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+/*
+ * Copyright © 2011,2012,2013 Google, Inc.
+ * Copyright © 2021 Khaled Hosny
+ *
+ * This is part of HarfBuzz, a text shaping library.
+ *
+ * Permission is hereby granted, without written agreement and without
+ * license or royalty fees, to use, copy, modify, and distribute this
+ * software and its documentation for any purpose, provided that the
+ * above copyright notice and the following two paragraphs appear in
+ * all copies of this software.
+ *
+ * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
+ * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
+ * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
+ * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
+ * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
+ * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
+ * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+ *
+ * Google Author(s): Behdad Esfahbod
+ */
+
+#ifndef HB_MS_FEATURE_RANGES_HH
+#define HB_MS_FEATURE_RANGES_HH
+
+#include "hb.hh"
+
+/* Variations of this code exist in hb-coretext.cc as well
+ * as hb-aat-map.cc... */
+
+typedef struct hb_ms_feature_t {
+ uint32_t tag_le;
+ uint32_t value;
+} hb_ms_feature_t;
+
+typedef struct hb_ms_features_t {
+ hb_ms_feature_t *features;
+ uint32_t num_features;
+} hb_ms_features_t;
+
+struct hb_ms_active_feature_t {
+ hb_ms_feature_t fea;
+ unsigned int order;
+
+ HB_INTERNAL static int cmp (const void *pa, const void *pb) {
+ const auto *a = (const hb_ms_active_feature_t *) pa;
+ const auto *b = (const hb_ms_active_feature_t *) pb;
+ return a->fea.tag_le < b->fea.tag_le ? -1 : a->fea.tag_le > b->fea.tag_le ? 1 :
+ a->order < b->order ? -1 : a->order > b->order ? 1 :
+ a->fea.value < b->fea.value ? -1 : a->fea.value > b->fea.value ? 1 :
+ 0;
+ }
+ bool operator== (const hb_ms_active_feature_t& f) const
+ { return cmp (this, &f) == 0; }
+};
+
+struct hb_ms_feature_event_t {
+ unsigned int index;
+ bool start;
+ hb_ms_active_feature_t feature;
+
+ HB_INTERNAL static int cmp (const void *pa, const void *pb)
+ {
+ const auto *a = (const hb_ms_feature_event_t *) pa;
+ const auto *b = (const hb_ms_feature_event_t *) pb;
+ return a->index < b->index ? -1 : a->index > b->index ? 1 :
+ a->start < b->start ? -1 : a->start > b->start ? 1 :
+ hb_ms_active_feature_t::cmp (&a->feature, &b->feature);
+ }
+};
+
+struct hb_ms_range_record_t {
+ hb_ms_features_t features;
+ unsigned int index_first; /* == start */
+ unsigned int index_last; /* == end - 1 */
+};
+
+static inline bool
+hb_ms_setup_features (const hb_feature_t *features,
+ unsigned int num_features,
+ hb_vector_t<hb_ms_feature_t> &feature_records, /* OUT */
+ hb_vector_t<hb_ms_range_record_t> &range_records /* OUT */)
+{
+ feature_records.shrink(0);
+ range_records.shrink(0);
+
+ /* Sort features by start/end events. */
+ hb_vector_t<hb_ms_feature_event_t> feature_events;
+ for (unsigned int i = 0; i < num_features; i++)
+ {
+ hb_ms_active_feature_t feature;
+ feature.fea.tag_le = hb_uint32_swap (features[i].tag);
+ feature.fea.value = features[i].value;
+ feature.order = i;
+
+ hb_ms_feature_event_t *event;
+
+ event = feature_events.push ();
+ event->index = features[i].start;
+ event->start = true;
+ event->feature = feature;
+
+ event = feature_events.push ();
+ event->index = features[i].end;
+ event->start = false;
+ event->feature = feature;
+ }
+ feature_events.qsort ();
+ /* Add a strategic final event. */
+ {
+ hb_ms_active_feature_t feature;
+ feature.fea.tag_le = 0;
+ feature.fea.value = 0;
+ feature.order = num_features + 1;
+
+ auto *event = feature_events.push ();
+ event->index = 0; /* This value does magic. */
+ event->start = false;
+ event->feature = feature;
+ }
+
+ /* Scan events and save features for each range. */
+ hb_vector_t<hb_ms_active_feature_t> active_features;
+ unsigned int last_index = 0;
+ for (unsigned int i = 0; i < feature_events.length; i++)
+ {
+ auto *event = &feature_events[i];
+
+ if (event->index != last_index)
+ {
+ /* Save a snapshot of active features and the range. */
+ auto *range = range_records.push ();
+ auto offset = feature_records.length;
+
+ active_features.qsort ();
+ for (unsigned int j = 0; j < active_features.length; j++)
+ {
+ if (!j || active_features[j].fea.tag_le != feature_records[feature_records.length - 1].tag_le)
+ {
+ feature_records.push (active_features[j].fea);
+ }
+ else
+ {
+ /* Overrides value for existing feature. */
+ feature_records[feature_records.length - 1].value = active_features[j].fea.value;
+ }
+ }
+
+ /* Will convert to pointer after all is ready, since feature_records.array
+ * may move as we grow it. */
+ range->features.features = reinterpret_cast<hb_ms_feature_t *> (offset);
+ range->features.num_features = feature_records.length - offset;
+ range->index_first = last_index;
+ range->index_last = event->index - 1;
+
+ last_index = event->index;
+ }
+
+ if (event->start)
+ {
+ active_features.push (event->feature);
+ }
+ else
+ {
+ auto *feature = active_features.lsearch (event->feature);
+ if (feature)
+ active_features.remove_ordered (feature - active_features.arrayZ);
+ }
+ }
+
+ if (!range_records.length) /* No active feature found. */
+ num_features = 0;
+
+ /* Fixup the pointers. */
+ for (unsigned int i = 0; i < range_records.length; i++)
+ {
+ auto *range = &range_records[i];
+ range->features.features = (hb_ms_feature_t *) feature_records + reinterpret_cast<uintptr_t> (range->features.features);
+ }
+
+ return !!num_features;
+}
+
+static inline void
+hb_ms_make_feature_ranges (hb_vector_t<hb_ms_feature_t> &feature_records,
+ hb_vector_t<hb_ms_range_record_t> &range_records,
+ unsigned int chars_offset,
+ unsigned int chars_len,
+ uint16_t *log_clusters,
+ hb_vector_t<hb_ms_features_t*> &range_features, /* OUT */
+ hb_vector_t<uint32_t> &range_counts /* OUT */)
+{
+ range_features.shrink (0);
+ range_counts.shrink (0);
+
+ auto *last_range = &range_records[0];
+ for (unsigned int i = chars_offset; i < chars_len; i++)
+ {
+ auto *range = last_range;
+ while (log_clusters[i] < range->index_first)
+ range--;
+ while (log_clusters[i] > range->index_last)
+ range++;
+ if (!range_features.length ||
+ &range->features != range_features[range_features.length - 1])
+ {
+ auto **features = range_features.push ();
+ auto *c = range_counts.push ();
+ if (unlikely (!features || !c))
+ {
+ range_features.shrink (0);
+ range_counts.shrink (0);
+ break;
+ }
+ *features = &range->features;
+ *c = 1;
+ }
+ else
+ {
+ range_counts[range_counts.length - 1]++;
+ }
+
+ last_range = range;
+ }
+}
+
+#endif /* HB_MS_FEATURE_RANGES_HH */
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