315 lines
9.9 KiB
PHP
Executable File
315 lines
9.9 KiB
PHP
Executable File
<?php
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/**
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* Parses a reference to a CASE 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\Context;
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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 CASE 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 CaseExpression extends Component
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{
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/**
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* The value to be compared.
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*
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* @var Expression
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*/
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public $value;
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/**
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* The conditions in WHEN clauses.
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*
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* @var array
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*/
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public $conditions = array();
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/**
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* The results matching with the WHEN clauses.
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*
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* @var array
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*/
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public $results = array();
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/**
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* The values to be compared against.
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*
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* @var array
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*/
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public $compare_values = array();
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/**
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* The result in ELSE section of expr.
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*
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* @var Expression
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*/
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public $else_result;
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/**
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* The alias of this CASE statement.
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*
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* @var string
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*/
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public $alias;
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/**
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* The sub-expression.
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*
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* @var string
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*/
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public $expr = '';
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/**
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* Constructor.
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*/
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public function __construct()
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{
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}
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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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* State of parser.
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*
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* @var int
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*/
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$state = 0;
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/**
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* Syntax type (type 0 or type 1).
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*
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* @var int
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*/
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$type = 0;
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++$list->idx; // Skip 'CASE'
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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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// Skipping whitespaces and comments.
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if (($token->type === Token::TYPE_WHITESPACE)
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|| ($token->type === Token::TYPE_COMMENT)
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) {
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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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switch ($token->keyword) {
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case 'WHEN':
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++$list->idx; // Skip 'WHEN'
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$new_condition = Condition::parse($parser, $list);
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$type = 1;
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$state = 1;
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$ret->conditions[] = $new_condition;
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break;
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case 'ELSE':
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++$list->idx; // Skip 'ELSE'
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$ret->else_result = Expression::parse($parser, $list);
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$state = 0; // last clause of CASE expression
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break;
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case 'END':
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$state = 3; // end of CASE expression
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++$list->idx;
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break 2;
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default:
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$parser->error('Unexpected keyword.', $token);
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break 2;
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}
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} else {
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$ret->value = Expression::parse($parser, $list);
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$type = 0;
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$state = 1;
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}
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} elseif ($state === 1) {
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if ($type === 0) {
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if ($token->type === Token::TYPE_KEYWORD) {
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switch ($token->keyword) {
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case 'WHEN':
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++$list->idx; // Skip 'WHEN'
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$new_value = Expression::parse($parser, $list);
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$state = 2;
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$ret->compare_values[] = $new_value;
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break;
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case 'ELSE':
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++$list->idx; // Skip 'ELSE'
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$ret->else_result = Expression::parse($parser, $list);
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$state = 0; // last clause of CASE expression
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break;
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case 'END':
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$state = 3; // end of CASE expression
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++$list->idx;
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break 2;
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default:
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$parser->error('Unexpected keyword.', $token);
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break 2;
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}
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}
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} else {
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if ($token->type === Token::TYPE_KEYWORD
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&& $token->keyword === 'THEN'
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) {
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++$list->idx; // Skip 'THEN'
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$new_result = Expression::parse($parser, $list);
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$state = 0;
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$ret->results[] = $new_result;
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} elseif ($token->type === Token::TYPE_KEYWORD) {
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$parser->error('Unexpected keyword.', $token);
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break;
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}
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}
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} elseif ($state === 2) {
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if ($type === 0) {
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if ($token->type === Token::TYPE_KEYWORD
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&& $token->keyword === 'THEN'
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) {
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++$list->idx; // Skip 'THEN'
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$new_result = Expression::parse($parser, $list);
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$ret->results[] = $new_result;
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$state = 1;
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} elseif ($token->type === Token::TYPE_KEYWORD) {
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$parser->error('Unexpected keyword.', $token);
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break;
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}
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}
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}
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}
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if ($state !== 3) {
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$parser->error(
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'Unexpected end of CASE expression',
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$list->tokens[$list->idx - 1]
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);
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} else {
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// Parse for alias of CASE expression
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$asFound = false;
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for (; $list->idx < $list->count; ++$list->idx) {
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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)
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|| ($token->type === Token::TYPE_COMMENT)
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) {
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continue;
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}
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// Handle optional AS keyword before alias
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if ($token->type === Token::TYPE_KEYWORD
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&& $token->keyword === 'AS') {
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if ($asFound || ! empty($ret->alias)) {
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$parser->error('Potential duplicate alias of CASE expression.', $token);
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break;
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}
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$asFound = true;
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continue;
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}
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if ($asFound
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&& $token->type === Token::TYPE_KEYWORD
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&& ($token->flags & Token::FLAG_KEYWORD_RESERVED || $token->flags & Token::FLAG_KEYWORD_FUNCTION)) {
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$parser->error('An alias expected after AS but got ' . $token->value, $token);
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$asFound = false;
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break;
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}
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if ($asFound
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|| $token->type === Token::TYPE_STRING
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|| ($token->type === Token::TYPE_SYMBOL && ! $token->flags & Token::FLAG_SYMBOL_VARIABLE)
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|| $token->type === Token::TYPE_NONE
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) {
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// An alias is expected (the keyword `AS` was previously found).
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if (! empty($ret->alias)) {
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$parser->error('An alias was previously found.', $token);
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break;
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}
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$ret->alias = $token->value;
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$asFound = false;
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continue;
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}
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break;
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}
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if ($asFound) {
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$parser->error('An alias was expected after AS.', $list->tokens[$list->idx - 1]);
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}
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$ret->expr = self::build($ret);
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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 CaseExpression $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 $options = array())
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{
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$ret = 'CASE ';
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if (isset($component->value)) {
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// Syntax type 0
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$ret .= $component->value . ' ';
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$val_cnt = count($component->compare_values);
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$res_cnt = count($component->results);
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for ($i = 0; $i < $val_cnt && $i < $res_cnt; ++$i) {
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$ret .= 'WHEN ' . $component->compare_values[$i] . ' ';
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$ret .= 'THEN ' . $component->results[$i] . ' ';
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}
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} else {
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// Syntax type 1
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$val_cnt = count($component->conditions);
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$res_cnt = count($component->results);
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for ($i = 0; $i < $val_cnt && $i < $res_cnt; ++$i) {
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$ret .= 'WHEN ' . Condition::build($component->conditions[$i]) . ' ';
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$ret .= 'THEN ' . $component->results[$i] . ' ';
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}
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}
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if (isset($component->else_result)) {
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$ret .= 'ELSE ' . $component->else_result . ' ';
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}
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$ret .= 'END';
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if ($component->alias) {
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$ret .= ' AS ' . Context::escape($component->alias);
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}
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return $ret;
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}
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}
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