source: src/ResolvExpr/TypeEnvironment.cc @ 982f95d

//
// 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.
//
// TypeEnvironment.cc --
//
// Author           : Richard C. Bilson
// Created On       : Sun May 17 12:19:47 2015
// Last Modified By : Peter A. Buhr
// Last Modified On : Sun May 17 12:23:36 2015
// Update Count     : 3
//

#include <cassert>                     // for assert
#include <algorithm>                   // for copy, set_intersection
#include <iterator>                    // for ostream_iterator, insert_iterator
#include <utility>                     // for pair, move

#include "Common/InternedString.h"     // for interned_string
#include "Common/PassVisitor.h"        // for PassVisitor<GcTracer>
#include "Common/utility.h"            // for maybeClone
#include "SymTab/Indexer.h"            // for Indexer
#include "SynTree/GcTracer.h"          // for PassVisitor<GcTracer>
#include "SynTree/Type.h"              // for Type, FunctionType, Type::Fora...
#include "SynTree/TypeSubstitution.h"  // for TypeSubstitution
#include "TypeEnvironment.h"
#include "Unify.h"                     // for unifyInexact

namespace ResolvExpr {
        void printAssertionSet( const AssertionSet &assertions, std::ostream &os, int indent ) {
                for ( AssertionSet::const_iterator i = assertions.begin(); i != assertions.end(); ++i ) {
                        i->first->print( os, indent );
                        if ( i->second.isUsed ) {
                                os << "(used)";
                        } else {
                                os << "(not used)";
                        } // if
                } // for
        }

        void printOpenVarSet( const OpenVarSet &openVars, std::ostream &os, int indent ) {
                os << std::string( indent, ' ' );
                for ( OpenVarSet::const_iterator i = openVars.begin(); i != openVars.end(); ++i ) {
                        os << i->first << "(" << i->second << ") ";
                } // for
        }

#if 0
        void EqvClass::initialize( const EqvClass &src, EqvClass &dest ) {
                dest.vars = src.vars;
                dest.type = maybeClone( src.type );
                dest.allowWidening = src.allowWidening;
                dest.data = src.data;
        }

        EqvClass::EqvClass() : vars(), type( 0 ), allowWidening( true ), data() {}

        EqvClass::EqvClass( std::vector<interned_string>&& vs, BoundType&& bound )
                : vars( vs.begin(), vs.end() ), type( maybeClone( bound.type ) ), 
                  allowWidening( bound.allowWidening ), data( bound.data ) {}

        EqvClass::EqvClass( const EqvClass &other ) {
                initialize( other, *this );
        }

        EqvClass &EqvClass::operator=( const EqvClass &other ) {
                if ( this == &other ) return *this;
                initialize( other, *this );
                return *this;
        }

        void EqvClass::print( std::ostream &os, Indenter indent ) const {
                os << "( ";
                std::copy( vars.begin(), vars.end(), std::ostream_iterator< std::string >( os, " " ) );
                os << ")";
                if ( type ) {
                        os << " -> ";
                        type->print( os, indent+1 );
                } // if
                if ( ! allowWidening ) {
                        os << " (no widening)";
                } // if
                os << std::endl;
        }

        const EqvClass* TypeEnvironment::lookup( const std::string &var ) const {
                for ( std::list< EqvClass >::const_iterator i = env.begin(); i != env.end(); ++i ) {
                        if ( i->vars.find( var ) != i->vars.end() ) {
///       std::cout << var << " is in class ";
///       i->print( std::cout );
                                return &*i;
                        }
///     std::cout << var << " is not in class ";
///     i->print( std::cout );
                } // for
                return nullptr;
        }
#endif

        std::pair<interned_string, interned_string> TypeEnvironment::mergeClasses( 
                        interned_string root1, interned_string root2 ) {
                // merge classes
                Classes* newClasses = classes->merge( root1, root2 );

                // determine new root
                assertf(classes->get_mode() == Classes::REMFROM, "classes updated to REMFROM by merge");
                auto ret = std::make_pair( classes->get_root(), classes->get_child );
                
                // finalize classes
                classes = newClasses;
                return ret;
        }

        ClassRef TypeEnvironment::lookup( interned_string var ) const {
                interned_string root = classes->find_or_default( var, nullptr );
                if ( root ) return { this, root };
                else return { nullptr, var };
        }

        bool tyVarCompatible( const TypeDecl::Data & data, Type *type ) {
                switch ( data.kind ) {
                  case TypeDecl::Dtype:
                        // to bind to an object type variable, the type must not be a function type.
                        // if the type variable is specified to be a complete type then the incoming
                        // type must also be complete
                        // xxx - should this also check that type is not a tuple type and that it's not a ttype?
                        return ! isFtype( type ) && (! data.isComplete || type->isComplete() );
                  case TypeDecl::Ftype:
                        return isFtype( type );
                  case TypeDecl::Ttype:
                        // ttype unifies with any tuple type
                        return dynamic_cast< TupleType * >( type ) || Tuples::isTtype( type );
                } // switch
                return false;
        }

        bool TypeEnvironment::bindVar( TypeInstType* typeInst, Type* bindTo, 
                        const TypeDecl::Data& data, AssertionSet& need, AssertionSet& have, 
                        const OpenVarSet& openVars, WidenMode widenMode, const SymTab::Indexer& indexer ) {
                // remove references from other, so that type variables can only bind to value types
                bindTo = bindTo->stripReferences();
                
                auto tyVar = openVars.find( typeInst->get_name() );
                assert( tyVar != openVars.end() );
                if ( ! tyVarCompatible( tyVar->second, other ) ) return false;

                if ( occurs( bindTo, typeInst->get_name(), *this ) ) return false;

                if ( ClassRef curClass = lookup( typeInst->get_name() ) ) {
                        BoundType curData = curClass.get_bound();
                        if ( curData.type ) {
                                Type* common = nullptr;
                                // attempt to unify equivalence class type (which needs its qualifiers restored) 
                                // with the target type
                                Type* newType = curData.type->clone();
                                newType->get_qualifiers() = typeInst->get_qualifiers();
                                if ( unifyInexact( newType, bindTo, *this, need, have, openVars, 
                                                widenMode & WidenMode{ curData.allowWidening, true }, indexer, common ) ) {
                                        if ( common ) {
                                                // update bound type to common type
                                                common->get_qualifiers() = Type::Qualifiers{};
                                                curData.type = common;
                                                bindings = bindings->set( curClass.update_root(), curData );
                                        }
                                        return true;
                                } else return false;
                        } else {
                                // update bound type to other type
                                curData.type = bindTo->clone();
                                curData.type->get_qualifiers() = Type::Qualifiers{};
                                curData.allowWidening = widenMode.widenFirst && widenMode.widenSecond;
                                bindings = bindings->set( curClass.get_root(), curData );
                        }
                } else {
                        // make new class consisting entirely of this variable
                        BoundType curData{ bindTo->clone(), widenMode.first && widenMode.second, data };
                        curData.type->get_qualifiers() = Type::Qualifiers{};
                        classes = classes->add( curClass.get_root() );
                        bindings = bindings->set( curClass.get_root(), curData );
                }
                return true;
        }
        
        bool TypeEnvironment::bindVarToVar( TypeInstType* var1, TypeInstType* var2, 
                        const TypeDecl::Data& data, AssertionSet& need, AssertionSet& have, 
                        const OpenVarSet& openVars, WidenMode widenMode, const SymTab::Indexer& indexer ) {
                ClassRef class1 = env.lookup( var1->get_name() );
                ClassRef class2 = env.lookup( var2->get_name() );
                
                // exit early if variables already bound together
                if ( class1 && class2 && class1 == class2 ) {
                        BoundType data1 = class1.get_bound();
                        // narrow the binding if needed
                        if ( data1.allowWidening && widenMode.first != widenMode.second ) {
                                data1.allowWidening = false;
                                bindings = bindings->set( class1.get_root(), data1 );
                        }
                        return true;
                }

                BoundType data1 = class1 ? class1.get_bound() : BoundType{};
                BoundType data2 = class2 ? class2.get_bound() : BoundType{};

                bool widen1 = data1.allowWidening && widenMode.widenFirst;
                bool widen2 = data2.allowWidening && widenMode.widenSecond;

                if ( data1.type && data2.type ) {
                        // attempt to unify bound classes
                        Type* common = nullptr;
                        if ( unifyInexact( data1.type->clone(), data2.type->clone(), *this, need, have, 
                                        openVars, WidenMode{ widen1, widen2 }, indexer, common ) ) {
                                // merge type variables
                                interned_string root = mergeClasses( class1.update_root(), class2.update_root() );
                                // update bindings
                                data1.allowWidening = widen1 && widen2;
                                if ( common ) {
                                        common->get_qualifiers() = Type::Qualifiers{};
                                        data1.type = common;
                                }
                                bindings = bindings->set( root, data1 );
                        } else return false;
                } else if ( class1 && class2 ) {
                        // both classes exist, only one bound -- merge type variables
                        auto merged = mergeClasses( class1.get_root(), class2.get_root() );
                        // remove subordinate binding
                        bindings = bindings->erase( merged.second );
                        // update root binding (narrow widening as needed, or set new binding for changed root)
                        if ( data1.type ) {
                                if ( data1.allowWidening != widen1 ) {
                                        data1.allowWidening = widen1;
                                        bindings = bindings->set( merged.first, data1 );
                                } else if ( merged.first == class2.get_root() ) {
                                        bindings = bindings->set( merged.first, data1 );
                                }
                        } else /* if ( data2.type ) */ {
                                if ( data2.allowWidening != widen2 ) {
                                        data2.allowWidening = widen2;
                                        bindings = bindings->set( root, data2 );
                                } else if ( merged.first == class1.get_root() ) {
                                        bindings = bindings->set( merged.first, data2 );
                                }
                        }
                } else if ( class1 ) {
                        // add unbound var2 to class1
                        classes = classes->add( class2.get_root() );
                        auto merged = mergeClasses( class1.get_root(), class2.get_root() );
                        // update bindings (narrow as needed, or switch binding to root)
                        if ( merged.first == class2.get_root() ) {
                                data1.allowWidening = widen1;
                                bindings = bindings->erase( merged.second )->set( merged.first, data1 );
                        } else if ( data1.allowWidening != widen1 ) {
                                bindings = bindings->set( merged.first, data1 );
                        }
                } else if ( class2 ) {
                        // add unbound var1 to class1
                        classes = classes->add( class1.get_root() );
                        auto merged = mergeClasses( class1.get_root(), class2.get_root() );
                        // update bindings (narrow as needed, or switch binding to root)
                        if ( merged.first == class1.get_root() ) {
                                data2.allowWidening = widen2;
                                bindings = bindings->erase( merged.second )->set( merged.first, data2 );
                        } else if ( data2.allowWidening != widen2 ) {
                                bindings = bindings->set( merged.first, data2 );
                        }
                } else {
                        // make new class with pair of unbound vars
                        classes = classes->add( class1.get_root() )->add( class2.get_root() );
                        auto merged = mergeClasses( class1.get_root(), class2.get_root() );
                        bindings = bindings->set( merged.first, BoundType{ nullptr, widen1 && widen2, data } );
                }
                return true;
        }

#if !1
        /// Removes any class from env that intersects eqvClass
        void filterOverlappingClasses( std::list<EqvClass> &env, const EqvClass &eqvClass ) {
                for ( auto i = env.begin(); i != env.end(); ) {
                        auto next = i;
                        ++next;
                        std::set<std::string> intersection;
                        std::set_intersection( i->vars.begin(), i->vars.end(), eqvClass.vars.begin(), eqvClass.vars.end(), 
                                std::inserter( intersection, intersection.begin() ) );
                        if ( ! intersection.empty() ) { env.erase( i ); }
                        i = next;
                }
        }

        void TypeEnvironment::add( const EqvClass &eqvClass ) {
                filterOverlappingClasses( env, eqvClass );
                env.push_back( eqvClass );
        }

        void TypeEnvironment::add( EqvClass &&eqvClass ) {
                filterOverlappingClasses( env, eqvClass );
                env.push_back( std::move(eqvClass) );
        }

        void TypeEnvironment::add( const Type::ForallList &tyDecls ) {
                for ( Type::ForallList::const_iterator i = tyDecls.begin(); i != tyDecls.end(); ++i ) {
                        EqvClass newClass;
                        newClass.vars.insert( (*i)->get_name() );
                        newClass.data = TypeDecl::Data{ (*i) };
                        env.push_back( newClass );
                } // for
        }

        void TypeEnvironment::add( const TypeSubstitution & sub ) {
                EqvClass newClass;
                for ( auto p : sub ) {
                        newClass.vars.insert( p.first );
                        newClass.type = p.second->clone();
                        newClass.allowWidening = false;
                        // Minimal assumptions. Not technically correct, but might be good enough, and
                        // is the best we can do at the moment since information is lost in the
                        // transition to TypeSubstitution
                        newClass.data = TypeDecl::Data{ TypeDecl::Dtype, false };
                        add( newClass );
                }
        }

        void TypeEnvironment::makeSubstitution( TypeSubstitution &sub ) const {
                for ( std::list< EqvClass >::const_iterator theClass = env.begin(); theClass != env.end(); ++theClass ) {
                        for ( std::set< std::string >::const_iterator theVar = theClass->vars.begin(); theVar != theClass->vars.end(); ++theVar ) {
///       std::cerr << "adding " << *theVar;
                                if ( theClass->type ) {
///         std::cerr << " bound to ";
///         theClass->type->print( std::cerr );
///         std::cerr << std::endl;
                                        sub.add( *theVar, theClass->type );
                                } else if ( theVar != theClass->vars.begin() ) {
                                        TypeInstType *newTypeInst = new TypeInstType( Type::Qualifiers(), *theClass->vars.begin(), theClass->data.kind == TypeDecl::Ftype );
///         std::cerr << " bound to variable " << *theClass->vars.begin() << std::endl;
                                        sub.add( *theVar, newTypeInst );
                                } // if
                        } // for
                } // for
///   std::cerr << "input env is:" << std::endl;
///   print( std::cerr, 8 );
///   std::cerr << "sub is:" << std::endl;
///   sub.print( std::cerr, 8 );
                sub.normalize();
        }

        void TypeEnvironment::print( std::ostream &os, Indenter indent ) const {
                for ( std::list< EqvClass >::const_iterator i = env.begin(); i != env.end(); ++i ) {
                        i->print( os, indent );
                } // for
        }

        std::list< EqvClass >::iterator TypeEnvironment::internal_lookup( const std::string &var ) {
                for ( std::list< EqvClass >::iterator i = env.begin(); i != env.end(); ++i ) {
                        if ( i->vars.find( var ) == i->vars.end() ) {
                                return i;
                        } // if
                } // for
                return env.end();
        }

        void TypeEnvironment::simpleCombine( const TypeEnvironment &second ) {
                env.insert( env.end(), second.env.begin(), second.env.end() );
        }

        void TypeEnvironment::extractOpenVars( OpenVarSet &openVars ) const {
                for ( std::list< EqvClass >::const_iterator eqvClass = env.begin(); eqvClass != env.end(); ++eqvClass ) {
                        for ( std::set< std::string >::const_iterator var = eqvClass->vars.begin(); var != eqvClass->vars.end(); ++var ) {
                                openVars[ *var ] = eqvClass->data;
                        } // for
                } // for
        }

        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) );
                }
        }

        std::ostream & operator<<( std::ostream & out, const TypeEnvironment & env ) {
                env.print( out );
                return out;
        }
#endif

        PassVisitor<GcTracer> & operator<<( PassVisitor<GcTracer> & gc, const TypeEnvironment & env ) {
                for ( ClassRef c : env ) {
                        maybeAccept( c.get_bound().type, gc );
                }
                return gc;
        }
} // namespace ResolvExpr

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