/*
 * Copyright (c) 2012 Sean Bartell
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup bithenge
 * @{
 */
/**
 * @file
 * Expressions.
 */

#ifndef BITHENGE_EXPRESSION_H_
#define BITHENGE_EXPRESSION_H_

#include "transform.h"
#include "tree.h"

/** An expression that calculates a value given a scope. */
typedef struct {
	/** @privatesection */
	const struct bithenge_expression_ops *ops;
	unsigned int refs;
} bithenge_expression_t;

/** Operations provided by an expression. */
typedef struct bithenge_expression_ops {
	/** @copydoc bithenge_expression_t::bithenge_expression_evaluate */
	int (*evaluate)(bithenge_expression_t *self, bithenge_scope_t *scope,
	    bithenge_node_t **out);
	/** Destroy the expression.
	 * @param self The expression. */
	void (*destroy)(bithenge_expression_t *self);
} bithenge_expression_ops_t;

/** Increment an expression's reference count.
 * @param self The expression to reference. */
static inline void bithenge_expression_inc_ref(bithenge_expression_t *self)
{
	assert(self);
	self->refs++;
}

/** Decrement an expression's reference count and free it if appropriate.
 * @param self The expression to dereference, or NULL. */
static inline void bithenge_expression_dec_ref(bithenge_expression_t *self)
{
	if (!self)
		return;
	assert(self->ops);
	if (--self->refs == 0)
		self->ops->destroy(self);
}

/** Evaluate an expression. Takes ownership of nothing.
 * @memberof bithenge_expression_t
 * @param self The expression.
 * @param scope The scope.
 * @param[out] out Where the output tree will be stored.
 * @return EOK on success or an error code from errno.h. */
static inline int bithenge_expression_evaluate(bithenge_expression_t *self,
    bithenge_scope_t *scope, bithenge_node_t **out)
{
	assert(self);
	assert(self->ops);
	return self->ops->evaluate(self, scope, out);
}

typedef enum {
	BITHENGE_EXPRESSION_EQUALS,
} bithenge_binary_op_t;

int bithenge_init_expression(bithenge_expression_t *,
    const bithenge_expression_ops_t *);
int bithenge_binary_expression(bithenge_expression_t **, bithenge_binary_op_t,
    bithenge_expression_t *, bithenge_expression_t *);
int bithenge_current_node_expression(bithenge_expression_t **);
int bithenge_param_expression(bithenge_expression_t **, int);
int bithenge_const_expression(bithenge_expression_t **, bithenge_node_t *);
int bithenge_member_expression(bithenge_expression_t **,
    bithenge_expression_t *, bithenge_node_t *);
int bithenge_scope_member_expression(bithenge_expression_t **,
    bithenge_node_t *);
int bithenge_param_wrapper(bithenge_transform_t **, bithenge_transform_t *,
    bithenge_expression_t **);
int bithenge_expression_transform(bithenge_transform_t **,
    bithenge_expression_t *);
int bithenge_if_transform(bithenge_transform_t **, bithenge_expression_t *,
    bithenge_transform_t *, bithenge_transform_t *);

#endif

/** @}
 */