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authorDavid Robillard <d@drobilla.net>2011-11-20 23:08:57 +0000
committerDavid Robillard <d@drobilla.net>2011-11-20 23:08:57 +0000
commit725d4a404b838da6b67d9da66228a1125bddef57 (patch)
treea1daab3d767c85b1b67ff3a9eb60d54721b2e5fc /ns/ext/uri-map/uri-map.h
parent5ae0165d6d0420e95e22c1451e319b9e83398c28 (diff)
downloadlv2-725d4a404b838da6b67d9da66228a1125bddef57.tar.xz
Lay out repository structure to match include and URI structure.
Treat lv2core like all the other specifications in gendoc.py.
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+/*
+ Copyright 2008-2011 David Robillard <http://drobilla.net>
+
+ Permission to use, copy, modify, and/or distribute this software for any
+ purpose with or without fee is hereby granted, provided that the above
+ copyright notice and this permission notice appear in all copies.
+
+ THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+
+/**
+ @file
+ C header for the LV2 URI Map extension <http://lv2plug.in/ns/ext/uri-map>.
+
+ This extension defines a simple mechanism for plugins to map URIs to
+ integers, usually for performance reasons (e.g. processing events typed by
+ URIs in real time). The expected use case is for plugins to map URIs to
+ integers for things they 'understand' at instantiation time, and store those
+ values for use in the audio thread without doing any string comparison.
+ This allows the extensibility of RDF with the performance of integers (or
+ centrally defined enumerations).
+*/
+
+#ifndef LV2_URI_MAP_H
+#define LV2_URI_MAP_H
+
+#define LV2_URI_MAP_URI "http://lv2plug.in/ns/ext/uri-map"
+
+#include <stdint.h>
+
+/**
+ Opaque pointer to host data.
+*/
+typedef void* LV2_URI_Map_Callback_Data;
+
+/**
+ URI Map Feature.
+
+ To support this feature the host must pass an LV2_Feature struct to the
+ plugin's instantiate method with URI "http://lv2plug.in/ns/ext/uri-map"
+ and data pointed to an instance of this struct.
+*/
+typedef struct {
+
+ /**
+ Opaque pointer to host data.
+
+ The plugin MUST pass this to any call to functions in this struct.
+ Otherwise, it must not be interpreted in any way.
+ */
+ LV2_URI_Map_Callback_Data callback_data;
+
+ /**
+ Get the numeric ID of a URI from the host.
+
+ @param callback_data Must be the callback_data member of this struct.
+ @param map The 'context' of this URI. Certain extensions may define a
+ URI that must be passed here with certain restrictions on the return
+ value (e.g. limited range). This value may be NULL if the plugin needs
+ an ID for a URI in general. Extensions SHOULD NOT define a context
+ unless there is a specific need to do so, e.g. to restrict the range of
+ the returned value.
+ @param uri The URI to be mapped to an integer ID.
+
+ This function is referentially transparent; any number of calls with the
+ same arguments is guaranteed to return the same value over the life of a
+ plugin instance (though the same URI may return different values with a
+ different map parameter). However, this function is not necessarily very
+ fast: plugins SHOULD cache any IDs they might need in performance
+ critical situations.
+
+ The return value 0 is reserved and indicates that an ID for that URI
+ could not be created for whatever reason. Extensions MAY define more
+ precisely what this means in a certain context, but in general plugins
+ SHOULD handle this situation as gracefully as possible. However, hosts
+ SHOULD NOT return 0 from this function in non-exceptional circumstances
+ (e.g. the URI map SHOULD be dynamic). Hosts that statically support only
+ a fixed set of URIs should not expect plugins to function correctly.
+ */
+ uint32_t (*uri_to_id)(LV2_URI_Map_Callback_Data callback_data,
+ const char* map,
+ const char* uri);
+
+} LV2_URI_Map_Feature;
+
+#endif /* LV2_URI_MAP_H */