ClickHouse/src/Interpreters/TreeOptimizer.h

#pragma once

#include <Interpreters/Aliases.h>
#include <Interpreters/Context_fwd.h>
#include <Interpreters/DatabaseAndTableWithAlias.h>
#include <Storages/IStorage_fwd.h>
#include <Parsers/IAST_fwd.h>

namespace DB
{

struct TreeRewriterResult;

/// Part of of Tree Rewriter (SyntaxAnalyzer) that optimizes AST.
/// Query should be ready to execute either before either after it. But resulting query could be faster.
class TreeOptimizer
{
public:

    static void apply(
        ASTPtr & query,
        TreeRewriterResult & result,
        const std::vector<TableWithColumnNamesAndTypes> & tables_with_columns,
        ContextPtr context);

    static void optimizeIf(ASTPtr & query, Aliases & aliases, bool if_chain_to_multiif, bool multiif_to_if);
    static void optimizeCountConstantAndSumOne(ASTPtr & query, ContextPtr context);
    static void optimizeGroupByFunctionKeys(ASTSelectQuery * select_query);
};

}