1 /* 2 Copyright 2008-2011 David Robillard <http://drobilla.net> 3 4 Permission to use, copy, modify, and/or distribute this software for any 5 purpose with or without fee is hereby granted, provided that the above 6 copyright notice and this permission notice appear in all copies. 7 8 THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 9 WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 10 MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 11 ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 12 WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 13 ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 14 OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 15 */ 16 17 /** 18 @file 19 C header for the LV2 URI Map extension <http://lv2plug.in/ns/ext/uri-map>. 20 21 This extension defines a simple mechanism for plugins to map URIs to 22 integers, usually for performance reasons (e.g. processing events typed by 23 URIs in real time). The expected use case is for plugins to map URIs to 24 integers for things they 'understand' at instantiation time, and store those 25 values for use in the audio thread without doing any string comparison. 26 This allows the extensibility of RDF with the performance of integers (or 27 centrally defined enumerations). 28 */ 29 30 #ifndef LV2_URI_MAP_H 31 #define LV2_URI_MAP_H 32 33 #define LV2_URI_MAP_URI "http://lv2plug.in/ns/ext/uri-map" 34 35 #include <stdint.h> 36 37 #ifdef __cplusplus 38 extern "C" { 39 #endif 40 41 /** 42 Opaque pointer to host data. 43 */ 44 typedef void* LV2_URI_Map_Callback_Data; 45 46 /** 47 URI Map Feature. 48 49 To support this feature the host must pass an LV2_Feature struct to the 50 plugin's instantiate method with URI "http://lv2plug.in/ns/ext/uri-map" 51 and data pointed to an instance of this struct. 52 */ 53 typedef struct { 54 /** 55 Opaque pointer to host data. 56 57 The plugin MUST pass this to any call to functions in this struct. 58 Otherwise, it must not be interpreted in any way. 59 */ 60 LV2_URI_Map_Callback_Data callback_data; 61 62 /** 63 Get the numeric ID of a URI from the host. 64 65 @param callback_data Must be the callback_data member of this struct. 66 @param map The 'context' of this URI. Certain extensions may define a 67 URI that must be passed here with certain restrictions on the return 68 value (e.g. limited range). This value may be NULL if the plugin needs 69 an ID for a URI in general. Extensions SHOULD NOT define a context 70 unless there is a specific need to do so, e.g. to restrict the range of 71 the returned value. 72 @param uri The URI to be mapped to an integer ID. 73 74 This function is referentially transparent; any number of calls with the 75 same arguments is guaranteed to return the same value over the life of a 76 plugin instance (though the same URI may return different values with a 77 different map parameter). However, this function is not necessarily very 78 fast: plugins SHOULD cache any IDs they might need in performance 79 critical situations. 80 81 The return value 0 is reserved and indicates that an ID for that URI 82 could not be created for whatever reason. Extensions MAY define more 83 precisely what this means in a certain context, but in general plugins 84 SHOULD handle this situation as gracefully as possible. However, hosts 85 SHOULD NOT return 0 from this function in non-exceptional circumstances 86 (e.g. the URI map SHOULD be dynamic). Hosts that statically support only 87 a fixed set of URIs should not expect plugins to function correctly. 88 */ 89 uint32_t (*uri_to_id)(LV2_URI_Map_Callback_Data callback_data, 90 const char* map, 91 const char* uri); 92 } LV2_URI_Map_Feature; 93 94 #ifdef __cplusplus 95 } /* extern "C" */ 96 #endif 97 98 #endif /* LV2_URI_MAP_H */ 99