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// -*- C++ -*-
/*
* Gnome Chemistry Utils
* gcu/loader.h
*
* Copyright (C) 2007-2011 Jean Bréfort <jean.brefort@normalesup.org>
*
* 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, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
* USA
*/
#ifndef GCU_LOADER_H
#define GCU_LOADER_H
#include "structs.h"
#include <list>
#include <map>
#include <string>
#include <goffice/goffice.h>
#include <gsf/gsf-input.h>
#include <gsf/gsf-output.h>
/*!\file*/
namespace gcu {
class Document;
class Loader;
class Object;
/*!\struct LoaderStruct gcu/loader.h
Stores data for loaders. They are created when Loader::Init is called for
the first time. Using Loader::GetFirstLoader and Loader::GetNextLoader is
the way used to access the list of available loaders and what they provide.
*/
typedef struct {
/*!
The loader instance associated to a mime type. Might be NULL if not in use.
*/
Loader *loader;
/*!
If true, the loader can read files of the mime type.
*/
bool read;
/*!
If true, the loader can write files of the mime type.
*/
bool write;
/*!
If true, the mime type is able to store 2D chemical structures.
*/
bool supports2D;
/*!
If true, the mime type is able to store 3D chemical structures.
*/
bool supports3D;
/*!
If true, the mime type is able to store crystal structures.
*/
bool supportsCrystals;
/*!
If true, the mime type is able to store spectral data.
*/
bool supportsSpectra;
} LoaderStruct;
/*!\class Loader gcu/loader.h
\brief class used to implement serialization engines.
This class is used to load and save files of various types, using the
gcu::Object framework. Derived classes should be implemented in plugins, using
the goffice plugins API. When Loader::Init is called, the framework collects
informations about the services exposed by each plugin in XML files. For the CDX
file loader plugin, the corresponding plugin.xml.in file content is:
\code
<?xml version="1.0" encoding="UTF-8"?>
<plugin id="GCULoader_cdxml">
<information>
<_name>Loader : cdxml</_name>
<_description>Chemdraw XML files loader.</_description>
</information>
<loader type="Gnumeric_Builtin:module">
<attribute name="module_file" value="cdxml"/>
</loader>
<services>
<service type="chemical_loader" id="GCULoader_cdxml">
<mime_type name="chemical/x-cdxml" capabilities="r" scope="2"/>
<information>
<_description>Chemdraw XML files loader</_description>
</information>
</service>
</services>
</plugin>
\endcode
In the present context, the important node is the mime type related one. Its
attributes are:
- name: the mime type.
- capabilities: what is supported: r for reading, w for writing. Both "rw" and
"wr" are valid.
- scope: 2 and 3 mean 2D and 3D structures, repectively, c means crystal
structure, and s, spectra . Any combination might be used.
Other fields are standard in the goffice world. The plugin is loaded
only when needed.
Each plugin should implement at least one derived class and a static instance
of this class. The CDX loader has:
\code
class CDXLoader: public gcu::Loader
{
public:
CDXLoader ();
virtual ~CDXLoader ();
bool Read (Document *doc, GsfInput *in, char const *mime_type, IOContext *io);
bool Write (Document *doc, GsfOutput *out, char const *mime_type, IOContext *io);
private:
...
};
...
static CDXLoader loader;
\endcode
*/
class Loader
{
public:
/*!
The constructor. Derived class need to call Loader::AddMimeType for each
mime type they support.
*/
Loader ();
/*!
The destructor Derived class should call Loader::RemoveMimeType for each
mime type they support.
*/
virtual ~Loader ();
// static methods
/*!
@param app an Application instance.
Initializes the load/save engines system. This must be called before trying to use
any loader (no one will be available before, anyway).
*/
static void Init (Application *app);
/*!
@param it a std::map iterator.
Must be called to access the first LoaderStruct instance. When successful
the iterator can be used to retrieve both the mime type ((*it).first), and the
corresponding LoaderStruct ((*it).second)
@return true if successful, false otherwise.
*/
static bool GetFirstLoader (std::map<std::string, LoaderStruct>::iterator &it);
/*!
@param it a std::map iterator initialized by Loader::GetFirstLoader
Gets the next LoderStruct and its associated mime type.
@return true if successful, false otherwise.
*/
static bool GetNextLoader (std::map<std::string, LoaderStruct>::iterator &it);
/*!
@param mime_type a mime type.
@return the Loader instance able to read the mime type if any.
*/
static Loader *GetLoader (char const *mime_type);
/*!
@param mime_type a mime type.
@return the Loader instance able to write the mime type if any.
*/
static Loader *GetSaver (char const *mime_type);
// virtual methods
/*!
@param doc the gcu::Document being read.
@param in a GsfInput (see the libgsf documentation at
http://library.gnome.org/devel/gsf/stable/gsf-Input-from-unstructured-files.html#GsfInput).
@param mime_type the mime type of the data.
@param io a GOffice IOContext.
This function must be overloaded by a derived class able to read. Default
implementation just return false.
@return true on success, false otherwise.
*/
virtual ContentType Read (Document *doc, GsfInput *in, char const *mime_type, GOIOContext *io);
/*!
@param obj the gcu::Object being written.
@param out a GsfOutput (see the libgsf documentation at
http://library.gnome.org/devel/gsf/stable/gsf-Output-to-unstructured-files.html#GsfOutput).
@param mime_type the mime type of the data.
@param io a GOffice IOContext.
@param type the type of the data to be saved (see gcu::ContentType).
This function must be overloaded by a derived class able to write. Default
implementation just return false.
@return true on success, false otherwise.
*/
virtual bool Write (Object const *obj, GsfOutput *out, char const *mime_type, GOIOContext *io, ContentType type = ContentTypeMisc);
protected:
/*!
@param mime_type a mime type.
Registers a mime type and stores the instance calling it as the Loader for this mime type.
*/
void AddMimeType (const char *mime_type);
/*!
@param mime_type a mime type.
Unregisters a mime type.
*/
void RemoveMimeType (const char *mime_type);
private:
static bool Inited;
protected:
/*!
The list of supported mime types.
*/
std::list<std::string> MimeTypes;
};
}
#endif // GCU_LOADER_H
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