From fe05e48086be9ed685b8a6ca4af966660744bc0f Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Sat, 30 Mar 2019 15:06:25 -0700
Subject: [PATCH 01/25] [serialize] Add ran_out_of_room

---
 src/hb-serialize.hh | 8 +++++++-
 src/hb-subset.cc    | 7 ++++++-
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/src/hb-serialize.hh b/src/hb-serialize.hh
index f5e4df521..679ae4ed6 100644
--- a/src/hb-serialize.hh
+++ b/src/hb-serialize.hh
@@ -51,6 +51,7 @@ struct hb_serialize_context_t
   void reset ()
   {
     this->successful = true;
+    this->ran_out_of_room = false;
     this->head = this->start;
     this->debug_depth = 0;
   }
@@ -111,7 +112,11 @@ struct hb_serialize_context_t
   template <typename Type>
   Type *allocate_size (unsigned int size)
   {
-    if (unlikely (!this->successful || this->end - this->head < ptrdiff_t (size))) {
+    if (unlikely (!this->successful)) return nullptr;
+
+    if (this->end - this->head < ptrdiff_t (size))
+    {
+      this->ran_out_of_room = true;
       this->successful = false;
       return nullptr;
     }
@@ -190,6 +195,7 @@ struct hb_serialize_context_t
   unsigned int debug_depth;
   char *start, *end, *head;
   bool successful;
+  bool ran_out_of_room;
 };
 
 
diff --git a/src/hb-subset.cc b/src/hb-subset.cc
index 135265fc1..b3f064697 100644
--- a/src/hb-subset.cc
+++ b/src/hb-subset.cc
@@ -83,7 +83,7 @@ _subset2 (hb_subset_plan_t *plan)
     hb_serialize_context_t serializer ((void *) buf, buf_size);
     hb_subset_context_t c (plan, &serializer);
     result = table->subset (&c);
-    if (serializer.in_error ())
+    if (serializer.ran_out_of_room)
     {
       buf_size += (buf_size >> 1) + 32;
       DEBUG_MSG(SUBSET, nullptr, "OT::%c%c%c%c ran out of room; reallocating to %u bytes.", HB_UNTAG (tag), buf_size);
@@ -94,6 +94,11 @@ _subset2 (hb_subset_plan_t *plan)
       }
       goto retry;
     }
+    if (serializer.in_error ())
+    {
+      abort ();
+    }
+
     if (result)
     {
       hb_blob_t *dest_blob = serializer.copy_blob ();

From 6dcf7c4017619c782dbc8bd2c584bb33df96fc83 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Sat, 30 Mar 2019 15:08:39 -0700
Subject: [PATCH 02/25] [serialize] Add unused 'tail'

---
 src/hb-serialize.hh | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/hb-serialize.hh b/src/hb-serialize.hh
index 679ae4ed6..ea389c0c0 100644
--- a/src/hb-serialize.hh
+++ b/src/hb-serialize.hh
@@ -53,6 +53,7 @@ struct hb_serialize_context_t
     this->successful = true;
     this->ran_out_of_room = false;
     this->head = this->start;
+    this->tail = this->end;
     this->debug_depth = 0;
   }
 
@@ -114,7 +115,7 @@ struct hb_serialize_context_t
   {
     if (unlikely (!this->successful)) return nullptr;
 
-    if (this->end - this->head < ptrdiff_t (size))
+    if (this->tail - this->head < ptrdiff_t (size))
     {
       this->ran_out_of_room = true;
       this->successful = false;
@@ -192,8 +193,8 @@ struct hb_serialize_context_t
   }
 
   public:
+  char *start, *head, *tail, *end;
   unsigned int debug_depth;
-  char *start, *end, *head;
   bool successful;
   bool ran_out_of_room;
 };

From 7fd940f899da4948d2c61ed497c1face42776187 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Sat, 30 Mar 2019 16:29:19 -0700
Subject: [PATCH 03/25] [map] Add TODO

---
 src/hb-map.hh | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/hb-map.hh b/src/hb-map.hh
index d36515a74..a2bbff5c1 100644
--- a/src/hb-map.hh
+++ b/src/hb-map.hh
@@ -46,6 +46,10 @@ struct hb_hashmap_t
   static_assert (hb_is_integer (K) || hb_is_pointer (K), "");
   static_assert (hb_is_integer (V) || hb_is_pointer (V), "");
 
+  /* TODO If key type is a pointer, keep hash in item_t and use to:
+   * 1. avoid rehashing when resizing table, and
+   * 2. compare hash before comparing keys, for speed.
+   */
   struct item_t
   {
     K key;
@@ -248,6 +252,10 @@ struct hb_hashmap_t
   }
 };
 
+/*
+ * hb_map_t
+ */
+
 struct hb_map_t : hb_hashmap_t<hb_codepoint_t,
 			       hb_codepoint_t,
 			       HB_MAP_VALUE_INVALID,

From 38d57b9a66008c9722125d4d677d759a910cf2a1 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Sat, 30 Mar 2019 16:38:06 -0700
Subject: [PATCH 04/25] [map] Add another TODO item

---
 src/hb-map.hh | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/hb-map.hh b/src/hb-map.hh
index a2bbff5c1..341c15929 100644
--- a/src/hb-map.hh
+++ b/src/hb-map.hh
@@ -34,6 +34,8 @@
  * hb_hashmap_t
  */
 
+/* TODO if K/V is signed integer, -1 is not a good default.
+ * Don't know how to get to -MAX using bit work. */
 template <typename K, typename V,
 	  K kINVALID = hb_is_pointer (K) ? 0 : (K) -1,
 	  V vINVALID = hb_is_pointer (V) ? 0 : (V) -1>

From dbe9ba6711c6d35374de645097babfd81bc295b2 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Sat, 30 Mar 2019 17:10:59 -0700
Subject: [PATCH 05/25] [serialize] Add object_t, link_t, and snapshot_t

---
 src/hb-serialize.hh | 32 +++++++++++++++++++++++++++++++-
 1 file changed, 31 insertions(+), 1 deletion(-)

diff --git a/src/hb-serialize.hh b/src/hb-serialize.hh
index ea389c0c0..2af34dc07 100644
--- a/src/hb-serialize.hh
+++ b/src/hb-serialize.hh
@@ -55,6 +55,9 @@ struct hb_serialize_context_t
     this->head = this->start;
     this->tail = this->end;
     this->debug_depth = 0;
+
+    this->packed.resize (1);
+    this->current.resize (0);
   }
 
   bool propagate_error (bool e)
@@ -192,11 +195,38 @@ struct hb_serialize_context_t
 			   nullptr, nullptr);
   }
 
-  public:
+  public: /* TODO Make private. */
   char *start, *head, *tail, *end;
   unsigned int debug_depth;
   bool successful;
   bool ran_out_of_room;
+
+  private:
+
+  /* Stack of packed objects.  Object 0 is always nil object. */
+  struct object_t
+  {
+    void fini () { links.fini (); }
+
+    struct link_t
+    {
+      bool wide: 1;
+      unsigned offset : 31;
+      unsigned objidx;
+    };
+
+    hb_bytes_t bytes;
+    hb_vector_t<link_t> links;
+  };
+  hb_vector_t<object_t> packed;
+
+  /* Stack of currently under construction object locations. */
+  struct snapshot_t
+  {
+    char *head, *tail;
+  };
+  snapshot_t snapshot () { snapshot_t s = {head, tail} ; return s; }
+  hb_vector_t<snapshot_t> current;
 };
 
 

From 63c35651893b2a1c555f728012e9ad36c0f84145 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Sat, 30 Mar 2019 17:12:40 -0700
Subject: [PATCH 06/25] [serialize] Simplify propagate_error()

---
 src/hb-serialize.hh | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/src/hb-serialize.hh b/src/hb-serialize.hh
index 2af34dc07..8ca660f53 100644
--- a/src/hb-serialize.hh
+++ b/src/hb-serialize.hh
@@ -66,15 +66,10 @@ struct hb_serialize_context_t
   { return this->successful = this->successful && !obj.in_error (); }
   template <typename T> bool propagate_error (const T *obj)
   { return this->successful = this->successful && !obj->in_error (); }
-  template <typename T1, typename T2> bool propagate_error (T1 &o1, T2 &o2)
-  { return propagate_error (o1) && propagate_error (o2); }
-  template <typename T1, typename T2> bool propagate_error (T1 *o1, T2 *o2)
+  template <typename T1, typename T2> bool propagate_error (T1 &&o1, T2 &&o2)
   { return propagate_error (o1) && propagate_error (o2); }
   template <typename T1, typename T2, typename T3>
-  bool propagate_error (T1 &o1, T2 &o2, T3 &o3)
-  { return propagate_error (o1) && propagate_error (o2, o3); }
-  template <typename T1, typename T2, typename T3>
-  bool propagate_error (T1 *o1, T2 *o2, T3 *o3)
+  bool propagate_error (T1 &&o1, T2 &&o2, T3 &&o3)
   { return propagate_error (o1) && propagate_error (o2, o3); }
 
   /* To be called around main operation. */

From bed150bd2e8d61950ea17d1b5a4bf4705801c1cc Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Sat, 30 Mar 2019 17:26:35 -0700
Subject: [PATCH 07/25] [serialize] Start fleshing out object stack

---
 src/hb-serialize.hh | 91 ++++++++++++++++++++++++++++++++-------------
 src/hb-vector.hh    |  9 +++--
 2 files changed, 72 insertions(+), 28 deletions(-)

diff --git a/src/hb-serialize.hh b/src/hb-serialize.hh
index 8ca660f53..86f802a26 100644
--- a/src/hb-serialize.hh
+++ b/src/hb-serialize.hh
@@ -39,6 +39,30 @@
 
 struct hb_serialize_context_t
 {
+  typedef unsigned objidx_t;
+
+  struct object_t
+  {
+    void fini () { links.fini (); }
+
+    struct link_t
+    {
+      bool wide: 1;
+      unsigned offset : 31;
+      objidx_t objidx;
+    };
+
+    hb_bytes_t bytes;
+    hb_vector_t<link_t> links;
+  };
+
+  struct snapshot_t
+  {
+    char *head, *tail;
+  };
+  snapshot_t snapshot () { snapshot_t s = {head, tail} ; return s; }
+
+
   hb_serialize_context_t (void *start_, unsigned int size)
   {
     this->start = (char *) start_;
@@ -56,7 +80,8 @@ struct hb_serialize_context_t
     this->tail = this->end;
     this->debug_depth = 0;
 
-    this->packed.resize (1);
+    this->packed.resize (0);
+    this->packed.push ()->bytes.arrayZ = this->end;
     this->current.resize (0);
   }
 
@@ -81,18 +106,53 @@ struct hb_serialize_context_t
 		     this->start, this->end,
 		     (unsigned long) (this->end - this->start));
 
-    return start_embed<Type> ();
+    assert (!current.length);
+    return push<Type> ();
   }
-  void end_serialize ()
+  objidx_t end_serialize ()
   {
     DEBUG_MSG_LEVEL (SERIALIZE, this->start, 0, -1,
-		     "end [%p..%p] serialized %d bytes; %s",
+		     "end [%p..%p] serialized %u bytes; %s",
 		     this->start, this->end,
-		     (int) (this->head - this->start),
+		     (unsigned) (this->head - this->start),
 		     this->successful ? "successful" : "UNSUCCESSFUL");
+    assert (current.length == 1);
+    return pop_pack ();
   }
 
-  unsigned int length () const { return this->head - this->start; }
+  template <typename Type>
+  Type *push ()
+  {
+    current.push (snapshot ());
+    return start_embed<Type> ();
+  }
+  void pop_discard ()
+  {
+    revert (current.pop ());
+  }
+  objidx_t pop_pack ()
+  {
+    return 0;
+  }
+
+  void revert (snapshot_t snap)
+  {
+    assert (snap.head <= head);
+    assert (tail <= snap.tail);
+    head = snap.head;
+    tail = snap.tail;
+    discard_stale_objects ();
+  }
+
+  void discard_stale_objects ()
+  {
+    while (packed.length > 1 &&
+	   packed.tail ().bytes.arrayZ < tail)
+      packed.pop ();
+    assert (packed.tail ().bytes.arrayZ == tail);
+  }
+
+  unsigned int length () const { return this->head - current.tail ().head; }
 
   void align (unsigned int alignment)
   {
@@ -199,28 +259,9 @@ struct hb_serialize_context_t
   private:
 
   /* Stack of packed objects.  Object 0 is always nil object. */
-  struct object_t
-  {
-    void fini () { links.fini (); }
-
-    struct link_t
-    {
-      bool wide: 1;
-      unsigned offset : 31;
-      unsigned objidx;
-    };
-
-    hb_bytes_t bytes;
-    hb_vector_t<link_t> links;
-  };
   hb_vector_t<object_t> packed;
 
   /* Stack of currently under construction object locations. */
-  struct snapshot_t
-  {
-    char *head, *tail;
-  };
-  snapshot_t snapshot () { snapshot_t s = {head, tail} ; return s; }
   hb_vector_t<snapshot_t> current;
 };
 
diff --git a/src/hb-vector.hh b/src/hb-vector.hh
index 0354845c4..fd24950f7 100644
--- a/src/hb-vector.hh
+++ b/src/hb-vector.hh
@@ -87,6 +87,9 @@ struct hb_vector_t
     return arrayZ()[i];
   }
 
+  Type& tail () { return (*this)[length - 1]; }
+  const Type& tail () const { return (*this)[length - 1]; }
+
   explicit operator bool () const { return length; }
 
   /* Sink interface. */
@@ -188,10 +191,10 @@ struct hb_vector_t
     return true;
   }
 
-  void pop ()
+  Type pop ()
   {
-    if (!length) return;
-    length--;
+    if (!length) return Null(Type);
+    return arrayZ()[--length];
   }
 
   void remove (unsigned int i)

From a43290192beedc6335efc3841c05ec7fa54e8871 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Sat, 30 Mar 2019 17:51:26 -0700
Subject: [PATCH 08/25] [serialize] Add packed_map

---
 src/hb-map.hh       |  7 +++++++
 src/hb-serialize.hh | 24 +++++++++++++++++++++---
 2 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/src/hb-map.hh b/src/hb-map.hh
index 341c15929..a176ccd28 100644
--- a/src/hb-map.hh
+++ b/src/hb-map.hh
@@ -96,6 +96,13 @@ struct hb_hashmap_t
     fini_shallow ();
   }
 
+  void reset ()
+  {
+    /* TODO Keep array? */
+    fini_shallow ();
+    init_shallow ();
+  }
+
   bool in_error () const { return !successful; }
 
   bool resize ()
diff --git a/src/hb-serialize.hh b/src/hb-serialize.hh
index 86f802a26..6911e92a5 100644
--- a/src/hb-serialize.hh
+++ b/src/hb-serialize.hh
@@ -31,6 +31,7 @@
 
 #include "hb.hh"
 #include "hb-blob.hh"
+#include "hb-map.hh"
 
 
 /*
@@ -80,9 +81,10 @@ struct hb_serialize_context_t
     this->tail = this->end;
     this->debug_depth = 0;
 
+    this->current.resize (0);
     this->packed.resize (0);
     this->packed.push ()->bytes.arrayZ = this->end;
-    this->current.resize (0);
+    this->packed_map.reset ();
   }
 
   bool propagate_error (bool e)
@@ -132,6 +134,19 @@ struct hb_serialize_context_t
   }
   objidx_t pop_pack ()
   {
+    snapshot_t snap = current.pop ();
+
+    char *s = snap.head;
+    char *e = head;
+    unsigned l = e - s;
+
+    tail -= l;
+    memmove (tail, s, l);
+
+    /* TODO... */
+    packed.push ();
+
+    head = snap.head;
     return 0;
   }
 
@@ -258,11 +273,14 @@ struct hb_serialize_context_t
 
   private:
 
+  /* Stack of currently under construction object locations. */
+  hb_vector_t<snapshot_t> current;
+
   /* Stack of packed objects.  Object 0 is always nil object. */
   hb_vector_t<object_t> packed;
 
-  /* Stack of currently under construction object locations. */
-  hb_vector_t<snapshot_t> current;
+  /* Map view of packed objects. */
+  hb_hashmap_t<const object_t *, objidx_t> packed_map;
 };
 
 

From 6f69c9d26fa53cd8a2331395bbc146bfc85fd1e3 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Sat, 30 Mar 2019 18:00:03 -0700
Subject: [PATCH 09/25] [serialize] Minor

---
 src/hb-serialize.hh | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/src/hb-serialize.hh b/src/hb-serialize.hh
index 6911e92a5..204055c60 100644
--- a/src/hb-serialize.hh
+++ b/src/hb-serialize.hh
@@ -53,7 +53,8 @@ struct hb_serialize_context_t
       objidx_t objidx;
     };
 
-    hb_bytes_t bytes;
+    char *head;
+    unsigned length;
     hb_vector_t<link_t> links;
   };
 
@@ -83,7 +84,7 @@ struct hb_serialize_context_t
 
     this->current.resize (0);
     this->packed.resize (0);
-    this->packed.push ()->bytes.arrayZ = this->end;
+    this->packed.push ()->head = this->end;
     this->packed_map.reset ();
   }
 
@@ -162,9 +163,9 @@ struct hb_serialize_context_t
   void discard_stale_objects ()
   {
     while (packed.length > 1 &&
-	   packed.tail ().bytes.arrayZ < tail)
+	   packed.tail ().head < tail)
       packed.pop ();
-    assert (packed.tail ().bytes.arrayZ == tail);
+    assert (packed.tail ().head == tail);
   }
 
   unsigned int length () const { return this->head - current.tail ().head; }

From 357c7c611cc20f86c646bd2d392c243140f92d34 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Sat, 30 Mar 2019 18:13:57 -0700
Subject: [PATCH 10/25] [vector] Add copy constructor and assignment operator

---
 src/hb-vector.hh | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/src/hb-vector.hh b/src/hb-vector.hh
index fd24950f7..5b1a83c56 100644
--- a/src/hb-vector.hh
+++ b/src/hb-vector.hh
@@ -38,8 +38,13 @@ struct hb_vector_t
   typedef Type item_t;
   static constexpr unsigned item_size = hb_static_size (Type);
 
-  HB_NO_COPY_ASSIGN_TEMPLATE (hb_vector_t, Type);
   hb_vector_t ()  { init (); }
+  hb_vector_t (const hb_vector_t &o)
+  {
+    init ();
+    alloc (o.length);
+    hb_iter (o) | hb_sink (this);
+  }
   ~hb_vector_t () { fini (); }
 
   unsigned int length;
@@ -69,6 +74,16 @@ struct hb_vector_t
     fini ();
   }
 
+  void reset () { resize (0); }
+
+  hb_vector_t& operator = (const hb_vector_t &o)
+  {
+    reset ();
+    alloc (o.length);
+    hb_iter (o) | hb_sink (this);
+    return *this;
+  }
+
   const Type * arrayZ () const { return arrayZ_; }
         Type * arrayZ ()       { return arrayZ_; }
 

From 9a19b885f9136b0b7cdfa04679274cd4b6d16188 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Sat, 30 Mar 2019 18:14:30 -0700
Subject: [PATCH 11/25] [serialize] Flesh out packing

---
 src/hb-serialize.hh | 58 ++++++++++++++++++++++++++-------------------
 1 file changed, 34 insertions(+), 24 deletions(-)

diff --git a/src/hb-serialize.hh b/src/hb-serialize.hh
index 204055c60..828d23992 100644
--- a/src/hb-serialize.hh
+++ b/src/hb-serialize.hh
@@ -42,7 +42,12 @@ struct hb_serialize_context_t
 {
   typedef unsigned objidx_t;
 
-  struct object_t
+  struct range_t
+  {
+    char *head, *tail;
+  };
+
+  struct object_t : range_t
   {
     void fini () { links.fini (); }
 
@@ -53,16 +58,10 @@ struct hb_serialize_context_t
       objidx_t objidx;
     };
 
-    char *head;
-    unsigned length;
     hb_vector_t<link_t> links;
   };
 
-  struct snapshot_t
-  {
-    char *head, *tail;
-  };
-  snapshot_t snapshot () { snapshot_t s = {head, tail} ; return s; }
+  range_t snapshot () { range_t s = {head, tail} ; return s; }
 
 
   hb_serialize_context_t (void *start_, unsigned int size)
@@ -82,8 +81,8 @@ struct hb_serialize_context_t
     this->tail = this->end;
     this->debug_depth = 0;
 
-    this->current.resize (0);
-    this->packed.resize (0);
+    this->current.reset ();
+    this->packed.reset ();
     this->packed.push ()->head = this->end;
     this->packed_map.reset ();
   }
@@ -119,6 +118,9 @@ struct hb_serialize_context_t
 		     this->start, this->end,
 		     (unsigned) (this->head - this->start),
 		     this->successful ? "successful" : "UNSUCCESSFUL");
+
+    /* TODO Propagate errors. */
+
     assert (current.length == 1);
     return pop_pack ();
   }
@@ -126,7 +128,10 @@ struct hb_serialize_context_t
   template <typename Type>
   Type *push ()
   {
-    current.push (snapshot ());
+    object_t obj;
+    obj.head = head;
+    obj.tail = tail;
+    current.push (obj);
     return start_embed<Type> ();
   }
   void pop_discard ()
@@ -135,23 +140,27 @@ struct hb_serialize_context_t
   }
   objidx_t pop_pack ()
   {
-    snapshot_t snap = current.pop ();
+    object_t obj = current.pop ();
 
-    char *s = snap.head;
-    char *e = head;
-    unsigned l = e - s;
+    unsigned len = head - obj.head;
 
-    tail -= l;
-    memmove (tail, s, l);
+    tail -= len;
+    memmove (tail, obj.head, len);
+    head = obj.head;
 
-    /* TODO... */
-    packed.push ();
+    obj.head = tail;
+    obj.tail = tail + len;
 
-    head = snap.head;
-    return 0;
+    packed.push (obj);
+
+    /* TODO Handle error. */
+    if (unlikely (packed.in_error ()))
+      return 0;
+
+    return packed.length - 1;
   }
 
-  void revert (snapshot_t snap)
+  void revert (range_t snap)
   {
     assert (snap.head <= head);
     assert (tail <= snap.tail);
@@ -274,8 +283,9 @@ struct hb_serialize_context_t
 
   private:
 
-  /* Stack of currently under construction object locations. */
-  hb_vector_t<snapshot_t> current;
+  /* Stack of currently under construction objects. */
+  /* Note.  We store the "end - tail" distance in the length member of these. */
+  hb_vector_t<object_t> current;
 
   /* Stack of packed objects.  Object 0 is always nil object. */
   hb_vector_t<object_t> packed;

From 7c9ceabcef426ca6fc54b70db9dd8cb63937710b Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Sat, 30 Mar 2019 18:19:36 -0700
Subject: [PATCH 12/25] [meta] Add hb_move and hb_forward ala std::

---
 src/hb-meta.hh | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/hb-meta.hh b/src/hb-meta.hh
index a303c67a7..63c8a8cf5 100644
--- a/src/hb-meta.hh
+++ b/src/hb-meta.hh
@@ -72,6 +72,17 @@ static const struct
 } hb_deref_pointer HB_UNUSED;
 
 
+/* std::move and std::forward */
+
+template <typename T>
+hb_remove_reference (T)&& hb_move (T&& t) { return (hb_remove_reference (T)&&) (t); }
+
+template <typename T>
+T&& hb_forward (hb_remove_reference (T)& t) { return (T&&) t; }
+template <typename T>
+T&& hb_forward (hb_remove_reference (T)&& t) { return (T&&) t; }
+
+
 /* Void!  For when we need a expression-type of void. */
 struct hb_void_t { typedef void value; };
 

From 4c4d3c3ed55a8f1eea20593c08322e61fe1cdd3c Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Sat, 30 Mar 2019 18:30:50 -0700
Subject: [PATCH 13/25] [vector] Add some move and forwarding

---
 src/hb-serialize.hh | 2 +-
 src/hb-vector.hh    | 8 ++++----
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/hb-serialize.hh b/src/hb-serialize.hh
index 828d23992..407a330a0 100644
--- a/src/hb-serialize.hh
+++ b/src/hb-serialize.hh
@@ -151,7 +151,7 @@ struct hb_serialize_context_t
     obj.head = tail;
     obj.tail = tail + len;
 
-    packed.push (obj);
+    packed.push (hb_move (obj));
 
     /* TODO Handle error. */
     if (unlikely (packed.in_error ()))
diff --git a/src/hb-vector.hh b/src/hb-vector.hh
index 5b1a83c56..879340506 100644
--- a/src/hb-vector.hh
+++ b/src/hb-vector.hh
@@ -109,7 +109,7 @@ struct hb_vector_t
 
   /* Sink interface. */
   template <typename T>
-  hb_vector_t& operator << (const T& v) { push (v); return *this; }
+  hb_vector_t& operator << (T&& v) { push (hb_forward<T> (v)); return *this; }
 
   hb_array_t<      Type> as_array ()       { return hb_array (arrayZ(), length); }
   hb_array_t<const Type> as_array () const { return hb_array (arrayZ(), length); }
@@ -149,10 +149,10 @@ struct hb_vector_t
     return &arrayZ()[length - 1];
   }
   template <typename T>
-  Type *push (const T& v)
+  Type *push (T&& v)
   {
     Type *p = push ();
-    *p = v;
+    *p = hb_forward<T> (v);
     return p;
   }
 
@@ -209,7 +209,7 @@ struct hb_vector_t
   Type pop ()
   {
     if (!length) return Null(Type);
-    return arrayZ()[--length];
+    return hb_move (arrayZ()[--length]); /* Does this move actually work? */
   }
 
   void remove (unsigned int i)

From e6b78003efbe02ba4542cadcc13bc1dd0b1d57b0 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Sat, 30 Mar 2019 18:33:30 -0700
Subject: [PATCH 14/25] [vector] Add move semantics

---
 src/hb-vector.hh | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/src/hb-vector.hh b/src/hb-vector.hh
index 879340506..f68943987 100644
--- a/src/hb-vector.hh
+++ b/src/hb-vector.hh
@@ -45,6 +45,13 @@ struct hb_vector_t
     alloc (o.length);
     hb_iter (o) | hb_sink (this);
   }
+  hb_vector_t (hb_vector_t &&o)
+  {
+    allocated = o.allocated;
+    length = o.length;
+    arrayZ_ = o.arrayZ_;
+    o.init ();
+  }
   ~hb_vector_t () { fini (); }
 
   unsigned int length;
@@ -83,6 +90,15 @@ struct hb_vector_t
     hb_iter (o) | hb_sink (this);
     return *this;
   }
+  hb_vector_t& operator = (hb_vector_t &&o)
+  {
+    fini ();
+    allocated = o.allocated;
+    length = o.length;
+    arrayZ_ = o.arrayZ_;
+    o.init ();
+    return *this;
+  }
 
   const Type * arrayZ () const { return arrayZ_; }
         Type * arrayZ ()       { return arrayZ_; }

From 10f062234eb7c762a36cf750e75fe6f74ee89a3d Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Sat, 30 Mar 2019 18:44:01 -0700
Subject: [PATCH 15/25] [map] Shuffle fini code

---
 src/hb-map.hh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/hb-map.hh b/src/hb-map.hh
index a176ccd28..f5c999170 100644
--- a/src/hb-map.hh
+++ b/src/hb-map.hh
@@ -88,10 +88,10 @@ struct hb_hashmap_t
   {
     free (items);
     items = nullptr;
+    population = occupancy = 0;
   }
   void fini ()
   {
-    population = occupancy = 0;
     hb_object_fini (this);
     fini_shallow ();
   }

From 0b1fe7b716628f7b7b4098da9ef544e1518008f5 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Sat, 30 Mar 2019 18:48:26 -0700
Subject: [PATCH 16/25] [serializer] Unbreak for now

---
 src/hb-serialize.hh | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/hb-serialize.hh b/src/hb-serialize.hh
index 407a330a0..805ac492c 100644
--- a/src/hb-serialize.hh
+++ b/src/hb-serialize.hh
@@ -111,7 +111,7 @@ struct hb_serialize_context_t
     assert (!current.length);
     return push<Type> ();
   }
-  objidx_t end_serialize ()
+  void end_serialize ()
   {
     DEBUG_MSG_LEVEL (SERIALIZE, this->start, 0, -1,
 		     "end [%p..%p] serialized %u bytes; %s",
@@ -122,7 +122,8 @@ struct hb_serialize_context_t
     /* TODO Propagate errors. */
 
     assert (current.length == 1);
-    return pop_pack ();
+    /* TODO Enable when callers are updated. */
+    //pop_pack ();
   }
 
   template <typename Type>

From 8512dc565d310e9fd80d831282736284cc3ecd2e Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Sat, 30 Mar 2019 19:01:23 -0700
Subject: [PATCH 17/25] [serialize] Simplify copy

---
 src/hb-serialize.hh | 22 +++++++---------------
 1 file changed, 7 insertions(+), 15 deletions(-)

diff --git a/src/hb-serialize.hh b/src/hb-serialize.hh
index 805ac492c..733536153 100644
--- a/src/hb-serialize.hh
+++ b/src/hb-serialize.hh
@@ -246,16 +246,6 @@ struct hb_serialize_context_t
   Type *extend (Type &obj) { return extend_size (obj, obj.get_size ()); }
 
   /* Output routines. */
-  template <typename Type>
-  Type *copy () const
-  {
-    assert (this->successful);
-    unsigned int len = this->head - this->start;
-    void *p = malloc (len);
-    if (p)
-      memcpy (p, this->start, len);
-    return reinterpret_cast<Type *> (p);
-  }
   hb_bytes_t copy_bytes () const
   {
     assert (this->successful);
@@ -267,13 +257,15 @@ struct hb_serialize_context_t
       return hb_bytes_t ();
     return hb_bytes_t ((char *) p, len);
   }
+  template <typename Type>
+  Type *copy () const
+  { return reinterpret_cast<Type *> ((char *) copy_bytes ().arrayZ); }
   hb_blob_t *copy_blob () const
   {
-    assert (this->successful);
-    return hb_blob_create (this->start,
-			   this->head - this->start,
-			   HB_MEMORY_MODE_DUPLICATE,
-			   nullptr, nullptr);
+    hb_bytes_t b = copy_bytes ();
+    return hb_blob_create (b.arrayZ, b.length,
+			   HB_MEMORY_MODE_WRITABLE,
+			   (char *) b.arrayZ, free);
   }
 
   public: /* TODO Make private. */

From 946d446f9b795f657d56ca443edbc0b77d660a50 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Sat, 30 Mar 2019 19:03:55 -0700
Subject: [PATCH 18/25] [serialize] Copy both sides of the buffer

---
 src/hb-serialize.hh | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/src/hb-serialize.hh b/src/hb-serialize.hh
index 733536153..7f3206702 100644
--- a/src/hb-serialize.hh
+++ b/src/hb-serialize.hh
@@ -249,13 +249,18 @@ struct hb_serialize_context_t
   hb_bytes_t copy_bytes () const
   {
     assert (this->successful);
-    unsigned int len = this->head - this->start;
-    void *p = malloc (len);
+    /* Copy both items from head side and tail side... */
+    unsigned int len = (this->head - this->start)
+		     + (this->end  - this->tail);
+    char *p = (char *) malloc (len);
     if (p)
-      memcpy (p, this->start, len);
+    {
+      memcpy (p, this->start, this->head - this->start);
+      memcpy (p + (this->head - this->start), this->tail, this->end - this->tail);
+    }
     else
       return hb_bytes_t ();
-    return hb_bytes_t ((char *) p, len);
+    return hb_bytes_t (p, len);
   }
   template <typename Type>
   Type *copy () const

From f254f45a1e6b1de6d83c97033773d20408772763 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Sat, 30 Mar 2019 19:05:51 -0700
Subject: [PATCH 19/25] [serialize] Only pack main object if there are other
 objects

Avoids a memmove for tables that don't use the object packing mechanism.
---
 src/hb-serialize.hh | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/hb-serialize.hh b/src/hb-serialize.hh
index 7f3206702..617928815 100644
--- a/src/hb-serialize.hh
+++ b/src/hb-serialize.hh
@@ -122,8 +122,11 @@ struct hb_serialize_context_t
     /* TODO Propagate errors. */
 
     assert (current.length == 1);
-    /* TODO Enable when callers are updated. */
-    //pop_pack ();
+
+    /* Only "pack" if there exist other objects... Otherwise, don't bother.
+     * Saves a copy. */
+    if (packed.length > 1)
+      pop_pack ();
   }
 
   template <typename Type>

From 7fd82283263f8caded4870d6e12f74c7e660fa8d Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Sat, 30 Mar 2019 19:16:20 -0700
Subject: [PATCH 20/25] [serialize] Towards maintaining hashmap

---
 src/hb-algs.hh      |  2 +-
 src/hb-serialize.hh | 16 ++++++++++++++--
 src/hb-vector.hh    |  1 +
 3 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/src/hb-algs.hh b/src/hb-algs.hh
index 128e49036..ab6782de3 100644
--- a/src/hb-algs.hh
+++ b/src/hb-algs.hh
@@ -45,7 +45,7 @@ static const struct
 
   template <typename T>
   uint32_t operator () (const T *v) const
-  { return hb_hash (v); }
+  { return operator() (v); }
 
   template <typename T,
 	    hb_enable_if (hb_is_integer (T))>
diff --git a/src/hb-serialize.hh b/src/hb-serialize.hh
index 617928815..e7873ab69 100644
--- a/src/hb-serialize.hh
+++ b/src/hb-serialize.hh
@@ -51,6 +51,14 @@ struct hb_serialize_context_t
   {
     void fini () { links.fini (); }
 
+    bool operator == (const object_t &o) const
+    {
+      return (tail - head == o.tail - o.head)
+	  && (links.length != o.links.length)
+	  && 0 == memcmp (head, o.head, tail - head)
+	  && 0 == memcmp (&links, &o.links, links.get_size ());
+    }
+
     struct link_t
     {
       bool wide: 1;
@@ -155,13 +163,17 @@ struct hb_serialize_context_t
     obj.head = tail;
     obj.tail = tail + len;
 
-    packed.push (hb_move (obj));
+    object_t *key = packed.push (hb_move (obj));
 
     /* TODO Handle error. */
     if (unlikely (packed.in_error ()))
       return 0;
 
-    return packed.length - 1;
+    objidx_t objidx = packed.length - 1;
+
+    packed_map.set (key, objidx);
+
+    return objidx;
   }
 
   void revert (range_t snap)
diff --git a/src/hb-vector.hh b/src/hb-vector.hh
index f68943987..2a92a892e 100644
--- a/src/hb-vector.hh
+++ b/src/hb-vector.hh
@@ -122,6 +122,7 @@ struct hb_vector_t
   const Type& tail () const { return (*this)[length - 1]; }
 
   explicit operator bool () const { return length; }
+  unsigned get_size () const { return length * item_size; }
 
   /* Sink interface. */
   template <typename T>

From d74dc3ef65a159fe585e906deccdb32b570433aa Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Sat, 30 Mar 2019 19:26:37 -0700
Subject: [PATCH 21/25] [serialize] Don't insert empty object into tree

---
 src/hb-serialize.hh | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/hb-serialize.hh b/src/hb-serialize.hh
index e7873ab69..3bbff7541 100644
--- a/src/hb-serialize.hh
+++ b/src/hb-serialize.hh
@@ -160,6 +160,9 @@ struct hb_serialize_context_t
     memmove (tail, obj.head, len);
     head = obj.head;
 
+    if (!len)
+      return 0;
+
     obj.head = tail;
     obj.tail = tail + len;
 
@@ -304,7 +307,7 @@ struct hb_serialize_context_t
   hb_vector_t<object_t> packed;
 
   /* Map view of packed objects. */
-  hb_hashmap_t<const object_t *, objidx_t> packed_map;
+  hb_hashmap_t<const object_t *, objidx_t, nullptr, 0> packed_map;
 };
 
 

From d6b28057a5cc636138cd453947d3a2008f18729f Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Sat, 30 Mar 2019 19:31:51 -0700
Subject: [PATCH 22/25] Fix hb_hash(pointer)

---
 src/hb-algs.hh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/hb-algs.hh b/src/hb-algs.hh
index ab6782de3..c1b38e877 100644
--- a/src/hb-algs.hh
+++ b/src/hb-algs.hh
@@ -45,7 +45,7 @@ static const struct
 
   template <typename T>
   uint32_t operator () (const T *v) const
-  { return operator() (v); }
+  { return operator() (*v); }
 
   template <typename T,
 	    hb_enable_if (hb_is_integer (T))>

From b189bbc48fb4b7c251d30b26a57ad84d1cb6dbe4 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Sat, 30 Mar 2019 19:41:48 -0700
Subject: [PATCH 23/25] Implement hashing of objects

Should be improved for hb_bytes_t.
---
 src/hb-algs.hh      |  2 +-
 src/hb-array.hh     | 13 +++++++++++++
 src/hb-serialize.hh |  5 +++++
 src/hb-vector.hh    |  5 +++++
 4 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/src/hb-algs.hh b/src/hb-algs.hh
index c1b38e877..adf5c483f 100644
--- a/src/hb-algs.hh
+++ b/src/hb-algs.hh
@@ -40,7 +40,7 @@ static const struct
   //{ return hb_deref_pointer (v).hash (); }
   /* Instead, the following ugly soution: */
   template <typename T,
-	    hb_enable_if (!hb_is_integer (hb_remove_reference (T)) && !hb_is_pointer (T))>
+	    hb_enable_if (!hb_is_integer (hb_remove_const (hb_remove_reference (T))) && !hb_is_pointer (T))>
   uint32_t operator () (T&& v) const { return v.hash (); }
 
   template <typename T>
diff --git a/src/hb-array.hh b/src/hb-array.hh
index ab453f5a2..16f53cc8f 100644
--- a/src/hb-array.hh
+++ b/src/hb-array.hh
@@ -79,6 +79,8 @@ struct hb_array_t : hb_iter_with_fallback_t<hb_array_t<Type>, Type&>
   operator hb_array_t<const Type> () { return hb_array_t<const Type> (arrayZ, length); }
   template <typename T> operator T * () const { return arrayZ; }
 
+  uint32_t hash () const;
+
   /*
    * Compare, Sort, and Search.
    */
@@ -273,9 +275,20 @@ template <typename T, unsigned int length_> inline hb_sorted_array_t<T>
 hb_sorted_array (T (&array_)[length_])
 { return hb_sorted_array_t<T> (array_); }
 
+template <typename T>
+uint32_t hb_array_t<T>::hash () const
+{
+  uint32_t h = 0;
+  for (unsigned i = 0; i < length; i++)
+    h ^= hb_hash (arrayZ[i]);
+  return h;
+}
 
 typedef hb_array_t<const char> hb_bytes_t;
 typedef hb_array_t<const unsigned char> hb_ubytes_t;
 
+/* TODO Specialize hashing for hb_bytes_t and hb_ubytes_t. */
+//template <>
+//uint32_t hb_array_t<const char>::hash () const { return 0; }
 
 #endif /* HB_ARRAY_HH */
diff --git a/src/hb-serialize.hh b/src/hb-serialize.hh
index 3bbff7541..d8e1e2fb8 100644
--- a/src/hb-serialize.hh
+++ b/src/hb-serialize.hh
@@ -58,6 +58,11 @@ struct hb_serialize_context_t
 	  && 0 == memcmp (head, o.head, tail - head)
 	  && 0 == memcmp (&links, &o.links, links.get_size ());
     }
+    uint32_t hash () const
+    {
+      return hb_bytes_t (head, tail - head).hash () ^
+	     links.as_bytes ().hash ();
+    }
 
     struct link_t
     {
diff --git a/src/hb-vector.hh b/src/hb-vector.hh
index 2a92a892e..4621b5134 100644
--- a/src/hb-vector.hh
+++ b/src/hb-vector.hh
@@ -100,6 +100,11 @@ struct hb_vector_t
     return *this;
   }
 
+  hb_bytes_t as_bytes () const { return hb_bytes_t ((const char *) arrayZ_,
+						    length * item_size); }
+
+  uint32_t hash () const { return as_bytes ().hash (); }
+
   const Type * arrayZ () const { return arrayZ_; }
         Type * arrayZ ()       { return arrayZ_; }
 

From 313b3057c335da6baa4cd447bac95812992413b9 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Sat, 30 Mar 2019 19:46:35 -0700
Subject: [PATCH 24/25] [serializer] Implement dedup!

---
 src/hb-serialize.hh | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/src/hb-serialize.hh b/src/hb-serialize.hh
index d8e1e2fb8..4de87d823 100644
--- a/src/hb-serialize.hh
+++ b/src/hb-serialize.hh
@@ -83,6 +83,12 @@ struct hb_serialize_context_t
     this->end = this->start + size;
     reset ();
   }
+  ~hb_serialize_context_t ()
+  {
+    current.fini_deep ();
+    packed.fini_deep ();
+    packed_map.fini ();
+  }
 
   bool in_error () const { return !this->successful; }
 
@@ -158,8 +164,15 @@ struct hb_serialize_context_t
   objidx_t pop_pack ()
   {
     object_t obj = current.pop ();
+    obj.tail = head;
+    unsigned len = obj.tail - obj.head;
 
-    unsigned len = head - obj.head;
+    objidx_t objidx = packed_map.get (&obj);
+    if (objidx)
+    {
+      obj.fini ();
+      return objidx;
+    }
 
     tail -= len;
     memmove (tail, obj.head, len);
@@ -177,7 +190,7 @@ struct hb_serialize_context_t
     if (unlikely (packed.in_error ()))
       return 0;
 
-    objidx_t objidx = packed.length - 1;
+    objidx = packed.length - 1;
 
     packed_map.set (key, objidx);
 
@@ -305,7 +318,6 @@ struct hb_serialize_context_t
   private:
 
   /* Stack of currently under construction objects. */
-  /* Note.  We store the "end - tail" distance in the length member of these. */
   hb_vector_t<object_t> current;
 
   /* Stack of packed objects.  Object 0 is always nil object. */

From d6005b49b32410543a8dfa93ce2a213223cf8f01 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Sat, 30 Mar 2019 19:49:56 -0700
Subject: [PATCH 25/25] [serialize] Start implementing linking

---
 src/hb-serialize.hh | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/src/hb-serialize.hh b/src/hb-serialize.hh
index 4de87d823..ab07080b8 100644
--- a/src/hb-serialize.hh
+++ b/src/hb-serialize.hh
@@ -143,9 +143,13 @@ struct hb_serialize_context_t
     assert (current.length == 1);
 
     /* Only "pack" if there exist other objects... Otherwise, don't bother.
-     * Saves a copy. */
-    if (packed.length > 1)
-      pop_pack ();
+     * Saves a move. */
+    if (packed.length == 1)
+      return;
+
+    pop_pack ();
+
+    link ();
   }
 
   template <typename Type>
@@ -214,6 +218,11 @@ struct hb_serialize_context_t
     assert (packed.tail ().head == tail);
   }
 
+  void link ()
+  {
+    // XXX
+  }
+
   unsigned int length () const { return this->head - current.tail ().head; }
 
   void align (unsigned int alignment)