More work on the query parser

common/framework/parsers/dbquery/query.php

@@ -18,4 +18,215 @@ class Query
 	public $conditions = array();
 	public $groupby = null;
 	public $navigation = null;
+	
+	/**
+	 * Attributes for query generation.
+	 */
+	protected $_prefix = '';
+	protected $_args = array();
+	protected $_column_list = array();
+	protected $_params = array();
+	protected $_temp_num = 0;
+	
+	/**
+	 * Generate the query string for this query.
+	 * 
+	 * @param string $prefix
+	 * @param array $args
+	 * @param array $column_list
+	 * @return string
+	 */
+	public function getQueryString(string $prefix = '', array $args, array $column_list = []): string
+	{
+		// Save the query information.
+		$this->_prefix = $prefix;
+		$this->_args = $args;
+		$this->_column_list = $column_list;
+		$this->_temp_num = 0;
+		
+		// Call different internal methods depending on the query type.
+		switch ($this->type)
+		{
+			case 'SELECT':
+				return $this->_getSelectQueryString();
+			default:
+				return '';
+		}
+	}
+	
+	/**
+	 * Get the query parameters to use with the query string generated above.
+	 * 
+	 * @return array
+	 */
+	public function getQueryParams()
+	{
+		return $this->_params;
+	}
+	
+	/**
+	 * Generate a SELECT query string.
+	 * 
+	 * @return string
+	 */
+	protected function _getSelectQueryString(): string
+	{
+		// Initialize the query string.
+		$result = 'SELECT ';
+		
+		// Compose the column list.
+		$columns = array();
+		if ($this->_column_list)
+		{
+			$result .= implode(', ', array_map(function($str) {
+				return '`' . $str . '`';
+			}, $this->_column_list));
+		}
+		else
+		{
+			foreach ($this->columns as $column)
+			{
+				if ($column instanceof self)
+				{
+					$subquery = $column->getQueryString($this->_prefix, $this->_args);
+					foreach ($column->getQueryParams() as $key => $val)
+					{
+						$this->_params[$key] = $val;
+					}
+					$columns[] = sprintf('(%s) AS %s', $subquery, self::quoteName($column->alias));
+				}
+				elseif ($column->is_expression && !$column->is_wildcard)
+				{
+					$columns[] = $column->name . ($column->alias ? (' AS ' . self::quoteName($column->alias)) : '');
+				}
+				else
+				{
+					$columns[] = self::quoteName($column->name) . ($column->alias ? (' AS ' . self::quoteName($column->alias)) : '');
+				}
+			}
+			$result .= implode(', ', $columns);
+		}
+		
+		// Compose the table list.
+		$tables = array();
+		foreach ($this->tables as $table)
+		{
+			if ($table instanceof self)
+			{
+				$subquery = $table->getQueryString($this->_prefix, $this->_args);
+				foreach ($table->getQueryParams() as $key => $val)
+				{
+					$this->_params[$key] = $val;
+				}
+				$tables[] = sprintf('(%s) AS `%s`', $subquery, $table->alias);
+			}
+			else
+			{
+				$tabledef = self::quoteName($table->name) . ($table->alias ? (' AS `' . $table->alias . '`') : '');
+				if ($table->join_type)
+				{
+					$tabledef = $table->join_type . ' ' . $tabledef;
+					$join_where = $this->_arrangeConditions($table->join_conditions);
+					if ($join_where !== '')
+					{
+						$tabledef = $tabledef . ' ON ' . $join_where;
+					}
+				}
+				$tables[] = $tabledef;
+			}
+		}
+		$result .= ' FROM ' . implode(', ', $tables);
+		
+		// Compose the conditions.
+		if (count($this->conditions))
+		{
+			$where = $this->_arrangeConditions($this->conditions);
+			if ($where !== '')
+			{
+				$result .= ' WHERE ' . $where;
+			}
+		}
+		
+		// Compose the GROUP BY clause.
+		
+		// Compose the LIMIT clause.
+		
+		// Return the final query string.
+		return $result;
+	}
+	
+	/**
+	 * Generate a WHERE clause from a list of conditions.
+	 * 
+	 * @param array $conditions
+	 * @return string
+	 */
+	protected function _arrangeConditions(array $conditions): string
+	{
+		// Initialize the result.
+		$result = '';
+		
+		// Process each condition.
+		foreach ($conditions as $condition)
+		{
+			// Subquery
+			if ($condition instanceof self)
+			{
+				// TODO
+			}
+			
+			// Condition group
+			elseif ($condition instanceof ConditionGroup)
+			{
+				$condition_string = $this->_arrangeConditions($condition->conditions);
+				if ($condition_string === '')
+				{
+					continue;
+				}
+				$result .= ($result === '' ? '' : (' ' . $condition->pipe . ' ')) . '(' . $condition_string . ')';
+			}
+			
+			// Simple condition
+			else
+			{
+				$condition_string = $this->_parseCondition($condition);
+				if ($condition_string === '')
+				{
+					continue;
+				}
+				$result .= ($result === '' ? '' : (' ' . $condition->pipe . ' ')) . $condition_string;
+			}
+		}
+		
+		// Return the WHERE clause.
+		return $result;
+	}
+	
+	/**
+	 * Generate each condition in a WHERE clause.
+	 * 
+	 * @param object $condition
+	 * @return string
+	 */
+	protected function _parseCondition(Condition $condition): string
+	{
+		list($where, $params) = $condition->getQueryStringAndParams($this->_args);
+		foreach ($params as $key => $val)
+		{
+			$this->_params[$key] = $val;
+		}
+		return $where;
+	}
+	
+	/**
+	 * Quote a column name.
+	 */
+	public static function quoteName($column_name): string
+	{
+		$columns = explode('.', $column_name);
+		$columns = array_map(function($str) {
+			return $str === '*' ? $str : ('`' . $str . '`');
+		}, $columns);
+		return implode('.', $columns);
+	}
 }