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source: src/ResolvExpr/AlternativeFinder.cc @ 1ced874

ADTaaron-thesisarm-ehast-experimentalcleanup-dtorsdeferred_resndemanglerenumforall-pointer-decayjacob/cs343-translationjenkins-sandboxnew-astnew-ast-unique-exprnew-envno_listpersistent-indexerpthread-emulationqualifiedEnumresolv-newwith_gc

Last change on this file since 1ced874 was 1ced874, checked in by Rob Schluntz <rschlunt@…>, 9 years ago
Merge branch 'master' into tuples
Property mode set to `100644`
File size: 43.6 KB

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1	//
2	// Cforall Version 1.0.0 Copyright (C) 2015 University of Waterloo
3	//
4	// The contents of this file are covered under the licence agreement in the
5	// file "LICENCE" distributed with Cforall.
6	//
7	// AlternativeFinder.cc --
8	//
9	// Author : Richard C. Bilson
10	// Created On : Sat May 16 23:52:08 2015
11	// Last Modified By : Peter A. Buhr
12	// Last Modified On : Mon Jul 4 17:02:51 2016
13	// Update Count : 29
14	//
15
16	#include <list>
17	#include <iterator>
18	#include <algorithm>
19	#include <functional>
20	#include <cassert>
21	#include <unordered_map>
22	#include <utility>
23	#include <vector>
24
25	#include "AlternativeFinder.h"
26	#include "Alternative.h"
27	#include "Cost.h"
28	#include "typeops.h"
29	#include "Unify.h"
30	#include "RenameVars.h"
31	#include "SynTree/Type.h"
32	#include "SynTree/Declaration.h"
33	#include "SynTree/Expression.h"
34	#include "SynTree/Initializer.h"
35	#include "SynTree/Visitor.h"
36	#include "SymTab/Indexer.h"
37	#include "SymTab/Mangler.h"
38	#include "SynTree/TypeSubstitution.h"
39	#include "SymTab/Validate.h"
40	#include "Tuples/TupleAssignment.h"
41	#include "Tuples/NameMatcher.h"
42	#include "Common/utility.h"
43	#include "InitTweak/InitTweak.h"
44	#include "ResolveTypeof.h"
45
46	extern bool resolvep;
47	#define PRINT( text ) if ( resolvep ) { text }
48	//#define DEBUG_COST
49
50	namespace ResolvExpr {
51	Expression resolveInVoidContext( Expression expr, const SymTab::Indexer &indexer, TypeEnvironment &env ) {
52	CastExpr *castToVoid = new CastExpr( expr );
53
54	AlternativeFinder finder( indexer, env );
55	finder.findWithAdjustment( castToVoid );
56
57	// it's a property of the language that a cast expression has either 1 or 0 interpretations; if it has 0
58	// interpretations, an exception has already been thrown.
59	assert( finder.get_alternatives().size() == 1 );
60	CastExpr newExpr = dynamic_cast< CastExpr >( finder.get_alternatives().front().expr );
61	assert( newExpr );
62	env = finder.get_alternatives().front().env;
63	return newExpr->get_arg()->clone();
64	}
65
66	namespace {
67	void printAlts( const AltList &list, std::ostream &os, int indent = 0 ) {
68	for ( AltList::const_iterator i = list.begin(); i != list.end(); ++i ) {
69	i->print( os, indent );
70	os << std::endl;
71	}
72	}
73
74	void makeExprList( const AltList &in, std::list< Expression* > &out ) {
75	for ( AltList::const_iterator i = in.begin(); i != in.end(); ++i ) {
76	out.push_back( i->expr->clone() );
77	}
78	}
79
80	Cost sumCost( const AltList &in ) {
81	Cost total;
82	for ( AltList::const_iterator i = in.begin(); i != in.end(); ++i ) {
83	total += i->cost;
84	}
85	return total;
86	}
87
88	struct PruneStruct {
89	bool isAmbiguous;
90	AltList::iterator candidate;
91	PruneStruct() {}
92	PruneStruct( AltList::iterator candidate ): isAmbiguous( false ), candidate( candidate ) {}
93	};
94
95	/// Prunes a list of alternatives down to those that have the minimum conversion cost for a given return type; skips ambiguous interpretations
96	template< typename InputIterator, typename OutputIterator >
97	void pruneAlternatives( InputIterator begin, InputIterator end, OutputIterator out, const SymTab::Indexer &indexer ) {
98	// select the alternatives that have the minimum conversion cost for a particular set of result types
99	std::map< std::string, PruneStruct > selected;
100	for ( AltList::iterator candidate = begin; candidate != end; ++candidate ) {
101	PruneStruct current( candidate );
102	std::string mangleName;
103	for ( std::list< Type* >::const_iterator retType = candidate->expr->get_results().begin(); retType != candidate->expr->get_results().end(); ++retType ) {
104	Type newType = (retType)->clone();
105	candidate->env.apply( newType );
106	mangleName += SymTab::Mangler::mangle( newType );
107	delete newType;
108	}
109	std::map< std::string, PruneStruct >::iterator mapPlace = selected.find( mangleName );
110	if ( mapPlace != selected.end() ) {
111	if ( candidate->cost < mapPlace->second.candidate->cost ) {
112	PRINT(
113	std::cerr << "cost " << candidate->cost << " beats " << mapPlace->second.candidate->cost << std::endl;
114	)
115	selected[ mangleName ] = current;
116	} else if ( candidate->cost == mapPlace->second.candidate->cost ) {
117	PRINT(
118	std::cerr << "marking ambiguous" << std::endl;
119	)
120	mapPlace->second.isAmbiguous = true;
121	}
122	} else {
123	selected[ mangleName ] = current;
124	}
125	}
126
127	PRINT(
128	std::cerr << "there are " << selected.size() << " alternatives before elimination" << std::endl;
129	)
130
131	// accept the alternatives that were unambiguous
132	for ( std::map< std::string, PruneStruct >::iterator target = selected.begin(); target != selected.end(); ++target ) {
133	if ( ! target->second.isAmbiguous ) {
134	Alternative &alt = *target->second.candidate;
135	for ( std::list< Type* >::iterator result = alt.expr->get_results().begin(); result != alt.expr->get_results().end(); ++result ) {
136	alt.env.applyFree( *result );
137	}
138	*out++ = alt;
139	}
140	}
141
142	}
143
144	template< typename InputIterator, typename OutputIterator >
145	void findMinCost( InputIterator begin, InputIterator end, OutputIterator out ) {
146	AltList alternatives;
147
148	// select the alternatives that have the minimum parameter cost
149	Cost minCost = Cost::infinity;
150	for ( AltList::iterator i = begin; i != end; ++i ) {
151	if ( i->cost < minCost ) {
152	minCost = i->cost;
153	i->cost = i->cvtCost;
154	alternatives.clear();
155	alternatives.push_back( *i );
156	} else if ( i->cost == minCost ) {
157	i->cost = i->cvtCost;
158	alternatives.push_back( *i );
159	}
160	}
161	std::copy( alternatives.begin(), alternatives.end(), out );
162	}
163
164	template< typename InputIterator >
165	void simpleCombineEnvironments( InputIterator begin, InputIterator end, TypeEnvironment &result ) {
166	while ( begin != end ) {
167	result.simpleCombine( (*begin++).env );
168	}
169	}
170
171	void renameTypes( Expression *expr ) {
172	for ( std::list< Type* >::iterator i = expr->get_results().begin(); i != expr->get_results().end(); ++i ) {
173	(*i)->accept( global_renamer );
174	}
175	}
176	}
177
178	template< typename InputIterator, typename OutputIterator >
179	void AlternativeFinder::findSubExprs( InputIterator begin, InputIterator end, OutputIterator out ) {
180	while ( begin != end ) {
181	AlternativeFinder finder( indexer, env );
182	finder.findWithAdjustment( *begin );
183	// XXX either this
184	//Designators::fixDesignations( finder, (*begin++)->get_argName() );
185	// or XXX this
186	begin++;
187	PRINT(
188	std::cerr << "findSubExprs" << std::endl;
189	printAlts( finder.alternatives, std::cerr );
190	)
191	*out++ = finder;
192	}
193	}
194
195	AlternativeFinder::AlternativeFinder( const SymTab::Indexer &indexer, const TypeEnvironment &env )
196	: indexer( indexer ), env( env ) {
197	}
198
199	void AlternativeFinder::find( Expression *expr, bool adjust ) {
200	expr->accept( *this );
201	if ( alternatives.empty() ) {
202	throw SemanticError( "No reasonable alternatives for expression ", expr );
203	}
204	for ( AltList::iterator i = alternatives.begin(); i != alternatives.end(); ++i ) {
205	if ( adjust ) {
206	adjustExprTypeList( i->expr->get_results().begin(), i->expr->get_results().end(), i->env, indexer );
207	}
208	}
209	PRINT(
210	std::cerr << "alternatives before prune:" << std::endl;
211	printAlts( alternatives, std::cerr );
212	)
213	AltList::iterator oldBegin = alternatives.begin();
214	pruneAlternatives( alternatives.begin(), alternatives.end(), front_inserter( alternatives ), indexer );
215	if ( alternatives.begin() == oldBegin ) {
216	std::ostringstream stream;
217	stream << "Can't choose between alternatives for expression ";
218	expr->print( stream );
219	stream << "Alternatives are:";
220	AltList winners;
221	findMinCost( alternatives.begin(), alternatives.end(), back_inserter( winners ) );
222	printAlts( winners, stream, 8 );
223	throw SemanticError( stream.str() );
224	}
225	alternatives.erase( oldBegin, alternatives.end() );
226	PRINT(
227	std::cerr << "there are " << alternatives.size() << " alternatives after elimination" << std::endl;
228	)
229
230	// Central location to handle gcc extension keyword for all expression types.
231	for ( Alternative &iter: alternatives ) {
232	iter.expr->set_extension( expr->get_extension() );
233	} // for
234	}
235
236	void AlternativeFinder::findWithAdjustment( Expression *expr ) {
237	find( expr, true );
238	}
239
240	template< typename StructOrUnionType >
241	void AlternativeFinder::addAggMembers( StructOrUnionType aggInst, Expression expr, const Cost &newCost, const std::string &name ) {
242	std::list< Declaration* > members;
243	aggInst->lookup( name, members );
244	for ( std::list< Declaration* >::const_iterator i = members.begin(); i != members.end(); ++i ) {
245	if ( DeclarationWithType dwt = dynamic_cast< DeclarationWithType >( *i ) ) {
246	alternatives.push_back( Alternative( new MemberExpr( dwt, expr->clone() ), env, newCost ) );
247	renameTypes( alternatives.back().expr );
248	} else {
249	assert( false );
250	}
251	}
252	}
253
254	void AlternativeFinder::visit( ApplicationExpr *applicationExpr ) {
255	alternatives.push_back( Alternative( applicationExpr->clone(), env, Cost::zero ) );
256	}
257
258	Cost computeConversionCost( Alternative &alt, const SymTab::Indexer &indexer ) {
259	ApplicationExpr appExpr = dynamic_cast< ApplicationExpr >( alt.expr );
260	assert( appExpr );
261	PointerType pointer = dynamic_cast< PointerType >( appExpr->get_function()->get_results().front() );
262	assert( pointer );
263	FunctionType function = dynamic_cast< FunctionType >( pointer->get_base() );
264	assert( function );
265
266	Cost convCost( 0, 0, 0 );
267	std::list< DeclarationWithType* >& formals = function->get_parameters();
268	std::list< DeclarationWithType* >::iterator formal = formals.begin();
269	std::list< Expression* >& actuals = appExpr->get_args();
270
271	for ( std::list< Expression* >::iterator actualExpr = actuals.begin(); actualExpr != actuals.end(); ++actualExpr ) {
272	PRINT(
273	std::cerr << "actual expression:" << std::endl;
274	(*actualExpr)->print( std::cerr, 8 );
275	std::cerr << "--- results are" << std::endl;
276	printAll( (*actualExpr)->get_results(), std::cerr, 8 );
277	)
278	std::list< DeclarationWithType* >::iterator startFormal = formal;
279	Cost actualCost;
280	for ( std::list< Type* >::iterator actualType = (actualExpr)->get_results().begin(); actualType != (actualExpr)->get_results().end(); ++actualType ) {
281	// xxx - need tuple handling code here
282	if ( formal == formals.end() ) {
283	if ( function->get_isVarArgs() ) {
284	convCost += Cost( 1, 0, 0 );
285	break;
286	} else {
287	return Cost::infinity;
288	}
289	}
290	PRINT(
291	std::cerr << std::endl << "converting ";
292	(*actualType)->print( std::cerr, 8 );
293	std::cerr << std::endl << " to ";
294	(*formal)->get_type()->print( std::cerr, 8 );
295	)
296	Cost newCost = conversionCost( actualType, (formal)->get_type(), indexer, alt.env );
297	PRINT(
298	std::cerr << std::endl << "cost is" << newCost << std::endl;
299	)
300
301	if ( newCost == Cost::infinity ) {
302	return newCost;
303	}
304	convCost += newCost;
305	actualCost += newCost;
306
307	convCost += Cost( 0, polyCost( (formal)->get_type(), alt.env, indexer ) + polyCost( actualType, alt.env, indexer ), 0 );
308
309	formal++;
310	}
311	if ( actualCost != Cost( 0, 0, 0 ) ) {
312	std::list< DeclarationWithType* >::iterator startFormalPlusOne = startFormal;
313	startFormalPlusOne++;
314	if ( formal == startFormalPlusOne ) {
315	// not a tuple type
316	Type newType = (startFormal)->get_type()->clone();
317	alt.env.apply( newType );
318	actualExpr = new CastExpr( actualExpr, newType );
319	} else {
320	TupleType *newType = new TupleType( Type::Qualifiers() );
321	for ( std::list< DeclarationWithType* >::iterator i = startFormal; i != formal; ++i ) {
322	newType->get_types().push_back( (*i)->get_type()->clone() );
323	}
324	alt.env.apply( newType );
325	actualExpr = new CastExpr( actualExpr, newType );
326	}
327	}
328
329	}
330	if ( formal != formals.end() ) {
331	return Cost::infinity;
332	}
333
334	for ( InferredParams::const_iterator assert = appExpr->get_inferParams().begin(); assert != appExpr->get_inferParams().end(); ++assert ) {
335	PRINT(
336	std::cerr << std::endl << "converting ";
337	assert->second.actualType->print( std::cerr, 8 );
338	std::cerr << std::endl << " to ";
339	assert->second.formalType->print( std::cerr, 8 );
340	)
341	Cost newCost = conversionCost( assert->second.actualType, assert->second.formalType, indexer, alt.env );
342	PRINT(
343	std::cerr << std::endl << "cost of conversion is " << newCost << std::endl;
344	)
345	if ( newCost == Cost::infinity ) {
346	return newCost;
347	}
348	convCost += newCost;
349
350	convCost += Cost( 0, polyCost( assert->second.formalType, alt.env, indexer ) + polyCost( assert->second.actualType, alt.env, indexer ), 0 );
351	}
352
353	return convCost;
354	}
355
356	/// Adds type variables to the open variable set and marks their assertions
357	void makeUnifiableVars( Type *type, OpenVarSet &unifiableVars, AssertionSet &needAssertions ) {
358	for ( std::list< TypeDecl* >::const_iterator tyvar = type->get_forall().begin(); tyvar != type->get_forall().end(); ++tyvar ) {
359	unifiableVars[ (tyvar)->get_name() ] = (tyvar)->get_kind();
360	for ( std::list< DeclarationWithType* >::iterator assert = (tyvar)->get_assertions().begin(); assert != (tyvar)->get_assertions().end(); ++assert ) {
361	needAssertions[ *assert ] = true;
362	}
363	/// needAssertions.insert( needAssertions.end(), (tyvar)->get_assertions().begin(), (tyvar)->get_assertions().end() );
364	}
365	}
366
367	template< typename OutputIterator >
368	void flatten( Type * type, OutputIterator out ) {
369	if ( TupleType * tupleType = dynamic_cast< TupleType * >( type ) ) {
370	for ( Type * t : *tupleType ) {
371	flatten( t, out );
372	}
373	} else {
374	*out++ = type;
375	}
376	}
377
378	bool AlternativeFinder::instantiateFunction( std::list< DeclarationWithType* >& formals, /const/ AltList &actuals, bool isVarArgs, OpenVarSet& openVars, TypeEnvironment &resultEnv, AssertionSet &resultNeed, AssertionSet &resultHave ) {
379	simpleCombineEnvironments( actuals.begin(), actuals.end(), resultEnv );
380	// make sure we don't widen any existing bindings
381	for ( TypeEnvironment::iterator i = resultEnv.begin(); i != resultEnv.end(); ++i ) {
382	i->allowWidening = false;
383	}
384	resultEnv.extractOpenVars( openVars );
385
386	/*
387	Tuples::NameMatcher matcher( formals );
388	try {
389	matcher.match( actuals );
390	} catch ( Tuples::NoMatch &e ) {
391	std::cerr << "Alternative doesn't match: " << e.message << std::endl;
392	}
393	*/
394	std::list< DeclarationWithType* >::iterator formal = formals.begin();
395
396	std::list< Type * > formalTypes;
397	std::list< Type * >::iterator formalType = formalTypes.end();
398
399	for ( AltList::const_iterator actualExpr = actuals.begin(); actualExpr != actuals.end(); ++actualExpr ) {
400	std::list< Type* > & actualTypes = actualExpr->expr->get_results();
401	for ( std::list< Type* >::iterator actualType = actualTypes.begin(); actualType != actualTypes.end(); ++actualType ) {
402	if ( formalType == formalTypes.end() ) {
403	// the type of the formal parameter may be a tuple type. To make this easier to work with,
404	// flatten the tuple type and traverse the resulting list of types, incrementing the formal
405	// iterator once its types have been extracted. Once a particular formal parameter's type has
406	// been exhausted load the next formal parameter's type.
407	if ( formal == formals.end() ) {
408	return isVarArgs;
409	}
410	formalTypes.clear();
411	flatten( (*formal)->get_type(), back_inserter( formalTypes ) );
412	formalType = formalTypes.begin();
413	++formal;
414	}
415	PRINT(
416	std::cerr << "formal type is ";
417	(*formal)->get_type()->print( std::cerr );
418	std::cerr << std::endl << "actual type is ";
419	(*actualType)->print( std::cerr );
420	std::cerr << std::endl;
421	)
422	if ( ! unify( formalType, actualType, resultEnv, resultNeed, resultHave, openVars, indexer ) ) {
423	return false;
424	}
425	++formalType;
426	}
427	}
428
429	// xxx - a tuple type was not completely matched
430	// partially handle the tuple with default arguments??
431	if ( formalType != formalTypes.end() ) return false;
432
433	// Handling of default values
434	while ( formal != formals.end() ) {
435	if ( ObjectDecl od = dynamic_cast<ObjectDecl >( *formal ) )
436	if ( SingleInit si = dynamic_cast<SingleInit >( od->get_init() ))
437	// so far, only constant expressions are accepted as default values
438	if ( ConstantExpr cnstexpr = dynamic_cast<ConstantExpr >( si->get_value()) )
439	if ( Constant cnst = dynamic_cast<Constant >( cnstexpr->get_constant() ) )
440	if ( unify( (*formal)->get_type(), cnst->get_type(), resultEnv, resultNeed, resultHave, openVars, indexer ) ) {
441	// XXX Don't know if this is right
442	actuals.push_back( Alternative( cnstexpr->clone(), env, Cost::zero ) );
443	formal++;
444	if ( formal == formals.end()) break;
445	}
446	return false;
447	}
448	return true;
449	}
450
451	// /// Map of declaration uniqueIds (intended to be the assertions in an AssertionSet) to their parents and the number of times they've been included
452	//typedef std::unordered_map< UniqueId, std::unordered_map< UniqueId, unsigned > > AssertionParentSet;
453
454	static const int recursionLimit = /10/ 4; ///< Limit to depth of recursion satisfaction
455	//static const unsigned recursionParentLimit = 1; ///< Limit to the number of times an assertion can recursively use itself
456
457	void addToIndexer( AssertionSet &assertSet, SymTab::Indexer &indexer ) {
458	for ( AssertionSet::iterator i = assertSet.begin(); i != assertSet.end(); ++i ) {
459	if ( i->second == true ) {
460	i->first->accept( indexer );
461	}
462	}
463	}
464
465	template< typename ForwardIterator, typename OutputIterator >
466	void inferRecursive( ForwardIterator begin, ForwardIterator end, const Alternative &newAlt, OpenVarSet &openVars, const SymTab::Indexer &decls, const AssertionSet &newNeed, /const AssertionParentSet &needParents,/
467	int level, const SymTab::Indexer &indexer, OutputIterator out ) {
468	if ( begin == end ) {
469	if ( newNeed.empty() ) {
470	*out++ = newAlt;
471	return;
472	} else if ( level >= recursionLimit ) {
473	throw SemanticError( "Too many recursive assertions" );
474	} else {
475	AssertionSet newerNeed;
476	PRINT(
477	std::cerr << "recursing with new set:" << std::endl;
478	printAssertionSet( newNeed, std::cerr, 8 );
479	)
480	inferRecursive( newNeed.begin(), newNeed.end(), newAlt, openVars, decls, newerNeed, /needParents,/ level+1, indexer, out );
481	return;
482	}
483	}
484
485	ForwardIterator cur = begin++;
486	if ( ! cur->second ) {
487	inferRecursive( begin, end, newAlt, openVars, decls, newNeed, /needParents,/ level, indexer, out );
488	}
489	DeclarationWithType *curDecl = cur->first;
490	PRINT(
491	std::cerr << "inferRecursive: assertion is ";
492	curDecl->print( std::cerr );
493	std::cerr << std::endl;
494	)
495	std::list< DeclarationWithType* > candidates;
496	decls.lookupId( curDecl->get_name(), candidates );
497	/// if ( candidates.empty() ) { std::cerr << "no candidates!" << std::endl; }
498	for ( std::list< DeclarationWithType* >::const_iterator candidate = candidates.begin(); candidate != candidates.end(); ++candidate ) {
499	PRINT(
500	std::cerr << "inferRecursive: candidate is ";
501	(*candidate)->print( std::cerr );
502	std::cerr << std::endl;
503	)
504
505	AssertionSet newHave, newerNeed( newNeed );
506	TypeEnvironment newEnv( newAlt.env );
507	OpenVarSet newOpenVars( openVars );
508	Type adjType = (candidate)->get_type()->clone();
509	adjustExprType( adjType, newEnv, indexer );
510	adjType->accept( global_renamer );
511	PRINT(
512	std::cerr << "unifying ";
513	curDecl->get_type()->print( std::cerr );
514	std::cerr << " with ";
515	adjType->print( std::cerr );
516	std::cerr << std::endl;
517	)
518	if ( unify( curDecl->get_type(), adjType, newEnv, newerNeed, newHave, newOpenVars, indexer ) ) {
519	PRINT(
520	std::cerr << "success!" << std::endl;
521	)
522	SymTab::Indexer newDecls( decls );
523	addToIndexer( newHave, newDecls );
524	Alternative newerAlt( newAlt );
525	newerAlt.env = newEnv;
526	assert( (*candidate)->get_uniqueId() );
527	DeclarationWithType candDecl = static_cast< DeclarationWithType >( Declaration::declFromId( (*candidate)->get_uniqueId() ) );
528	//AssertionParentSet newNeedParents( needParents );
529	// skip repeatingly-self-recursive assertion satisfaction
530	// DOESN'T WORK: grandchild nodes conflict with their cousins
531	//if ( newNeedParents[ curDecl->get_uniqueId() ][ candDecl->get_uniqueId() ]++ > recursionParentLimit ) continue;
532	Expression *varExpr = new VariableExpr( candDecl );
533	deleteAll( varExpr->get_results() );
534	varExpr->get_results().clear();
535	varExpr->get_results().push_front( adjType->clone() );
536	PRINT(
537	std::cerr << "satisfying assertion " << curDecl->get_uniqueId() << " ";
538	curDecl->print( std::cerr );
539	std::cerr << " with declaration " << (*candidate)->get_uniqueId() << " ";
540	(*candidate)->print( std::cerr );
541	std::cerr << std::endl;
542	)
543	ApplicationExpr appExpr = static_cast< ApplicationExpr >( newerAlt.expr );
544	// XXX: this is a memory leak, but adjType can't be deleted because it might contain assertions
545	appExpr->get_inferParams()[ curDecl->get_uniqueId() ] = ParamEntry( (*candidate)->get_uniqueId(), adjType->clone(), curDecl->get_type()->clone(), varExpr );
546	inferRecursive( begin, end, newerAlt, newOpenVars, newDecls, newerNeed, /newNeedParents,/ level, indexer, out );
547	} else {
548	delete adjType;
549	}
550	}
551	}
552
553	template< typename OutputIterator >
554	void AlternativeFinder::inferParameters( const AssertionSet &need, AssertionSet &have, const Alternative &newAlt, OpenVarSet &openVars, OutputIterator out ) {
555	// PRINT(
556	// std::cerr << "inferParameters: assertions needed are" << std::endl;
557	// printAll( need, std::cerr, 8 );
558	// )
559	SymTab::Indexer decls( indexer );
560	PRINT(
561	std::cerr << "============= original indexer" << std::endl;
562	indexer.print( std::cerr );
563	std::cerr << "============= new indexer" << std::endl;
564	decls.print( std::cerr );
565	)
566	addToIndexer( have, decls );
567	AssertionSet newNeed;
568	//AssertionParentSet needParents;
569	inferRecursive( need.begin(), need.end(), newAlt, openVars, decls, newNeed, /needParents,/ 0, indexer, out );
570	// PRINT(
571	// std::cerr << "declaration 14 is ";
572	// Declaration::declFromId
573	// *out++ = newAlt;
574	// )
575	}
576
577	template< typename OutputIterator >
578	void AlternativeFinder::makeFunctionAlternatives( const Alternative &func, FunctionType *funcType, AltList &actualAlt, OutputIterator out ) {
579	OpenVarSet openVars;
580	AssertionSet resultNeed, resultHave;
581	TypeEnvironment resultEnv;
582	makeUnifiableVars( funcType, openVars, resultNeed );
583	if ( instantiateFunction( funcType->get_parameters(), actualAlt, funcType->get_isVarArgs(), openVars, resultEnv, resultNeed, resultHave ) ) {
584	ApplicationExpr *appExpr = new ApplicationExpr( func.expr->clone() );
585	Alternative newAlt( appExpr, resultEnv, sumCost( actualAlt ) );
586	makeExprList( actualAlt, appExpr->get_args() );
587	PRINT(
588	std::cerr << "need assertions:" << std::endl;
589	printAssertionSet( resultNeed, std::cerr, 8 );
590	)
591	inferParameters( resultNeed, resultHave, newAlt, openVars, out );
592	}
593	}
594
595	void AlternativeFinder::visit( UntypedExpr *untypedExpr ) {
596	bool doneInit = false;
597	AlternativeFinder funcOpFinder( indexer, env );
598
599	AlternativeFinder funcFinder( indexer, env );
600
601	{
602	std::string fname = InitTweak::getFunctionName( untypedExpr );
603	if ( fname == "&&" ) {
604	VoidType v = Type::Qualifiers(); // resolve to type void *
605	PointerType pt( Type::Qualifiers(), v.clone() );
606	UntypedExpr *vexpr = untypedExpr->clone();
607	vexpr->get_results().push_front( pt.clone() );
608	alternatives.push_back( Alternative( vexpr, env, Cost()) );
609	return;
610	}
611	}
612
613	funcFinder.findWithAdjustment( untypedExpr->get_function() );
614	std::list< AlternativeFinder > argAlternatives;
615	findSubExprs( untypedExpr->begin_args(), untypedExpr->end_args(), back_inserter( argAlternatives ) );
616
617	std::list< AltList > possibilities;
618	combos( argAlternatives.begin(), argAlternatives.end(), back_inserter( possibilities ) );
619
620	Tuples::TupleAssignSpotter tassign( this );
621	if ( tassign.isTupleAssignment( untypedExpr, possibilities ) ) {
622	// take care of possible tuple assignments, or discard expression
623	return;
624	} // else ...
625
626	AltList candidates;
627	SemanticError errors;
628
629	for ( AltList::const_iterator func = funcFinder.alternatives.begin(); func != funcFinder.alternatives.end(); ++func ) {
630	try {
631	PRINT(
632	std::cerr << "working on alternative: " << std::endl;
633	func->print( std::cerr, 8 );
634	)
635	// check if the type is pointer to function
636	PointerType *pointer;
637	if ( func->expr->get_results().size() == 1 && ( pointer = dynamic_cast< PointerType* >( func->expr->get_results().front() ) ) ) {
638	if ( FunctionType function = dynamic_cast< FunctionType >( pointer->get_base() ) ) {
639	for ( std::list< AltList >::iterator actualAlt = possibilities.begin(); actualAlt != possibilities.end(); ++actualAlt ) {
640	// XXX
641	//Designators::check_alternative( function, *actualAlt );
642	makeFunctionAlternatives( func, function, actualAlt, std::back_inserter( candidates ) );
643	}
644	} else if ( TypeInstType typeInst = dynamic_cast< TypeInstType >( pointer->get_base() ) ) {
645	EqvClass eqvClass;
646	if ( func->env.lookup( typeInst->get_name(), eqvClass ) && eqvClass.type ) {
647	if ( FunctionType function = dynamic_cast< FunctionType >( eqvClass.type ) ) {
648	for ( std::list< AltList >::iterator actualAlt = possibilities.begin(); actualAlt != possibilities.end(); ++actualAlt ) {
649	makeFunctionAlternatives( func, function, actualAlt, std::back_inserter( candidates ) );
650	} // for
651	} // if
652	} // if
653	} // if
654	} else {
655	// seek a function operator that's compatible
656	if ( ! doneInit ) {
657	doneInit = true;
658	NameExpr *opExpr = new NameExpr( "?()" );
659	try {
660	funcOpFinder.findWithAdjustment( opExpr );
661	} catch( SemanticError &e ) {
662	// it's ok if there aren't any defined function ops
663	}
664	PRINT(
665	std::cerr << "known function ops:" << std::endl;
666	printAlts( funcOpFinder.alternatives, std::cerr, 8 );
667	)
668	}
669
670	for ( AltList::const_iterator funcOp = funcOpFinder.alternatives.begin(); funcOp != funcOpFinder.alternatives.end(); ++funcOp ) {
671	// check if the type is pointer to function
672	PointerType *pointer;
673	if ( funcOp->expr->get_results().size() == 1
674	&& ( pointer = dynamic_cast< PointerType* >( funcOp->expr->get_results().front() ) ) ) {
675	if ( FunctionType function = dynamic_cast< FunctionType >( pointer->get_base() ) ) {
676	for ( std::list< AltList >::iterator actualAlt = possibilities.begin(); actualAlt != possibilities.end(); ++actualAlt ) {
677	AltList currentAlt;
678	currentAlt.push_back( *func );
679	currentAlt.insert( currentAlt.end(), actualAlt->begin(), actualAlt->end() );
680	makeFunctionAlternatives( *funcOp, function, currentAlt, std::back_inserter( candidates ) );
681	} // for
682	} // if
683	} // if
684	} // for
685	} // if
686	} catch ( SemanticError &e ) {
687	errors.append( e );
688	}
689	} // for
690
691	// Implement SFINAE; resolution errors are only errors if there aren't any non-erroneous resolutions
692	if ( candidates.empty() && ! errors.isEmpty() ) { throw errors; }
693
694	for ( AltList::iterator withFunc = candidates.begin(); withFunc != candidates.end(); ++withFunc ) {
695	Cost cvtCost = computeConversionCost( *withFunc, indexer );
696
697	PRINT(
698	ApplicationExpr appExpr = dynamic_cast< ApplicationExpr >( withFunc->expr );
699	assert( appExpr );
700	PointerType pointer = dynamic_cast< PointerType >( appExpr->get_function()->get_results().front() );
701	assert( pointer );
702	FunctionType function = dynamic_cast< FunctionType >( pointer->get_base() );
703	assert( function );
704	std::cerr << "Case +++++++++++++" << std::endl;
705	std::cerr << "formals are:" << std::endl;
706	printAll( function->get_parameters(), std::cerr, 8 );
707	std::cerr << "actuals are:" << std::endl;
708	printAll( appExpr->get_args(), std::cerr, 8 );
709	std::cerr << "bindings are:" << std::endl;
710	withFunc->env.print( std::cerr, 8 );
711	std::cerr << "cost of conversion is:" << cvtCost << std::endl;
712	)
713	if ( cvtCost != Cost::infinity ) {
714	withFunc->cvtCost = cvtCost;
715	alternatives.push_back( *withFunc );
716	} // if
717	} // for
718	candidates.clear();
719	candidates.splice( candidates.end(), alternatives );
720
721	findMinCost( candidates.begin(), candidates.end(), std::back_inserter( alternatives ) );
722	}
723
724	bool isLvalue( Expression *expr ) {
725	for ( std::list< Type* >::const_iterator i = expr->get_results().begin(); i != expr->get_results().end(); ++i ) {
726	if ( !(*i)->get_isLvalue() ) return false;
727	} // for
728	return true;
729	}
730
731	void AlternativeFinder::visit( AddressExpr *addressExpr ) {
732	AlternativeFinder finder( indexer, env );
733	finder.find( addressExpr->get_arg() );
734	for ( std::list< Alternative >::iterator i = finder.alternatives.begin(); i != finder.alternatives.end(); ++i ) {
735	if ( isLvalue( i->expr ) ) {
736	alternatives.push_back( Alternative( new AddressExpr( i->expr->clone() ), i->env, i->cost ) );
737	} // if
738	} // for
739	}
740
741	void AlternativeFinder::visit( CastExpr *castExpr ) {
742	for ( std::list< Type* >::iterator i = castExpr->get_results().begin(); i != castExpr->get_results().end(); ++i ) {
743	i = resolveTypeof( i, indexer );
744	SymTab::validateType( *i, &indexer );
745	adjustExprType( *i, env, indexer );
746	} // for
747
748	AlternativeFinder finder( indexer, env );
749	finder.findWithAdjustment( castExpr->get_arg() );
750
751	AltList candidates;
752	for ( std::list< Alternative >::iterator i = finder.alternatives.begin(); i != finder.alternatives.end(); ++i ) {
753	AssertionSet needAssertions, haveAssertions;
754	OpenVarSet openVars;
755
756	// It's possible that a cast can throw away some values in a multiply-valued expression. (An example is a
757	// cast-to-void, which casts from one value to zero.) Figure out the prefix of the subexpression results
758	// that are cast directly. The candidate is invalid if it has fewer results than there are types to cast
759	// to.
760	int discardedValues = (*i).expr->get_results().size() - castExpr->get_results().size();
761	if ( discardedValues < 0 ) continue;
762	std::list< Type* >::iterator candidate_end = (*i).expr->get_results().begin();
763	std::advance( candidate_end, castExpr->get_results().size() );
764	// unification run for side-effects
765	unifyList( castExpr->get_results().begin(), castExpr->get_results().end(),
766	(*i).expr->get_results().begin(), candidate_end,
767	i->env, needAssertions, haveAssertions, openVars, indexer );
768	Cost thisCost = castCostList( (*i).expr->get_results().begin(), candidate_end,
769	castExpr->get_results().begin(), castExpr->get_results().end(),
770	indexer, i->env );
771	if ( thisCost != Cost::infinity ) {
772	// count one safe conversion for each value that is thrown away
773	thisCost += Cost( 0, 0, discardedValues );
774	CastExpr *newExpr = castExpr->clone();
775	newExpr->set_arg( i->expr->clone() );
776	candidates.push_back( Alternative( newExpr, i->env, i->cost, thisCost ) );
777	} // if
778	} // for
779
780	// findMinCost selects the alternatives with the lowest "cost" members, but has the side effect of copying the
781	// cvtCost member to the cost member (since the old cost is now irrelevant). Thus, calling findMinCost twice
782	// selects first based on argument cost, then on conversion cost.
783	AltList minArgCost;
784	findMinCost( candidates.begin(), candidates.end(), std::back_inserter( minArgCost ) );
785	findMinCost( minArgCost.begin(), minArgCost.end(), std::back_inserter( alternatives ) );
786	}
787
788	void AlternativeFinder::visit( UntypedMemberExpr *memberExpr ) {
789	AlternativeFinder funcFinder( indexer, env );
790	funcFinder.findWithAdjustment( memberExpr->get_aggregate() );
791
792	for ( AltList::const_iterator agg = funcFinder.alternatives.begin(); agg != funcFinder.alternatives.end(); ++agg ) {
793	if ( agg->expr->get_results().size() == 1 ) {
794	if ( StructInstType structInst = dynamic_cast< StructInstType >( agg->expr->get_results().front() ) ) {
795	addAggMembers( structInst, agg->expr, agg->cost, memberExpr->get_member() );
796	} else if ( UnionInstType unionInst = dynamic_cast< UnionInstType >( agg->expr->get_results().front() ) ) {
797	addAggMembers( unionInst, agg->expr, agg->cost, memberExpr->get_member() );
798	} // if
799	} // if
800	} // for
801	}
802
803	void AlternativeFinder::visit( MemberExpr *memberExpr ) {
804	alternatives.push_back( Alternative( memberExpr->clone(), env, Cost::zero ) );
805	}
806
807	void AlternativeFinder::visit( NameExpr *nameExpr ) {
808	std::list< DeclarationWithType* > declList;
809	indexer.lookupId( nameExpr->get_name(), declList );
810	PRINT( std::cerr << "nameExpr is " << nameExpr->get_name() << std::endl; )
811	for ( std::list< DeclarationWithType* >::iterator i = declList.begin(); i != declList.end(); ++i ) {
812	VariableExpr newExpr( *i, nameExpr->get_argName() );
813	alternatives.push_back( Alternative( newExpr.clone(), env, Cost() ) );
814	PRINT(
815	std::cerr << "decl is ";
816	(*i)->print( std::cerr );
817	std::cerr << std::endl;
818	std::cerr << "newExpr is ";
819	newExpr.print( std::cerr );
820	std::cerr << std::endl;
821	)
822	renameTypes( alternatives.back().expr );
823	if ( StructInstType structInst = dynamic_cast< StructInstType >( (*i)->get_type() ) ) {
824	addAggMembers( structInst, &newExpr, Cost( 0, 0, 1 ), "" );
825	} else if ( UnionInstType unionInst = dynamic_cast< UnionInstType >( (*i)->get_type() ) ) {
826	addAggMembers( unionInst, &newExpr, Cost( 0, 0, 1 ), "" );
827	} // if
828	} // for
829	}
830
831	void AlternativeFinder::visit( VariableExpr *variableExpr ) {
832	// not sufficient to clone here, because variable's type may have changed
833	// since the VariableExpr was originally created.
834	alternatives.push_back( Alternative( new VariableExpr( variableExpr->get_var() ), env, Cost::zero ) );
835	}
836
837	void AlternativeFinder::visit( ConstantExpr *constantExpr ) {
838	alternatives.push_back( Alternative( constantExpr->clone(), env, Cost::zero ) );
839	}
840
841	void AlternativeFinder::visit( SizeofExpr *sizeofExpr ) {
842	if ( sizeofExpr->get_isType() ) {
843	// xxx - resolveTypeof?
844	alternatives.push_back( Alternative( sizeofExpr->clone(), env, Cost::zero ) );
845	} else {
846	// find all alternatives for the argument to sizeof
847	AlternativeFinder finder( indexer, env );
848	finder.find( sizeofExpr->get_expr() );
849	// find the lowest cost alternative among the alternatives, otherwise ambiguous
850	AltList winners;
851	findMinCost( finder.alternatives.begin(), finder.alternatives.end(), back_inserter( winners ) );
852	if ( winners.size() != 1 ) {
853	throw SemanticError( "Ambiguous expression in sizeof operand: ", sizeofExpr->get_expr() );
854	} // if
855	// return the lowest cost alternative for the argument
856	Alternative &choice = winners.front();
857	alternatives.push_back( Alternative( new SizeofExpr( choice.expr->clone() ), choice.env, Cost::zero ) );
858	} // if
859	}
860
861	void AlternativeFinder::visit( AlignofExpr *alignofExpr ) {
862	if ( alignofExpr->get_isType() ) {
863	// xxx - resolveTypeof?
864	alternatives.push_back( Alternative( alignofExpr->clone(), env, Cost::zero ) );
865	} else {
866	// find all alternatives for the argument to sizeof
867	AlternativeFinder finder( indexer, env );
868	finder.find( alignofExpr->get_expr() );
869	// find the lowest cost alternative among the alternatives, otherwise ambiguous
870	AltList winners;
871	findMinCost( finder.alternatives.begin(), finder.alternatives.end(), back_inserter( winners ) );
872	if ( winners.size() != 1 ) {
873	throw SemanticError( "Ambiguous expression in alignof operand: ", alignofExpr->get_expr() );
874	} // if
875	// return the lowest cost alternative for the argument
876	Alternative &choice = winners.front();
877	alternatives.push_back( Alternative( new AlignofExpr( choice.expr->clone() ), choice.env, Cost::zero ) );
878	} // if
879	}
880
881	template< typename StructOrUnionType >
882	void AlternativeFinder::addOffsetof( StructOrUnionType *aggInst, const std::string &name ) {
883	std::list< Declaration* > members;
884	aggInst->lookup( name, members );
885	for ( std::list< Declaration* >::const_iterator i = members.begin(); i != members.end(); ++i ) {
886	if ( DeclarationWithType dwt = dynamic_cast< DeclarationWithType >( *i ) ) {
887	alternatives.push_back( Alternative( new OffsetofExpr( aggInst->clone(), dwt ), env, Cost::zero ) );
888	renameTypes( alternatives.back().expr );
889	} else {
890	assert( false );
891	}
892	}
893	}
894
895	void AlternativeFinder::visit( UntypedOffsetofExpr *offsetofExpr ) {
896	AlternativeFinder funcFinder( indexer, env );
897	// xxx - resolveTypeof?
898	if ( StructInstType structInst = dynamic_cast< StructInstType >( offsetofExpr->get_type() ) ) {
899	addOffsetof( structInst, offsetofExpr->get_member() );
900	} else if ( UnionInstType unionInst = dynamic_cast< UnionInstType >( offsetofExpr->get_type() ) ) {
901	addOffsetof( unionInst, offsetofExpr->get_member() );
902	}
903	}
904
905	void AlternativeFinder::visit( OffsetofExpr *offsetofExpr ) {
906	alternatives.push_back( Alternative( offsetofExpr->clone(), env, Cost::zero ) );
907	}
908
909	void AlternativeFinder::visit( OffsetPackExpr *offsetPackExpr ) {
910	alternatives.push_back( Alternative( offsetPackExpr->clone(), env, Cost::zero ) );
911	}
912
913	void AlternativeFinder::resolveAttr( DeclarationWithType funcDecl, FunctionType function, Type *argType, const TypeEnvironment &env ) {
914	// assume no polymorphism
915	// assume no implicit conversions
916	assert( function->get_parameters().size() == 1 );
917	PRINT(
918	std::cerr << "resolvAttr: funcDecl is ";
919	funcDecl->print( std::cerr );
920	std::cerr << " argType is ";
921	argType->print( std::cerr );
922	std::cerr << std::endl;
923	)
924	if ( typesCompatibleIgnoreQualifiers( argType, function->get_parameters().front()->get_type(), indexer, env ) ) {
925	alternatives.push_back( Alternative( new AttrExpr( new VariableExpr( funcDecl ), argType->clone() ), env, Cost::zero ) );
926	for ( std::list< DeclarationWithType* >::iterator i = function->get_returnVals().begin(); i != function->get_returnVals().end(); ++i ) {
927	alternatives.back().expr->get_results().push_back( (*i)->get_type()->clone() );
928	} // for
929	} // if
930	}
931
932	void AlternativeFinder::visit( AttrExpr *attrExpr ) {
933	// assume no 'pointer-to-attribute'
934	NameExpr nameExpr = dynamic_cast< NameExpr >( attrExpr->get_attr() );
935	assert( nameExpr );
936	std::list< DeclarationWithType* > attrList;
937	indexer.lookupId( nameExpr->get_name(), attrList );
938	if ( attrExpr->get_isType() \|\| attrExpr->get_expr() ) {
939	for ( std::list< DeclarationWithType* >::iterator i = attrList.begin(); i != attrList.end(); ++i ) {
940	// check if the type is function
941	if ( FunctionType function = dynamic_cast< FunctionType >( (*i)->get_type() ) ) {
942	// assume exactly one parameter
943	if ( function->get_parameters().size() == 1 ) {
944	if ( attrExpr->get_isType() ) {
945	resolveAttr( *i, function, attrExpr->get_type(), env );
946	} else {
947	AlternativeFinder finder( indexer, env );
948	finder.find( attrExpr->get_expr() );
949	for ( AltList::iterator choice = finder.alternatives.begin(); choice != finder.alternatives.end(); ++choice ) {
950	if ( choice->expr->get_results().size() == 1 ) {
951	resolveAttr(*i, function, choice->expr->get_results().front(), choice->env );
952	} // fi
953	} // for
954	} // if
955	} // if
956	} // if
957	} // for
958	} else {
959	for ( std::list< DeclarationWithType* >::iterator i = attrList.begin(); i != attrList.end(); ++i ) {
960	VariableExpr newExpr( *i );
961	alternatives.push_back( Alternative( newExpr.clone(), env, Cost() ) );
962	renameTypes( alternatives.back().expr );
963	} // for
964	} // if
965	}
966
967	void AlternativeFinder::visit( LogicalExpr *logicalExpr ) {
968	AlternativeFinder firstFinder( indexer, env );
969	firstFinder.findWithAdjustment( logicalExpr->get_arg1() );
970	for ( AltList::const_iterator first = firstFinder.alternatives.begin(); first != firstFinder.alternatives.end(); ++first ) {
971	AlternativeFinder secondFinder( indexer, first->env );
972	secondFinder.findWithAdjustment( logicalExpr->get_arg2() );
973	for ( AltList::const_iterator second = secondFinder.alternatives.begin(); second != secondFinder.alternatives.end(); ++second ) {
974	LogicalExpr *newExpr = new LogicalExpr( first->expr->clone(), second->expr->clone(), logicalExpr->get_isAnd() );
975	alternatives.push_back( Alternative( newExpr, second->env, first->cost + second->cost ) );
976	}
977	}
978	}
979
980	void AlternativeFinder::visit( ConditionalExpr *conditionalExpr ) {
981	AlternativeFinder firstFinder( indexer, env );
982	firstFinder.findWithAdjustment( conditionalExpr->get_arg1() );
983	for ( AltList::const_iterator first = firstFinder.alternatives.begin(); first != firstFinder.alternatives.end(); ++first ) {
984	AlternativeFinder secondFinder( indexer, first->env );
985	secondFinder.findWithAdjustment( conditionalExpr->get_arg2() );
986	for ( AltList::const_iterator second = secondFinder.alternatives.begin(); second != secondFinder.alternatives.end(); ++second ) {
987	AlternativeFinder thirdFinder( indexer, second->env );
988	thirdFinder.findWithAdjustment( conditionalExpr->get_arg3() );
989	for ( AltList::const_iterator third = thirdFinder.alternatives.begin(); third != thirdFinder.alternatives.end(); ++third ) {
990	OpenVarSet openVars;
991	AssertionSet needAssertions, haveAssertions;
992	Alternative newAlt( 0, third->env, first->cost + second->cost + third->cost );
993	std::list< Type* > commonTypes;
994	if ( unifyList( second->expr->get_results().begin(), second->expr->get_results().end(), third->expr->get_results().begin(), third->expr->get_results().end(), newAlt.env, needAssertions, haveAssertions, openVars, indexer, commonTypes ) ) {
995	ConditionalExpr *newExpr = new ConditionalExpr( first->expr->clone(), second->expr->clone(), third->expr->clone() );
996	std::list< Type* >::const_iterator original = second->expr->get_results().begin();
997	std::list< Type* >::const_iterator commonType = commonTypes.begin();
998	for ( ; original != second->expr->get_results().end() && commonType != commonTypes.end(); ++original, ++commonType ) {
999	if ( *commonType ) {
1000	newExpr->get_results().push_back( *commonType );
1001	} else {
1002	newExpr->get_results().push_back( (*original)->clone() );
1003	} // if
1004	} // for
1005	newAlt.expr = newExpr;
1006	inferParameters( needAssertions, haveAssertions, newAlt, openVars, back_inserter( alternatives ) );
1007	} // if
1008	} // for
1009	} // for
1010	} // for
1011	}
1012
1013	void AlternativeFinder::visit( CommaExpr *commaExpr ) {
1014	TypeEnvironment newEnv( env );
1015	Expression *newFirstArg = resolveInVoidContext( commaExpr->get_arg1(), indexer, newEnv );
1016	AlternativeFinder secondFinder( indexer, newEnv );
1017	secondFinder.findWithAdjustment( commaExpr->get_arg2() );
1018	for ( AltList::const_iterator alt = secondFinder.alternatives.begin(); alt != secondFinder.alternatives.end(); ++alt ) {
1019	alternatives.push_back( Alternative( new CommaExpr( newFirstArg->clone(), alt->expr->clone() ), alt->env, alt->cost ) );
1020	} // for
1021	delete newFirstArg;
1022	}
1023
1024	void AlternativeFinder::visit( TupleExpr *tupleExpr ) {
1025	std::list< AlternativeFinder > subExprAlternatives;
1026	findSubExprs( tupleExpr->get_exprs().begin(), tupleExpr->get_exprs().end(), back_inserter( subExprAlternatives ) );
1027	std::list< AltList > possibilities;
1028	combos( subExprAlternatives.begin(), subExprAlternatives.end(), back_inserter( possibilities ) );
1029	for ( std::list< AltList >::const_iterator i = possibilities.begin(); i != possibilities.end(); ++i ) {
1030	TupleExpr *newExpr = new TupleExpr;
1031	makeExprList( *i, newExpr->get_exprs() );
1032	for ( std::list< Expression* >::const_iterator resultExpr = newExpr->get_exprs().begin(); resultExpr != newExpr->get_exprs().end(); ++resultExpr ) {
1033	for ( std::list< Type* >::const_iterator resultType = (resultExpr)->get_results().begin(); resultType != (resultExpr)->get_results().end(); ++resultType ) {
1034	newExpr->get_results().push_back( (*resultType)->clone() );
1035	} // for
1036	} // for
1037
1038	TypeEnvironment compositeEnv;
1039	simpleCombineEnvironments( i->begin(), i->end(), compositeEnv );
1040	alternatives.push_back( Alternative( newExpr, compositeEnv, sumCost( *i ) ) );
1041	} // for
1042	}
1043
1044	void AlternativeFinder::visit( ImplicitCopyCtorExpr * impCpCtorExpr ) {
1045	alternatives.push_back( Alternative( impCpCtorExpr->clone(), env, Cost::zero ) );
1046	}
1047	} // namespace ResolvExpr
1048
1049	// Local Variables: //
1050	// tab-width: 4 //
1051	// mode: c++ //
1052	// compile-command: "make install" //
1053	// End: //

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