From ad95948e09bde3357faf57b6b13e63ae74fe60bb Mon Sep 17 00:00:00 2001
From: Philipp Gesang <phg42.2a@gmail.com>
Date: Fri, 17 May 2013 14:56:59 +0200
Subject: load character data on demand

---
 luaotfload-auxiliary.lua | 42 +++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 41 insertions(+), 1 deletion(-)

diff --git a/luaotfload-auxiliary.lua b/luaotfload-auxiliary.lua
index 64fac90..1a48914 100644
--- a/luaotfload-auxiliary.lua
+++ b/luaotfload-auxiliary.lua
@@ -26,6 +26,9 @@ local identifiers   = fonts.hashes.identifiers
 local fontid        = font.id
 local texsprint     = tex.sprint
 
+local dofile        = dofile
+local getmetatable  = getmetatable
+local setmetatable  = setmetatable
 local utf8          = unicode.utf8
 local stringlower   = string.lower
 local stringformat  = string.format
@@ -227,7 +230,7 @@ luatexbase.add_to_callback(
   "luaotfload.aux.set_capheight")
 
 -----------------------------------------------------------------------
----                             glyphs
+---                      glyphs and characters
 -----------------------------------------------------------------------
 
 local agl = fonts.encodings.agl
@@ -321,6 +324,43 @@ end
 
 aux.name_of_slot      = name_of_slot
 
+--[[doc--
+
+  In Context, characters.data is where the data from char-def.lua
+  resides. The file is huge (>3.7 MB as of 2013) and not part of the
+  isolated font loader. Nevertheless, we include a partial version
+  generated by the mkcharacters script that contains only the
+  “direction” and “mirror” fields of each character defined.
+
+--doc]]--
+
+characters      = characters or { } --- should be created in basics-gen
+characters.data = { }
+local chardef   = "luaotfload-characters"
+
+do
+  local chardata
+  local index = function (t, k)
+    if chardata == nil then
+      log("Loading character metadata from %s.", chardef)
+      chardata = dofile(kpse.find_file("luaotfload-characters.lua"))
+      if chardata == nil then
+        warning("Could not load %s; continuing with empty character table.",
+                chardef)
+        chardata = { }
+      end
+    end
+    return chardata[k]
+  end
+
+  local mt = getmetatable(characters.data)
+  if mt then
+    mt.__index = index
+  else
+    setmetatable(characters.data, { __index = index })
+  end
+end
+
 -----------------------------------------------------------------------
 ---                 features / scripts / languages
 -----------------------------------------------------------------------
-- 
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