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/* lv2_uri_map.h - C header file for the LV2 URI Map extension. |
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* |
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* Copyright (C) 2008-2009 David Robillard <http://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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/** @file |
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* C header for the LV2 URI Map extension <http://lv2plug.in/ns/ext/uri-map>. |
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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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#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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/** 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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