From a4e0fd1685a8ea0a6ae7ddf034edbe1a622c57c1 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Fri, 5 Aug 2022 15:05:51 -0600
Subject: [PATCH] [MultipleSubst] Rewrite serialize signature as single
 iterator

---
 src/OT/Layout/GSUB/MultipleSubst.hh        | 10 ++++------
 src/OT/Layout/GSUB/MultipleSubstFormat1.hh | 19 +++++++++++++------
 src/OT/Layout/GSUB/SubstLookup.hh          | 12 ++++--------
 3 files changed, 21 insertions(+), 20 deletions(-)

diff --git a/src/OT/Layout/GSUB/MultipleSubst.hh b/src/OT/Layout/GSUB/MultipleSubst.hh
index 15d726177..852ca3eac 100644
--- a/src/OT/Layout/GSUB/MultipleSubst.hh
+++ b/src/OT/Layout/GSUB/MultipleSubst.hh
@@ -35,19 +35,17 @@ struct MultipleSubst
     }
   }
 
-  template<typename GlyphIterator, typename SequenceIterator,
-           hb_requires (hb_is_sorted_source_of (GlyphIterator, hb_codepoint_t)),
-           hb_requires (hb_is_source_of (typename SequenceIterator::item_t, hb_codepoint_t))>
+  template<typename Iterator,
+           hb_requires (hb_is_sorted_iterator (Iterator))>
   bool serialize (hb_serialize_context_t *c,
-		  GlyphIterator glyphs,
-		  SequenceIterator sequences)
+		  Iterator it)
   {
     TRACE_SERIALIZE (this);
     if (unlikely (!c->extend_min (u.format))) return_trace (false);
     unsigned int format = 1;
     u.format = format;
     switch (u.format) {
-    case 1: return_trace (u.format1.serialize (c, glyphs, sequences));
+    case 1: return_trace (u.format1.serialize (c, it));
     default:return_trace (false);
     }
   }
diff --git a/src/OT/Layout/GSUB/MultipleSubstFormat1.hh b/src/OT/Layout/GSUB/MultipleSubstFormat1.hh
index dbcc6f6df..3b4bd1169 100644
--- a/src/OT/Layout/GSUB/MultipleSubstFormat1.hh
+++ b/src/OT/Layout/GSUB/MultipleSubstFormat1.hh
@@ -71,16 +71,23 @@ struct MultipleSubstFormat1_2
     return_trace ((this+sequence[index]).apply (c));
   }
 
-  template<typename GlyphIterator, typename SequenceIterator,
-           hb_requires (hb_is_sorted_source_of (GlyphIterator, hb_codepoint_t)),
-           hb_requires (hb_is_source_of (typename SequenceIterator::item_t, hb_codepoint_t))>
+  template<typename Iterator,
+           hb_requires (hb_is_sorted_iterator (Iterator))>
   bool serialize (hb_serialize_context_t *c,
-		  GlyphIterator glyphs,
-		  SequenceIterator sequences)
+		  Iterator it)
   {
     TRACE_SERIALIZE (this);
+    auto sequences =
+      + 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 (!sequence.serialize (c, glyphs.length))) return_trace (false);
+
+    if (unlikely (!sequence.serialize (c, sequences.length))) return_trace (false);
 
     for (auto& pair : hb_zip (sequences, sequence))
     {
diff --git a/src/OT/Layout/GSUB/SubstLookup.hh b/src/OT/Layout/GSUB/SubstLookup.hh
index 28db0e428..d49dcc0e0 100644
--- a/src/OT/Layout/GSUB/SubstLookup.hh
+++ b/src/OT/Layout/GSUB/SubstLookup.hh
@@ -119,20 +119,16 @@ struct SubstLookup : Lookup
     return_trace (false);
   }
 
-  template<typename GlyphIterator, typename SequenceIterator,
-           hb_requires (hb_is_sorted_source_of (GlyphIterator, hb_codepoint_t)),
-           hb_requires (hb_is_source_of (typename SequenceIterator::item_t, hb_codepoint_t))>
+  template<typename Iterator,
+           hb_requires (hb_is_sorted_iterator (Iterator))>
   bool serialize (hb_serialize_context_t *c,
 		  uint32_t lookup_props,
-		  GlyphIterator glyphs,
-		  SequenceIterator sequences)
+		  Iterator it)
   {
     TRACE_SERIALIZE (this);
     if (unlikely (!Lookup::serialize (c, SubTable::Multiple, lookup_props, 1))) return_trace (false);
     if (c->push<SubTable> ()->u.multiple.
-        serialize (c,
-		   glyphs,
-		   sequences))
+        serialize (c, it))
     {
       c->add_link (get_subtables<SubTable> ()[0], c->pop_pack ());
       return_trace (true);