diff options
| -rw-r--r-- | ext/atom.lv2/atom-helpers.h | 52 |
1 files changed, 52 insertions, 0 deletions
diff --git a/ext/atom.lv2/atom-helpers.h b/ext/atom.lv2/atom-helpers.h index 7fc125f..d0308ff 100644 --- a/ext/atom.lv2/atom-helpers.h +++ b/ext/atom.lv2/atom-helpers.h @@ -77,6 +77,21 @@ lv2_atom_object_iter_get(LV2_Atom_Object_Iter iter) return (LV2_Atom_Property*)iter; } +/** A macro for iterating over all properties of an Object. + * @param obj The object to iterate over + * @param iter The name of the iterator + * This macro is used similarly to a for loop (which it expands to), e.g.: + * <pre> + * LV2_OBJECT_FOREACH(object, i) { + * LV2_Atom_Property* prop = lv2_atom_object_iter_get(i); + * // Do things with prop here... + * } + */ +#define LV2_OBJECT_FOREACH(obj, iter) \ + for (LV2_Atom_Object_Iter (iter) = lv2_atom_object_get_iter((LV2_Atom_Property*)(obj)->body); \ + !lv2_atom_object_iter_is_end(obj, (iter)); \ + (iter) = lv2_atom_object_iter_next(iter)) + /** Append a Property body to an Atom that contains properties (e.g. atom:Object). * This function will write the property body (not including an LV2_Object * header) at lv2_atom_pad_size(body + size). Thus, it can be used with any @@ -146,6 +161,43 @@ lv2_atom_is_a(LV2_Atom* object, return false; } + +/** A single entry in an Object query. */ +typedef struct { + uint32_t key; ///< Set by the user to the desired key to query. + LV2_Atom* value; ///< Possibly set by query function to the found value +} LV2_Atom_Object_Query; + +/** "Query" an object, getting a pointer to the values for various keys. + * The value pointer of each item in @a q will be set to the location of + * the corresponding value in @a object. Every value pointer in @a query + * MUST be initialised to NULL. This function reads @a object in a single + * linear sweep. By allocating @a q on the stack, objects can be "queried" + * quickly without allocating any memory. This function is realtime safe. + */ +int +lv2_atom_object_query(LV2_Atom* object, LV2_Atom_Object_Query* query) +{ + int matches = 0; + int n_queries = 0; + + // Count number of query keys so we can short-circuit when done + for (LV2_Atom_Object_Query* q = query; q->key; ++q) + ++n_queries; + LV2_OBJECT_FOREACH(object, o) { + LV2_Atom_Property* prop = lv2_atom_object_iter_get(o); + for (LV2_Atom_Object_Query* q = query; q->key; ++q) { + if (q->key == prop->predicate && !q->value) { + q->value = &prop->object; + if (++matches == n_queries) + return matches; + break; + } + } + } + return matches; +} + #endif /* LV2_ATOM_HELPERS_H */ |