//
// 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           : Rodolfo G. Esteves
// 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 <iterator>
#include <iostream>
#include <cassert>
#include "Tuples.h"
#include "GenPoly/DeclMutator.h"
#include "SynTree/Mutator.h"
#include "SynTree/Statement.h"
#include "SynTree/Declaration.h"
#include "SynTree/Type.h"
#include "SynTree/Expression.h"
#include "SynTree/Initializer.h"
#include "SymTab/Mangler.h"
#include "Common/ScopedMap.h"
#include "ResolvExpr/typeops.h"
#include "InitTweak/GenInit.h"

namespace Tuples {
	namespace {
		class MemberTupleExpander : public Mutator {
		public:
			typedef Mutator Parent;
			virtual Expression * mutate( UntypedMemberExpr * memberExpr );
		};

		class UniqueExprExpander : public GenPoly::DeclMutator {
		public:
			typedef GenPoly::DeclMutator Parent;
			virtual Expression * mutate( UniqueExpr * unqExpr );
			std::map< int, ObjectDecl * > decls; // not vector, because order added may not be increasing order
		};

		class TupleAssignExpander : public Mutator {
		public:
			typedef Mutator Parent;
			virtual Expression * mutate( TupleAssignExpr * tupleExpr );
		};

		class TupleTypeReplacer : public GenPoly::DeclMutator {
		  public:
			typedef GenPoly::DeclMutator Parent;

			virtual Type * mutate( TupleType * tupleType );

			virtual CompoundStmt * mutate( CompoundStmt * stmt ) {
				typeMap.beginScope();
				stmt = Parent::mutate( stmt );
				typeMap.endScope();
				return stmt;
			}
		  private:
			ScopedMap< std::string, StructDecl * > typeMap;
		};

		class TupleIndexExpander : public Mutator {
		public:
			typedef Mutator Parent;
			virtual Expression * mutate( TupleIndexExpr * tupleExpr );
		};

		class TupleExprExpander : public Mutator {
		public:
			typedef Mutator Parent;
			virtual Expression * mutate( TupleExpr * tupleExpr );
		};
	}

	void expandMemberTuples( std::list< Declaration * > & translationUnit ) {
		MemberTupleExpander expander;
		mutateAll( translationUnit, expander );
	}

	void expandUniqueExpr( std::list< Declaration * > & translationUnit ) {
		UniqueExprExpander unqExpander;
		unqExpander.mutateDeclarationList( translationUnit );
	}

	void expandTuples( std::list< Declaration * > & translationUnit ) {
		TupleAssignExpander assnExpander;
		mutateAll( translationUnit, assnExpander );

		TupleTypeReplacer replacer;
		replacer.mutateDeclarationList( translationUnit );

		TupleIndexExpander idxExpander;
		mutateAll( translationUnit, idxExpander );

		TupleExprExpander exprExpander;
		mutateAll( translationUnit, exprExpander );
	}

	namespace {
		/// given a expression representing the member and an expression representing the aggregate,
		/// reconstructs a flattened UntypedMemberExpr with the right precedence
		Expression * reconstructMemberExpr( Expression * member, UniqueExpr * aggr ) {
			if ( UntypedMemberExpr * memberExpr = dynamic_cast< UntypedMemberExpr * >( member ) ) {
				// construct a new UntypedMemberExpr with the correct structure , and recursively
				// expand that member expression.
				MemberTupleExpander expander;
				UntypedMemberExpr * newMemberExpr = new UntypedMemberExpr( memberExpr->get_member(), new UntypedMemberExpr( memberExpr->get_aggregate(), aggr->clone() ) );

				memberExpr->set_member(nullptr);
				memberExpr->set_aggregate(nullptr);
				delete memberExpr;
				return newMemberExpr->acceptMutator( expander );
			} else {
				// not a member expression, so there is nothing to do but attach and return
				return new UntypedMemberExpr( member, aggr->clone() );
			}
		}
	}

	Expression * MemberTupleExpander::mutate( UntypedMemberExpr * memberExpr ) {
		if ( TupleExpr * tupleExpr = dynamic_cast< TupleExpr * > ( memberExpr->get_member() ) ) {
			UniqueExpr * unqExpr = new UniqueExpr( memberExpr->get_aggregate()->clone() );
			for ( Expression *& expr : tupleExpr->get_exprs() ) {
				expr = reconstructMemberExpr( expr, unqExpr );
			}
			delete unqExpr;
			return tupleExpr;
		} else {
			// there may be a tuple expr buried in the aggregate
			// xxx - this is a memory leak
			return new UntypedMemberExpr( memberExpr->get_member()->clone(), memberExpr->get_aggregate()->acceptMutator( *this ) );
		}
	}

	Expression * UniqueExprExpander::mutate( UniqueExpr * unqExpr ) {
		static UniqueName tempNamer( "_unq_expr_" );
		unqExpr = safe_dynamic_cast< UniqueExpr * > ( Parent::mutate( unqExpr ) );
		if ( ! decls.count( unqExpr->get_id() ) ) {
			// xxx - it's possible (likely?) that expressions can appear in the wrong order because of this. Need to ensure they're placed in the correct location.

			// xxx - this doesn't work, because it would need to be placed after fixInit, but fixInit doesn't know (and shouldn't have to know) about the existance of UniqueExprs - i.e. it will visit them twice
			// need to construct/destruct unique exprs in general - maybe it's not worth it and fixInit should handle UniqueExpr explicitly?
			// currently, tmp is being destructed before unqExpr is used, which suggests there should be a separate lifetime for unqExpr from the tmp_ret

			// if ( CommaExpr * commaExpr = dynamic_cast< CommaExpr * >( unqExpr->get_expr() ) ) {
			// 	if ( VariableExpr * varExpr = dynamic_cast< VariableExpr * >( commaExpr->get_arg2() ) ) {
			// 		// steal existing decl from expr
			// 		if ( ObjectDecl * decl = dynamic_cast< ObjectDecl * >( varExpr->get_var() ) ) {
			// 			decls[unqExpr->get_id()] = decl;
			// 			return unqExpr->get_expr()->clone();
			// 		}
			// 	}
			// }

			// xxx - attach a resolved ConstructorInit node?
			// xxx - is it possible to make the objDecl's type const?
			ObjectDecl * objDecl = new ObjectDecl( tempNamer.newName(), DeclarationNode::NoStorageClass, LinkageSpec::Cforall, nullptr, unqExpr->get_result()->clone(), nullptr );
			// must be done on two lines because genCtorInit accesses objDecl's fields
			objDecl->set_init( InitTweak::genCtorInit( objDecl ) );

			decls[unqExpr->get_id()] = objDecl;
			addDeclaration( objDecl );
		}
		return new VariableExpr( decls[unqExpr->get_id()] );
	}

	Expression * TupleAssignExpander::mutate( TupleAssignExpr * assnExpr ) {
		// xxx - Parent::mutate?
		CompoundStmt * compoundStmt = new CompoundStmt( noLabels );
		std::list< Statement * > & stmts = compoundStmt->get_kids();
		for ( ObjectDecl * obj : assnExpr->get_tempDecls() ) {
			stmts.push_back( new DeclStmt( noLabels, obj ) );
		}
		TupleExpr * tupleExpr = new TupleExpr( assnExpr->get_assigns() );
		assert( tupleExpr->get_result() );
		stmts.push_back( new ExprStmt( noLabels, tupleExpr ) );
		assnExpr->get_tempDecls().clear();
		assnExpr->get_assigns().clear();
		delete assnExpr;
		return new StmtExpr( compoundStmt );
	}

	Type * TupleTypeReplacer::mutate( TupleType * tupleType ) {
		std::string mangleName = SymTab::Mangler::mangleType( tupleType );
		TupleType * newType = safe_dynamic_cast< TupleType * > ( Parent::mutate( tupleType ) );
		if ( ! typeMap.count( mangleName ) ) {
			// generate struct type to replace tuple type
			StructDecl * decl = new StructDecl( "_tuple_type_" + mangleName );
			decl->set_body( true );
			int cnt = 0;
			for ( Type * t : *newType ) {
				decl->get_members().push_back( new ObjectDecl( "field_"+std::to_string(++cnt), DeclarationNode::NoStorageClass, LinkageSpec::C, nullptr, t->clone(), nullptr ) );
			}
			typeMap[mangleName] = decl;
			addDeclaration( decl );
		}
		Type::Qualifiers qualifiers = newType->get_qualifiers();
		delete newType;
		return new StructInstType( qualifiers, typeMap[mangleName] );
	}

	Expression * TupleIndexExpander::mutate( TupleIndexExpr * tupleExpr ) {
		Expression * tuple = maybeMutate( tupleExpr->get_tuple(), *this );
		assert( tuple );
		tupleExpr->set_tuple( nullptr );
		unsigned int idx = tupleExpr->get_index();
		delete tupleExpr;

		StructInstType * type = safe_dynamic_cast< StructInstType * >( tuple->get_result() );
		StructDecl * structDecl = type->get_baseStruct();
		assert( structDecl->get_members().size() > idx );
		Declaration * member = *std::next(structDecl->get_members().begin(), idx);
		return new MemberExpr( safe_dynamic_cast< DeclarationWithType * >( member ), tuple );
	}

	Expression * replaceTupleExpr( Type * result, const std::list< Expression * > & exprs ) {
		if ( result->isVoid() ) {
			// void result - don't need to produce a value for cascading - just output a chain of comma exprs
			assert( ! exprs.empty() );
			std::list< Expression * >::const_iterator iter = exprs.begin();
			Expression * expr = *iter++;
			for ( ; iter != exprs.end(); ++iter ) {
				expr = new CommaExpr( expr, *iter );
			}
			return expr;
		} else {
			// typed tuple expression - produce a compound literal which performs each of the expressions
			// as a distinct part of its initializer - the produced compound literal may be used as part of
			// another expression
			std::list< Initializer * > inits;
			for ( Expression * expr : exprs ) {
				inits.push_back( new SingleInit( expr ) );
			}
			return new CompoundLiteralExpr( result, new ListInit( inits ) );
		}
	}

	Expression * TupleExprExpander::mutate( TupleExpr * tupleExpr ) {
		// recursively expand sub-tuple-expressions
		tupleExpr = safe_dynamic_cast<TupleExpr *>(Parent::mutate(tupleExpr));
		Type * result = tupleExpr->get_result();
		std::list< Expression * > exprs = tupleExpr->get_exprs();
		assert( result );

		// remove data from shell and delete it
		tupleExpr->set_result( nullptr );
		tupleExpr->get_exprs().clear();
		delete tupleExpr;

		return replaceTupleExpr( result, exprs );
	}

	Type * makeTupleType( const std::list< Expression * > & exprs ) {
		// produce the TupleType which aggregates the types of the exprs
		TupleType *tupleType = new TupleType( Type::Qualifiers(true, true, true, true, true, false) );
		Type::Qualifiers &qualifiers = tupleType->get_qualifiers();
		for ( Expression * expr : exprs ) {
			assert( expr->get_result() );
			if ( expr->get_result()->isVoid() ) {
				// if the type of any expr is void, the type of the entire tuple is void
				delete tupleType;
				return new VoidType( Type::Qualifiers() );
			}
			Type * type = expr->get_result()->clone();
			tupleType->get_types().push_back( type );
			// the qualifiers on the tuple type are the qualifiers that exist on all component types
			qualifiers &= type->get_qualifiers();
		} // for
		return tupleType;
	}

	namespace {
		/// determines if impurity (read: side-effects) may exist in a piece of code. Currently gives a very crude approximation, wherein any function call expression means the code may be impure
		class ImpurityDetector : public Visitor {
		public:
			typedef Visitor Parent;
			virtual void visit( ApplicationExpr * appExpr ) { maybeImpure = true;	}
			virtual void visit( UntypedExpr * untypedExpr ) { maybeImpure = true; }
			bool maybeImpure = false;
		};
	} // namespace

	bool maybeImpure( Expression * expr ) {
		ImpurityDetector detector;
		expr->accept( detector );
		return detector.maybeImpure;
	}
} // namespace Tuples

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