//
// 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.
//
// RenameVars.cpp --
//
// Author           : Richard C. Bilson
// Created On       : Sun May 17 12:05:18 2015
// Last Modified By : Andrew Beach
// Last Modified On : Thr Jun 20 17:39:00 2019
// Update Count     : 8
//

#include <ext/alloc_traits.h>         // for __alloc_traits<>::value_type
#include <memory>                     // for allocator_traits<>::value_type
#include <sstream>                    // for operator<<, basic_ostream, ostr...
#include <utility>                    // for pair

#include "AST/Pass.hpp"
#include "AST/Type.hpp"
#include "Common/ScopedMap.hpp"
#include "Common/SemanticError.hpp"   // for SemanticError
#include "RenameVars.hpp"

#include "AST/Copy.hpp"

namespace ResolvExpr {

namespace {

class RenamingData {
	int level = 0;
	int resetCount = 0;

	int next_expr_id = 1;
	int next_usage_id = 1;
	ScopedMap< std::string, std::string > nameMap;
	ScopedMap< std::string, ast::TypeEnvKey > idMap;
public:
	void reset() {
		level = 0;
		++resetCount;
	}

	void nextUsage() {
		++next_usage_id;
	}

	const ast::TypeInstType * rename( const ast::TypeInstType * type ) {
		auto it = idMap.find( type->name );
		if ( it == idMap.end() ) return type;

		// Unconditionally mutate because map will *always* have different name.
		ast::TypeInstType * mut = ast::shallowCopy( type );
		// Reconcile base node since some copies might have been made.
		mut->base = it->second.base;
		mut->formal_usage = it->second.formal_usage;
		mut->expr_id = it->second.expr_id;
		return mut;
	}

	const ast::FunctionType * openLevel( const ast::FunctionType * type, RenameMode mode ) {
		if ( type->forall.empty() ) return type;
		idMap.beginScope();

		// Load new names from this forall clause and perform renaming.
		auto mutType = ast::shallowCopy( type );
		// assert( type == mutType && "mutated type must be unique from ForallSubstitutor" );
		for ( auto & td : mutType->forall ) {
			auto mut = ast::shallowCopy( td.get() );
			// assert( td == mutDecl && "mutated decl must be unique from ForallSubstitutor" );

			if ( mode == GEN_EXPR_ID ) {
				mut->expr_id = next_expr_id;
				mut->formal_usage = -1;
				++next_expr_id;
			} else if ( mode == GEN_USAGE ) {
				assertf( mut->expr_id, "unfilled expression id in generating candidate type" );
				mut->formal_usage = next_usage_id;
			} else {
				assert(false);
			}
			idMap[ td->name ] = ast::TypeEnvKey( *mut );

			td = mut;
		}

		return mutType;
	}

	void closeLevel( const ast::FunctionType * type ) {
		if ( type->forall.empty() ) return;
		idMap.endScope();
	}
};

// Global State:
RenamingData renaming;

struct RenameVars final : public ast::PureVisitor /*: public ast::WithForallSubstitutor*/ {
	RenameMode mode;

	const ast::FunctionType * previsit( const ast::FunctionType * type ) {
		return renaming.openLevel( type, mode );
	}

	/*
	const ast::StructInstType * previsit( const ast::StructInstType * type ) {
		return renaming.openLevel( type );
	}
	const ast::UnionInstType * previsit( const ast::UnionInstType * type ) {
		return renaming.openLevel( type );
	}
	const ast::TraitInstType * previsit( const ast::TraitInstType * type ) {
		return renaming.openLevel( type );
	}
	*/

	const ast::TypeInstType * previsit( const ast::TypeInstType * type ) {
		// Do not rename an actual type.
		if ( mode == GEN_USAGE && !type->formal_usage ) return type;
		return renaming.rename( type );
	}
	void postvisit( const ast::FunctionType * type ) {
		renaming.closeLevel( type );
	}
};

} // namespace

const ast::Type * renameTyVars( const ast::Type * t, RenameMode mode, bool reset ) {
	ast::Pass<RenameVars> renamer;
	renamer.core.mode = mode;
	if (mode == GEN_USAGE && reset) {
		renaming.nextUsage();
	}
	return t->accept( renamer );
}

void resetTyVarRenaming() {
	renaming.reset();
	renaming.nextUsage();
}

} // namespace ResolvExpr

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