181 lines
6.3 KiB
C++
181 lines
6.3 KiB
C++
/*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Library General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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#ifndef _DIJON_FILTER_H
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#define _DIJON_FILTER_H
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#include <string>
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#include <set>
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#include <map>
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namespace Dijon
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{
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class Filter;
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/** Provides the list of MIME types supported by the filter(s).
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* The character string is allocated with new[].
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* This function is exported by dynamically loaded filter libraries.
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*/
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typedef bool (get_filter_types_func)(std::set<std::string> &);
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/** Returns what data should be passed to the filter(s).
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* Output is cast from Filter::DataInput to int for convenience.
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* This function is exported by dynamically loaded filter libraries.
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* The aim is to let the client application know before-hand whether
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* it should load documents or not.
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*/
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typedef bool (check_filter_data_input_func)(int);
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/** Returns a Filter that handles the given MIME type.
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* The Filter object is allocated with new.
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* This function is exported by dynamically loaded filter libraries
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* and serves as a factory for Filter objects, so that the client
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* application doesn't have to know which Filter sub-types handle
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* which MIME types.
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*/
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typedef Filter *(get_filter_func)(const std::string &);
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/// Filter interface.
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class Filter
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{
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public:
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/// Builds an empty filter.
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Filter(const std::string &mime_type) : m_mimeType(mime_type) {}
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/// Destroys the filter.
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virtual ~Filter() {}
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// Enumerations.
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/** What data a filter supports as input.
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* It can be either the whole document data, its file name, or its URI.
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*/
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typedef enum { DOCUMENT_DATA=0, DOCUMENT_STRING, DOCUMENT_FILE_NAME, DOCUMENT_URI } DataInput;
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/** Input properties supported by the filter.
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* - DEFAULT_CHARSET is the charset preferred by the client application.
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* The filter will convert document's content to this charset if possible.
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* - OPERATING_MODE can be set to either view or index.
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*/
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typedef enum { DEFAULT_CHARSET=0, OPERATING_MODE } Properties;
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// Information.
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/// Returns the MIME type handled by the filter.
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std::string get_mime_type(void) const
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{
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return m_mimeType;
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}
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/// Returns what data the filter requires as input.
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virtual bool is_data_input_ok(DataInput input) const = 0;
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// Initialization.
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/** Sets a property, prior to calling set_document_XXX().
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* Returns false if the property is not supported.
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*/
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virtual bool set_property(Properties prop_name, const std::string &prop_value) = 0;
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/** (Re)initializes the filter with the given data.
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* Caller should ensure the given pointer is valid until the
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* Filter object is destroyed, as some filters may not need to
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* do a deep copy of the data.
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* Call next_document() to position the filter onto the first document.
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* Returns false if this input is not supported or an error occured.
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*/
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virtual bool set_document_data(const char *data_ptr, unsigned int data_length) = 0;
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/** (Re)initializes the filter with the given data.
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* Call next_document() to position the filter onto the first document.
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* Returns false if this input is not supported or an error occured.
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*/
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virtual bool set_document_string(const std::string &data_str) = 0;
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/** (Re)initializes the filter with the given file.
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* Call next_document() to position the filter onto the first document.
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* Returns false if this input is not supported or an error occured.
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*/
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virtual bool set_document_file(const std::string &file_path) = 0;
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/** (Re)initializes the filter with the given URI.
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* Call next_document() to position the filter onto the first document.
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* Returns false if this input is not supported or an error occured.
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*/
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virtual bool set_document_uri(const std::string &uri) = 0;
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// Going from one nested document to the next.
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/** Returns true if there are nested documents left to extract.
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* Returns false if the end of the parent document was reached
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* or an error occured.
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*/
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virtual bool has_documents(void) const = 0;
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/** Moves to the next nested document.
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* Returns false if there are none left.
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*/
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virtual bool next_document(void) = 0;
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/** Skips to the nested document with the given ipath.
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* Returns false if no such document exists.
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*/
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virtual bool skip_to_document(const std::string &ipath) = 0;
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// Accessing documents' contents.
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/// Returns the message for the most recent error that has occured.
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virtual std::string get_error(void) const = 0;
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/** Returns a dictionary of metadata extracted from the current document.
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* Metadata fields may include one or more of the following :
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* content, title, ipath, mimetype, language, charset, author, creator,
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* publisher, modificationdate, creationdate, size
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* Special considerations apply :
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* - content may contain binary data, watch out !
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* - ipath is an internal path to the nested document that can be
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* later passed to skip_to_document(). It may be empty if the parent
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* document's type doesn't allow embedding, in which case the filter
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* should only return one document.
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* - mimetype should be text/plain if the document could be handled
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* internally, empty if unknown. If any other value, it is expected
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* that the client application can pass the nested document's content
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* to another filter that supports this particular type.
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*/
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const std::map<std::string, std::string> &get_meta_data(void) const
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{
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return m_metaData;
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}
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protected:
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/// The MIME type handled by the filter.
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std::string m_mimeType;
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/// Metadata dictionary.
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std::map<std::string, std::string> m_metaData;
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private:
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/// Filter objects cannot be copied.
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Filter(const Filter &other);
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/// Filter objects cannot be copied.
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Filter& operator=(const Filter& other);
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};
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}
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#endif // _DIJON_FILTER_H
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