 ),
				null,
				true
			);
		}

		if ( \T_VARIABLE === $this->tokens[ $next_non_empty ]['code'] ) {
			return;
		}

		$this->phpcsFile->addError( 'Use Yoda Condition checks, you must.', $stackPtr, 'NotYoda' );
	}
public function process_token( $stackPtr ) {

		$start = $this->phpcsFile->findPrevious( $this->condition_start_tokens, $stackPtr, null, false, null, true );

		$needs_yoda = false;

		// Note: going backwards!
		for ( $i = $stackPtr; $i > $start; $i-- ) {

			// Ignore whitespace.
			if ( isset( Tokens::$emptyTokens[ $this->tokens[ $i ]['code'] ] ) ) {
				continue;
			}

			// If this is a variable or array, we've seen all we need to see.
			if ( \T_VARIABLE === $this->tokens[ $i ]['code']
				|| \T_CLOSE_SQUARE_BRACKET === $this->tokens[ $i ]['code']
			) {
				$needs_yoda = true;
				break;
			}

			// If this is a function call or something, we are OK.
			if ( \T_CLOSE_PARENTHESIS === $this->tokens[ $i ]['code'] ) {
				return;
			}
		}

		if ( ! $needs_yoda ) {
			return;
		}

		// Check if this is a var to var comparison, e.g.: if ( $var1 == $var2 ).
		$next_non_empty = $this->phpcsFile->findNext( Tokens::$emptyTokens, ( $stackPtr + 1 ), null, true );

		if ( isset( Tokens::$castTokens[ $this->tokens[ $next_non_empty ]['code'] ] ) ) {
			$next_non_empty = $this->phpcsFile->findNext( Tokens::$emptyTokens, ( $next_non_empty + 1 ), null, true );
		}

		if ( \in_array( $this->tokens[ $next_non_empty ]['code'], array( \T_SELF, \T_PARENT, \T_STATIC ), true ) ) {
			$next_non_empty = $this->phpcsFile->findNext(
				array_merge( Tokens::$emptyTokens, array( \T_DOUBLE_COLON ) ),
				( $next_non_empty + 1 ),
				null,
				true
			);
		}

		if ( \T_VARIABLE === $this->tokens[ $next_non_empty ]['code'] ) {
			return;
		}

		$this->phpcsFile->addError( 'Use Yoda Condition checks, you must.', $stackPtr, 'NotYoda' );
	}
Processes this test, when one of its tokens is encountered.

@param int $stackPtr The position of the current token in the stack.

@return void