ClickHouse/dbms/include/DB/Analyzers/AnalyzeColumns.h
2017-01-14 12:09:38 +03:00

49 lines
1.1 KiB
C++

#pragma once
#include <DB/Parsers/IAST.h>
#include <DB/Analyzers/CollectTables.h>
#include <unordered_map>
namespace DB
{
class WriteBuffer;
struct CollectAliases;
struct CollectTables;
/** For every identifier, that is not an alias,
* determine from what table it comes,
* its original name in table,
* and its data type.
*
* Also:
* - expand asterisks (such as *, t.*, db.table.* and (TODO) even db.table.nested.*) to corresponding list of columns;
* - translate count(*) to count();
* - TODO expand alias columns that come from table definition;
* - TODO replace column names to fully qualified names: identical columns will have same names.
*
* If column is not found or in case of ambiguity, throw an exception.
*/
struct AnalyzeColumns
{
void process(ASTPtr & ast, const CollectAliases & aliases, const CollectTables & tables);
struct ColumnInfo
{
ASTPtr node;
CollectTables::TableInfo table;
String name_in_table;
DataTypePtr data_type;
};
using Columns = std::unordered_map<String, ColumnInfo>;
Columns columns;
/// Debug output
void dump(WriteBuffer & out) const;
};
}