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<?php
/**
* Parses a reference to an expression (column, table or database name, function
* call, mathematical expression, etc.).
*/
declare(strict_types=1);
namespace PhpMyAdmin\SqlParser\Components;
use PhpMyAdmin\SqlParser\Component;
use PhpMyAdmin\SqlParser\Context;
use PhpMyAdmin\SqlParser\Exceptions\ParserException;
use PhpMyAdmin\SqlParser\Parser;
use PhpMyAdmin\SqlParser\Token;
use PhpMyAdmin\SqlParser\TokensList;
use function implode;
use function is_array;
use function strlen;
use function trim;
/**
* Parses a reference to an expression (column, table or database name, function
* call, mathematical expression, etc.).
*/
class Expression extends Component
{
/**
* List of allowed reserved keywords in expressions.
*
* @var array
*/
private static $ALLOWED_KEYWORDS = [
'AS' => 1,
'DUAL' => 1,
'NULL' => 1,
'REGEXP' => 1,
'CASE' => 1,
'DIV' => 1,
'AND' => 1,
'OR' => 1,
'XOR' => 1,
'NOT' => 1,
'MOD' => 1,
];
/**
* The name of this database.
*
* @var string
*/
public $database;
/**
* The name of this table.
*
* @var string
*/
public $table;
/**
* The name of the column.
*
* @var string
*/
public $column;
/**
* The sub-expression.
*
* @var string
*/
public $expr = '';
/**
* The alias of this expression.
*
* @var string
*/
public $alias;
/**
* The name of the function.
*
* @var mixed
*/
public $function;
/**
* The type of subquery.
*
* @var string
*/
public $subquery;
/**
* Syntax:
* new Expression('expr')
* new Expression('expr', 'alias')
* new Expression('database', 'table', 'column')
* new Expression('database', 'table', 'column', 'alias')
*
* If the database, table or column name is not required, pass an empty
* string.
*
* @param string $database The name of the database or the the expression.
* the the expression.
* @param string $table The name of the table or the alias of the expression.
* the alias of the expression.
* @param string $column the name of the column
* @param string $alias the name of the alias
*/
public function __construct($database = null, $table = null, $column = null, $alias = null)
{
if (($column === null) && ($alias === null)) {
$this->expr = $database; // case 1
$this->alias = $table; // case 2
} else {
$this->database = $database; // case 3
$this->table = $table; // case 3
$this->column = $column; // case 3
$this->alias = $alias; // case 4
}
}
/**
* Possible options:.
*
* `field`
*
* First field to be filled.
* If this is not specified, it takes the value of `parseField`.
*
* `parseField`
*
* Specifies the type of the field parsed. It may be `database`,
* `table` or `column`. These expressions may not include
* parentheses.
*
* `breakOnAlias`
*
* If not empty, breaks when the alias occurs (it is not included).
*
* `breakOnParentheses`
*
* If not empty, breaks when the first parentheses occurs.
*
* `parenthesesDelimited`
*
* If not empty, breaks after last parentheses occurred.
*
* @param Parser $parser the parser that serves as context
* @param TokensList $list the list of tokens that are being parsed
* @param array $options parameters for parsing
*
* @return Expression|null
*
* @throws ParserException
*/
public static function parse(Parser $parser, TokensList $list, array $options = [])
{
$ret = new static();
/**
* Whether current tokens make an expression or a table reference.
*
* @var bool
*/
$isExpr = false;
/**
* Whether a period was previously found.
*
* @var bool
*/
$dot = false;
/**
* Whether an alias is expected. Is 2 if `AS` keyword was found.
*
* @var bool
*/
$alias = false;
/**
* Counts brackets.
*
* @var int
*/
$brackets = 0;
/**
* Keeps track of the last two previous tokens.
*
* @var Token[]
*/
$prev = [
null,
null,
];
// When a field is parsed, no parentheses are expected.
if (! empty($options['parseField'])) {
$options['breakOnParentheses'] = true;
$options['field'] = $options['parseField'];
}
for (; $list->idx < $list->count; ++$list->idx) {
/**
* Token parsed at this moment.
*
* @var Token
*/
$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)
|| ($token->type === Token::TYPE_COMMENT)
) {
if ($isExpr) {
$ret->expr .= $token->token;
}
continue;
}
if ($token->type === Token::TYPE_KEYWORD) {
if (($brackets > 0) && empty($ret->subquery)
&& ! empty(Parser::$STATEMENT_PARSERS[$token->keyword])
) {
// A `(` was previously found and this keyword is the
// beginning of a statement, so this is a subquery.
$ret->subquery = $token->keyword;
} elseif (($token->flags & Token::FLAG_KEYWORD_FUNCTION)
&& (empty($options['parseField'])
&& ! $alias)
) {
$isExpr = true;
} elseif (($token->flags & Token::FLAG_KEYWORD_RESERVED)
&& ($brackets === 0)
) {
if (empty(self::$ALLOWED_KEYWORDS[$token->keyword])) {
// A reserved keyword that is not allowed in the
// expression was found so the expression must have
// ended and a new clause is starting.
break;
}
if ($token->keyword === 'AS') {
if (! empty($options['breakOnAlias'])) {
break;
}
if ($alias) {
$parser->error(
'An alias was expected.',
$token
);
break;
}
$alias = true;
continue;
} elseif ($token->keyword === 'CASE') {
// For a use of CASE like
// 'SELECT a = CASE .... END, b=1, `id`, ... FROM ...'
$tempCaseExpr = CaseExpression::parse($parser, $list);
$ret->expr .= CaseExpression::build($tempCaseExpr);
$isExpr = true;
continue;
}
$isExpr = true;
} elseif ($brackets === 0 && strlen((string) $ret->expr) > 0 && ! $alias) {
/* End of expression */
break;
}
}
if (($token->type === Token::TYPE_NUMBER)
|| ($token->type === Token::TYPE_BOOL)
|| (($token->type === Token::TYPE_SYMBOL)
&& ($token->flags & Token::FLAG_SYMBOL_VARIABLE))
|| (($token->type === Token::TYPE_SYMBOL)
&& ($token->flags & Token::FLAG_SYMBOL_PARAMETER))
|| (($token->type === Token::TYPE_OPERATOR)
&& ($token->value !== '.'))
) {
if (! empty($options['parseField'])) {
break;
}
// Numbers, booleans and operators (except dot) are usually part
// of expressions.
$isExpr = true;
}
if ($token->type === Token::TYPE_OPERATOR) {
if (! empty($options['breakOnParentheses'])
&& (($token->value === '(') || ($token->value === ')'))
) {
// No brackets were expected.
break;
}
if ($token->value === '(') {
++$brackets;
if (empty($ret->function) && ($prev[1] !== null)
&& (($prev[1]->type === Token::TYPE_NONE)
|| ($prev[1]->type === Token::TYPE_SYMBOL)
|| (($prev[1]->type === Token::TYPE_KEYWORD)
&& ($prev[1]->flags & Token::FLAG_KEYWORD_FUNCTION)))
) {
$ret->function = $prev[1]->value;
}
} elseif ($token->value === ')') {
if ($brackets === 0) {
// Not our bracket
break;
} else {
--$brackets;
if ($brackets === 0) {
if (! empty($options['parenthesesDelimited'])) {
// The current token is the last bracket, the next
// one will be outside the expression.
$ret->expr .= $token->token;
++$list->idx;
break;
}
} elseif ($brackets < 0) {
// $parser->error('Unexpected closing bracket.', $token);
// $brackets = 0;
break;
}
}
} elseif ($token->value === ',') {
// Expressions are comma-delimited.
if ($brackets === 0) {
break;
}
}
}
// Saving the previous tokens.
$prev[0] = $prev[1];
$prev[1] = $token;
if ($alias) {
// 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;
$alias = false;
} elseif ($isExpr) {
// Handling aliases.
if ($brackets === 0
&& ($prev[0] === null
|| (($prev[0]->type !== Token::TYPE_OPERATOR || $prev[0]->token === ')')
&& ($prev[0]->type !== Token::TYPE_KEYWORD
|| ! ($prev[0]->flags & Token::FLAG_KEYWORD_RESERVED))))
&& (($prev[1]->type === Token::TYPE_STRING)
|| ($prev[1]->type === Token::TYPE_SYMBOL
&& ! ($prev[1]->flags & Token::FLAG_SYMBOL_VARIABLE))
|| ($prev[1]->type === Token::TYPE_NONE))
) {
if (! empty($ret->alias)) {
$parser->error('An alias was previously found.', $token);
break;
}
$ret->alias = $prev[1]->value;
} else {
$ret->expr .= $token->token;
}
} elseif (! $isExpr) {
if (($token->type === Token::TYPE_OPERATOR) && ($token->value === '.')) {
// Found a `.` which means we expect a column name and
// the column name we parsed is actually the table name
// and the table name is actually a database name.
if (! empty($ret->database) || $dot) {
$parser->error('Unexpected dot.', $token);
}
$ret->database = $ret->table;
$ret->table = $ret->column;
$ret->column = null;
$dot = true;
$ret->expr .= $token->token;
} else {
$field = empty($options['field']) ? 'column' : $options['field'];
if (empty($ret->$field)) {
$ret->$field = $token->value;
$ret->expr .= $token->token;
$dot = false;
} else {
// No alias is expected.
if (! empty($options['breakOnAlias'])) {
break;
}
if (! empty($ret->alias)) {
$parser->error('An alias was previously found.', $token);
break;
}
$ret->alias = $token->value;
}
}
}
}
if ($alias) {
$parser->error(
'An alias was expected.',
$list->tokens[$list->idx - 1]
);
}
// White-spaces might be added at the end.
$ret->expr = trim((string) $ret->expr);
if ($ret->expr === '') {
return null;
}
--$list->idx;
return $ret;
}
/**
* @param Expression|Expression[] $component the component to be built
* @param array $options parameters for building
*
* @return string
*/
public static function build($component, array $options = [])
{
if (is_array($component)) {
return implode(', ', $component);
}
if ($component->expr !== '' && $component->expr !== null) {
$ret = $component->expr;
} else {
$fields = [];
if (isset($component->database) && ($component->database !== '')) {
$fields[] = $component->database;
}
if (isset($component->table) && ($component->table !== '')) {
$fields[] = $component->table;
}
if (isset($component->column) && ($component->column !== '')) {
$fields[] = $component->column;
}
$ret = implode('.', Context::escape($fields));
}
if (! empty($component->alias)) {
$ret .= ' AS ' . Context::escape($component->alias);
}
return $ret;
}
}
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