//
// 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.
//
// InstantiateGeneric.h --
//
// Author           : Aaron B. Moss
// Created On       : Wed Nov 11 14:55:01 2015
// Last Modified By : Aaron B. Moss
// Last Modified On : Wed Nov 11 14:55:01 2015
// Update Count     : 1
//

#include <list>
#include <map>
#include <string>
#include <utility>
#include <vector>

#include "InstantiateGeneric.h"
#include "PolyMutator.h"

#include "ResolvExpr/typeops.h"
#include "SymTab/Indexer.h"
#include "SynTree/Declaration.h"
#include "SynTree/Mutator.h"
#include "SynTree/Statement.h"
#include "SynTree/Type.h"
#include "SynTree/TypeSubstitution.h"

#include "UniqueName.h"
#include "utility.h"

namespace GenPoly {

	/// Key for a unique concrete type; generic base type paired with type parameter list
	struct ConcreteType {
		ConcreteType() : base(NULL), params() {}

		ConcreteType(AggregateDecl *_base, const std::list< Type* >& _params) : base(_base), params() { cloneAll(_params, params); }

		ConcreteType(const ConcreteType& that) : base(that.base), params() { cloneAll(that.params, params); }

		/// Extracts types from a list of Expression* (which should be TypeExpr*)
		ConcreteType(AggregateDecl *_base, const std::list< Expression* >& _params) : base(_base), params() {
			for ( std::list< Expression* >::const_iterator it = _params.begin(); it != _params.end(); ++it ) {
				TypeExpr *param = dynamic_cast< TypeExpr* >(*it);
				assert(param && "Aggregate parameters should be type expressions");
				params.push_back( param->get_type()->clone() );
			}
		}

		ConcreteType& operator= (const ConcreteType& that) {
			deleteAll( params );
			params.clear();

			base = that.base;
			cloneAll( that.params, params );

			return *this;
		}

		~ConcreteType() { deleteAll( params ); }

		bool operator== (const ConcreteType& that) const {
			SymTab::Indexer dummy;

			if ( base != that.base ) return false;
			if ( params.size() != that.params.size() ) return false;
			for ( std::list< Type* >::const_iterator it = params.begin(), jt = that.params.begin(); it != params.end(); ++it, ++jt ) {
				if ( ! ResolvExpr::typesCompatible( *it, *jt, dummy ) ) return false;
			}
			return true;
		}

		AggregateDecl *base;        ///< Base generic type
		std::list< Type* > params;  ///< Instantiation parameters
	};

	/// Maps a concrete type to the instantiated struct type, accounting for scope
	class InstantiationMap {
		/// Pair of concrete type and declaration that instantiates it
		typedef std::pair< ConcreteType, AggregateDecl* > Instantiation;
		/// Map of generic types to instantiations of them
		typedef std::map< AggregateDecl*, std::vector< Instantiation > > Scope;

		std::vector< Scope > scopes;  ///< list of scopes, from outermost to innermost

	public:
		/// Starts a new scope
		void beginScope() {
			Scope scope;
			scopes.push_back(scope);
		}

		/// Ends a scope
		void endScope() {
			scopes.pop_back();
		}

		/// Default constructor initializes with one scope
		InstantiationMap() { beginScope(); }

	private:
		/// Gets the declaration for the concrete instantiation of this type, assuming it has already been instantiated in the current scope.
		/// Returns NULL on none such.
		AggregateDecl* lookup( AggregateDecl *generic, std::list< Expression* >& params ) {
			ConcreteType key(generic, params);
			// scan scopes from innermost out
			for ( std::vector< Scope >::const_reverse_iterator scope = scopes.rbegin(); scope != scopes.rend(); ++scope ) {
				// skip scope if no instantiations of this generic type
				Scope::const_iterator insts = scope->find( generic );
				if ( insts == scope->end() ) continue;
				// look through instantiations for matches to concrete type
				for ( std::vector< Instantiation >::const_iterator inst = insts->second.begin(); inst != insts->second.end(); ++inst ) {
					if ( inst->first == key ) return inst->second;
				}
			}
			// no matching instantiation found
			return NULL;
		}
	public:
		StructDecl* lookup( StructInstType *inst ) { return (StructDecl*)lookup( inst->get_baseStruct(), inst->get_parameters() ); }
		UnionDecl* lookup( UnionInstType *inst ) { return (UnionDecl*)lookup( inst->get_baseUnion(), inst->get_parameters() ); }

	private:
		/// Adds a declaration for a concrete type to the current scope
		void insert( AggregateDecl *generic, std::list< Expression* >& params, AggregateDecl *decl ) {
			ConcreteType key(generic, params);
			scopes.back()[generic].push_back( std::make_pair( key, decl ) );
		}
	public:
		void insert( StructInstType *inst, StructDecl *decl ) { insert( inst->get_baseStruct(), inst->get_parameters(), decl ); }
		void insert( UnionInstType *inst, UnionDecl *decl ) { insert( inst->get_baseUnion(), inst->get_parameters(), decl ); }
	};

	/// Mutator pass that replaces concrete instantiations of generic types with actual struct declarations, scoped appropriately
	class Instantiate : public PolyMutator {
		InstantiationMap instantiations;
		UniqueName typeNamer;

	public:
		Instantiate() : instantiations(), typeNamer("_conc_") {}

		/// Mutates the whole translation unit, inserting new struct declarations as appropriate
		void mutateAll( std::list< Declaration* >& translationUnit );
		
		virtual Type* mutate( StructInstType *inst );
		virtual Type* mutate( UnionInstType *inst );
		
		virtual void doBeginScope();
		virtual void doEndScope();

	private:
		/// Adds a declaration to the current environment and the statements to add
		void addDeclaration( AggregateDecl *decl ) {
			std::list< Label > nolabels;
			DeclStmt *stmt = new DeclStmt( nolabels, decl );
			PolyMutator::stmtsToAdd.push_back( stmt );
		}
	};
	
	void instantiateGeneric( std::list< Declaration* >& translationUnit ) {
		Instantiate instantiator;
//		mutateAll( translationUnit, instantiator );
		instantiator.mutateAll( translationUnit );
	}

	void Instantiate::mutateAll( std::list< Declaration* >& translationUnit ) {
		// below copied and modified from Mutator.h:mutateAll()
		SemanticError errors;
		for ( std::list< Declaration* >::iterator decl = translationUnit.begin(); decl != translationUnit.end(); ++decl ) {
			try {
				if ( *decl ) {
					*decl = dynamic_cast< Declaration* >( (*decl)->acceptMutator( *this ) );
					assert( *decl );
					// account for missing top-level declarations
					for ( std::list< Statement* >::const_iterator stmt = PolyMutator::stmtsToAdd.begin(); stmt != PolyMutator::stmtsToAdd.end(); ++stmt ) {
						DeclStmt *declStmt = dynamic_cast< DeclStmt* >( *stmt );
						assert( declStmt );
						translationUnit.insert( decl, declStmt->get_decl() );
					}
					PolyMutator::stmtsToAdd.clear();
				} // if
			} catch( SemanticError &e ) {
				errors.append( e );
			} // try
		} // for
		if ( ! errors.isEmpty() ) {
			throw errors;
		} // if
	}

	/// Substitutes types of members of in according to baseParams => params, appending the result to out
	void substituteMembers( const std::list< Declaration* >& in,
							const std::list< TypeDecl * >& baseParams, const std::list< Expression* >& params,
						    std::list< Declaration* >& out ) {
		// substitute types into new members
		TypeSubstitution subs( baseParams.begin(), baseParams.end(), params.begin() );
		for ( std::list< Declaration* >::const_iterator member = in.begin(); member != in.end(); ++member ) {
			Declaration *newMember = (*member)->clone();
			subs.apply(newMember);
			out.push_back( newMember );
		}
	}

	Type* Instantiate::mutate( StructInstType *inst ) {
		// mutate subtypes
		Type *mutated = Mutator::mutate( inst );
		inst = dynamic_cast< StructInstType* >( mutated );
		if ( ! inst ) return mutated;

		// exit early if no need for further mutation
		if ( inst->get_parameters().empty() ) return inst;
		
		// make concrete instantiation of generic type
		StructDecl *concDecl = instantiations.lookup( inst );
		if ( ! concDecl ) {
			// set concDecl to new type, insert type declaration into statements to add
			concDecl = new StructDecl( typeNamer.newName( inst->get_name() ) );
			substituteMembers( inst->get_baseStruct()->get_members(),
								inst->get_baseParameters(), inst->get_parameters(),
								concDecl->get_members() );
			addDeclaration( concDecl );
			instantiations.insert( inst, concDecl );
		}
		StructInstType *newInst = new StructInstType( inst->get_qualifiers(), concDecl->get_name() );
		newInst->set_baseStruct( concDecl );
		delete inst;
		return newInst;
	}
	
	Type* Instantiate::mutate( UnionInstType *inst ) {
		// mutate subtypes
		Type *mutated = Mutator::mutate( inst );
		inst = dynamic_cast< UnionInstType* >( mutated );
		if ( ! inst ) return mutated;

		// exit early if no need for further mutation
		if ( inst->get_parameters().empty() ) return inst;

		// make concrete instantiation of generic type
		UnionDecl *concDecl = instantiations.lookup( inst );
		if ( ! concDecl ) {
			// set concDecl to new type, insert type declaration into statements to add
			concDecl = new UnionDecl( typeNamer.newName( inst->get_name() ) );
			substituteMembers( inst->get_baseUnion()->get_members(),
								inst->get_baseParameters(), inst->get_parameters(),
								concDecl->get_members() );
			addDeclaration( concDecl );
			instantiations.insert( inst, concDecl );
		}
		UnionInstType *newInst = new UnionInstType( inst->get_qualifiers(), concDecl->get_name() );
		newInst->set_baseUnion( concDecl );
		delete inst;
		return newInst;
	}
	
	void Instantiate::doBeginScope() {
		// push a new concrete type scope
		instantiations.beginScope();
	}

	void Instantiate::doEndScope() {
		// pop the last concrete type scope
		instantiations.endScope();
	}
	
}  // namespace GenPoly

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