1 /* lv2_uri_map.h - C header file for the LV2 URI Map extension.
3 * Copyright (C) 2008 David Robillard <d@drobilla.net>
5 * This header is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU Lesser General Public License as published
7 * by the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
10 * This header is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
13 * License for more details.
15 * You should have received a copy of the GNU Lesser General Public License
16 * along with this header; if not, write to the Free Software Foundation,
17 * Inc., 59 Temple Place, Suite 330, Boston, MA 01222-1307 USA
23 #define LV2_URI_MAP_URI "http://lv2plug.in/ns/ext/uri-map"
28 * This header defines the LV2 URI Map extension with the URI
29 * <http://lv2plug.in/ns/ext/uri-map> (preferred prefix 'lv2urimap').
31 * This extension defines a simple mechanism for plugins to map URIs to
32 * integers, usually for performance reasons (e.g. processing events
33 * typed by URIs in real time). The expected use case is for plugins to
34 * map URIs to integers for things they 'understand' at instantiation time,
35 * and store those values for use in the audio thread without doing any string
36 * comparison. This allows the extensibility of RDF with the performance of
37 * integers (or centrally defined enumerations).
41 /** Opaque pointer to host data. */
42 typedef void* LV2_URI_Map_Callback_Data
;
45 /** The data field of the LV2_Feature for this extension.
47 * To support this feature the host must pass an LV2_Feature struct to the
48 * plugin's instantiate method with URI "http://lv2plug.in/ns/ext/uri-map"
49 * and data pointed to an instance of this struct.
53 /** Opaque pointer to host data.
55 * The plugin MUST pass this to any call to functions in this struct.
56 * Otherwise, it must not be interpreted in any way.
58 LV2_URI_Map_Callback_Data callback_data
;
60 /** Get the numeric ID of a URI from the host.
62 * @param callback_data Must be the callback_data member of this struct.
63 * @param map The 'context' of this URI. Certain extensions may define a
64 * URI that must be passed here with certain restrictions on the
65 * return value (e.g. limited range). This value may be NULL if
66 * the plugin needs an ID for a URI in general.
67 * @param uri The URI to be mapped to an integer ID.
69 * This function is referentially transparent - any number of calls with
70 * the same arguments is guaranteed to return the same value over the life
71 * of a plugin instance (though the same URI may return different values
72 * with a different map parameter). However, this function is not
73 * necessarily very fast: plugins should cache any IDs they might need in
74 * performance critical situations.
75 * The return value 0 is reserved and means an ID for that URI could not
76 * be created for whatever reason. Extensions may define more precisely
77 * what this means, but in general plugins should gracefully handle 0
78 * and consider whatever they wanted the URI for "unsupported".
80 uint32_t (*uri_to_id
)(LV2_URI_Map_Callback_Data callback_data
,
84 } LV2_URI_Map_Feature
;
87 #endif // LV2_URI_MAP_H