<?php
declare(strict_types=1);
namespace PhpMyAdmin\SqlParser\Components;
use PhpMyAdmin\SqlParser\Component;
use PhpMyAdmin\SqlParser\Context;
use PhpMyAdmin\SqlParser\Parser;
use PhpMyAdmin\SqlParser\Token;
use PhpMyAdmin\SqlParser\TokensList;
use function count;
/**
* Parses a reference to a CASE expression.
*
* @final
*/
class CaseExpression extends Component
{
/**
* The value to be compared.
*
* @var Expression|null
*/
public $value;
/**
* The conditions in WHEN clauses.
*
* @var Condition[][]
*/
public $conditions = [];
/**
* The results matching with the WHEN clauses.
*
* @var Expression[]
*/
public $results = [];
/**
* The values to be compared against.
*
* @var Expression[]
*/
public $compare_values = [];
/**
* The result in ELSE section of expr.
*
* @var Expression|null
*/
public $else_result;
/**
* The alias of this CASE statement.
*
* @var string|null
*/
public $alias;
/**
* The sub-expression.
*
* @var string
*/
public $expr = '';
public function __construct()
{
}
/**
* @param Parser $parser the parser that serves as context
* @param TokensList $list the list of tokens that are being parsed
* @param array<string, mixed> $options parameters for parsing
*
* @return CaseExpression
*/
public static function parse(Parser $parser, TokensList $list, array $options = [])
{
$ret = new static();
/**
* State of parser.
*
* @var int
*/
$state = 0;
/**
* Syntax type (type 0 or type 1).
*
* @var int
*/
$type = 0;
++$list->idx; // Skip 'CASE'
for (; $list->idx < $list->count; ++$list->idx) {
/**
* Token parsed at this moment.
*/
$token = $list->tokens[$list->idx];
// Skipping whitespaces and comments.
if (($token->type === Token::TYPE_WHITESPACE) || ($token->type === Token::TYPE_COMMENT)) {
continue;
}
if ($state === 0) {
if ($token->type === Token::TYPE_KEYWORD) {
switch ($token->keyword) {
case 'WHEN':
++$list->idx; // Skip 'WHEN'
$newCondition = Condition::parse($parser, $list);
$type = 1;
$state = 1;
$ret->conditions[] = $newCondition;
break;
case 'ELSE':
++$list->idx; // Skip 'ELSE'
$ret->else_result = Expression::parse($parser, $list);
$state = 0; // last clause of CASE expression
break;
case 'END':
$state = 3; // end of CASE expression
++$list->idx;
break 2;
default:
$parser->error('Unexpected keyword.', $token);
break 2;
}
} else {
$ret->value = Expression::parse($parser, $list);
$type = 0;
$state = 1;
}
} elseif ($state === 1) {
if ($type === 0) {
if ($token->type === Token::TYPE_KEYWORD) {
switch ($token->keyword) {
case 'WHEN':
++$list->idx; // Skip 'WHEN'
$newValue = Expression::parse($parser, $list);
$state = 2;
$ret->compare_values[] = $newValue;
break;
case 'ELSE':
++$list->idx; // Skip 'ELSE'
$ret->else_result = Expression::parse($parser, $list);
$state = 0; // last clause of CASE expression
break;
case 'END':
$state = 3; // end of CASE expression
++$list->idx;
break 2;
default:
$parser->error('Unexpected keyword.', $token);
break 2;
}
}
} else {
if ($token->type === Token::TYPE_KEYWORD && $token->keyword === 'THEN') {
++$list->idx; // Skip 'THEN'
$newResult = Expression::parse($parser, $list);
$state = 0;
$ret->results[] = $newResult;
} elseif ($token->type === Token::TYPE_KEYWORD) {
$parser->error('Unexpected keyword.', $token);
break;
}
}
} elseif ($state === 2) {
if ($type === 0) {
if ($token->type === Token::TYPE_KEYWORD && $token->keyword === 'THEN') {
++$list->idx; // Skip 'THEN'
$newResult = Expression::parse($parser, $list);
$ret->results[] = $newResult;
$state = 1;
} elseif ($token->type === Token::TYPE_KEYWORD) {
$parser->error('Unexpected keyword.', $token);
break;
}
}
}
}
if ($state !== 3) {
$parser->error('Unexpected end of CASE expression', $list->tokens[$list->idx - 1]);
} else {
// Parse for alias of CASE expression
$asFound = false;
for (; $list->idx < $list->count; ++$list->idx) {
$token = $list->tokens[$list->idx];
// End of statement.
if ($token->type === Token::TYPE_DELIMITER) {
break;
}
// Skipping whitespaces and comments.
if (($token->type === Token::TYPE_WHITESPACE) || ($token->type === Token::TYPE_COMMENT)) {
continue;
}
// Handle optional AS keyword before alias
if ($token->type === Token::TYPE_KEYWORD && $token->keyword === 'AS') {
if ($asFound || ! empty($ret->alias)) {
$parser->error('Potential duplicate alias of CASE expression.', $token);
break;
}
$asFound = true;
continue;
}
if (
$asFound
&& $token->type === Token::TYPE_KEYWORD
&& ($token->flags & Token::FLAG_KEYWORD_RESERVED || $token->flags & Token::FLAG_KEYWORD_FUNCTION)
) {
$parser->error('An alias expected after AS but got ' . $token->value, $token);
$asFound = false;
break;
}
if (
$asFound
|| $token->type === Token::TYPE_STRING
|| ($token->type === Token::TYPE_SYMBOL && ! $token->flags & Token::FLAG_SYMBOL_VARIABLE)
|| $token->type === Token::TYPE_NONE
) {
// An alias is expected (the keyword `AS` was previously found).
if (! empty($ret->alias)) {
$parser->error('An alias was previously found.', $token);
break;
}
$ret->alias = $token->value;
$asFound = false;
continue;
}
break;
}
if ($asFound) {
$parser->error('An alias was expected after AS.', $list->tokens[$list->idx - 1]);
}
$ret->expr = self::build($ret);
}
--$list->idx;
return $ret;
}
/**
* @param CaseExpression $component the component to be built
* @param array<string, mixed> $options parameters for building
*
* @return string
*/
public static function build($component, array $options = [])
{
$ret = 'CASE ';
if (isset($component->value)) {
// Syntax type 0
$ret .= $component->value . ' ';
$valuesCount = count($component->compare_values);
$resultsCount = count($component->results);
for ($i = 0; $i < $valuesCount && $i < $resultsCount; ++$i) {
$ret .= 'WHEN ' . $component->compare_values[$i] . ' ';
$ret .= 'THEN ' . $component->results[$i] . ' ';
}
} else {
// Syntax type 1
$valuesCount = count($component->conditions);
$resultsCount = count($component->results);
for ($i = 0; $i < $valuesCount && $i < $resultsCount; ++$i) {
$ret .= 'WHEN ' . Condition::build($component->conditions[$i]) . ' ';
$ret .= 'THEN ' . $component->results[$i] . ' ';
}
}
if (isset($component->else_result)) {
$ret .= 'ELSE ' . $component->else_result . ' ';
}
$ret .= 'END';
if ($component->alias) {
$ret .= ' AS ' . Context::escape($component->alias);
}
return $ret;
}
}