[main,loaders] regroup callback handling code with loaders

... changing the meaning of the file’s designation instead of adding yet
another file.

All the callback manipulation is now contained inside that module which
will inject most of its functionality only when its main ``.install()``
method is called.

1 files changed, 120 insertions, 27 deletions

diff --git a/src/luaotfload-loaders.lua b/src/luaotfload-loaders.lua
index 901d4d8..061789c 100644
--- a/src/luaotfload-loaders.lua
+++ b/src/luaotfload-loaders.lua
@@ -1,34 +1,127 @@
-if not modules then modules = { } end modules ["loaders"] = {
-    version   = "2.5",
-    comment   = "companion to luaotfload-main.lua",
-    author    = "Hans Hagen, Khaled Hosny, Elie Roux, Philipp Gesang",
-    copyright = "PRAGMA ADE / ConTeXt Development Team",
-    license   = "see context related readme files"
-}
+#!/usr/bin/env texlua
+-----------------------------------------------------------------------
+--         FILE:  luaotfload-loaders.lua
+--  DESCRIPTION:  Luaotfload callback handling
+-- REQUIREMENTS:  luatex v.0.80 or later; packages lualibs, luatexbase
+--       AUTHOR:  Philipp Gesang (Phg), <phg@phi-gamma.net>, Hans Hagen, Khaled Hosny, Elie Roux
+--      VERSION:  just consult Git, okay?
+-----------------------------------------------------------------------
+--
+--- Contains parts of the earlier main script.
+
+if not lualibs    then error "this module requires Luaotfload" end
+if not luaotfload then error "this module requires Luaotfload" end
+
+local logreport        = luaotfload.log and luaotfload.log.report or print
+local add_to_callback  = luatexbase.add_to_callback
+local create_callback  = luatexbase.create_callback
+local reset_callback   = luatexbase.reset_callback
+local call_callback    = luatexbase.call_callback
+local dummy_function   = function () end
+
+local install_formats = function ()
+  local fonts = fonts
+  if not fonts then return false end
+
+  local readers  = fonts.readers
+  local handlers = fonts.handlers
+  local formats  = fonts.formats
+  if not readers or not handlers or not formats then return false end
+
+  local aux = function (which, reader)
+    if not which or type (which) ~= "string" then return false end
+    formats  [which] = "type1"
+    readers  [which] = reader
+    handlers [which] = { }
+    return true
+  end
+
+  return aux ("pfa", function (spec) return readers.opentype (spec, "pfa", "type1") end)
+     and aux ("pfb", function (spec) return readers.opentype (spec, "pfb", "type1") end)
+     and aux ("ofm", readers.tfm)
+end
+
+--[[doc--
 
-local fonts           = fonts
-local readers         = fonts.readers
-local handlers        = fonts.handlers
-local formats         = fonts.formats
-
-local pfb_reader = function (specification)
-  return readers.opentype (specification, "pfb", "type1")
-end 
- 
-local pfa_reader = function (specification)
-  return readers.opentype (specification, "pfa", "type1")
+    \subsection{\CONTEXT override}
+    \label{define-font}
+    We provide a simplified version of the original font definition
+    callback.
+
+--doc]]--
+
+
+local definers = { } --- (string, spec -> size -> id -> tmfdata) hash_t
+do
+  local read = fonts.definers.read
+
+  local patch = function (specification, size, id)
+    local fontdata = read (specification, size, id)
+    if type (fontdata) == "table" and fontdata.shared then
+      --- We need to test for the “shared” field here
+      --- or else the fontspec capheight callback will
+      --- operate on tfm fonts.
+      call_callback ("luaotfload.patch_font", fontdata, specification)
+    else
+      call_callback ("luaotfload.patch_font_unsafe", fontdata, specification)
+    end
+    return fontdata
+  end
+
+  local mk_info = function (name)
+    local definer = name == "patch" and patch or read
+    return function (specification, size, id)
+      logreport ("both", 0, "main", "defining font no. %d", id)
+      logreport ("both", 0, "main", "   > active font definer: %q", name)
+      logreport ("both", 0, "main", "   > spec %q", specification)
+      logreport ("both", 0, "main", "   > at size %.2f pt", size / 2^16)
+      local result = definer (specification, size, id)
+      if not result then
+        logreport ("both", 0, "main", "   > font definition failed")
+        return
+      elseif type (result) == "number" then
+        logreport ("both", 0, "main", "   > font definition yielded id %d", result)
+        return result
+      end
+      logreport ("both", 0, "main", "   > font definition successful")
+      logreport ("both", 0, "main", "   > name %q",     result.name     or "<nil>")
+      logreport ("both", 0, "main", "   > fontname %q", result.fontname or "<nil>")
+      logreport ("both", 0, "main", "   > fullname %q", result.fullname or "<nil>")
+      return result
+    end
+  end
+
+  definers.patch          = patch
+  definers.generic        = read
+  definers.info_patch     = mk_info "patch"
+  definers.info_generic   = mk_info "generic"
 end
 
-formats.pfa  = "type1"
-readers.pfa  = pfa_reader
-handlers.pfa = { }
+--[[doc--
+
+  We create callbacks for patching fonts on the fly, to be used by
+  other packages. In addition to the regular \identifier{patch_font}
+  callback there is an unsafe variant \identifier{patch_font_unsafe}
+  that will be invoked even if the target font lacks certain essential
+  tfmdata tables.
 
-formats.pfb  = "type1"
-readers.pfb  = pfb_reader
-handlers.pfb = { }
+  The callbacks initially contain the empty function that we are going
+  to override below.
 
-formats.ofm  = "type1"
-readers.ofm  = readers.tfm
-handlers.ofm = { }
+--doc]]--
 
+return {
+  install = function ()
+    if not install_formats () then
+      logreport ("both", 0, "main", "error initializing OFM/PF{A,B} loaders")
+    end
+    create_callback("luaotfload.patch_font",        "simple", dummy_function)
+    create_callback("luaotfload.patch_font_unsafe", "simple", dummy_function)
+
+    reset_callback "define_font"
+    local definer = config.luaotfload.run.definer
+    add_to_callback ("define_font", definers[definer or "patch"],
+                     "luaotfload.define_font", 1)
+  end
+}
 -- vim:tw=71:sw=2:ts=2:expandtab