source: src/Tuples/Explode.h @ b54ad9c

//
// 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.
//
// Explode.h --
//
// Author           : Rob Schluntz
// Created On       : Wed Nov 9 13:12:24 2016
// Last Modified By : Peter A. Buhr
// Last Modified On : Sat Jul 22 09:55:16 2017
// Update Count     : 3
//

#pragma once

#include <iterator>                     // for back_inserter, back_insert_iterator
#include <utility>                      // for forward

#include "ResolvExpr/Alternative.h"     // for Alternative, AltList
#include "ResolvExpr/ExplodedActual.h"  // for ExplodedActual
#include "SynTree/Expression.h"         // for Expression, UniqueExpr, AddressExpr
#include "SynTree/Type.h"               // for TupleType, Type
#include "Tuples.h"                     // for maybeImpure

namespace SymTab {
class Indexer;
}  // namespace SymTab

namespace Tuples {
        Expression * distributeReference( Expression * );

        static inline CastExpr * isReferenceCast( Expression * expr ) {
                if ( CastExpr * castExpr = dynamic_cast< CastExpr * >( expr ) ) {
                        if ( dynamic_cast< ReferenceType * >( castExpr->result ) ) {
                                return castExpr;
                        }
                }
                return nullptr;
        }

        /// Append alternative to an OutputIterator of Alternatives
        template<typename OutputIterator>
        void append( OutputIterator out, Expression* expr, const ResolvExpr::TypeEnvironment& env,
                        const ResolvExpr::Cost& cost, const ResolvExpr::Cost& cvtCost ) {
                *out++ = ResolvExpr::Alternative{ expr, env, cost, cvtCost };
        }

        /// Append alternative to an ExplodedActual
        static inline void append( ResolvExpr::ExplodedActual& ea, Expression* expr,
                        const ResolvExpr::TypeEnvironment&, const ResolvExpr::Cost&, const ResolvExpr::Cost& ) {
                ea.exprs.emplace_back( expr );
                /// xxx -- merge environment, cost?
        }

        /// helper function used by explode
        template< typename Output >
        void explodeUnique( Expression * expr, const ResolvExpr::Alternative & alt,
                        const SymTab::Indexer & indexer, Output&& out, bool isTupleAssign ) {
                if ( isTupleAssign ) {
                        // tuple assignment needs CastExprs to be recursively exploded to easily get at all of the components
                        if ( CastExpr * castExpr = isReferenceCast( expr ) ) {
                                ResolvExpr::AltList alts;
                                explodeUnique(
                                        castExpr->get_arg(), alt, indexer, back_inserter( alts ), isTupleAssign );
                                for ( ResolvExpr::Alternative & alt : alts ) {
                                        // distribute reference cast over all components
                                        append( std::forward<Output>(out), distributeReference( alt.release_expr() ),
                                                alt.env, alt.cost, alt.cvtCost );
                                }
                                // in tuple assignment, still need to handle the other cases, but only if not already handled here (don't want to output too many alternatives)
                                return;
                        }
                }
                Type * res = expr->get_result()->stripReferences();
                if ( TupleType * tupleType = dynamic_cast< TupleType * > ( res ) ) {
                        if ( TupleExpr * tupleExpr = dynamic_cast< TupleExpr * >( expr ) ) {
                                // can open tuple expr and dump its exploded components
                                for ( Expression * expr : tupleExpr->get_exprs() ) {
                                        explodeUnique( expr, alt, indexer, std::forward<Output>(out), isTupleAssign );
                                }
                        } else {
                                // tuple type, but not tuple expr - recursively index into its components.
                                // if expr type is reference, convert to value type
                                Expression * arg = expr->clone();
                                if ( Tuples::maybeImpureIgnoreUnique( arg ) ) {
                                        // expressions which may contain side effects require a single unique instance of the expression.
                                        arg = new UniqueExpr( arg );
                                }
                                // cast reference to value type to facilitate further explosion
                                if ( dynamic_cast<ReferenceType *>( arg->get_result() ) ) {
                                        arg = new CastExpr( arg, tupleType->clone() );
                                }
                                for ( unsigned int i = 0; i < tupleType->size(); i++ ) {
                                        TupleIndexExpr * idx = new TupleIndexExpr( arg->clone(), i );
                                        explodeUnique( idx, alt, indexer, std::forward<Output>(out), isTupleAssign );
                                        delete idx;
                                }
                                delete arg;
                        }
                } else {
                        // atomic (non-tuple) type - output a clone of the expression in a new alternative
                        append( std::forward<Output>(out), expr->clone(), alt.env, alt.cost, alt.cvtCost );
                }
        }

        /// expands a tuple-valued alternative into multiple alternatives, each with a non-tuple-type
        template< typename Output >
        void explode( const ResolvExpr::Alternative &alt, const SymTab::Indexer & indexer,
                        Output&& out, bool isTupleAssign = false ) {
                explodeUnique( alt.expr, alt, indexer, std::forward<Output>(out), isTupleAssign );
        }

        // explode list of alternatives
        template< typename AltIterator, typename Output >
        void explode( AltIterator altBegin, AltIterator altEnd, const SymTab::Indexer & indexer,
                        Output&& out, bool isTupleAssign = false ) {
                for ( ; altBegin != altEnd; ++altBegin ) {
                        explode( *altBegin, indexer, std::forward<Output>(out), isTupleAssign );
                }
        }

        template< typename Output >
        void explode( const ResolvExpr::AltList & alts, const SymTab::Indexer & indexer, Output&& out,
                        bool isTupleAssign = false ) {
                explode( alts.begin(), alts.end(), indexer, std::forward<Output>(out), isTupleAssign );
        }
} // namespace Tuples

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// mode: c++ //
// compile-command: "make install" //
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