403 lines
10 KiB
C++
403 lines
10 KiB
C++
/*
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* Copyright © 2012 Google, Inc.
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*
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* This is part of HarfBuzz, a text shaping library.
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*
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* Permission is hereby granted, without written agreement and without
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* license or royalty fees, to use, copy, modify, and distribute this
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* software and its documentation for any purpose, provided that the
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* above copyright notice and the following two paragraphs appear in
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* all copies of this software.
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*
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* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
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* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
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* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
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* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
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* DAMAGE.
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*
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* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
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* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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* FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
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* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
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* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
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*
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* Google Author(s): Behdad Esfahbod
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*/
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#ifndef HB_SET_PRIVATE_HH
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#define HB_SET_PRIVATE_HH
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#include "hb-private.hh"
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#include "hb-object-private.hh"
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/*
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* The set digests here implement various "filters" that support
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* "approximate member query". Conceptually these are like Bloom
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* Filter and Quotient Filter, however, much smaller, faster, and
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* designed to fit the requirements of our uses for glyph coverage
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* queries.
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*
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* Our filters are highly accurate if the lookup covers fairly local
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* set of glyphs, but fully flooded and ineffective if coverage is
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* all over the place.
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*
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* The frozen-set can be used instead of a digest, to trade more
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* memory for 100% accuracy, but in practice, that doesn't look like
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* an attractive trade-off.
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*/
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template <typename mask_t, unsigned int shift>
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struct hb_set_digest_lowest_bits_t
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{
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ASSERT_POD ();
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static const unsigned int mask_bytes = sizeof (mask_t);
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static const unsigned int mask_bits = sizeof (mask_t) * 8;
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static const unsigned int num_bits = 0
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+ (mask_bytes >= 1 ? 3 : 0)
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+ (mask_bytes >= 2 ? 1 : 0)
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+ (mask_bytes >= 4 ? 1 : 0)
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+ (mask_bytes >= 8 ? 1 : 0)
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+ (mask_bytes >= 16? 1 : 0)
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+ 0;
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ASSERT_STATIC (shift < sizeof (hb_codepoint_t) * 8);
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ASSERT_STATIC (shift + num_bits <= sizeof (hb_codepoint_t) * 8);
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inline void init (void) {
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mask = 0;
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}
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inline void add (hb_codepoint_t g) {
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mask |= mask_for (g);
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}
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inline void add_range (hb_codepoint_t a, hb_codepoint_t b) {
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if ((b >> shift) - (a >> shift) >= mask_bits - 1)
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mask = (mask_t) -1;
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else {
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mask_t ma = mask_for (a);
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mask_t mb = mask_for (b);
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mask |= mb + (mb - ma) - (mb < ma);
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}
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}
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inline bool may_have (hb_codepoint_t g) const {
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return !!(mask & mask_for (g));
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}
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private:
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static inline mask_t mask_for (hb_codepoint_t g) {
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return ((mask_t) 1) << ((g >> shift) & (mask_bits - 1));
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}
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mask_t mask;
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};
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template <typename head_t, typename tail_t>
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struct hb_set_digest_combiner_t
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{
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ASSERT_POD ();
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inline void init (void) {
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head.init ();
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tail.init ();
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}
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inline void add (hb_codepoint_t g) {
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head.add (g);
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tail.add (g);
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}
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inline void add_range (hb_codepoint_t a, hb_codepoint_t b) {
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head.add_range (a, b);
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tail.add_range (a, b);
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}
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inline bool may_have (hb_codepoint_t g) const {
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return head.may_have (g) && tail.may_have (g);
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}
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private:
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head_t head;
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tail_t tail;
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};
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/*
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* hb_set_digest_t
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*
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* This is a combination of digests that performs "best".
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* There is not much science to this: it's a result of intuition
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* and testing.
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*/
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typedef hb_set_digest_combiner_t
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<
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hb_set_digest_lowest_bits_t<unsigned long, 4>,
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hb_set_digest_combiner_t
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<
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hb_set_digest_lowest_bits_t<unsigned long, 0>,
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hb_set_digest_lowest_bits_t<unsigned long, 9>
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>
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> hb_set_digest_t;
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/*
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* hb_set_t
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*/
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/* TODO Make this faster and memmory efficient. */
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struct hb_set_t
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{
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friend struct hb_frozen_set_t;
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hb_object_header_t header;
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ASSERT_POD ();
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bool in_error;
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inline void init (void) {
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hb_object_init (this);
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clear ();
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}
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inline void fini (void) {
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}
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inline void clear (void) {
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if (unlikely (hb_object_is_inert (this)))
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return;
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in_error = false;
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memset (elts, 0, sizeof elts);
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}
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inline bool is_empty (void) const {
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for (unsigned int i = 0; i < ARRAY_LENGTH (elts); i++)
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if (elts[i])
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return false;
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return true;
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}
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inline void add (hb_codepoint_t g)
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{
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if (unlikely (in_error)) return;
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if (unlikely (g == INVALID)) return;
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if (unlikely (g > MAX_G)) return;
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elt (g) |= mask (g);
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}
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inline void add_range (hb_codepoint_t a, hb_codepoint_t b)
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{
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if (unlikely (in_error)) return;
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/* TODO Speedup */
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for (unsigned int i = a; i < b + 1; i++)
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add (i);
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}
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inline void del (hb_codepoint_t g)
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{
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if (unlikely (in_error)) return;
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if (unlikely (g > MAX_G)) return;
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elt (g) &= ~mask (g);
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}
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inline void del_range (hb_codepoint_t a, hb_codepoint_t b)
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{
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if (unlikely (in_error)) return;
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/* TODO Speedup */
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for (unsigned int i = a; i < b + 1; i++)
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del (i);
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}
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inline bool has (hb_codepoint_t g) const
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{
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if (unlikely (g > MAX_G)) return false;
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return !!(elt (g) & mask (g));
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}
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inline bool intersects (hb_codepoint_t first,
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hb_codepoint_t last) const
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{
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if (unlikely (first > MAX_G)) return false;
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if (unlikely (last > MAX_G)) last = MAX_G;
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unsigned int end = last + 1;
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for (hb_codepoint_t i = first; i < end; i++)
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if (has (i))
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return true;
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return false;
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}
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inline bool is_equal (const hb_set_t *other) const
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{
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for (unsigned int i = 0; i < ELTS; i++)
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if (elts[i] != other->elts[i])
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return false;
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return true;
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}
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inline void set (const hb_set_t *other)
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{
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if (unlikely (in_error)) return;
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for (unsigned int i = 0; i < ELTS; i++)
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elts[i] = other->elts[i];
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}
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inline void union_ (const hb_set_t *other)
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{
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if (unlikely (in_error)) return;
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for (unsigned int i = 0; i < ELTS; i++)
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elts[i] |= other->elts[i];
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}
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inline void intersect (const hb_set_t *other)
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{
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if (unlikely (in_error)) return;
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for (unsigned int i = 0; i < ELTS; i++)
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elts[i] &= other->elts[i];
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}
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inline void subtract (const hb_set_t *other)
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{
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if (unlikely (in_error)) return;
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for (unsigned int i = 0; i < ELTS; i++)
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elts[i] &= ~other->elts[i];
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}
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inline void symmetric_difference (const hb_set_t *other)
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{
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if (unlikely (in_error)) return;
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for (unsigned int i = 0; i < ELTS; i++)
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elts[i] ^= other->elts[i];
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}
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inline void invert (void)
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{
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if (unlikely (in_error)) return;
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for (unsigned int i = 0; i < ELTS; i++)
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elts[i] = ~elts[i];
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}
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inline bool next (hb_codepoint_t *codepoint) const
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{
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if (unlikely (*codepoint == INVALID)) {
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hb_codepoint_t i = get_min ();
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if (i != INVALID) {
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*codepoint = i;
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return true;
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} else {
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*codepoint = INVALID;
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return false;
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}
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}
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for (hb_codepoint_t i = *codepoint + 1; i < MAX_G + 1; i++)
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if (has (i)) {
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*codepoint = i;
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return true;
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}
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*codepoint = INVALID;
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return false;
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}
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inline bool next_range (hb_codepoint_t *first, hb_codepoint_t *last) const
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{
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hb_codepoint_t i;
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i = *last;
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if (!next (&i))
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{
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*last = *first = INVALID;
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return false;
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}
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*last = *first = i;
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while (next (&i) && i == *last + 1)
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(*last)++;
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return true;
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}
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inline unsigned int get_population (void) const
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{
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unsigned int count = 0;
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for (unsigned int i = 0; i < ELTS; i++)
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count += _hb_popcount32 (elts[i]);
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return count;
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}
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inline hb_codepoint_t get_min (void) const
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{
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for (unsigned int i = 0; i < ELTS; i++)
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if (elts[i])
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for (unsigned int j = 0; j < BITS; j++)
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if (elts[i] & (1 << j))
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return i * BITS + j;
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return INVALID;
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}
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inline hb_codepoint_t get_max (void) const
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{
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for (unsigned int i = ELTS; i; i--)
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if (elts[i - 1])
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for (unsigned int j = BITS; j; j--)
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if (elts[i - 1] & (1 << (j - 1)))
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return (i - 1) * BITS + (j - 1);
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return INVALID;
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}
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typedef uint32_t elt_t;
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static const unsigned int MAX_G = 65536 - 1; /* XXX Fix this... */
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static const unsigned int SHIFT = 5;
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static const unsigned int BITS = (1 << SHIFT);
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static const unsigned int MASK = BITS - 1;
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static const unsigned int ELTS = (MAX_G + 1 + (BITS - 1)) / BITS;
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static const hb_codepoint_t INVALID = HB_SET_VALUE_INVALID;
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elt_t &elt (hb_codepoint_t g) { return elts[g >> SHIFT]; }
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elt_t const &elt (hb_codepoint_t g) const { return elts[g >> SHIFT]; }
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elt_t mask (hb_codepoint_t g) const { return elt_t (1) << (g & MASK); }
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elt_t elts[ELTS]; /* XXX 8kb */
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ASSERT_STATIC (sizeof (elt_t) * 8 == BITS);
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ASSERT_STATIC (sizeof (elt_t) * 8 * ELTS > MAX_G);
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};
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struct hb_frozen_set_t
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{
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static const unsigned int SHIFT = hb_set_t::SHIFT;
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static const unsigned int BITS = hb_set_t::BITS;
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static const unsigned int MASK = hb_set_t::MASK;
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typedef hb_set_t::elt_t elt_t;
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inline void init (const hb_set_t &set)
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{
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start = count = 0;
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elts = NULL;
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unsigned int max = set.get_max ();
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if (max == set.INVALID)
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return;
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unsigned int min = set.get_min ();
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const elt_t &min_elt = set.elt (min);
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start = min & ~MASK;
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count = max - start + 1;
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unsigned int num_elts = (count + BITS - 1) / BITS;
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unsigned int elts_size = num_elts * sizeof (elt_t);
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elts = (elt_t *) malloc (elts_size);
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if (unlikely (!elts))
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{
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start = count = 0;
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return;
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}
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memcpy (elts, &min_elt, elts_size);
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}
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inline void fini (void)
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{
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if (elts)
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free (elts);
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}
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inline bool has (hb_codepoint_t g) const
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{
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/* hb_codepoint_t is unsigned. */
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g -= start;
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if (unlikely (g > count)) return false;
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return !!(elt (g) & mask (g));
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}
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elt_t const &elt (hb_codepoint_t g) const { return elts[g >> SHIFT]; }
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elt_t mask (hb_codepoint_t g) const { return elt_t (1) << (g & MASK); }
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private:
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hb_codepoint_t start, count;
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elt_t *elts;
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};
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#endif /* HB_SET_PRIVATE_HH */
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