--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/harfbuzz/src/OT/Layout/GSUB/SingleSubstFormat2.hh	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,151 @@
+#ifndef OT_LAYOUT_GSUB_SINGLESUBSTFORMAT2_HH
+#define OT_LAYOUT_GSUB_SINGLESUBSTFORMAT2_HH
+
+#include "Common.hh"
+
+namespace OT {
+namespace Layout {
+namespace GSUB_impl {
+
+template <typename Types>
+struct SingleSubstFormat2_4
+{
+  protected:
+  HBUINT16      format;                 /* Format identifier--format = 2 */
+  typename Types::template OffsetTo<Coverage>
+                coverage;               /* Offset to Coverage table--from
+                                         * beginning of Substitution table */
+  Array16Of<typename Types::HBGlyphID>
+                substitute;             /* Array of substitute
+                                         * GlyphIDs--ordered by Coverage Index */
+
+  public:
+  DEFINE_SIZE_ARRAY (4 + Types::size, substitute);
+
+  bool sanitize (hb_sanitize_context_t *c) const
+  {
+    TRACE_SANITIZE (this);
+    return_trace (coverage.sanitize (c, this) && substitute.sanitize (c));
+  }
+
+  bool intersects (const hb_set_t *glyphs) const
+  { return (this+coverage).intersects (glyphs); }
+
+  bool may_have_non_1to1 () const
+  { return false; }
+
+  void closure (hb_closure_context_t *c) const
+  {
+    auto &cov = this+coverage;
+    auto &glyph_set = c->parent_active_glyphs ();
+
+    if (substitute.len > glyph_set.get_population () * 4)
+    {
+      for (auto g : glyph_set)
+      {
+	unsigned i = cov.get_coverage (g);
+	if (i == NOT_COVERED || i >= substitute.len)
+	  continue;
+	c->output->add (substitute.arrayZ[i]);
+      }
+
+      return;
+    }
+
+    + hb_zip (cov, substitute)
+    | hb_filter (glyph_set, hb_first)
+    | hb_map (hb_second)
+    | hb_sink (c->output)
+    ;
+  }
+
+  void closure_lookups (hb_closure_lookups_context_t *c) const {}
+
+  void collect_glyphs (hb_collect_glyphs_context_t *c) const
+  {
+    if (unlikely (!(this+coverage).collect_coverage (c->input))) return;
+    + hb_zip (this+coverage, substitute)
+    | hb_map (hb_second)
+    | hb_sink (c->output)
+    ;
+  }
+
+  const Coverage &get_coverage () const { return this+coverage; }
+
+  bool would_apply (hb_would_apply_context_t *c) const
+  { return c->len == 1 && (this+coverage).get_coverage (c->glyphs[0]) != NOT_COVERED; }
+
+  bool apply (hb_ot_apply_context_t *c) const
+  {
+    TRACE_APPLY (this);
+    unsigned int index = (this+coverage).get_coverage (c->buffer->cur().codepoint);
+    if (likely (index == NOT_COVERED)) return_trace (false);
+
+    if (unlikely (index >= substitute.len)) return_trace (false);
+
+    if (HB_BUFFER_MESSAGE_MORE && c->buffer->messaging ())
+    {
+      c->buffer->sync_so_far ();
+      c->buffer->message (c->font,
+			  "replacing glyph at %d (single substitution)",
+			  c->buffer->idx);
+    }
+
+    c->replace_glyph (substitute[index]);
+
+    if (HB_BUFFER_MESSAGE_MORE && c->buffer->messaging ())
+    {
+      c->buffer->message (c->font,
+			  "replaced glyph at %d (single substitution)",
+			  c->buffer->idx - 1);
+    }
+
+    return_trace (true);
+  }
+
+  template<typename Iterator,
+           hb_requires (hb_is_sorted_source_of (Iterator,
+                                                hb_codepoint_pair_t))>
+  bool serialize (hb_serialize_context_t *c,
+                  Iterator it)
+  {
+    TRACE_SERIALIZE (this);
+    auto substitutes =
+      + it
+      | hb_map (hb_second)
+      ;
+    auto glyphs =
+      + it
+      | hb_map_retains_sorting (hb_first)
+      ;
+    if (unlikely (!c->extend_min (this))) return_trace (false);
+    if (unlikely (!substitute.serialize (c, substitutes))) return_trace (false);
+    if (unlikely (!coverage.serialize_serialize (c, glyphs))) return_trace (false);
+    return_trace (true);
+  }
+
+  bool subset (hb_subset_context_t *c) const
+  {
+    TRACE_SUBSET (this);
+    const hb_set_t &glyphset = *c->plan->glyphset_gsub ();
+    const hb_map_t &glyph_map = *c->plan->glyph_map;
+
+    auto it =
+    + hb_zip (this+coverage, substitute)
+    | hb_filter (glyphset, hb_first)
+    | hb_filter (glyphset, hb_second)
+    | hb_map_retains_sorting ([&] (hb_pair_t<hb_codepoint_t, const typename Types::HBGlyphID &> p) -> hb_codepoint_pair_t
+                              { return hb_pair (glyph_map[p.first], glyph_map[p.second]); })
+    ;
+
+    bool ret = bool (it);
+    SingleSubst_serialize (c->serializer, it);
+    return_trace (ret);
+  }
+};
+
+}
+}
+}
+
+#endif /* OT_LAYOUT_GSUB_SINGLESUBSTFORMAT2_HH */