source: translator/Tuples/TupleAssignment.cc @ 01aeade

//
// Cforall Version 1.0.0 Copyright (C) 2015 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// TupleAssignment.cc -- 
//
// Author           : Richard C. Bilson
// Created On       : Mon May 18 07:44:20 2015
// Last Modified By : Peter A. Buhr
// Last Modified On : Mon May 18 15:02:53 2015
// Update Count     : 2
//

#include "ResolvExpr/AlternativeFinder.h"
#include "ResolvExpr/Alternative.h"
#include "ResolvExpr/typeops.h"
#include "SynTree/Expression.h"
#include "TupleAssignment.h"
#include "SemanticError.h"

#include <functional>
#include <algorithm>
#include <iterator>
#include <iostream>
#include <cassert>
#include <set>

namespace Tuples {
        TupleAssignSpotter::TupleAssignSpotter( ResolvExpr::AlternativeFinder *f = 0 )
                : currentFinder(f), matcher(0), hasMatched( false ) {}

        bool TupleAssignSpotter::pointsToTuple( Expression *expr ) {
                // also check for function returning tuple of reference types
                if (AddressExpr *addr = dynamic_cast<AddressExpr *>(expr) )
                        if ( isTuple(addr->get_arg() ) )
                                return true;
                return false;
        }

        bool TupleAssignSpotter::isTupleVar( DeclarationWithType *decl ) {
                if ( dynamic_cast<TupleType *>(decl->get_type()) )
                        return true;
                return false;
        }

        bool TupleAssignSpotter::isTuple( Expression *expr, bool isRight ) {
                // true if `expr' is an expression returning a tuple: tuple, tuple variable or MRV function
                if ( ! expr ) return false;

                if ( dynamic_cast<TupleExpr *>(expr) )
                        return true;
                else if ( VariableExpr *var = dynamic_cast<VariableExpr *>(expr) ) {
                        if ( isTupleVar(var->get_var()) )
                                return true;
                }

                return false;
        }

        bool TupleAssignSpotter::match() {
                assert ( matcher != 0 );

                std::list< Expression * > new_assigns;
                if (! matcher->match(new_assigns) )
                        return false;

                if ( new_assigns.empty() ) return false;
                /*return */matcher->solve( new_assigns );
                if ( dynamic_cast<TupleAssignSpotter::MultipleAssignMatcher *>( matcher ) ) {
                        // now resolve new assignments
                        std::list< Expression * > solved_assigns;
                        ResolvExpr::AltList solved_alts;
                        assert( currentFinder != 0 );

                        ResolvExpr::AltList current;
                        for ( std::list< Expression * >::iterator i = new_assigns.begin(); i != new_assigns.end(); ++i ) {
                                //try {
                                ResolvExpr::AlternativeFinder finder( currentFinder->get_indexer(), currentFinder->get_environ() );
                                finder.findWithAdjustment(*i);
                                // prune expressions that don't coincide with
                                ResolvExpr::AltList alts = finder.get_alternatives();
                                assert( alts.size() == 1 );
                                assert(alts.front().expr != 0 );
                                current.push_back( finder.get_alternatives().front() );
                                solved_assigns.push_back( alts.front().expr->clone() );
                                //solved_assigns.back()->print(std::cerr);
                                /*} catch( ... ) {
                                  continue; // no reasonable alternative found
                                  }*/
                        }
                        options.add_option( current );

                        return true;
                } else { // mass assignment
                        //if ( new_assigns.empty() ) return false;
                        std::list< Expression * > solved_assigns;
                        ResolvExpr::AltList solved_alts;
                        assert( currentFinder != 0 );

                        ResolvExpr::AltList current;
                        if ( optMass.empty() ) {
                                for ( std::list< Expression * >::size_type i = 0; i != new_assigns.size(); ++i )
                                        optMass.push_back( ResolvExpr::AltList() );
                        }
                        int cnt = 0;
                        for ( std::list< Expression * >::iterator i = new_assigns.begin(); i != new_assigns.end(); ++i, cnt++ ) {

                                ResolvExpr::AlternativeFinder finder( currentFinder->get_indexer(), currentFinder->get_environ() );
                                finder.findWithAdjustment(*i);
                                ResolvExpr::AltList alts = finder.get_alternatives();
                                assert( alts.size() == 1 );
                                assert(alts.front().expr != 0 );
                                current.push_back( finder.get_alternatives().front() );
                                optMass[cnt].push_back( finder.get_alternatives().front() );
                                solved_assigns.push_back( alts.front().expr->clone() );
                        }

                        return true;
                }

                return false;
        }

        bool TupleAssignSpotter::isMVR( Expression *expr ) {
                if ( expr->get_results().size() > 1 ) {
                        // MVR processing
                        return true;
                }
                return false;
        }

        bool TupleAssignSpotter::isTupleAssignment( UntypedExpr * expr, std::list<ResolvExpr::AltList> &possibilities ) {
                if (  NameExpr *assgnop = dynamic_cast< NameExpr * >(expr->get_function()) ) {

                        if ( assgnop->get_name() == std::string("?=?") ) {

                                for ( std::list<ResolvExpr::AltList>::iterator ali = possibilities.begin(); ali != possibilities.end(); ++ali ) {
                                        assert( ali->size() == 2 );
                                        ResolvExpr::AltList::iterator opit = ali->begin();
                                        ResolvExpr::Alternative op1 = *opit, op2 = *(++opit);

                                        if ( pointsToTuple(op1.expr) ) { // also handles tuple vars
                                                if ( isTuple( op2.expr, true ) )
                                                        matcher = new MultipleAssignMatcher(op1.expr, op2.expr);
                                                else if ( isMVR( op2.expr ) ) {
                                                        // handle MVR differently
                                                } else
                                                        // mass assignment
                                                        matcher = new MassAssignMatcher(op1.expr, op2.expr);

                                                std::list< ResolvExpr::AltList > options;
                                                if ( match() )
                                                        /*
                                                          if ( hasMatched ) {
                                                          // throw SemanticError("Ambiguous tuple assignment");
                                                          } else {*/
                                                        // Matched for the first time
                                                        hasMatched = true;
                                                /*} */
                                        } /* else if ( isTuple( op2 ) )
                                                 throw SemanticError("Inapplicable tuple assignment.");
                                          */
                                }

                                if ( hasMatched ) {
                                        if ( dynamic_cast<TupleAssignSpotter::MultipleAssignMatcher *>( matcher ) ) {
                                                //options.print( std::cerr );
                                                std::list< ResolvExpr::AltList >best = options.get_best();
                                                if ( best.size() == 1 ) {
                                                        std::list<Expression *> solved_assigns;
                                                        for ( ResolvExpr::AltList::iterator i = best.front().begin(); i != best.front().end(); ++i ){
                                                                solved_assigns.push_back( i->expr );
                                                        }
                                                        /* assigning cost zero? */
                                                        currentFinder->get_alternatives().push_front( ResolvExpr::Alternative(new SolvedTupleExpr(solved_assigns/*, SolvedTupleExpr::MULTIPLE*/), currentFinder->get_environ(), ResolvExpr::Cost() ) );
                                                }
                                        } else {
                                                assert(! optMass.empty() );
                                                ResolvExpr::AltList winners;
                                                for ( std::vector< ResolvExpr::AltList >::iterator i = optMass.begin(); i != optMass.end(); ++i )
                                                        findMinCostAlt( i->begin(), i->end(), back_inserter(winners) );

                                                std::list< Expression *> solved_assigns;
                                                for ( ResolvExpr::AltList::iterator i = winners.begin(); i != winners.end(); ++i )
                                                        solved_assigns.push_back( i->expr );
                                                currentFinder->get_alternatives().push_front( ResolvExpr::Alternative(new SolvedTupleExpr(solved_assigns/*, SolvedTupleExpr::MASS*/), currentFinder->get_environ(), ResolvExpr::Cost() ) );
                                        }
                                }
                        }
                }
                return hasMatched;
        }

        void TupleAssignSpotter::Matcher::init( Expression *_lhs, Expression *_rhs ) {
                lhs.clear();
                if (AddressExpr *addr = dynamic_cast<AddressExpr *>(_lhs) )
                        if ( TupleExpr *tuple = dynamic_cast<TupleExpr *>(addr->get_arg()) )
                                std::copy( tuple->get_exprs().begin(), tuple->get_exprs().end(), back_inserter(lhs) );

                rhs.clear();
        }

        TupleAssignSpotter::Matcher::Matcher( /*TupleAssignSpotter &spot,*/ Expression *_lhs, Expression *_rhs ) /*: own_spotter(spot) */{
                init(_lhs,_rhs);
        }

        TupleAssignSpotter::MultipleAssignMatcher::MultipleAssignMatcher( Expression *_lhs, Expression *_rhs )/* : own_spotter(spot) */{
                init(_lhs,_rhs);

                if ( TupleExpr *tuple = dynamic_cast<TupleExpr *>(_rhs) )
                        std::copy( tuple->get_exprs().begin(), tuple->get_exprs().end(), back_inserter(rhs) );
        }

        UntypedExpr *TupleAssignSpotter::Matcher::createAssgn( Expression *left, Expression *right ) {
                if ( left && right ) {
                        std::list< Expression * > args;
                        args.push_back(new AddressExpr(left->clone()));  args.push_back(right->clone());
                        return new UntypedExpr(new NameExpr("?=?"), args);
                } else
                        throw 0; // xxx - diagnose the problem
        }

        bool TupleAssignSpotter::MassAssignMatcher::match( std::list< Expression * > &out ) {
                if ( lhs.empty() || (rhs.size() != 1) ) return false;

                for ( std::list< Expression * >::iterator l = lhs.begin(); l != lhs.end(); l++ ) {
                        std::list< Expression * > args;
                        args.push_back( new AddressExpr(*l) );
                        args.push_back( rhs.front() );
                        out.push_back( new UntypedExpr(new NameExpr("?=?"), args) );
                }

                return true;
        }

        bool TupleAssignSpotter::MassAssignMatcher::solve( std::list< Expression * > &assigns ) {
                /*
                  std::list< Expression * > solved_assigns;
                  ResolvExpr::AltList solved_alts;
                  assert( currentFinder != 0 );

                  ResolvExpr::AltList current;
                  if ( optMass.empty() ) {
                  for ( std::list< Expression * >::size_type i = 0; i != new_assigns.size(); ++i )
                  optMass.push_back( ResolvExpr::AltList() );
                  }
                  int cnt = 0;
                  for ( std::list< Expression * >::iterator i = new_assigns.begin(); i != new_assigns.end(); ++i, cnt++ ) {

                  ResolvExpr::AlternativeFinder finder( currentFinder->get_indexer(), currentFinder->get_environ() );
                  finder.findWithAdjustment(*i);
                  ResolvExpr::AltList alts = finder.get_alternatives();
                  assert( alts.size() == 1 );
                  assert(alts.front().expr != 0 );
                  current.push_back( finder.get_alternatives().front() );
                  optMass[cnt].push_back( finder.get_alternatives().front() );
                  solved_assigns.push_back( alts.front().expr->clone() );
                  }
                */
                return true;
        }

        bool TupleAssignSpotter::MultipleAssignMatcher::match( std::list< Expression * > &out ) {
                // need more complicated matching
                if ( lhs.size() == rhs.size() ) {
                        zipWith( lhs.begin(), lhs.end(), rhs.begin(), rhs.end(), back_inserter(out), TupleAssignSpotter::Matcher::createAssgn );
                        return true;
                } //else
                //std::cerr << "The length of (left, right) is: (" << lhs.size() << "," << rhs.size() << ")" << std::endl;*/
                return false;
        }

        bool TupleAssignSpotter::MultipleAssignMatcher::solve( std::list< Expression * > &assigns ) {
                /*
                  std::list< Expression * > solved_assigns;
                  ResolvExpr::AltList solved_alts;
                  assert( currentFinder != 0 );

                  ResolvExpr::AltList current;
                  for ( std::list< Expression * >::iterator i = new_assigns.begin(); i != new_assigns.end(); ++i ) {
                  //try {
                  ResolvExpr::AlternativeFinder finder( currentFinder->get_indexer(), currentFinder->get_environ() );
                  finder.findWithAdjustment(*i);
                  // prune expressions that don't coincide with
                  ResolvExpr::AltList alts = finder.get_alternatives();
                  assert( alts.size() == 1 );
                  assert(alts.front().expr != 0 );
                  current.push_back( finder.get_alternatives().front() );
                  solved_assigns.push_back( alts.front().expr->clone() );
                  //solved_assigns.back()->print(std::cerr);
                  //} catch( ... ) {
                  //continue; // no reasonable alternative found
                  //}
                  }
                  options.add_option( current );
                */

                return true;
        }

        void TupleAssignSpotter::Options::add_option( ResolvExpr::AltList &opt ) {
                using namespace std;

                options.push_back( opt );
                /*
                  vector< Cost > costs;
                  costs.reserve( opt.size() );
                  transform( opt.begin(), opt.end(), back_inserter(costs), ptr_fun(extract_cost) );
                */
                // transpose matrix
                if ( costMatrix.empty() )
                        for ( unsigned int i = 0; i< opt.size(); ++i)
                                costMatrix.push_back( vector<ResolvExpr::Cost>() );

                int cnt = 0;
                for ( ResolvExpr::AltList::iterator i = opt.begin(); i != opt.end(); ++i, cnt++ )
                        costMatrix[cnt].push_back( i->cost );

                return;
        }

        std::list< ResolvExpr::AltList > TupleAssignSpotter::Options::get_best() {
                using namespace std;
                using namespace ResolvExpr;
                list< ResolvExpr::AltList > ret;
                list< multiset<int> > solns;
                for ( vector< vector<Cost> >::iterator i = costMatrix.begin(); i != costMatrix.end(); ++i ) {
                        list<int> current;
                        findMinCost( i->begin(), i->end(), back_inserter(current) );
                        solns.push_back( multiset<int>(current.begin(), current.end()) );
                }
                // need to combine
                multiset<int> result;
                lift_intersection( solns.begin(), solns.end(), inserter( result, result.begin() ) );
                if ( result.size() != 1 )
                        throw SemanticError("Ambiguous tuple expression");
                ret.push_back(get_option( *(result.begin() )));
                return ret;
        }

        void TupleAssignSpotter::Options::print( std::ostream &ostr ) {
                using namespace std;

                for ( vector< vector < ResolvExpr::Cost > >::iterator i = costMatrix.begin(); i != costMatrix.end(); ++i ) {
                        for ( vector < ResolvExpr::Cost >::iterator j = i->begin(); j != i->end(); ++j )
                                ostr << *j << " " ;
                        ostr << std::endl;
                } // for
                return;
        }

        ResolvExpr::Cost extract_cost( ResolvExpr::Alternative &alt ) {
                return alt.cost;
        }

        template< typename InputIterator, typename OutputIterator >
        void TupleAssignSpotter::Options::findMinCost( InputIterator begin, InputIterator end, OutputIterator out ) {
                using namespace ResolvExpr;
                std::list<int> alternatives;

                // select the alternatives that have the minimum parameter cost
                Cost minCost = Cost::infinity;
                unsigned int index = 0;
                for ( InputIterator i = begin; i != end; ++i, index++ ) {
                        if ( *i < minCost ) {
                                minCost = *i;
                                alternatives.clear();
                                alternatives.push_back( index );
                        } else if ( *i == minCost ) {
                                alternatives.push_back( index );
                        }
                }
                std::copy( alternatives.begin(), alternatives.end(), out );
        }

        template< class InputIterator, class OutputIterator >
        void TupleAssignSpotter::Options::lift_intersection( InputIterator begin, InputIterator end, OutputIterator out ){
                if ( begin == end ) return;
                InputIterator test = begin;

                if (++test == end)
                        { copy(begin->begin(), begin->end(), out); return; }


                std::multiset<int> cur; // InputIterator::value_type::value_type
                copy( begin->begin(), begin->end(), inserter( cur, cur.begin() ) );

                while ( test != end ) {
                        std::multiset<int> temp;
                        set_intersection( cur.begin(), cur.end(), test->begin(), test->end(), inserter(temp,temp.begin()) );
                        cur.clear();
                        copy( temp.begin(), temp.end(), inserter(cur,cur.begin()));
                        ++test;
                }

                copy( cur.begin(), cur.end(), out );
                return;
        }

        ResolvExpr::AltList TupleAssignSpotter::Options::get_option( std::list< ResolvExpr::AltList >::size_type index ) {
                if ( index >= options.size() )
                        throw 0; // XXX
                std::list< ResolvExpr::AltList >::iterator it = options.begin();
                for ( std::list< ResolvExpr::AltList >::size_type i = 0; i < index; ++i, ++it );
                return *it;
        }
} // namespace Tuples

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