ClickHouse/dbms/include/DB/Analyzers/CollectTables.h

#pragma once

#include <DB/Parsers/IAST.h>
#include <DB/Storages/IStorage.h>
#include <vector>


namespace DB
{

class Context;
class CollectAliases;
class WriteBuffer;


/** Collect and analyze table-like expressions in section FROM in a query.
  * For every expression, keep its alias.
  *
  * For ordinary tables, determine database and table name, obtain and keep StoragePtr.
  * For subqueries, determine result structure. This requires analysis of subquery, such as type inference.
  * For table functions, execute them to obtain resulting StoragePtr.
  *
  * NOTE: We assume, that execution of table functions is cheap, as we do it during analysis.
  */
struct CollectTables
{
	void process(ASTPtr & ast, Context & context, const CollectAliases & aliases);

	enum class Kind
	{
		OrdinaryTable,
		TableFunction,
		Subquery
	};

	struct TableInfo
	{
		ASTPtr node;
		String database_name;
		String table_name;
		String alias;
		StoragePtr storage;
		Block structure_of_subquery;
	};

	using Tables = std::vector<TableInfo>;
	Tables tables;

	/// Debug output
	void dump(WriteBuffer & out) const;
};

}