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Add support for LOCK and UNLOCK Statements
Signed-off-by: Deven Bansod <[email protected]>
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‎src/Components/LockExpression.php‎

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<?php
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/**
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* Parses a reference to a LOCK expression.
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*/
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namespace PhpMyAdmin\SqlParser\Components;
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use PhpMyAdmin\SqlParser\Component;
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use PhpMyAdmin\SqlParser\Parser;
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use PhpMyAdmin\SqlParser\Token;
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use PhpMyAdmin\SqlParser\TokensList;
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/**
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* Parses a reference to a LOCK expression.
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*
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* @category Components
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*
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* @license https://www.gnu.org/licenses/gpl-2.0.txt GPL-2.0+
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*/
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class LockExpression extends Component
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{
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/**
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* The table to be locked.
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*
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* @var Expression
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*/
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public $table;
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/**
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* The type of lock to be applied.
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*
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* @var string
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*/
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public $type;
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/**
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* @param Parser $parser the parser that serves as context
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* @param TokensList $list the list of tokens that are being parsed
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* @param array $options parameters for parsing
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*
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* @return CaseExpression
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*/
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public static function parse(Parser $parser, TokensList $list, array $options = array())
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{
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$ret = new self();
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/**
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* The state of the parser.
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*
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* Below are the states of the parser.
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*
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* 0 ---------------- [ tbl_name ] -----------------> 1
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* 1 ---------------- [ lock_type ] ----------------> 2
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* 2 -------------------- [ , ] --------------------> break
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*
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* @var int
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*/
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$state = 0;
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$prevToken = null;
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for (; $list->idx < $list->count; ++$list->idx) {
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/**
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* Token parsed at this moment.
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*
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* @var Token
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*/
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$token = $list->tokens[$list->idx];
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// End of statement.
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if ($token->type === Token::TYPE_DELIMITER
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|| ($token->type === Token::TYPE_OPERATOR
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&& $token->value === ',')
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) {
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break;
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}
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if ($state === 0) {
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$ret->table = Expression::parse($parser, $list, array('parseField' => 'table'));
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$state = 1;
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} elseif ($state === 1) {
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// parse lock type
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$ret->type = self::parseLockType($parser, $list);
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$state = 2;
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}
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$prevToken = $token;
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}
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// 2 is the only valid end state
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if ($state !== 2) {
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$parser->error('Unexpected end of LOCK expression.', $prevToken);
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}
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--$list->idx;
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return $ret;
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}
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/**
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* @param LockExpression|LockExpression[] $component the component to be built
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* @param array $options parameters for building
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*
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* @return string
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*/
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public static function build($component, array $options = array())
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{
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if (is_array($component)) {
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return implode(', ', $component);
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}
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return $component->table . ' ' . $component->type;
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}
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private static function parseLockType(Parser $parser, TokensList $list) {
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$lockType = '';
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/**
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* The state of the parser while parsing for lock type.
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*
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* Below are the states of the parser.
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*
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* 0 ---------------- [ READ ] -----------------> 1
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* 0 ------------- [ LOW_PRIORITY ] ------------> 2
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* 0 ---------------- [ WRITE ] ----------------> 3
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* 1 ---------------- [ LOCAL ] ----------------> 3
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* 2 ---------------- [ WRITE ] ----------------> 3
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*
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* @var int
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*/
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$state = 0;
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$prevToken = null;
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for (; $list->idx < $list->count; ++$list->idx) {
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/**
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* Token parsed at this moment.
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*
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* @var Token
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*/
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$token = $list->tokens[$list->idx];
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// End of statement.
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if ($token->type === Token::TYPE_DELIMITER
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|| ($token->type === Token::TYPE_OPERATOR
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&& $token->value === ',')
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) {
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--$list->idx;
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break;
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}
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// Skipping whitespaces and comments.
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if ($token->type === Token::TYPE_WHITESPACE || $token->type === Token::TYPE_COMMENT) {
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continue;
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}
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// We only expect keywords
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if ($token->type !== Token::TYPE_KEYWORD) {
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$parser->error('Unexpected token.', $token);
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break;
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}
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if ($state === 0) {
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if ($token->keyword === 'READ') {
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$state = 1;
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} elseif ($token->keyword === 'LOW_PRIORITY') {
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$state = 2;
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} elseif ($token->keyword === 'WRITE') {
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$state = 3;
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} else {
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$parser->error('Unexpected keyword.', $token);
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break;
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}
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$lockType .= $token->keyword;
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} elseif ($state === 1) {
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if ($token->keyword === 'LOCAL') {
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$lockType .= ' ' . $token->keyword;
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$state = 3;
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} else {
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$parser->error('Unexpected keyword.', $token);
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break;
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}
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} elseif ($state === 2) {
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if ($token->keyword === 'WRITE') {
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$lockType .= ' ' . $token->keyword;
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$state = 3; // parsing over
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} else {
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$parser->error('Unexpected keyword.', $token);
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break;
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}
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}
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$prevToken = $token;
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}
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// Only two possible end states
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if ($state !== 1 && $state !== 3) {
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$parser->error('Unexpected end of Lock expression.', $prevToken);
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}
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return $lockType;
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}
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}

‎src/Parser.php‎

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'START TRANSACTION' => 'PhpMyAdmin\\SqlParser\\Statements\\TransactionStatement',
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'PURGE' => 'PhpMyAdmin\\SqlParser\\Statements\\PurgeStatement',
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// Lock statements
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// https://dev.mysql.com/doc/refman/5.7/en/lock-tables.html
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'LOCK' => 'PhpMyAdmin\\SqlParser\\Statements\\LockStatement',
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'UNLOCK' => 'PhpMyAdmin\\SqlParser\\Statements\\LockStatement',
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);
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/**

‎src/Statements/LockStatement.php‎

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<?php
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/**
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* `LOCK` statement.
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*/
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namespace PhpMyAdmin\SqlParser\Statements;
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use PhpMyAdmin\SqlParser\Components\LockExpression;
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use PhpMyAdmin\SqlParser\Parser;
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use PhpMyAdmin\SqlParser\Statement;
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use PhpMyAdmin\SqlParser\Token;
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use PhpMyAdmin\SqlParser\TokensList;
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/**
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* `LOCK` statement.
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*
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* @category Statements
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*
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* @license https://www.gnu.org/licenses/gpl-2.0.txt GPL-2.0+
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*/
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class LockStatement extends Statement
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{
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/**
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* Tables with their Lock expressions.
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*
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* @var LockExpression[]
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*/
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public $locked = array();
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/**
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* Whether it's a LOCK statement
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* if false, it's an UNLOCK statement
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*/
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public $isLock = true;
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/**
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* @param Parser $parser the instance that requests parsing
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* @param TokensList $list the list of tokens to be parsed
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*/
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public function parse(Parser $parser, TokensList $list)
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{
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if ($list->tokens[$list->idx]->value === 'UNLOCK') {
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// this is in fact an UNLOCK statement
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$this->isLock = false;
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}
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++$list->idx; // Skipping `LOCK`.
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/**
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* The state of the parser.
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*
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* Below are the states of the parser.
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*
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* 0 ---------------- [ TABLES ] -----------------> 1
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* 1 -------------- [ lock_expr ] ----------------> 2
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* 2 ------------------ [ , ] --------------------> 1
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*
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* @var int
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*/
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$state = 0;
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/**
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* Previous parsed token
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*/
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$prevToken = null;
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for (; $list->idx < $list->count; ++$list->idx) {
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/**
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* Token parsed at this moment.
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*
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* @var Token
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*/
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$token = $list->tokens[$list->idx];
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// End of statement.
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if ($token->type === Token::TYPE_DELIMITER) {
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break;
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}
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// Skipping whitespaces and comments.
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if (($token->type === Token::TYPE_WHITESPACE) || ($token->type === Token::TYPE_COMMENT)) {
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continue;
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}
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if ($state === 0) {
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if ($token->type === Token::TYPE_KEYWORD) {
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if ($token->keyword !== 'TABLES') {
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$parser->error('Unexpected keyword.', $token);
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break;
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}
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$state = 1;
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continue;
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} else {
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$parser->error('Unexpected token.', $token);
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break;
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}
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} elseif ($state === 1) {
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if (!$this->isLock) {
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// UNLOCK statement should not have any more tokens
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$parser->error('Unexpected token.', $token);
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break;
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}
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$this->locked[] = LockExpression::parse($parser, $list);
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$state = 2;
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} elseif ($state === 2) {
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if ($token->value === ',') {
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// move over to parsing next lock expression
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$state = 1;
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}
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}
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$prevToken = $token;
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}
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if ($state !== 2 && $prevToken != null) {
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$parser->error('Unexpected end of LOCK statement.', $prevToken);
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}
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}
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/**
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* @return string
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*/
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public function build()
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{
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return trim(($this->isLock ? 'LOCK' : 'UNLOCK')
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. ' TABLES ' . LockExpression::build($this->locked));
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}
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}

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