[main, init] move fontloader-specific stuff completely into init

1 files changed, 252 insertions, 0 deletions

diff --git a/src/luaotfload-init.lua b/src/luaotfload-init.lua
index 4968877..22ad704 100644
--- a/src/luaotfload-init.lua
+++ b/src/luaotfload-init.lua
@@ -57,3 +57,255 @@ local load_fontloader_module = luaotfload.loaders.fontloader
 
 load_luaotfload_module "log"
 
+local log             = luaotfload.log
+local logreport       = log.report
+
+log.set_loglevel (default_log_level)
+
+--[[doc--
+
+    \subsection{Preparing the Font Loader}
+    We treat the fontloader as a black box so behavior is consistent
+    between formats.
+    We load the fontloader code directly in the same fashion as the
+    Plain format \identifier{luatex-fonts} that is part of Context.
+    How this is executed depends on the presence on the
+    \emphasis{merged font loader code}.
+    In \identifier{luaotfload} this is contained in the file
+    \fileent{luaotfload-merged.lua}.
+    If this file cannot be found, the original libraries from \CONTEXT
+    of which the merged code was composed are loaded instead.
+    Since these files are not shipped with Luaotfload, an installation
+    of Context is required.
+    (Since we pull the fontloader directly from the Context minimals,
+    the necessary Context version is likely to be more recent than that
+    of other TeX distributions like Texlive.)
+    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.
+    However, this problem might vanish if we decide to do the merging
+    ourselves, like the \identifier{lualibs} package does.
+    With this step we would obtain the freedom to load our own
+    overrides in the process right where they are needed, at the cost
+    of losing encapsulation.
+    The decision on how to progress is currently on indefinite hold.
+
+--doc]]--
+
+local starttime         = os.gettimeofday ()
+local trapped_register  = callback.register
+callback.register = function (id)
+  logreport ("log", 4, "main",
+             "Dummy callback.register() invoked on %s.",
+             id)
+end
+
+
+--[[doc--
+
+    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{luaotfload@}” to
+    avoid name clashes.
+
+--doc]]--
+
+do
+    local new_attribute    = luatexbase.new_attribute
+    local the_attributes   = luatexbase.attributes
+
+    attributes = attributes or { }
+
+    attributes.private = function (name)
+        local attr   = "luaotfload@" .. name --- used to be: “otfl@”
+        local number = the_attributes[attr]
+        if not number then
+            number = new_attribute(attr)
+        end
+        return number
+    end
+end
+
+--[[doc--
+
+    These next lines replicate the behavior of
+    \fileent{luatex-fonts.lua}.
+
+--doc]]--
+
+local context_environment = { }
+
+local push_namespaces = function ()
+    logreport ("log", 4, "main", "push namespace for font loader")
+    local normalglobal = { }
+    for k, v in next, _G do
+        normalglobal[k] = v
+    end
+    return normalglobal
+end
+
+local pop_namespaces = function (normalglobal, isolate)
+    if normalglobal then
+        local _G = _G
+        local mode = "non-destructive"
+        if isolate then mode = "destructive" end
+        logreport ("log", 4, "main", "pop namespace from font loader -- " .. mode)
+        for k, v in next, _G do
+            if not normalglobal[k] then
+                context_environment[k] = v
+                if isolate then
+                    _G[k] = nil
+                end
+            end
+        end
+        for k, v in next, normalglobal do
+            _G[k] = v
+        end
+        -- just to be sure:
+        setmetatable(context_environment,_G)
+    else
+        logreport ("both", 0, "main",
+                   "irrecoverable error during pop_namespace: no globals to restore")
+        os.exit()
+    end
+end
+
+luaotfload.context_environment  = context_environment
+luaotfload.push_namespaces      = push_namespaces
+luaotfload.pop_namespaces       = pop_namespaces
+
+local our_environment = push_namespaces()
+
+--[[doc--
+
+    The font loader requires that the attribute with index zero be
+    zero. We happily oblige.
+    (Cf. \fileent{luatex-fonts-nod.lua}.)
+
+--doc]]--
+
+tex.attribute[0] = 0
+
+--[[doc--
+
+    Now that things are sorted out we can finally load the fontloader.
+
+    For less current distibutions we ship the code from TL 2014 that should be
+    compatible with Luatex 0.76.
+
+--doc]]--
+
+load_fontloader_module (luaotfload.fontloader_package)
+
+---load_fontloader_module "font-odv.lua" --- <= Devanagari support from Context
+
+if fonts then
+
+    --- The Initialization is highly idiosyncratic.
+
+    if not fonts._merge_loaded_message_done_ then
+        logreport ("log", 5, "main", [["I am using the merged fontloader here.]])
+        logreport ("log", 5, "main", [[ If you run into problems or experience unexpected]])
+        logreport ("log", 5, "main", [[ behaviour, and if you have ConTeXt installed you can try]])
+        logreport ("log", 5, "main", [[ to delete the file 'fontloader-fontloader.lua' as I might]])
+        logreport ("log", 5, "main", [[ then use the possibly updated libraries. The merged]])
+        logreport ("log", 5, "main", [[ version is not supported as it is a frozen instance.]])
+        logreport ("log", 5, "main", [[ Problems can be reported to the ConTeXt mailing list."]])
+    end
+    fonts._merge_loaded_message_done_ = true
+
+else--- the loading sequence is known to change, so this might have to
+    --- be updated with future updates!
+    --- do not modify it though unless there is a change to the merged
+    --- package!
+    load_fontloader_module "l-lua"
+    load_fontloader_module "l-lpeg"
+    load_fontloader_module "l-function"
+    load_fontloader_module "l-string"
+    load_fontloader_module "l-table"
+    load_fontloader_module "l-io"
+    load_fontloader_module "l-file"
+    load_fontloader_module "l-boolean"
+    load_fontloader_module "l-math"
+    load_fontloader_module "util-str"
+    load_fontloader_module "luatex-basics-gen"
+    load_fontloader_module "data-con"
+    load_fontloader_module "luatex-basics-nod"
+    load_fontloader_module "font-ini"
+    load_fontloader_module "font-con"
+    load_fontloader_module "luatex-fonts-enc"
+    load_fontloader_module "font-cid"
+    load_fontloader_module "font-map"
+    load_fontloader_module "luatex-fonts-syn"
+    load_fontloader_module "luatex-fonts-tfm"
+    load_fontloader_module "font-oti"
+    load_fontloader_module "font-otf"
+    load_fontloader_module "font-otb"
+    load_fontloader_module "luatex-fonts-inj"  --> since 2014-01-07, replaces node-inj.lua
+    load_fontloader_module "luatex-fonts-ota"
+    load_fontloader_module "luatex-fonts-otn"  --> since 2014-01-07, replaces font-otn.lua
+    load_fontloader_module "font-otp"          --> since 2013-04-23
+    load_fontloader_module "luatex-fonts-lua"
+    load_fontloader_module "font-def"
+    load_fontloader_module "luatex-fonts-def"
+    load_fontloader_module "luatex-fonts-ext"
+    load_fontloader_module "luatex-fonts-cbk"
+end --- non-merge fallback scope
+
+--[[doc--
+
+    Here we adjust the globals created during font loader
+    initialization. If the second argument to
+    \luafunction{pop_namespaces()} is \verb|true| this will restore the
+    state of \luafunction{_G}, eliminating every global generated since
+    the last call to \luafunction{push_namespaces()}. At the moment we
+    see no reason to do this, and since the font loader is considered
+    an essential part of \identifier{luatex} as well as a very well
+    organized piece of code, we happily concede it the right to add to
+    \luafunction{_G} if needed.
+
+--doc]]--
+
+pop_namespaces(our_environment, false)-- true)
+
+logreport ("both", 1, "main",
+           "fontloader loaded in %0.3f seconds", os.gettimeofday()-starttime)
+
+--[[doc--
+
+    \subsection{Callbacks}
+    After the fontloader is ready we can restore the callback trap from
+    \identifier{luatexbase}.
+
+--doc]]--
+
+callback.register = trapped_register
+
+--[[doc--
+
+    We do our own callback handling with the means provided by
+    luatexbase.
+    Note: \luafunction{pre_linebreak_filter} and
+    \luafunction{hpack_filter} are coupled in \CONTEXT in the concept
+    of \emphasis{node processor}.
+
+--doc]]--
+
+luatexbase.add_to_callback("pre_linebreak_filter",
+                           nodes.simple_font_handler,
+                           "luaotfload.node_processor",
+                           1)
+luatexbase.add_to_callback("hpack_filter",
+                           nodes.simple_font_handler,
+                           "luaotfload.node_processor",
+                           1)
+