89 lines
3.5 KiB
C
89 lines
3.5 KiB
C
/* lv2_uri_map.h - C header file for the LV2 URI Map extension.
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*
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* Copyright (C) 2008 Dave Robillard <dave@drobilla.net>
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*
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* This header is free software; you can redistribute it and/or modify it
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* under the terms of the GNU Lesser General Public License as published
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* by 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 header is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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* License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this header; if not, write to the Free Software Foundation,
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* Inc., 59 Temple Place, Suite 330, Boston, MA 01222-1307 USA
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*/
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#ifndef LV2_URI_MAP_H
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#define LV2_URI_MAP_H
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#define LV2_URI_MAP_URI "http://lv2plug.in/ns/ext/uri-map"
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#include <stdint.h>
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/** @file
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* This header defines the LV2 URI Map extension with the URI
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* <http://lv2plug.in/ns/ext/uri-map> (preferred prefix 'lv2urimap').
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*
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* This extension defines a simple mechanism for plugins to map URIs to
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* integers, usually for performance reasons (e.g. processing events
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* typed by URIs in real time). The expected use case is for plugins to
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* map URIs to integers for things they 'understand' at instantiation time,
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* and store those values for use in the audio thread without doing any string
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* comparison. This allows the extensibility of RDF with the performance of
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* integers (or centrally defined enumerations).
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*/
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/** Opaque pointer to host data. */
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typedef void* LV2_URI_Map_Callback_Data;
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/** The data field of the LV2_Feature for this extension.
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*
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* To support this feature the host must pass an LV2_Feature struct to the
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* plugin's instantiate method with URI "http://lv2plug.in/ns/ext/uri-map"
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* and data pointed to an instance of this struct.
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*/
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typedef struct {
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/** Opaque pointer to host data.
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*
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* The plugin MUST pass this to any call to functions in this struct.
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* Otherwise, it must not be interpreted in any way.
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*/
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LV2_URI_Map_Callback_Data callback_data;
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/** Get the numeric ID of a URI from the host.
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*
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* @param callback_data Must be the callback_data member of this struct.
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* @param map The 'context' of this URI. Certain extensions may define a
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* URI that must be passed here with certain restrictions on the
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* return value (e.g. limited range). This value may be NULL if
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* the plugin needs an ID for a URI in general.
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* @param uri The URI to be mapped to an integer ID.
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*
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* This function is referentially transparent - any number of calls with
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* the same arguments is guaranteed to return the same value over the life
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* of a plugin instance (though the same URI may return different values
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* with a different map parameter). However, this function is not
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* necessarily very fast: plugins should cache any IDs they might need in
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* performance critical situations.
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* The return value 0 is reserved and means an ID for that URI could not
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* be created for whatever reason. Extensions may define more precisely
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* what this means, but in general plugins should gracefully handle 0
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* and consider whatever they wanted the URI for "unsupported".
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*/
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uint32_t (*uri_to_id)(LV2_URI_Map_Callback_Data callback_data,
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const char* map,
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const char* uri);
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} LV2_URI_Map_Feature;
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#endif // LV2_URI_MAP_H
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