source: src/AST/Expr.hpp @ 9e1d485

//
// Cforall Version 1.0.0 Copyright (C) 2015 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// Expr.hpp --
//
// Author           : Aaron B. Moss
// Created On       : Fri May 10 10:30:00 2019
// Last Modified By : Aaron B. Moss
// Created On       : Fri May 10 10:30:00 2019
// Update Count     : 1
//

#pragma once

#include <cassert>
#include <map>
#include <utility>        // for move
#include <vector>

#include "Fwd.hpp"        // for UniqueId
#include "ParseNode.hpp"
#include "Visitor.hpp"

namespace ast {

/// Contains the ID of a declaration and a type that is derived from that declaration, 
/// but subject to decay-to-pointer and type parameter renaming
struct ParamEntry {
        UniqueId decl;
        ptr<Type> actualType;
        ptr<Type> formalType;
        ptr<Expr> expr;

        ParamEntry() : decl( 0 ), actualType( nullptr ), formalType( nullptr ), expr( nullptr ) {}
        ParamEntry( UniqueId id, Type* actual, Type* formal, Expr* e )
        : decl( id ), actualType( actual ), formalType( formal ), expr( e ) {}
};

/// Pre-resolution list of parameters to infer
using ResnSlots = std::vector<UniqueId>;
/// Post-resolution map of inferred parameters
using InferredParams = std::map< UniqueId, ParamEntry >;

/// Base node for expressions
class Expr : public ParseNode {
public:
        /// Saves space (~16 bytes) by combining ResnSlots and InferredParams
        struct InferUnion {
                enum { Empty, Slots, Params } mode;
                union data_t {
                        char def;
                        ResnSlots resnSlots;
                        InferredParams inferParams;

                        data_t() : def('\0') {}
                        ~data_t() {}
                } data;

                /// initializes from other InferUnion
                void init_from( const InferUnion& o ) {
                        switch ( o.mode ) {
                        case Empty:  return;
                        case Slots:  new(&data.resnSlots) ResnSlots{ o.data.resnSlots }; return;
                        case Params: new(&data.inferParams) InferredParams{ o.data.inferParams }; return;
                        }
                }

                /// initializes from other InferUnion (move semantics)
                void init_from( InferUnion&& o ) {
                        switch ( o.mode ) {
                        case Empty:  return;
                        case Slots:  new(&data.resnSlots) ResnSlots{ std::move(o.data.resnSlots) }; return;
                        case Params: 
                                new(&data.inferParams) InferredParams{ std::move(o.data.inferParams) }; return;
                        }
                }

                /// clears variant fields
                void reset() {
                        switch( mode ) {
                        case Empty:  return;
                        case Slots:  data.resnSlots.~ResnSlots(); return;
                        case Params: data.inferParams.~InferredParams(); return;
                        }
                }

                InferUnion() : mode(Empty), data() {}
                InferUnion( const InferUnion& o ) : mode( o.mode ), data() { init_from( o ); }
                InferUnion( InferUnion&& o ) : mode( o.mode ), data() { init_from( std::move(o) ); }
                InferUnion& operator= ( const InferUnion& ) = delete;
                InferUnion& operator= ( InferUnion&& ) = delete;
                ~InferUnion() { reset(); }

                ResnSlots& resnSlots() {
                        switch (mode) {
                        case Empty: new(&data.resnSlots) ResnSlots{}; mode = Slots; // fallthrough
                        case Slots: return data.resnSlots;
                        case Params: assert(!"Cannot return to resnSlots from Params");
                        }
                }

                InferredParams& inferParams() {
                        switch (mode) {
                        case Slots: data.resnSlots.~ResnSlots(); // fallthrough
                        case Empty: new(&data.inferParams) InferredParams{}; mode = Params; // fallthrough
                        case Params: return data.inferParams;
                        }
                }
        };

        ptr<Type> result;
        ptr<TypeSubstitution> env;
        InferUnion inferred;
        bool extension = false;

        Expr(const CodeLocation & loc ) : ParseNode( loc ), result(), env(), inferred() {}

        Expr * set_extension( bool ex ) { extension = ex; return this; }

        virtual Expr * accept( Visitor & v ) override = 0;
private:
        virtual Expr * clone() const override = 0;
};

/// A type used as an expression (e.g. a type generator parameter)
class TypeExpr final : public Expr {
public:
        ptr<Type> type;

        TypeExpr( const CodeLocation & loc, const Type * t ) : Expr(loc), type(t) {}

        Expr * accept( Visitor & v ) override { return v.visit( this ); }
private:
        TypeExpr * clone() const override { return new TypeExpr{ *this }; }
};

}

// Local Variables: //
// tab-width: 4 //
// mode: c++ //
// compile-command: "make install" //
// End: //