//
// 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.
//
// ScrubTypeVars.cpp -- Remove polymorphic types.
//
// Author           : Richard C. Bilson
// Created On       : Mon May 18 07:44:20 2015
// Last Modified By : Andrew Beach
// Last Modified On : Wed Dec  7 17:01:00 2022
// Update Count     : 6
//

#include "ScrubTypeVars.hpp"

#include <utility>                      // for pair

#include "AST/Pass.hpp"
#include "GenPoly.h"                    // for mangleType, TyVarMap, alignof...
#include "GenPoly/ErasableScopedMap.h"  // for ErasableScopedMap<>::const_it...
#include "SymTab/Mangler.h"             // for mangleType

namespace GenPoly {

namespace {

struct ScrubTypeVars :
		public ast::WithGuards,
		public ast::WithShortCircuiting,
		public ast::WithVisitorRef<ScrubTypeVars> {

	ScrubTypeVars( ScrubMode m, TypeVarMap const * tv ) :
			mode ( m ), typeVars( tv ) {}

	void previsit( ast::TypeInstType const * ) { visit_children = false; }
	void previsit( ast::StructInstType const * ) { visit_children = false; }
	void previsit( ast::UnionInstType const * ) { visit_children = false; }
	void previsit( ast::SizeofExpr const * expr ) { primeBaseScrub( expr->type ); }
	void previsit( ast::AlignofExpr const * expr ) { primeBaseScrub( expr->type ); }
	void previsit( ast::PointerType const * type ) { primeBaseScrub( type->base ); }

	ast::Type const * postvisit( ast::TypeInstType const * type );
	ast::Type const * postvisit( ast::StructInstType const * type );
	ast::Type const * postvisit( ast::UnionInstType const * type );
	ast::Expr const * postvisit( ast::SizeofExpr const * expr );
	ast::Expr const * postvisit( ast::AlignofExpr const * expr );
	ast::Type const * postvisit( ast::PointerType const * type );

private:
	ScrubMode const mode;
	/// Type varriables to scrub.
	TypeVarMap const * const typeVars;
	/// Value cached by primeBaseScrub.
	ast::Type const * dynType = nullptr;

	/// Returns the type if it should be scrubbed, nullptr otherwise.
	ast::Type const * shouldScrub( ast::Type const * type ) {
		switch ( mode ) {
		case ScrubMode::FromMap:
			return isPolyType( type, *typeVars );
		case ScrubMode::DynamicFromMap:
			return isDynType( type, *typeVars );
		case ScrubMode::All:
			return isPolyType( type );
		default:
			assertf( false, "Invalid ScrubMode in shouldScrub." );
			throw;
		}
	}

	void primeBaseScrub( ast::Type const * type ) {
		// Need to determine whether type needs to be scrubbed to
		// determine whether automatic recursion is necessary.
		if ( ast::Type const * t = shouldScrub( type ) ) {
			visit_children = false;
			GuardValue( dynType ) = t;
		}
	}

	ast::Type const * postvisitAggregateType(
			ast::BaseInstType const * type ) {
		if ( !shouldScrub( type ) ) return type;
		return new ast::PointerType( new ast::VoidType( type->qualifiers ) );
	}
};

ast::Type const * ScrubTypeVars::postvisit( ast::TypeInstType const * type ) {
	ast::TypeDecl::Kind kind;
	// This implies that mode == ScrubMode::All.
	if ( !typeVars ) {
		kind = type->kind;
	} else {
		// Otherwise, only scrub the type var if it is in map.
		auto typeVar = typeVars->find( *type );
		if ( typeVar == typeVars->end() ) {
			return type;
		}
		kind = typeVar->second.kind;
	}

	switch ( kind ) {
	case ast::TypeDecl::Dtype:
	case ast::TypeDecl::Ttype:
		return new ast::PointerType(
			new ast::VoidType( type->qualifiers ) );
	case ast::TypeDecl::Ftype:
		return new ast::PointerType(
			new ast::FunctionType( ast::VariableArgs ) );
	default:
		assertf( false, "Unhandled type variable kind: %d", kind );
		throw; // Just in case the assert is removed, stop here.
	}
}

ast::Type const * ScrubTypeVars::postvisit( ast::StructInstType const * type ) {
	return postvisitAggregateType( type );
}

ast::Type const * ScrubTypeVars::postvisit( ast::UnionInstType const * type ) {
	return postvisitAggregateType( type );
}

ast::Expr const * ScrubTypeVars::postvisit( ast::SizeofExpr const * expr ) {
	// sizeof( T ) becomes the _sizeof_T parameter.
	if ( dynType ) {
		return new ast::NameExpr( expr->location,
			sizeofName( Mangle::mangleType( dynType ) ) );
	} else {
		return expr;
	}
}

ast::Expr const * ScrubTypeVars::postvisit( ast::AlignofExpr const * expr ) {
	// alignof( T ) becomes the _alignof_T parameter.
	if ( dynType ) {
		return new ast::NameExpr( expr->location,
			alignofName( Mangle::mangleType( dynType ) ) );
	} else {
		return expr;
	}
}

ast::Type const * ScrubTypeVars::postvisit( ast::PointerType const * type ) {
	if ( dynType ) {
		ast::Type * ret = ast::mutate( dynType->accept( *visitor ) );
		ret->qualifiers |= type->qualifiers;
		return ret;
	} else {
		return type;
	}
}

} // namespace

const ast::Node * scrubTypeVarsBase(
		const ast::Node * node, const TypeVarMap * typeVars, ScrubMode mode ) {
	if ( ScrubMode::All == mode ) {
		assert( nullptr == typeVars );
	} else {
		assert( nullptr != typeVars );
	}
	ast::Pass<ScrubTypeVars> visitor( mode, typeVars );
	return node->accept( visitor );
}

} // namespace GenPoly

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