QueryGraph.hpp

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#pragma once
 
#include "util/hash.hpp"
#include <mutable/IR/QueryGraph.hpp>
#include <mutable/parse/AST.hpp>
#include <unordered_map>
#include <unordered_set>
#include <utility>
 
 
namespace m {
 
struct GraphBuilder;
 
struct SubqueryInfo
{
    const ast::QueryExpr &expr;
    std::unique_ptr<GraphBuilder> builder;
    ThreadSafePooledString alias;
 
    SubqueryInfo(const ast::QueryExpr &expr, std::unique_ptr<GraphBuilder> builder, ThreadSafePooledString alias)
        : expr(expr)
        , builder(std::move(builder))
        , alias(std::move(alias))
    { }
};
 
struct ClauseInfo
{
    unsigned binding_depth = 0;
 
    std::unordered_set<ThreadSafePooledString> data_sources;
    std::vector<SubqueryInfo> nested_queries;
 
    ClauseInfo(const cnf::Clause &clause);
 
    bool is_constant() const { return data_sources.empty(); }
    bool is_selection() const { return data_sources.size() == 1; }
};
 
struct GraphBuilder : ast::ConstASTCommandVisitor
{
    using clause_map = std::unordered_map<cnf::Clause, ClauseInfo>;
 
    private:
    /*----- Fields tracking correlation information -----*/
    std::vector<std::reference_wrapper<const ast::Expr>> existing_grouping_keys_;
    std::unordered_set<std::reference_wrapper<const ast::Expr>> additional_grouping_keys_;
 
    clause_map bound_clauses_;
    clause_map deferred_clauses_;
 
    std::unique_ptr<QueryGraph> graph_;
    std::unordered_map<ThreadSafePooledString, std::reference_wrapper<DataSource>> named_sources_;
    bool needs_grouping_ = false;
 
    public:
    GraphBuilder();
 
    std::unique_ptr<QueryGraph> get() { return std::move(graph_); }
 
    /*----- Visitor methods -----*/
    using ConstASTCommandVisitor::operator();
    void operator()(Const<ast::Stmt> &s) { s.accept(*this); }
    void operator()(Const<ast::ErrorStmt>&) { M_unreachable("graph must not contain errors"); }
    void operator()(Const<ast::EmptyStmt>&) { /* nothing to be done */ }
    void operator()(Const<ast::CreateDatabaseStmt>&) { M_unreachable("not implemented"); }
    void operator()(Const<ast::DropDatabaseStmt>&) { M_unreachable("not implemented"); }
    void operator()(Const<ast::UseDatabaseStmt>&) { M_unreachable("not implemented"); }
    void operator()(Const<ast::CreateTableStmt>&) { M_unreachable("not implemented"); }
    void operator()(Const<ast::DropTableStmt>&) { M_unreachable("not implemented"); }
    void operator()(Const<ast::SelectStmt> &s);
    void operator()(Const<ast::InsertStmt>&) { M_unreachable("not implemented"); }
    void operator()(Const<ast::UpdateStmt>&) { M_unreachable("not implemented"); }
    void operator()(Const<ast::DeleteStmt>&) { M_unreachable("not implemented"); }
    void operator()(Const<ast::DSVImportStmt>&) { M_unreachable("not implemented"); }
 
    void process_selection(cnf::Clause &clause);
};
 
}