//
// Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// exception.hfa -- User facing tools for working with exceptions.
//
// Author           : Andrew Beach
// Created On       : Thu Apr  7 10:25:00 2020
// Last Modified By : Andrew Beach
// Last Modified On : Tue May 19 14:17:00 2020
// Update Count     : 2
//

// Everything below this line should be considered a patch while the exception
// objects themselves are designed and  created and should be removed in time.
// -----------------------------------------------------------------------------------------------

// All internals helper macros begin with an underscore.
#define _CLOSE(...) __VA_ARGS__ }
#define _GLUE2(left, right) left##right
#define _GLUE3(left, middle, right) left##middle##right
#define _EXC_DISPATCH(to, ...) to(__VA_ARGS__,__cfaehm_base_exception_t,)

// FWD_TRIVIAL_EXCEPTION(exception_name);
// Declare a trivial exception, one that adds no fields or features.
// This will make the exception visible and may go in a .hfa or .cfa file.
#define FWD_TRIVIAL_EXCEPTION(...) _EXC_DISPATCH(_FWD_TRIVIAL_EXCEPTION, __VA_ARGS__)
// INST_TRIVIAL_EXCEPTION(exception_name);
// Create the trival exception. This must be used exactly once and should be used in a .cfa file,
// as it creates the unique instance of the virtual table.
#define INST_TRIVIAL_EXCEPTION(...) _EXC_DISPATCH(_INST_TRIVIAL_EXCEPTION, __VA_ARGS__)
// TRIVIAL_EXCEPTION(exception_name[, parent_name]);
// Does both of the above, a short hand if the exception is only used in one .cfa file.
// For legacy reasons this is the only one that official supports having a parent other than the
// base exception. This feature may be removed or changed.
#define TRIVIAL_EXCEPTION(...) \
	_EXC_DISPATCH(_FWD_TRIVIAL_EXCEPTION, __VA_ARGS__); \
	_EXC_DISPATCH(_INST_TRIVIAL_EXCEPTION, __VA_ARGS__)
#define _FWD_TRIVIAL_EXCEPTION(exception_name, parent_name, ...) \
	_VTABLE_DECLARATION(exception_name, parent_name)(); \
	struct exception_name { \
		VTABLE_FIELD(exception_name); \
	}; \
	void ?{}(exception_name & this); \
	const char * _GLUE2(exception_name,_msg)(exception_name * this)
#define _INST_TRIVIAL_EXCEPTION(exception_name, parent_name, ...) \
	void ?{}(exception_name & this) { \
		VTABLE_INIT(this, exception_name); \
	} \
	const char * _GLUE2(exception_name,_msg)(exception_name * this) { \
		return #exception_name; \
	} \
	_VTABLE_INSTANCE(exception_name, parent_name,)(_GLUE2(exception_name,_msg))

// DATA_EXCEPTION(exception_name)(fields...);
// Forward declare an exception that adds fields but no features. The added fields go in the
// second argument list. The virtual table instance must be provided later (see VTABLE_INSTANCE).
#define DATA_EXCEPTION(...) _EXC_DISPATCH(_DATA_EXCEPTION, __VA_ARGS__)
#define _DATA_EXCEPTION(exception_name, parent_name, ...) \
	_VTABLE_DECLARATION(exception_name, parent_name)(); \
	struct exception_name { VTABLE_FIELD(exception_name); _CLOSE

// VTABLE_DECLARATION(exception_name)([new_features...]);
// Declare a virtual table type for an exception with exception_name. You may also add features
// (fields on the virtual table) by including them in the second list.
#define VTABLE_DECLARATION(...) _EXC_DISPATCH(_VTABLE_DECLARATION, __VA_ARGS__)
#define _VTABLE_DECLARATION(exception_name, parent_name, ...) \
	struct exception_name; \
	void mark_exception(exception_name *); \
	VTABLE_TYPE(exception_name); \
	extern VTABLE_TYPE(exception_name) VTABLE_NAME(exception_name); \
	VTABLE_TYPE(exception_name) { \
		VTABLE_TYPE(parent_name) const * parent; \
		size_t size; \
		void (*copy)(exception_name * this, exception_name * other); \
		void (*free)(exception_name & this); \
		const char * (*msg)(exception_name * this); \
		_CLOSE

// VTABLE_INSTANCE(exception_name)(msg [, others...]);
// Create the instance of the virtual table. There must be exactly one instance of a virtual table
// for each exception type. This fills in most of the fields of the virtual table (uses ?=? and
// ^?{}) but you must provide the message function and any other fields added in the declaration.
#define VTABLE_INSTANCE(...) _EXC_DISPATCH(_VTABLE_INSTANCE, __VA_ARGS__)
#define _VTABLE_INSTANCE(exception_name, parent_name, ...) \
	void mark_exception(exception_name *) {} \
	void _GLUE2(exception_name,_copy)(exception_name * this, exception_name * other) { \
		*this = *other; \
	} \
	VTABLE_TYPE(exception_name) VTABLE_NAME(exception_name) @= { \
		&VTABLE_NAME(parent_name), sizeof(exception_name), \
		_GLUE2(exception_name,_copy), ^?{}, \
		_CLOSE

// VTABLE_TYPE(exception_name) | VTABLE_NAME(exception_name)
// Get the name of the vtable type or the name of the vtable instance for an exception type.
#define VTABLE_TYPE(exception_name) struct _GLUE2(exception_name,_vtable)
#define VTABLE_NAME(exception_name) _GLUE3(_,exception_name,_vtable_instance)

// VTABLE_FIELD(exception_name);
// The declaration of the virtual table field. Should be the first declaration in a virtual type.
#define VTABLE_FIELD(exception_name) VTABLE_TYPE(exception_name) const * virtual_table

// VTABLE_INIT(object_reference, exception_name);
// Sets a virtual table field on an object to the virtual table instance for the type.
#define VTABLE_INIT(this, exception_name) (this).virtual_table = &VTABLE_NAME(exception_name)