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24 <a name="utilities-common-types-apis"></a>Common data types and APIs</h2></div></div></div>
26 HarfBuzz includes several APIs for working with general-purpose
27 data that you may find convenient to leverage in your own
28 software. They include set operations and integer-to-integer
32 HarfBuzz uses set operations for internal bookkeeping, such as
33 when it collects all of the glyph IDs covered by a particular
34 font feature. You can also use the set API to build sets, add
35 and remove elements, test whether or not sets contain particular
36 elements, or compute the unions, intersections, or differences
40 All set elements are integers (specifically,
41 <span class="type">hb_codepoint_t</span> 32-bit unsigned ints), and there are
42 functions for fetching the minimum and maximum element from a
43 set. The set API also includes some functions that might not
44 be part of a generic set facility, such as the ability to add a
45 contiguous range of integer elements to a set in bulk, and the
46 ability to fetch the next-smallest or next-largest element.
49 The HarfBuzz set API includes some conveniences as well. All
50 sets are lifecycle-managed, just like other HarfBuzz
51 objects. You increase the reference count on a set with
52 <code class="function">hb_set_reference()</code> and decrease it with
53 <code class="function">hb_set_destroy()</code>. You can also attach
54 user data to a set, just like you can to blobs, buffers, faces,
55 fonts, and other objects, and set destroy callbacks.
58 HarfBuzz also provides an API for keeping track of
59 integer-to-integer mappings. As with the set API, each integer is
60 stored as an unsigned 32-bit <span class="type">hb_codepoint_t</span>
61 element. Maps, like other objects, are reference counted with
62 reference and destroy functions, and you can attach user data to
63 them. The mapping operations include adding and deleting
64 integer-to-integer key:value pairs to the map, testing for the
65 presence of a key, fetching the population of the map, and so on.
68 There are several other internal HarfBuzz facilities that are
69 exposed publicly and which you may want to take advantage of
70 while processing text. HarfBuzz uses a common
71 <span class="type">hb_tag_t</span> for a variety of OpenType tag identifiers (for
72 scripts, languages, font features, table names, variation-axis
73 names, and more), and provides functions for converting strings
74 to tags and vice-versa.
77 Finally, HarfBuzz also includes data type for Booleans, bit
78 masks, and other simple types.
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