hedera/sql/sql-object.c

/*
 * Copyright (C) 2012 - Juan Ferrer Toribio
 *
 * 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 3 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, see <http://www.gnu.org/licenses/>.
 */

#include "sql-object.h"

/**
 * SECTION: sql-object
 * @Short_description: represents an SQL statement or a part of it
 * @Title: SqlObject
 * 
 * The #SqlObject is the base class for all objects in SqlLib.
 **/
G_DEFINE_ABSTRACT_TYPE (SqlObject, sql_object, G_TYPE_INITIALLY_UNOWNED);
 
enum {
	 CHANGED
	,LAST_SIGNAL
};

static guint signals[LAST_SIGNAL] = {0};

//+++++++++++++++++++++++++++++++++++++++++++++++++++ Private

static void sql_object_list_changed (SqlObject * sub, SqlObject * obj)
{
	g_signal_emit (obj, signals[CHANGED], 0);
}

static gboolean sql_object_is_ready_default (SqlObject * obj)
{
	return TRUE;
}

//+++++++++++++++++++++++++++++++++++++++++++++++++++ Protected

/**
 * sql_object_list_add:
 * @obj: #SqlObject where the new item will be appended
 * @list: (element-type Sql.Object): #GSList where @sub is appened
 * @sub: #SqlObject the object is appended
 * 
 * Appends an item into a list of @obj. This function was created to perform an
 * action very common in all objects that inherit from this class.
 *
 * Note that this function is considered a protected method and should only
 * be used in classes that inherit from #SqlObjectClass. Only this function
 * should be able to modify @list. To release the list you can use
 * sql_object_list_free().
 **/
void sql_object_list_add (SqlObject * obj, GSList ** list, SqlObject * sub)
{
	*list = g_slist_append (*list, g_object_ref_sink (sub));
	g_signal_connect (sub, "changed",
		G_CALLBACK (sql_object_list_changed), obj
	);
}

/**
 * sql_object_list_free:
 * @obj: #SqlObject where the item will be removed
 * @list: (element-type Sql.Object): #GSList to release
 * 
 * Releases a list of items, also disconnects its changed handler
 * and calls g_object_unref() on every item.
 *
 * Note that this function is considered a protected method and should only
 * be used in classes that inherit from #SqlObjectClass and whose list has only
 * been handled by the function sql_object_list_add().
 **/
void sql_object_list_free (SqlObject * obj, GSList * list)
{
	GSList * n;

	for (n = list; n; n = n->next)
	{
		g_signal_handlers_disconnect_by_func (n->data,
			G_CALLBACK (sql_object_list_changed), obj
		);
		g_object_unref (n->data);
	}
	
	g_slist_free (list);
}

//+++++++++++++++++++++++++++++++++++++++++++++++++++ Public

/**
 * sql_object_render:
 * @obj: a #SqlObject
 * @render: an #SqlRender
 *
 * Renders the object into a SQL string and stores it into the renderer.
 **/
void sql_object_render (SqlObject * obj, SqlRender * render)
{
	g_return_if_fail (SQL_IS_OBJECT (obj));
	g_return_if_fail (SQL_IS_RENDER (render));
	
	return SQL_OBJECT_GET_CLASS (obj)->render (obj, render);
}

/**
 * sql_object_is_ready:
 * @obj: a #SqlObject
 *
 * Checks if @obj and all of its elemens are ready to be rendered.
 * 
 * Return value: %TRUE if ready, %FALSE otherwise.
 **/
gboolean sql_object_is_ready (SqlObject * obj)
{	
	g_return_val_if_fail (SQL_IS_OBJECT (obj), FALSE);
	
	return SQL_OBJECT_GET_CLASS (obj)->is_ready (obj);
}

//+++++++++++++++++++++++++++++++++++++++++++++++++++ Class

static void sql_object_init (SqlObject * obj)
{
	obj->sql = NULL;
}

static void sql_object_finalize (GObject * obj)
{
	g_free (SQL_OBJECT (obj)->sql);
	G_OBJECT_CLASS (sql_object_parent_class)->finalize (obj);
}

static void sql_object_class_init (SqlObjectClass * klass)
{
	G_OBJECT_CLASS (klass)->finalize = sql_object_finalize;
	klass->is_ready = sql_object_is_ready_default;
	klass->render = NULL;

	/** 
	 * SqlObject::changed:
	 * @obj: the object which emit the signal.
	 * 
	 * This signal is emitted every time the statement or one of its attributes
	 * is modified. 
	 */
	signals[CHANGED] = g_signal_new ("changed", SQL_TYPE_OBJECT,
		G_SIGNAL_RUN_FIRST, 0, NULL, NULL,
			g_cclosure_marshal_VOID__VOID, G_TYPE_NONE, 0
	);
}