/*
	expr_bool.c

	short-circuit boolean expressions

	Copyright (C) 2001 Bill Currie <bill@taniwha.org>

	Author: Bill Currie <bill@taniwha.org>
	Date: 2001/06/15

	This program is free software; you can redistribute it and/or
	modify it under the terms of the GNU General Public License
	as published by the Free Software Foundation; either version 2
	of the License, or (at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

	See the GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with this program; if not, write to:

		Free Software Foundation, Inc.
		59 Temple Place - Suite 330
		Boston, MA  02111-1307, USA

*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#ifdef HAVE_STRING_H
# include <string.h>
#endif
#ifdef HAVE_STRINGS_H
# include <strings.h>
#endif
#include <stdlib.h>

#include "QF/alloc.h"
#include "QF/dstring.h"
#include "QF/mathlib.h"
#include "QF/sys.h"
#include "QF/va.h"

#include "tools/qfcc/include/qfcc.h"
#include "tools/qfcc/include/class.h"
#include "tools/qfcc/include/def.h"
#include "tools/qfcc/include/defspace.h"
#include "tools/qfcc/include/diagnostic.h"
#include "tools/qfcc/include/emit.h"
#include "tools/qfcc/include/expr.h"
#include "tools/qfcc/include/function.h"
#include "tools/qfcc/include/idstuff.h"
#include "tools/qfcc/include/method.h"
#include "tools/qfcc/include/options.h"
#include "tools/qfcc/include/reloc.h"
#include "tools/qfcc/include/rua-lang.h"
#include "tools/qfcc/include/shared.h"
#include "tools/qfcc/include/strpool.h"
#include "tools/qfcc/include/struct.h"
#include "tools/qfcc/include/symtab.h"
#include "tools/qfcc/include/type.h"
#include "tools/qfcc/include/value.h"

const expr_t *
test_expr (const expr_t *e)
{
	const expr_t *new = 0;

	if (e->type == ex_error)
		return e;

	auto type = get_type (e);
	if (e->type == ex_error)
		return e;
	scoped_src_loc (e);
	switch (type->type) {
		case ev_type_count:
			internal_error (e, 0);
		case ev_void:
			if (options.traditional) {
				if (options.warnings.traditional)
					warning (e, "void has no value");
				return e;
			}
			return error (e, "void has no value");
		case ev_string:
			if (!options.code.ifstring)
				return new_alias_expr (type_default, e);
			new = new_string_expr (0);
			break;
		case ev_long:
		case ev_ulong:
			if (type->width > 1) {
				e = new_horizontal_expr ('|', e, &type_long);
			}
			e = new_alias_expr (&type_ivec2, e);
			return new_horizontal_expr ('|', e, &type_int);
		case ev_ushort:
			internal_error (e, "ushort not implemented");
		case ev_uint:
		case ev_int:
		case ev_short:
			if (type->width > 1) {
				e = new_horizontal_expr ('|', e, &type_int);
			}
			if (!is_int(type_default)) {
				if (is_constant (e)) {
					return cast_expr (type_default, e);
				}
				return new_alias_expr (type_default, e);
			}
			return e;
		case ev_float:
			if (options.code.progsversion < PROG_VERSION
				&& (options.code.fast_float
					|| options.code.progsversion == PROG_ID_VERSION)) {
				if (!is_float(type_default)) {
					if (is_constant (e)) {
						return cast_expr (type_default, e);
					}
					return new_alias_expr (type_default, e);
				}
				return e;
			}
			new = new_zero_expr (type);
			new = binary_expr (QC_NE, e, new);
			return test_expr (new);
		case ev_double:
			new = new_zero_expr (type);
			new = binary_expr (QC_NE, e, new);
			return test_expr (new);
		case ev_vector:
			new = new_zero_expr (&type_vector);
			break;
		case ev_entity:
			return new_alias_expr (type_default, e);
		case ev_field:
			return new_alias_expr (type_default, e);
		case ev_func:
			return new_alias_expr (type_default, e);
		case ev_ptr:
			return new_alias_expr (type_default, e);
		case ev_quaternion:
			new = new_zero_expr (&type_quaternion);
			break;
		case ev_invalid:
			if (is_enum (type)) {
				new = new_nil_expr ();
				break;
			}
			return test_error (e, get_type (e));
	}
	new = binary_expr (QC_NE, e, new);
	return new;
}

void
backpatch (ex_boollist_t *list, const expr_t *label)
{
	int         i;
	expr_t     *e;

	if (!list)
		return;
	if (!label || label->type != ex_label)
		internal_error (label, "not a label");

	for (i = 0; i < list->size; i++) {
		e = list->e[i];
		if (e->type == ex_branch && e->branch.type < pr_branch_call) {
			e->branch.target = label;
		} else {
			internal_error (e, 0);
		}
		((expr_t *)label)->label.used++;
	}
}

static ex_boollist_t *
merge (ex_boollist_t *l1, ex_boollist_t *l2)
{
	ex_boollist_t  *m;

	if (!l1 && !l2)
		return 0;
	if (!l2)
		return l1;
	if (!l1)
		return l2;
	m = malloc (field_offset (ex_boollist_t, e[l1->size + l2->size]));
	m->size = l1->size + l2->size;
	memcpy (m->e, l1->e, l1->size * sizeof (expr_t *));
	memcpy (m->e + l1->size, l2->e, l2->size * sizeof (expr_t *));
	return m;
}

static ex_boollist_t *
make_list (const expr_t *e)
{
	ex_boollist_t  *m;

	m = malloc (field_offset (ex_boollist_t, e[1]));
	m->size = 1;
	m->e[0] = (expr_t *) e;
	return m;
}

const expr_t *
bool_expr (int op, const expr_t *label, const expr_t *e1, const expr_t *e2)
{
	expr_t     *block;

	if (!options.code.short_circuit)
		return binary_expr (op, e1, e2);

	e1 = convert_bool (e1, false);
	if (e1->type == ex_error)
		return e1;

	e2 = convert_bool (e2, false);
	if (e2->type == ex_error)
		return e2;

	block = new_block_expr (0);
	append_expr (block, e1);
	append_expr (block, label);
	append_expr (block, e2);

	switch (op) {
		case QC_OR:
			backpatch (e1->boolean.false_list, label);
			return new_boolean_expr (merge (e1->boolean.true_list,
											e2->boolean.true_list),
									 e2->boolean.false_list, block);
			break;
		case QC_AND:
			backpatch (e1->boolean.true_list, label);
			return new_boolean_expr (e2->boolean.true_list,
									 merge (e1->boolean.false_list,
											e2->boolean.false_list), block);
			break;
	}
	internal_error (e1, 0);
}

static int __attribute__((pure))
has_block_expr (const expr_t *e)
{
	while (e->type == ex_alias) {
		e = e->alias.expr;
	}
	return e->type == ex_block;
}

const expr_t *
convert_bool (const expr_t *e, bool block)
{
	if (e->type == ex_assign) {
		if (!e->paren && options.warnings.precedence)
			warning (e, "suggest parentheses around assignment "
					 "used as truth value");
		auto tst = e->assign.src;
		if (has_block_expr (tst) && has_block_expr (e->assign.dst)) {
			tst = new_temp_def_expr (get_type (tst));
			e = new_assign_expr (e->assign.dst,
								 assign_expr (tst, e->assign.src));
		} else if (has_block_expr (tst)) {
			tst = e->assign.dst;
		}
		auto b = convert_bool (tst, true);
		if (b->type == ex_error)
			return b;
		// insert the assignment into the boolean's block
		prepend_expr ((expr_t *) b->boolean.e, e);	//FIXME cast
		return b;
	}

	if (e->type == ex_uexpr && e->expr.op == '!'
		&& !is_string(get_type (e->expr.e1))) {
		e = convert_bool (e->expr.e1, false);
		if (e->type == ex_error)
			return (expr_t *) e;
		e = unary_expr ('!', e);
	}
	if (e->type != ex_bool) {
		e = test_expr (e);
		if (e->type == ex_error)
			return (expr_t *) e;
		if (is_constant (e)) {
			int         val;

			auto b = goto_expr (0);
			if (is_int_val (e)) {
				val = expr_int (e);
			} else {
				val = expr_float (e) != 0;
			}
			if (val)
				e = new_boolean_expr (make_list (b), 0, b);
			else
				e = new_boolean_expr (0, make_list (b), b);
		} else {
			auto b = new_block_expr (0);
			append_expr (b, branch_expr (QC_NE, e, 0));
			append_expr (b, goto_expr (0));
			e = new_boolean_expr (make_list (b->block.list.head->expr),
								  make_list (b->block.list.head->next->expr),
								  b);
		}
	}
	if (block && e->boolean.e->type != ex_block) {
		expr_t     *block = new_block_expr (0);
		append_expr (block, e->boolean.e);
		((expr_t *) e)->boolean.e = block;
	}
	return edag_add_expr (e);
}