From 2a430790adfac00a1280c0ebfcf579be1b557ffb Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Tue, 15 Feb 2022 17:33:52 -0600
Subject: [PATCH] [machinery] Add "core table" machinery

To be used in subsequent commit; or tried anyway.
---
 src/hb-machinery.hh          | 11 ++++++++---
 src/hb-ot-face-table-list.hh | 13 +++++++++++--
 src/hb-ot-face.hh            |  3 +++
 3 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/src/hb-machinery.hh b/src/hb-machinery.hh
index b529173fc..e52a6a412 100644
--- a/src/hb-machinery.hh
+++ b/src/hb-machinery.hh
@@ -273,14 +273,19 @@ struct hb_face_lazy_loader_t : hb_lazy_loader_t<T,
 						hb_face_lazy_loader_t<T, WheresFace>,
 						hb_face_t, WheresFace> {};
 
-template <typename T, unsigned int WheresFace>
+template <typename T, unsigned int WheresFace, bool core=false>
 struct hb_table_lazy_loader_t : hb_lazy_loader_t<T,
-						 hb_table_lazy_loader_t<T, WheresFace>,
+						 hb_table_lazy_loader_t<T, WheresFace, core>,
 						 hb_face_t, WheresFace,
 						 hb_blob_t>
 {
   static hb_blob_t *create (hb_face_t *face)
-  { return hb_sanitize_context_t ().reference_table<T> (face); }
+  {
+    auto c = hb_sanitize_context_t ();
+    if (core)
+      c.set_num_glyphs (0); // So we don't recurse ad infinitum...
+    return c.reference_table<T> (face);
+  }
   static void destroy (hb_blob_t *p) { hb_blob_destroy (p); }
 
   static const hb_blob_t *get_null ()
diff --git a/src/hb-ot-face-table-list.hh b/src/hb-ot-face-table-list.hh
index 65cb4e644..99a9c22fa 100644
--- a/src/hb-ot-face-table-list.hh
+++ b/src/hb-ot-face-table-list.hh
@@ -32,6 +32,11 @@
 #define HB_OT_FACE_TABLE_LIST_HH
 #endif /* HB_OT_FACE_TABLE_LIST_HH */ /* Dummy header guards */
 
+#ifndef HB_OT_CORE_TABLE
+#define HB_OT_CORE_TABLE(Namespace, Type) HB_OT_TABLE (Namespace, Type)
+#define _HB_OT_CORE_TABLE_UNDEF
+#endif
+
 #ifndef HB_OT_ACCELERATOR
 #define HB_OT_ACCELERATOR(Namespace, Type) HB_OT_TABLE (Namespace, Type)
 #define _HB_OT_ACCELERATOR_UNDEF
@@ -46,8 +51,8 @@
 
 
 /* OpenType fundamentals. */
-HB_OT_TABLE (OT, head)
-HB_OT_TABLE (OT, maxp)
+HB_OT_CORE_TABLE (OT, head)
+HB_OT_CORE_TABLE (OT, maxp)
 #if !defined(HB_NO_FACE_COLLECT_UNICODES) || !defined(HB_NO_OT_FONT)
 HB_OT_ACCELERATOR (OT, cmap)
 #endif
@@ -139,3 +144,7 @@ HB_OT_TABLE (OT, MATH)
 #ifdef _HB_OT_ACCELERATOR_UNDEF
 #undef HB_OT_ACCELERATOR
 #endif
+
+#ifdef _HB_OT_CORE_TABLE_UNDEF
+#undef HB_OT_CORE_TABLE
+#endif
diff --git a/src/hb-ot-face.hh b/src/hb-ot-face.hh
index e24d380bc..415dae8e2 100644
--- a/src/hb-ot-face.hh
+++ b/src/hb-ot-face.hh
@@ -63,10 +63,13 @@ struct hb_ot_face_t
   hb_face_t *face; /* MUST be JUST before the lazy loaders. */
 #define HB_OT_TABLE(Namespace, Type) \
   hb_table_lazy_loader_t<Namespace::Type, HB_OT_TABLE_ORDER (Namespace, Type)> Type;
+#define HB_OT_CORE_TABLE(Namespace, Type) \
+  hb_table_lazy_loader_t<Namespace::Type, HB_OT_TABLE_ORDER (Namespace, Type), true> Type;
 #define HB_OT_ACCELERATOR(Namespace, Type) \
   hb_face_lazy_loader_t<Namespace::Type##_accelerator_t, HB_OT_TABLE_ORDER (Namespace, Type)> Type;
 #include "hb-ot-face-table-list.hh"
 #undef HB_OT_ACCELERATOR
+#undef HB_OT_CORE_TABLE
 #undef HB_OT_TABLE
 };