From 71555eecef54adc6fee27c81afe20477c0dddea2 Mon Sep 17 00:00:00 2001
From: Philipp Gesang <phg42.2a@gmail.com>
Date: Tue, 16 Apr 2013 23:48:08 +0200
Subject: remove attribute allocation hack

---
 luaotfload.dtx | 235 ++++++++++++++++++++++++++++++++++++---------------------
 1 file changed, 148 insertions(+), 87 deletions(-)

(limited to 'luaotfload.dtx')

diff --git a/luaotfload.dtx b/luaotfload.dtx
index 9954a32..2446644 100644
--- a/luaotfload.dtx
+++ b/luaotfload.dtx
@@ -526,9 +526,6 @@ and the derived files
 % \iffalse
 %<*lua>
 % \fi
-%
-%    \section{Initializations}
-%
 %    \begin{macrocode}
 module("luaotfload", package.seeall)
 
@@ -553,30 +550,63 @@ local add_to_callback, create_callback =
 local reset_callback, call_callback =
       luatexbase.reset_callback, luatexbase.call_callback
 
-local dummy_function   = function () end
+local dummy_function = function () end
 
 %    \end{macrocode}
 %
-%    No final decision has been made on how to handle font definition.
-%    At the moment, there are three candidates: The \identifier{generic}
-%    callback as hard-coded in the font loader, the \identifier{old} wrapper,
-%    and a simplified version of the latter (\identifier{patch}) that does
-%    nothing besides applying font patches.
+%    No final decision has been made on how to handle font definition.  At
+%    the moment, there are three candidates: The \identifier{generic}
+%    callback as hard-coded in the font loader, the \identifier{old}
+%    wrapper, and a simplified version of the latter (\identifier{patch})
+%    that does nothing besides applying font patches.
 %
 %    \begin{macrocode}
 luaotfload.font_definer = "patch" --- | “generic” | “old”
 
-local fl_prefix = "otfl" -- “luatex” for luatex-plain
+local error, warning, info, log =
+    luatexbase.provides_module(luaotfload.module)
+
+%    \end{macrocode}
+%
+%    This is a necessary initalization in order not to rebuild an existing
+%    font.
+%    Maybe 600 should be replaced by \texmacro{pdfpkresolution} %% (why?)
+%    or \luafunction{texconfig.pk_dpi} (and it should be replaced
+%    dynamically), but we don't have access (yet) to the
+%    \identifier{texconfig} table, so we let it be 600.
+%    Anyway, it does still work fine even if \texmacro{pdfpkresolution} is
+%    changed.
+%
+%    \begin{macrocode}
+
+kpse.init_prog("", 600, "/")
 
-local error, warning, info, log = luatexbase.provides_module(luaotfload.module)
+%    \end{macrocode}
+%
+%    We set the minimum version requirement for \LUATEX to v0.74, as it was
+%    the first version to include version 5.2 of the \LUA interpreter.
+%
+%    \begin{macrocode}
 
-local luatex_version = 75
+local luatex_version = 74
 
 if tex.luatexversion < luatex_version then
     warning("LuaTeX v%.2f is old, v%.2f is recommended.",
              tex.luatexversion/100,
              luatex_version   /100)
 end
+
+%    \end{macrocode}
+%
+%    \subsection{Module loading}
+%
+%    We load the files imported from \CONTEXT with this function.
+%    It automatically prepends the prefix \fileent{otfl-} to its argument,
+%    so we can refer to the files with their actual \CONTEXT name.
+%
+%    \begin{macrocode}
+
+local fl_prefix = "otfl" -- “luatex” for luatex-plain
 local loadmodule = function (name)
     local tofind = fl_prefix .."-"..name
     local found = find_file(tofind,"tex")
@@ -584,7 +614,6 @@ local loadmodule = function (name)
         log("loading file %s.", found)
         dofile(found)
     else
-        --error("file %s not found.", tofind)
         error("file %s not found.", tofind)
     end
 end
@@ -592,8 +621,8 @@ end
 %    \end{macrocode}
 %
 %    Virtual fonts are resolved via a callback.
-%    \verb|find_vf_file| derives the name of the virtual font file from the
-%    filename.
+%    \luafunction{find_vf_file} derives the name of the virtual font file
+%    from the filename.
 %    (NB: \CONTEXT handles this likewise in \fileent{font-vf.lua}.)
 %
 %    \begin{macrocode}
@@ -655,10 +684,12 @@ end
 
 %    \end{macrocode}
 %
+%
+%    \subsection{Preparing the Font Loader}
 %    We treat the fontloader as a black box so behavior is consistent
 %    between formats.
-%    The wrapper file is |otfl-fonts.lua| which we imported from
-%    \LUATEX-Plain.
+%    The wrapper file is \fileent{otfl-fonts.lua} which we imported from
+%    \href{http://standalone.contextgarden.net/current/context/experimental/tex/generic/context/luatex/}{\LUATEX-Plain}.
 %    It has roughly two purposes:
 %
 %    \begin{enumerate}
@@ -670,32 +701,29 @@ end
 %    \end{enumerate}
 %
 %    How the first step is executed depends on the presence on the
-%    \emphasis{merged font loader code}.
+%    \emph{merged font loader code}.
 %    In \identifier{luaotfload} this is contained in the file
-%    |otfl-fonts-merged.lua|.
+%    \fileent{otfl-fonts-merged.lua}.
 %    If this file cannot be found,  the original libraries from \CONTEXT of
 %    which the merged code was composed are loaded instead.
 %
 %    Hans provides two global tables to control the font loader:
 %
-%    \begin{itemize}
-%
-%      \item  \luafunction{generic_context}:
-%             encapsulation mechanism, callback functions
-%
-%      \item  \luafunction{non generic_context}:
-%             customized code insertion
-%
-%    \end{itemize}
-%
-%    With \verb|non_generic_context| we can tailor the font loader insertion
-%    to our file naming habits (key \verb|load_before|).
-%    Additionally, \verb|skip_loading| can be unset to force loading of
-%    the original libraries as though the merged code was absent.
-%    Another key, \verb|load_after| is called at the time when the font
-%    loader is actually inserted.
-%    In combination with the option \verb|no_callbacks_yet| in
-%    \verb|generic_context|, we can insert our own,
+%      \begin{itemize}
+%        \item  \luafunction{generic_context}:
+%               encapsulation mechanism, callback functions
+%        \item  \luafunction{non generic_context}:
+%               customized code insertion
+%      \end{itemize}
+%
+%    With \luafunction{non_generic_context} we can tailor the font loader
+%    insertion to our file naming habits (key \luafunction{load_before}).
+%    Additionally, \luafunction{skip_loading} can be unset to force loading
+%    of the original libraries as though the merged code was absent.
+%    Another key, \luafunction{load_after} is called at the time when the
+%    font loader is actually inserted.
+%    In combination with the option \luafunction{no_callbacks_yet} in
+%    \luafunction{generic_context}, we can insert our own,
 %    \identifier{luatexbase}-style callback handling here.
 %
 %    \begin{macrocode}
@@ -715,23 +743,62 @@ _G.non_generic_context = { luatex_fonts = {
 
 %    \end{macrocode}
 %
-%    The imported font loader will call \verb|callback.register| once
-%    (during \verb|font-def.lua|).
-%    This is unavoidable but harmless, so we make it call a dummy instead.
+%    The imported font loader will call \luafunction{callback.register} once
+%    while reading \fileent{font-def.lua}.
+%    This is unavoidable unless we modify the imported files, but harmless
+%    if we make it call a dummy instead.
 %
 %    \begin{macrocode}
+
 local trapped_register = callback.register
 callback.register      = dummy_function
 
 %    \end{macrocode}
 %
-%    Now that things are sorted out we can load the fontloader.
+%    Now that things are sorted out we can finally load the fontloader.
 %
 %    \begin{macrocode}
+
 loadmodule"fonts.lua"
 
 %    \end{macrocode}
 %
+%    By default, the fontloader requires a number of \emphasis{private
+%    attributes} for internal use.
+%    These must be kept consistent with the attribute handling methods as
+%    provided by \identifier{luatexbase}.
+%    Our strategy is to override the function that allocates new attributes
+%    before we initialize the font loader, making it a wrapper around
+%    \luafunction{luatexbase.new_attribute}.\footnote{%
+%        Many thanks, again, to Hans Hagen for making this part
+%        configurable!
+%    }
+%    The attribute identifiers are prefixed “\fileent{otfl@}” to
+%    avoid name clashes.
+%
+%    \begin{macrocode}
+
+do
+    local new_attribute = luatexbase.new_attribute
+    local the_attributes = luatexbase.attributes
+
+    _G.attributes = _G.attributes or { }
+
+    _G.attributes.private = function (name)
+        local attr   = "otfl@" .. name
+        local number = the_attributes[attr]
+        if not number then
+            number = new_attribute(attr)
+        end
+        return number
+    end
+end
+
+%    \end{macrocode}
+%
+%
+%    \subsection{Callbacks}
+%
 %    After the fontloader is ready we can restore the callback trap from
 %    \identifier{luatexbase}.
 %
@@ -743,8 +810,8 @@ callback.register = trapped_register
 %
 %    We do our own callback handling with the means provided by luatexbase.
 %
-%    Note: \verb|pre_linebreak_filter| and \verb|hpack_filter| are coupled
-%    in \CONTEXT\ in the concept of \emphasis{node processor}.
+%    Note: \luafunction{pre_linebreak_filter} and \luafunction{hpack_filter}
+%    are coupled in \CONTEXT in the concept of \emph{node processor}.
 %
 %    \begin{macrocode}
 
@@ -776,26 +843,44 @@ if fonts and fonts.readers.tfm then
   fonts.readers.ofm  = fonts.readers.tfm
   fonts.handlers.ofm = fonts.handlers.tfm --- empty anyways
   fonts.formats.ofm  = fonts.formats.tfm  --- “type1”
+  --- fonts.readers.sequence[#fonts.readers.sequence+1] = "ofm"
   --------------------------------------------------------------------
 end
-loadmodule"font-pfb.lua"
 
+%    \end{macrocode}
+%
+%
+%    Now we load the modules written for \identifier{luaotfload}.
+%
+%    \begin{macrocode}
+loadmodule"font-pfb.lua"    --- new in 2.0, added 2011
 loadmodule"font-nms.lua"
 loadmodule"font-clr.lua"
-loadmodule"font-ltx.lua"
+loadmodule"font-ltx.lua"    --- new in 2.0, added 2011
+
+%    \end{macrocode}
+%
+%
+%    We create a callback for patching fonts on the fly, to be used by other
+%    packages.
+%    It initially contains the empty function that we are going to override
+%    below.
+%
+%    \begin{macrocode}
 
 create_callback("luaotfload.patch_font", "simple", dummy_function)
 
 %    \end{macrocode}
 %
+%
 %    This is a wrapper for the imported font loader.
-%    As of 2013, everything it does appears to be redundand, so we won’t use
-%    it.
+%    As of 2013, everything it does appear to be redundand, so we won’t use
+%    it unless somebody points out a cogent reason.
 %    Nevertheless, it has been adapted to work with the current structure of
-%    font data objects and will stay here for reference / until somebody
-%    reports breakage.
+%    font data objects and will stay here for reference / until breakage is
+%    reported.
 %
-%    TODO
+%    \emphasis{TODO}
 %    This one also enables patching fonts.
 %    The current fontloader apparently comes with a dedicated mechanism for
 %    that already: enhancers.
@@ -838,36 +923,36 @@ end
 
 %    \end{macrocode}
 %
+%
+%    \subsection{\CONTEXT override}
+%
 %    We provide a simplified version of the original font definition
 %    callback.
 %
 %    \begin{macrocode}
+
+local read_font_file = fonts.definers.read
 local patch_defined_font = function (...)
-    local tfmdata = fonts.definers.read(...)
+    local tfmdata = read_font_file(...)-- spec -> size -> id -> tmfdata
     if type(tfmdata) == "table" then
         call_callback("luaotfload.patch_font", tfmdata)
     end
-    --inspect(tfmdata.shared.features)
     return tfmdata
 end
 
-fonts.mode = "node"
 caches.compilemethod = "both"
 
-function attributes.private(name)
-    local attr   = "otfl@" .. name
-    local number = luatexbase.attributes[attr]
-    if not number then
-        number = luatexbase.new_attribute(attr)
-    end
-    return number
-end
-
 reset_callback("define_font")
 
+%    \end{macrocode}
+%
+%    Finally we register the callbacks
+%
+%    \begin{macrocode}
+
 if luaotfload.font_definer == "old"  then
   add_to_callback("define_font",
-                  old_define_font_wrapper,
+                  define_font_wrapper,
                   "luaotfload.define_font",
                   1)
 elseif luaotfload.font_definer == "generic"  then
@@ -884,30 +969,6 @@ end
 
 loadmodule"features.lua"
 
---[==[
----- is this still necessary?
-local set_sscale_diments = function (tfmdata)
-    local mathconstants = tfmdata.MathConstants
-    if mathconstants then
-        local tfmparameters = tfmdata.parameters
-        if mathconstants.ScriptPercentScaleDown then
-            tfmparameters[10] = mathconstants.ScriptPercentScaleDown
-        else -- resort to plain TeX default
-            tfmparameters[10] = 70
-        end
-        if mathconstants.ScriptScriptPercentScaleDown then
-            tfmparameters[11] = mathconstants.ScriptScriptPercentScaleDown
-        else -- resort to plain TeX default
-            tfmparameters[11] = 50
-        end
-    end
-end
-
-add_to_callback("luaotfload.patch_font",
-                set_sscale_diments,
-                "unicodemath.set_sscale_diments")
-]==]
-
 -- vim:tw=71:sw=4:ts=4:expandtab
 
 %    \end{macrocode}
-- 
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