Changes in / [954908d:bd41764]

Location:

src

Files:

• ResolvExpr/AlternativeFinder.cc (modified) (7 diffs)
• ResolvExpr/AlternativeFinder.h (modified) (2 diffs)
• ResolvExpr/TypeEnvironment.cc (modified) (1 diff)
• ResolvExpr/TypeEnvironment.h (modified) (1 diff)
• Tuples/TupleAssignment.cc (modified) (11 diffs)
• Tuples/Tuples.h (modified) (2 diffs)
• prelude/builtins.c (modified) (1 diff)

src/ResolvExpr/AlternativeFinder.cc

@@ -22 +22 @@
 #include <memory>                  // for allocator_traits<>::value_type
 #include <utility>                 // for pair
-#include <vector>                  // for vector
 
 #include "Alternative.h"           // for AltList, Alternative
@@ -334 +333 @@
                 tmpCost.incPoly( -tmpCost.get_polyCost() );
                 if ( tmpCost != Cost::zero ) {
+                // if ( convCost != Cost::zero ) {
                         Type *newType = formalType->clone();
                         env.apply( newType );
@@ -405 +405 @@
 ///     needAssertions.insert( needAssertions.end(), (*tyvar)->get_assertions().begin(), (*tyvar)->get_assertions().end() );
                 }
+        }
+
+        /// instantiate a single argument by matching actuals from [actualIt, actualEnd) against formalType,
+        /// producing expression(s) in out and their total cost in cost.
+        template< typename AltIterator, typename OutputIterator >
+        bool instantiateArgument( Type * formalType, Initializer * defaultValue, AltIterator & actualIt, AltIterator actualEnd, OpenVarSet & openVars, TypeEnvironment & resultEnv, AssertionSet & resultNeed, AssertionSet & resultHave, const SymTab::Indexer & indexer, Cost & cost, OutputIterator out ) {
+                if ( TupleType * tupleType = dynamic_cast< TupleType * >( formalType ) ) {
+                        // formalType is a TupleType - group actuals into a TupleExpr whose type unifies with the TupleType
+                        std::list< Expression * > exprs;
+                        for ( Type * type : *tupleType ) {
+                                if ( ! instantiateArgument( type, defaultValue, actualIt, actualEnd, openVars, resultEnv, resultNeed, resultHave, indexer, cost, back_inserter( exprs ) ) ) {
+                                        deleteAll( exprs );
+                                        return false;
+                                }
+                        }
+                        *out++ = new TupleExpr( exprs );
+                } else if ( TypeInstType * ttype = Tuples::isTtype( formalType ) ) {
+                        // xxx - mixing default arguments with variadic??
+                        std::list< Expression * > exprs;
+                        for ( ; actualIt != actualEnd; ++actualIt ) {
+                                exprs.push_back( actualIt->expr->clone() );
+                                cost += actualIt->cost;
+                        }
+                        Expression * arg = nullptr;
+                        if ( exprs.size() == 1 && Tuples::isTtype( exprs.front()->get_result() ) ) {
+                                // the case where a ttype value is passed directly is special, e.g. for argument forwarding purposes
+                                // xxx - what if passing multiple arguments, last of which is ttype?
+                                // xxx - what would happen if unify was changed so that unifying tuple types flattened both before unifying lists? then pass in TupleType(ttype) below.
+                                arg = exprs.front();
+                        } else {
+                                arg = new TupleExpr( exprs );
+                        }
+                        assert( arg && arg->get_result() );
+                        if ( ! unify( ttype, arg->get_result(), resultEnv, resultNeed, resultHave, openVars, indexer ) ) {
+                                return false;
+                        }
+                        *out++ = arg;
+                } else if ( actualIt != actualEnd ) {
+                        // both actualType and formalType are atomic (non-tuple) types - if they unify
+                        // then accept actual as an argument, otherwise return false (fail to instantiate argument)
+                        Expression * actual = actualIt->expr;
+                        Type * actualType = actual->get_result();
+
+                        PRINT(
+                                std::cerr << "formal type is ";
+                                formalType->print( std::cerr );
+                                std::cerr << std::endl << "actual type is ";
+                                actualType->print( std::cerr );
+                                std::cerr << std::endl;
+                        )
+                        if ( ! unify( formalType, actualType, resultEnv, resultNeed, resultHave, openVars, indexer ) ) {
+                                // std::cerr << "unify failed" << std::endl;
+                                return false;
+                        }
+                        // move the expression from the alternative to the output iterator
+                        *out++ = actual;
+                        actualIt->expr = nullptr;
+                        cost += actualIt->cost;
+                        ++actualIt;
+                } else {
+                        // End of actuals - Handle default values
+                        if ( SingleInit *si = dynamic_cast<SingleInit *>( defaultValue )) {
+                                if ( CastExpr * castExpr = dynamic_cast< CastExpr * >( si->get_value() ) ) {
+                                        // so far, only constant expressions are accepted as default values
+                                        if ( ConstantExpr *cnstexpr = dynamic_cast<ConstantExpr *>( castExpr->get_arg() ) ) {
+                                                if ( Constant *cnst = dynamic_cast<Constant *>( cnstexpr->get_constant() ) ) {
+                                                        if ( unify( formalType, cnst->get_type(), resultEnv, resultNeed, resultHave, openVars, indexer ) ) {
+                                                                *out++ = cnstexpr->clone();
+                                                                return true;
+                                                        } // if
+                                                } // if
+                                        } // if
+                                }
+                        } // if
+                        return false;
+                } // if
+                return true;
+        }
+
+        bool AlternativeFinder::instantiateFunction( std::list< DeclarationWithType* >& formals, const AltList &actuals, bool isVarArgs, OpenVarSet& openVars, TypeEnvironment &resultEnv, AssertionSet &resultNeed, AssertionSet &resultHave, AltList & out ) {
+                simpleCombineEnvironments( actuals.begin(), actuals.end(), resultEnv );
+                // make sure we don't widen any existing bindings
+                for ( TypeEnvironment::iterator i = resultEnv.begin(); i != resultEnv.end(); ++i ) {
+                        i->allowWidening = false;
+                }
+                resultEnv.extractOpenVars( openVars );
+
+                // flatten actuals so that each actual has an atomic (non-tuple) type
+                AltList exploded;
+                Tuples::explode( actuals, indexer, back_inserter( exploded ) );
+
+                AltList::iterator actualExpr = exploded.begin();
+                AltList::iterator actualEnd = exploded.end();
+                for ( DeclarationWithType * formal : formals ) {
+                        // match flattened actuals with formal parameters - actuals will be grouped to match
+                        // with formals as appropriate
+                        Cost cost = Cost::zero;
+                        std::list< Expression * > newExprs;
+                        ObjectDecl * obj = strict_dynamic_cast< ObjectDecl * >( formal );
+                        if ( ! instantiateArgument( obj->get_type(), obj->get_init(), actualExpr, actualEnd, openVars, resultEnv, resultNeed, resultHave, indexer, cost, back_inserter( newExprs ) ) ) {
+                                deleteAll( newExprs );
+                                return false;
+                        }
+                        // success - produce argument as a new alternative
+                        assert( newExprs.size() == 1 );
+                        out.push_back( Alternative( newExprs.front(), resultEnv, cost ) );
+                }
+                if ( actualExpr != actualEnd ) {
+                        // there are still actuals remaining, but we've run out of formal parameters to match against
+                        // this is okay only if the function is variadic
+                        if ( ! isVarArgs ) {
+                                return false;
+                        }
+                        out.splice( out.end(), exploded, actualExpr, actualEnd );
+                }
+                return true;
         }
 
@@ -559 +675 @@
         }
 
-        /// Gets a default value from an initializer, nullptr if not present
-        ConstantExpr* getDefaultValue( Initializer* init ) {
-                if ( SingleInit* si = dynamic_cast<SingleInit*>( init ) ) {
-                        if ( CastExpr* ce = dynamic_cast<CastExpr*>( si->get_value() ) ) {
-                                return dynamic_cast<ConstantExpr*>( ce->get_arg() );
-                        }
-                }
-                return nullptr;
-        }
-
-        /// State to iteratively build a match of parameter expressions to arguments
-        struct ArgPack {
-                AltList actuals;                 ///< Arguments included in this pack
-                TypeEnvironment env;             ///< Environment for this pack
-                AssertionSet need;               ///< Assertions outstanding for this pack
-                AssertionSet have;               ///< Assertions found for this pack
-                OpenVarSet openVars;             ///< Open variables for this pack
-                unsigned nextArg;                ///< Index of next argument in arguments list
-                std::vector<Alternative> expls;  ///< Exploded actuals left over from last match
-                unsigned nextExpl;               ///< Index of next exploded alternative to use
-                std::vector<unsigned> tupleEls;  /// Number of elements in current tuple element(s)
-
-                ArgPack(const TypeEnvironment& env, const AssertionSet& need, const AssertionSet& have, 
-                                const OpenVarSet& openVars)
-                        : actuals(), env(env), need(need), have(have), openVars(openVars), nextArg(0),
-                          expls(), nextExpl(0), tupleEls() {}
-                
-                /// Starts a new tuple expression
-                void beginTuple() {
-                        if ( ! tupleEls.empty() ) ++tupleEls.back();
-                        tupleEls.push_back(0);
-                }
-
-                /// Ends a tuple expression, consolidating the appropriate actuals
-                void endTuple() {
-                        // set up new Tuple alternative
-                        std::list<Expression*> exprs;
-                        Cost cost = Cost::zero;
-
-                        // transfer elements into alternative
-                        for (unsigned i = 0; i < tupleEls.back(); ++i) {
-                                exprs.push_front( actuals.back().expr );
-                                actuals.back().expr = nullptr;
-                                cost += actuals.back().cost;
-                                actuals.pop_back();
-                        }
-                        tupleEls.pop_back();
-
-                        // build new alternative
-                        actuals.emplace_back( new TupleExpr( exprs ), this->env, cost );
-                }
-
-                /// Clones and adds an actual, returns this
-                ArgPack& withArg( Expression* expr, Cost cost = Cost::zero ) {
-                        actuals.emplace_back( expr->clone(), this->env, cost );
-                        if ( ! tupleEls.empty() ) ++tupleEls.back();
-                        return *this;
-                }
-        };
-
-        /// Instantiates an argument to match a formal, returns false if no results left
-        bool instantiateArgument( Type* formalType, Initializer* initializer, 
-                        const std::vector< AlternativeFinder >& args, 
-                        std::vector<ArgPack>& results, std::vector<ArgPack>& nextResults, 
-                        const SymTab::Indexer& indexer ) {
-                if ( TupleType* tupleType = dynamic_cast<TupleType*>( formalType ) ) {
-                        // formalType is a TupleType - group actuals into a TupleExpr
-                        for ( ArgPack& result : results ) { result.beginTuple(); }
-                        for ( Type* type : *tupleType ) {
-                                // xxx - dropping initializer changes behaviour from previous, but seems correct
-                                if ( ! instantiateArgument( type, nullptr, args, results, nextResults, indexer ) ) 
-                                        return false;
-                        }
-                        for ( ArgPack& result : results ) { result.endTuple(); }
-                        return true;
-                } else if ( TypeInstType* ttype = Tuples::isTtype( formalType ) ) {
-                        // formalType is a ttype, consumes all remaining arguments
-                        // xxx - mixing default arguments with variadic??
-                        std::vector<ArgPack> finalResults{};  /// list of completed tuples
-                        // start tuples
-                        for ( ArgPack& result : results ) {
-                                result.beginTuple();
-
-                                // use rest of exploded tuple if present
-                                while ( result.nextExpl < result.expls.size() ) {
-                                        const Alternative& actual = result.expls[result.nextExpl];
-                                        result.env.addActual( actual.env, result.openVars );
-                                        result.withArg( actual.expr );
-                                        ++result.nextExpl;
-                                }
-                        }
-                        // iterate until all results completed
-                        while ( ! results.empty() ) {
-                                // add another argument to results
-                                for ( ArgPack& result : results ) {
-                                        // finish result when out of arguments
-                                        if ( result.nextArg >= args.size() ) {
-                                                Type* argType = result.actuals.back().expr->get_result();
-                                                if ( result.tupleEls.back() == 1 && Tuples::isTtype( argType ) ) {
-                                                        // the case where a ttype value is passed directly is special, e.g. for 
-                                                        // argument forwarding purposes
-                                                        // xxx - what if passing multiple arguments, last of which is ttype?
-                                                        // xxx - what would happen if unify was changed so that unifying tuple 
-                                                        // types flattened both before unifying lists? then pass in TupleType
-                                                        // (ttype) below.
-                                                        result.tupleEls.pop_back();
-                                                } else {
-                                                        // collapse leftover arguments into tuple
-                                                        result.endTuple();
-                                                        argType = result.actuals.back().expr->get_result();
-                                                }
-                                                // check unification for ttype before adding to final
-                                                if ( unify( ttype, argType, result.env, result.need, result.have, 
-                                                                result.openVars, indexer ) ) {
-                                                        finalResults.push_back( std::move(result) );
-                                                }
-                                                continue;
-                                        }
-
-                                        // add each possible next argument
-                                        for ( const Alternative& actual : args[result.nextArg] ) {
-                                                ArgPack aResult = result;  // copy to clone everything
-                                                // add details of actual to result
-                                                aResult.env.addActual( actual.env, aResult.openVars );
-                                                Cost cost = actual.cost;
-                
-                                                // explode argument
-                                                std::vector<Alternative> exploded;
-                                                Tuples::explode( actual, indexer, back_inserter( exploded ) );
-                                                
-                                                // add exploded argument to tuple
-                                                for ( Alternative& aActual : exploded ) {
-                                                        aResult.withArg( aActual.expr, cost );
-                                                        cost = Cost::zero;
-                                                }
-                                                ++aResult.nextArg;
-                                                nextResults.push_back( std::move(aResult) );
-                                        }
-                                }
-
-                                // reset for next round
-                                results.swap( nextResults );
-                                nextResults.clear();
-                        }
-                        results.swap( finalResults );
-                        return ! results.empty();
-                }
-                
-                // iterate each current subresult
-                for ( unsigned iResult = 0; iResult < results.size(); ++iResult ) {
-                        ArgPack& result = results[iResult];
-
-                        if ( result.nextExpl < result.expls.size() ) {
-                                // use remainder of exploded tuple if present
-                                const Alternative& actual = result.expls[result.nextExpl];
-                                result.env.addActual( actual.env, result.openVars );
-                                Type* actualType = actual.expr->get_result();
-
-                                PRINT(
-                                        std::cerr << "formal type is ";
-                                        formalType->print( std::cerr );
-                                        std::cerr << std::endl << "actual type is ";
-                                        actualType->print( std::cerr );
-                                        std::cerr << std::endl;
-                                )
-                                
-                                if ( unify( formalType, actualType, result.env, result.need, result.have, 
-                                                result.openVars, indexer ) ) {
-                                        ++result.nextExpl;
-                                        nextResults.push_back( std::move(result.withArg( actual.expr )) );
-                                }
-
-                                continue;
-                        } else if ( result.nextArg >= args.size() ) {
-                                // use default initializers if out of arguments
-                                if ( ConstantExpr* cnstExpr = getDefaultValue( initializer ) ) {
-                                        if ( Constant* cnst = dynamic_cast<Constant*>( cnstExpr->get_constant() ) ) {
-                                                if ( unify( formalType, cnst->get_type(), result.env, result.need, 
-                                                                result.have, result.openVars, indexer ) ) {
-                                                        nextResults.push_back( std::move(result.withArg( cnstExpr )) );
-                                                }
-                                        }
-                                }
-                                continue;
-                        }
-
-                        // Check each possible next argument
-                        for ( const Alternative& actual : args[result.nextArg] ) {
-                                ArgPack aResult = result;  // copy to clone everything
-                                // add details of actual to result
-                                aResult.env.addActual( actual.env, aResult.openVars );
-
-                                // explode argument
-                                std::vector<Alternative> exploded;
-                                Tuples::explode( actual, indexer, back_inserter( exploded ) );
-                                if ( exploded.empty() ) {
-                                        // skip empty tuple arguments
-                                        ++aResult.nextArg;
-                                        results.push_back( std::move(aResult) );
-                                        continue;
-                                }
-
-                                // consider only first exploded actual
-                                const Alternative& aActual = exploded.front();
-                                Type* actualType = aActual.expr->get_result()->clone();
-
-                                PRINT(
-                                        std::cerr << "formal type is ";
-                                        formalType->print( std::cerr );
-                                        std::cerr << std::endl << "actual type is ";
-                                        actualType->print( std::cerr );
-                                        std::cerr << std::endl;
-                                )
-
-                                // attempt to unify types
-                                if ( unify( formalType, actualType, aResult.env, aResult.need, aResult.have, aResult.openVars, indexer ) ) {
-                                        // add argument
-                                        aResult.withArg( aActual.expr, actual.cost );
-                                        ++aResult.nextArg;
-                                        if ( exploded.size() > 1 ) {
-                                                // other parts of tuple left over
-                                                aResult.expls = std::move( exploded );
-                                                aResult.nextExpl = 1;
-                                        }
-                                        nextResults.push_back( std::move(aResult) );
-                                }
-                        }
-                }
-
-                // reset for next parameter
-                results.swap( nextResults );
-                nextResults.clear();
-                
-                return ! results.empty();
-        }       
-
-        template<typename OutputIterator>
-        void AlternativeFinder::makeFunctionAlternatives( const Alternative &func, 
-                        FunctionType *funcType, const std::vector< AlternativeFinder > &args, 
-                        OutputIterator out ) {
-                OpenVarSet funcOpenVars;
-                AssertionSet funcNeed, funcHave;
-                TypeEnvironment funcEnv( func.env );
-                makeUnifiableVars( funcType, funcOpenVars, funcNeed );
-                // add all type variables as open variables now so that those not used in the parameter 
-                // list are still considered open.
-                funcEnv.add( funcType->get_forall() );
-                
+        template< typename OutputIterator >
+        void AlternativeFinder::makeFunctionAlternatives( const Alternative &func, FunctionType *funcType, const AltList &actualAlt, OutputIterator out ) {
+                OpenVarSet openVars;
+                AssertionSet resultNeed, resultHave;
+                TypeEnvironment resultEnv( func.env );
+                makeUnifiableVars( funcType, openVars, resultNeed );
+                resultEnv.add( funcType->get_forall() ); // add all type variables as open variables now so that those not used in the parameter list are still considered open
+                AltList instantiatedActuals; // filled by instantiate function
                 if ( targetType && ! targetType->isVoid() && ! funcType->get_returnVals().empty() ) {
                         // attempt to narrow based on expected target type
                         Type * returnType = funcType->get_returnVals().front()->get_type();
-                        if ( ! unify( returnType, targetType, funcEnv, funcNeed, funcHave, funcOpenVars, 
-                                        indexer ) ) {
-                                // unification failed, don't pursue this function alternative
+                        if ( ! unify( returnType, targetType, resultEnv, resultNeed, resultHave, openVars, indexer ) ) {
+                                // unification failed, don't pursue this alternative
                                 return;
                         }
                 }
 
-                // iteratively build matches, one parameter at a time
-                std::vector<ArgPack> results{ ArgPack{ funcEnv, funcNeed, funcHave, funcOpenVars } };
-                std::vector<ArgPack> nextResults{};
-                for ( DeclarationWithType* formal : funcType->get_parameters() ) {
-                        ObjectDecl* obj = strict_dynamic_cast< ObjectDecl* >( formal );
-                        if ( ! instantiateArgument( 
-                                        obj->get_type(), obj->get_init(), args, results, nextResults, indexer ) )
-                                return;
-                }
-
-                // filter out results that don't use all the arguments, and aren't variadic
-                std::vector<ArgPack> finalResults{};
-                if ( funcType->get_isVarArgs() ) {
-                        for ( ArgPack& result : results ) {
-                                // use rest of exploded tuple if present
-                                while ( result.nextExpl < result.expls.size() ) {
-                                        const Alternative& actual = result.expls[result.nextExpl];
-                                        result.env.addActual( actual.env, result.openVars );
-                                        result.withArg( actual.expr );
-                                        ++result.nextExpl;
-                                }
-                        }
-
-                        while ( ! results.empty() ) {
-                                // build combinations for all remaining arguments
-                                for ( ArgPack& result : results ) {
-                                        // keep if used all arguments
-                                        if ( result.nextArg >= args.size() ) {
-                                                finalResults.push_back( std::move(result) );
-                                                continue;
-                                        }
-
-                                        // add each possible next argument
-                                        for ( const Alternative& actual : args[result.nextArg] ) {
-                                                ArgPack aResult = result; // copy to clone everything
-                                                // add details of actual to result
-                                                aResult.env.addActual( actual.env, aResult.openVars );
-                                                Cost cost = actual.cost;
-
-                                                // explode argument
-                                                std::vector<Alternative> exploded;
-                                                Tuples::explode( actual, indexer, back_inserter( exploded ) );
-
-                                                // add exploded argument to arg list
-                                                for ( Alternative& aActual : exploded ) {
-                                                        aResult.withArg( aActual.expr, cost );
-                                                        cost = Cost::zero;
-                                                }
-                                                ++aResult.nextArg;
-                                                nextResults.push_back( std::move(aResult) );
-                                        }
-                                }
-
-                                // reset for next round
-                                results.swap( nextResults );
-                                nextResults.clear();
-                        }
-                } else {
-                        // filter out results that don't use all the arguments
-                        for ( ArgPack& result : results ) {
-                                if ( result.nextExpl >= result.expls.size() && result.nextArg >= args.size() ) {
-                                        finalResults.push_back( std::move(result) );
-                                }
-                        }
-                }
-
-                // validate matching combos, add to final result list
-                for ( ArgPack& result : finalResults ) {
+                if ( instantiateFunction( funcType->get_parameters(), actualAlt, funcType->get_isVarArgs(), openVars, resultEnv, resultNeed, resultHave, instantiatedActuals ) ) {
                         ApplicationExpr *appExpr = new ApplicationExpr( func.expr->clone() );
-                        Alternative newAlt( appExpr, result.env, sumCost( result.actuals ) );
-                        makeExprList( result.actuals, appExpr->get_args() );
+                        Alternative newAlt( appExpr, resultEnv, sumCost( instantiatedActuals ) );
+                        makeExprList( instantiatedActuals, appExpr->get_args() );
                         PRINT(
                                 std::cerr << "instantiate function success: " << appExpr << std::endl;
                                 std::cerr << "need assertions:" << std::endl;
-                                printAssertionSet( result.need, std::cerr, 8 );
+                                printAssertionSet( resultNeed, std::cerr, 8 );
                         )
-                        inferParameters( result.need, result.have, newAlt, result.openVars, out );
+                        inferParameters( resultNeed, resultHave, newAlt, openVars, out );
                 }
         }
@@ -903 +711 @@
                 if ( funcFinder.alternatives.empty() ) return;
 
-                std::vector< AlternativeFinder > argAlternatives;
-                findSubExprs( untypedExpr->begin_args(), untypedExpr->end_args(), 
-                        back_inserter( argAlternatives ) );
+                std::list< AlternativeFinder > argAlternatives;
+                findSubExprs( untypedExpr->begin_args(), untypedExpr->end_args(), back_inserter( argAlternatives ) );
+
+                std::list< AltList > possibilities;
+                combos( argAlternatives.begin(), argAlternatives.end(), back_inserter( possibilities ) );
 
                 // take care of possible tuple assignments
                 // if not tuple assignment, assignment is taken care of as a normal function call
-                Tuples::handleTupleAssignment( *this, untypedExpr, argAlternatives );
+                Tuples::handleTupleAssignment( *this, untypedExpr, possibilities );
 
                 // find function operators
@@ -934 +744 @@
                                                 Alternative newFunc( *func );
                                                 referenceToRvalueConversion( newFunc.expr );
-                                                makeFunctionAlternatives( newFunc, function, argAlternatives, 
-                                                        std::back_inserter( candidates ) );
+                                                for ( std::list< AltList >::iterator actualAlt = possibilities.begin(); actualAlt != possibilities.end(); ++actualAlt ) {
+                                                        // XXX
+                                                        //Designators::check_alternative( function, *actualAlt );
+                                                        makeFunctionAlternatives( newFunc, function, *actualAlt, std::back_inserter( candidates ) );
+                                                }
                                         }
                                 } else if ( TypeInstType *typeInst = dynamic_cast< TypeInstType* >( func->expr->get_result()->stripReferences() ) ) { // handle ftype (e.g. *? on function pointer)
@@ -943 +756 @@
                                                         Alternative newFunc( *func );
                                                         referenceToRvalueConversion( newFunc.expr );
-                                                        makeFunctionAlternatives( newFunc, function, argAlternatives, 
-                                                                std::back_inserter( candidates ) );
+                                                        for ( std::list< AltList >::iterator actualAlt = possibilities.begin(); actualAlt != possibilities.end(); ++actualAlt ) {
+                                                                makeFunctionAlternatives( newFunc, function, *actualAlt, std::back_inserter( candidates ) );
+                                                        } // for
                                                 } // if
                                         } // if
-                                }                       
+                                }
+
+                                // try each function operator ?() with the current function alternative and each of the argument combinations
+                                for ( AltList::iterator funcOp = funcOpFinder.alternatives.begin(); funcOp != funcOpFinder.alternatives.end(); ++funcOp ) {
+                                        // check if the type is pointer to function
+                                        if ( PointerType *pointer = dynamic_cast< PointerType* >( funcOp->expr->get_result()->stripReferences() ) ) {
+                                                if ( FunctionType *function = dynamic_cast< FunctionType* >( pointer->get_base() ) ) {
+                                                        Alternative newFunc( *funcOp );
+                                                        referenceToRvalueConversion( newFunc.expr );
+                                                        for ( std::list< AltList >::iterator actualAlt = possibilities.begin(); actualAlt != possibilities.end(); ++actualAlt ) {
+                                                                AltList currentAlt;
+                                                                currentAlt.push_back( *func );
+                                                                currentAlt.insert( currentAlt.end(), actualAlt->begin(), actualAlt->end() );
+                                                                makeFunctionAlternatives( newFunc, function, currentAlt, std::back_inserter( candidates ) );
+                                                        } // for
+                                                } // if
+                                        } // if
+                                } // for
                         } catch ( SemanticError &e ) {
                                 errors.append( e );
                         }
                 } // for
-
-                // try each function operator ?() with each function alternative
-                if ( ! funcOpFinder.alternatives.empty() ) {
-                        // add function alternatives to front of argument list
-                        argAlternatives.insert( argAlternatives.begin(), std::move(funcFinder) );
-
-                        for ( AltList::iterator funcOp = funcOpFinder.alternatives.begin();
-                                        funcOp != funcOpFinder.alternatives.end(); ++funcOp ) {
-                                try {
-                                        // check if type is a pointer to function
-                                        if ( PointerType* pointer = dynamic_cast<PointerType*>( 
-                                                        funcOp->expr->get_result()->stripReferences() ) ) {
-                                                if ( FunctionType* function = 
-                                                                dynamic_cast<FunctionType*>( pointer->get_base() ) ) {
-                                                        Alternative newFunc( *funcOp );
-                                                        referenceToRvalueConversion( newFunc.expr );
-                                                        makeFunctionAlternatives( newFunc, function, argAlternatives, 
-                                                                std::back_inserter( candidates ) );
-                                                }
-                                        }
-                                } catch ( SemanticError &e ) {
-                                        errors.append( e );
-                                }
-                        }
-                }
 
                 // Implement SFINAE; resolution errors are only errors if there aren't any non-erroneous resolutions

src/ResolvExpr/AlternativeFinder.h

@@ -34 +34 @@
           public:
                 AlternativeFinder( const SymTab::Indexer &indexer, const TypeEnvironment &env );
-
-                AlternativeFinder( const AlternativeFinder& o )
-                        : indexer(o.indexer), alternatives(o.alternatives), env(o.env), 
-                          targetType(o.targetType) {}
-                
-                AlternativeFinder( AlternativeFinder&& o )
-                        : indexer(o.indexer), alternatives(std::move(o.alternatives)), env(o.env), 
-                          targetType(o.targetType) {}
-                
-                AlternativeFinder& operator= ( const AlternativeFinder& o ) {
-                        if (&o == this) return *this;
-                        
-                        // horrific nasty hack to rebind references...
-                        alternatives.~AltList();
-                        new(this) AlternativeFinder(o);
-                        return *this;
-                }
-
-                AlternativeFinder& operator= ( AlternativeFinder&& o ) {
-                        if (&o == this) return *this;
-                        
-                        // horrific nasty hack to rebind references...
-                        alternatives.~AltList();
-                        new(this) AlternativeFinder(std::move(o));
-                        return *this;
-                }
-
                 void find( Expression *expr, bool adjust = false, bool prune = true, bool failFast = true );
                 /// Calls find with the adjust flag set; adjustment turns array and function types into equivalent pointer types
@@ -126 +99 @@
                 /// Adds alternatives for offsetof expressions, given the base type and name of the member
                 template< typename StructOrUnionType > void addOffsetof( StructOrUnionType *aggInst, const std::string &name );
-                template<typename OutputIterator>
-                void makeFunctionAlternatives( const Alternative &func, FunctionType *funcType, const std::vector< AlternativeFinder >& args, OutputIterator out );
+                bool instantiateFunction( std::list< DeclarationWithType* >& formals, const AltList &actuals, bool isVarArgs, OpenVarSet& openVars, TypeEnvironment &resultEnv, AssertionSet &resultNeed, AssertionSet &resultHave, AltList & out );
+                template< typename OutputIterator >
+                void makeFunctionAlternatives( const Alternative &func, FunctionType *funcType, const AltList &actualAlt, OutputIterator out );
                 template< typename OutputIterator >
                 void inferParameters( const AssertionSet &need, AssertionSet &have, const Alternative &newAlt, OpenVarSet &openVars, OutputIterator out );

src/ResolvExpr/TypeEnvironment.cc

@@ -201 +201 @@
         }
 
-        void TypeEnvironment::addActual( const TypeEnvironment& actualEnv, OpenVarSet& openVars ) {
-                for ( const EqvClass& c : actualEnv ) {
-                        EqvClass c2 = c;
-                        c2.allowWidening = false;
-                        for ( const std::string& var : c2.vars ) {
-                                openVars[ var ] = c2.data;
-                        }
-                        env.push_back( std::move(c2) );
-                }
-        }
-
 } // namespace ResolvExpr
 

src/ResolvExpr/TypeEnvironment.h

@@ -86 +86 @@
                 TypeEnvironment *clone() const { return new TypeEnvironment( *this ); }
 
-                /// Iteratively adds the environment of a new actual (with allowWidening = false), 
-                /// and extracts open variables.
-                void addActual( const TypeEnvironment& actualEnv, OpenVarSet& openVars );
-
                 typedef std::list< EqvClass >::iterator iterator;
                 iterator begin() { return env.begin(); }

src/Tuples/TupleAssignment.cc

@@ -20 +20 @@
 #include <memory>                          // for unique_ptr, allocator_trai...
 #include <string>                          // for string
-#include <vector>
 
 #include "CodeGen/OperatorTable.h"
@@ -34 +33 @@
 #include "ResolvExpr/Resolver.h"           // for resolveCtorInit
 #include "ResolvExpr/TypeEnvironment.h"    // for TypeEnvironment
-#include "ResolvExpr/typeops.h"            // for combos
 #include "SynTree/Declaration.h"           // for ObjectDecl
 #include "SynTree/Expression.h"            // for Expression, CastExpr, Name...
@@ -54 +52 @@
                 // dispatcher for Tuple (multiple and mass) assignment operations
                 TupleAssignSpotter( ResolvExpr::AlternativeFinder & );
-                void spot( UntypedExpr * expr, std::vector<ResolvExpr::AlternativeFinder> &args );
+                void spot( UntypedExpr * expr, const std::list<ResolvExpr::AltList> &possibilities );
 
           private:
@@ -61 +59 @@
                 struct Matcher {
                   public:
-                        Matcher( TupleAssignSpotter &spotter, const ResolvExpr::AltList& lhs, const 
-                                ResolvExpr::AltList& rhs );
+                        Matcher( TupleAssignSpotter &spotter, const ResolvExpr::AltList & alts );
                         virtual ~Matcher() {}
                         virtual void match( std::list< Expression * > &out ) = 0;
@@ -75 +72 @@
                 struct MassAssignMatcher : public Matcher {
                   public:
-                        MassAssignMatcher( TupleAssignSpotter &spotter, const ResolvExpr::AltList& lhs, 
-                                const ResolvExpr::AltList& rhs ) : Matcher(spotter, lhs, rhs) {}
+                        MassAssignMatcher( TupleAssignSpotter &spotter, const ResolvExpr::AltList & alts );
                         virtual void match( std::list< Expression * > &out );
                 };
@@ -82 +78 @@
                 struct MultipleAssignMatcher : public Matcher {
                   public:
-                        MultipleAssignMatcher( TupleAssignSpotter &spotter, const ResolvExpr::AltList& lhs, 
-                                const ResolvExpr::AltList& rhs ) : Matcher(spotter, lhs, rhs) {}
+                        MultipleAssignMatcher( TupleAssignSpotter &spot, const ResolvExpr::AltList & alts );
                         virtual void match( std::list< Expression * > &out );
                 };
@@ -119 +114 @@
         }
 
-        void handleTupleAssignment( ResolvExpr::AlternativeFinder & currentFinder, UntypedExpr * expr, 
-                                std::vector<ResolvExpr::AlternativeFinder> &args ) {
+        void handleTupleAssignment( ResolvExpr::AlternativeFinder & currentFinder, UntypedExpr * expr, const std::list<ResolvExpr::AltList> &possibilities ) {
                 TupleAssignSpotter spotter( currentFinder );
-                spotter.spot( expr, args );
+                spotter.spot( expr, possibilities );
         }
 
@@ -128 +122 @@
                 : currentFinder(f) {}
 
-        void TupleAssignSpotter::spot( UntypedExpr * expr, 
-                        std::vector<ResolvExpr::AlternativeFinder> &args ) {
+        void TupleAssignSpotter::spot( UntypedExpr * expr, const std::list<ResolvExpr::AltList> &possibilities ) {
                 if (  NameExpr *op = dynamic_cast< NameExpr * >(expr->get_function()) ) {
                         if ( CodeGen::isCtorDtorAssign( op->get_name() ) ) {
-                                fname = op->get_name();
-
-                                // AlternativeFinder will naturally handle this case case, if it's legal
-                                if ( args.size() == 0 ) return;
-
-                                // if an assignment only takes 1 argument, that's odd, but maybe someone wrote 
-                                // the function, in which case AlternativeFinder will handle it normally
-                                if ( args.size() == 1 && CodeGen::isAssignment( fname ) ) return;
-
-                                // look over all possible left-hand-sides
-                                for ( ResolvExpr::Alternative& lhsAlt : args[0] ) {
-                                        // skip non-tuple LHS
-                                        if ( ! refToTuple(lhsAlt.expr) ) continue;
-
-                                        // explode is aware of casts - ensure every LHS expression is sent into explode 
-                                        // with a reference cast
-                                        // xxx - this seems to change the alternatives before the normal 
-                                        //  AlternativeFinder flow; maybe this is desired?
-                                        if ( ! dynamic_cast<CastExpr*>( lhsAlt.expr ) ) {
-                                                lhsAlt.expr = new CastExpr( lhsAlt.expr, 
-                                                                new ReferenceType( Type::Qualifiers(), 
-                                                                        lhsAlt.expr->get_result()->clone() ) );
+                               fname = op->get_name();
+                                PRINT( std::cerr << "TupleAssignment: " << fname << std::endl; )
+                                for ( std::list<ResolvExpr::AltList>::const_iterator ali = possibilities.begin(); ali != possibilities.end(); ++ali ) {
+                                        if ( ali->size() == 0 ) continue; // AlternativeFinder will natrually handle this case, if it's legal
+                                        if ( ali->size() <= 1 && CodeGen::isAssignment( op->get_name() ) ) {
+                                                // what does it mean if an assignment takes 1 argument? maybe someone defined such a function, in which case AlternativeFinder will naturally handle it
+                                                continue;
                                         }
 
-                                        // explode the LHS so that each field of a tuple-valued-expr is assigned
-                                        ResolvExpr::AltList lhs;
-                                        explode( lhsAlt, currentFinder.get_indexer(), back_inserter(lhs), true );
-                                        for ( ResolvExpr::Alternative& alt : lhs ) {
-                                                // each LHS value must be a reference - some come in with a cast expression, 
-                                                // if not just cast to reference here
-                                                if ( ! dynamic_cast<ReferenceType*>( alt.expr->get_result() ) ) {
-                                                        alt.expr = new CastExpr( alt.expr, 
-                                                                new ReferenceType( Type::Qualifiers(), 
-                                                                        alt.expr->get_result()->clone() ) );
+                                        assert( ! ali->empty() );
+                                        // grab args 2-N and group into a TupleExpr
+                                        const ResolvExpr::Alternative & alt1 = ali->front();
+                                        auto begin = std::next(ali->begin(), 1), end = ali->end();
+                                        PRINT( std::cerr << "alt1 is " << alt1.expr << std::endl; )
+                                        if ( refToTuple(alt1.expr) ) {
+                                                PRINT( std::cerr << "and is reference to tuple" << std::endl; )
+                                                if ( isMultAssign( begin, end ) ) {
+                                                        PRINT( std::cerr << "possible multiple assignment" << std::endl; )
+                                                        matcher.reset( new MultipleAssignMatcher( *this, *ali ) );
+                                                } else {
+                                                        // mass assignment
+                                                        PRINT( std::cerr << "possible mass assignment" << std::endl; )
+                                                        matcher.reset( new MassAssignMatcher( *this,  *ali ) );
                                                 }
-                                        }
-
-                                        if ( args.size() == 1 ) {
-                                                // mass default-initialization/destruction
-                                                ResolvExpr::AltList rhs{};
-                                                matcher.reset( new MassAssignMatcher( *this, lhs, rhs ) );
                                                 match();
-                                        } else if ( args.size() > 2 ) {
-                                                // expand all possible RHS possibilities
-                                                // TODO build iterative version of this instead of using combos
-                                                std::vector< ResolvExpr::AltList > rhsAlts;
-                                                combos( std::next(args.begin(), 1), args.end(), 
-                                                        std::back_inserter( rhsAlts ) );
-                                                for ( const ResolvExpr::AltList& rhsAlt : rhsAlts ) {
-                                                        // multiple assignment
-                                                        ResolvExpr::AltList rhs;
-                                                        explode( rhsAlt, currentFinder.get_indexer(), 
-                                                                std::back_inserter(rhs), true );
-                                                        matcher.reset( new MultipleAssignMatcher( *this, lhs, rhs ) );
-                                                        match();
-                                                }
-                                        } else {
-                                                for ( const ResolvExpr::Alternative& rhsAlt : args[1] ) {
-                                                        ResolvExpr::AltList rhs;
-                                                        if ( isTuple(rhsAlt.expr) ) {
-                                                                // multiple assignment
-                                                                explode( rhsAlt, currentFinder.get_indexer(),  
-                                                                        std::back_inserter(rhs), true );
-                                                                matcher.reset( new MultipleAssignMatcher( *this, lhs, rhs ) );
-                                                        } else {
-                                                                // mass assignment
-                                                                rhs.push_back( rhsAlt );
-                                                                matcher.reset( new MassAssignMatcher( *this, lhs, rhs ) );
-                                                        }
-                                                        match();
-                                                }
                                         }
                                 }
@@ -222 +169 @@
                 ResolvExpr::AltList current;
                 // now resolve new assignments
-                for ( std::list< Expression * >::iterator i = new_assigns.begin(); 
-                                i != new_assigns.end(); ++i ) {
+                for ( std::list< Expression * >::iterator i = new_assigns.begin(); i != new_assigns.end(); ++i ) {
                         PRINT(
                                 std::cerr << "== resolving tuple assign ==" << std::endl;
@@ -229 +175 @@
                         )
 
-                        ResolvExpr::AlternativeFinder finder{ currentFinder.get_indexer(), 
-                                currentFinder.get_environ() };
+                        ResolvExpr::AlternativeFinder finder( currentFinder.get_indexer(), currentFinder.get_environ() );
                         try {
                                 finder.findWithAdjustment(*i);
@@ -251 +196 @@
                 // combine assignment environments into combined expression environment
                 simpleCombineEnvironments( current.begin(), current.end(), matcher->compositeEnv );
-                currentFinder.get_alternatives().push_front( ResolvExpr::Alternative(
-                        new TupleAssignExpr(solved_assigns, matcher->tmpDecls), matcher->compositeEnv, 
-                        ResolvExpr::sumCost( current ) + matcher->baseCost ) );
-        }
-
-        TupleAssignSpotter::Matcher::Matcher( TupleAssignSpotter &spotter, 
-                const ResolvExpr::AltList &lhs, const ResolvExpr::AltList &rhs ) 
-        : lhs(lhs), rhs(rhs), spotter(spotter), 
-          baseCost( ResolvExpr::sumCost( lhs ) + ResolvExpr::sumCost( rhs ) ) {
-                simpleCombineEnvironments( lhs.begin(), lhs.end(), compositeEnv );
-                simpleCombineEnvironments( rhs.begin(), rhs.end(), compositeEnv );
+                currentFinder.get_alternatives().push_front( ResolvExpr::Alternative(new TupleAssignExpr(solved_assigns, matcher->tmpDecls), matcher->compositeEnv, ResolvExpr::sumCost( current  ) + matcher->baseCost ) );
+        }
+
+        TupleAssignSpotter::Matcher::Matcher( TupleAssignSpotter &spotter, const ResolvExpr::AltList &alts ) : spotter(spotter), baseCost( ResolvExpr::sumCost( alts ) ) {
+                assert( ! alts.empty() );
+                // combine argument environments into combined expression environment
+                simpleCombineEnvironments( alts.begin(), alts.end(), compositeEnv );
+
+                ResolvExpr::Alternative lhsAlt = alts.front();
+                // explode is aware of casts - ensure every LHS expression is sent into explode with a reference cast
+                if ( ! dynamic_cast< CastExpr * >( lhsAlt.expr ) ) {
+                        lhsAlt.expr = new CastExpr( lhsAlt.expr, new ReferenceType( Type::Qualifiers(), lhsAlt.expr->get_result()->clone() ) );
+                }
+
+                // explode the lhs so that each field of the tuple-valued-expr is assigned.
+                explode( lhsAlt, spotter.currentFinder.get_indexer(), back_inserter(lhs), true );
+
+                for ( ResolvExpr::Alternative & alt : lhs ) {
+                        // every LHS value must be a reference - some come in with a cast expression, if it doesn't just cast to reference here.
+                        if ( ! dynamic_cast< ReferenceType * >( alt.expr->get_result() ) ) {
+                                alt.expr = new CastExpr( alt.expr, new ReferenceType( Type::Qualifiers(), alt.expr->get_result()->clone() ) );
+                        }
+                }
+        }
+
+        TupleAssignSpotter::MassAssignMatcher::MassAssignMatcher( TupleAssignSpotter &spotter, const ResolvExpr::AltList & alts ) : Matcher( spotter, alts ) {
+                assert( alts.size() == 1 || alts.size() == 2 );
+                if ( alts.size() == 2 ) {
+                        rhs.push_back( alts.back() );
+                }
+        }
+
+        TupleAssignSpotter::MultipleAssignMatcher::MultipleAssignMatcher( TupleAssignSpotter &spotter, const ResolvExpr::AltList & alts ) : Matcher( spotter, alts ) {
+                // explode the rhs so that each field of the tuple-valued-expr is assigned.
+                explode( std::next(alts.begin(), 1), alts.end(), spotter.currentFinder.get_indexer(), back_inserter(rhs), true );
         }
 

src/Tuples/Tuples.h

@@ -17 +17 @@
 
 #include <string>
-#include <vector>
 
 #include "SynTree/Expression.h"
@@ -27 +26 @@
 namespace Tuples {
         // TupleAssignment.cc
-        void handleTupleAssignment( ResolvExpr::AlternativeFinder & currentFinder, UntypedExpr * assign, 
-                std::vector< ResolvExpr::AlternativeFinder >& args );
-        
+        void handleTupleAssignment( ResolvExpr::AlternativeFinder & currentFinder, UntypedExpr * assign, const std::list<ResolvExpr::AltList> & possibilities );
+
         // TupleExpansion.cc
         /// expands z.[a, b.[x, y], c] into [z.a, z.b.x, z.b.y, z.c], inserting UniqueExprs as appropriate

src/prelude/builtins.c

@@ -80 +80 @@
 } // ?\?
 
-// FIXME (x \ (unsigned long int)y) relies on X ?\?(T, unsigned long) a function that is neither 
-// defined, nor passed as an assertion parameter. Without user-defined conversions, cannot specify 
-// X as a type that casts to double, yet it doesn't make sense to write functions with that type 
-// signature where X is double.
-
-// static inline forall( otype T | { void ?{}( T & this, one_t ); T ?*?( T, T ); double ?/?( double, T ); } )
-// double ?\?( T x, signed long int y ) {
-//     if ( y >=  0 ) return (double)(x \ (unsigned long int)y);
-//     else return 1.0 / x \ (unsigned long int)(-y);
-// } // ?\?
+static inline forall( otype T | { void ?{}( T & this, one_t ); T ?*?( T, T ); double ?/?( double, T ); } )
+double ?\?( T x, signed long int y ) {
+    if ( y >=  0 ) return (double)(x \ (unsigned long int)y);
+    else return 1.0 / x \ (unsigned long int)(-y);
+} // ?\?
 
 static inline long int ?\=?( long int & x, unsigned long int y ) { x = x \ y; return x; }