path: root/src/luaotfload-init.lua

#!/usr/bin/env texlua
-----------------------------------------------------------------------
--         FILE:  luaotfload-init.lua
--  DESCRIPTION:  Luaotfload font loader initialization
-- REQUIREMENTS:  luatex v.0.80 or later; packages lualibs, luatexbase
--       AUTHOR:  Philipp Gesang (Phg), <phg@phi-gamma.net>
--      VERSION:  1.0
--      CREATED:  2015-05-26 07:50:54+0200
-----------------------------------------------------------------------
--

--[[doc--

  Initialization phases:

      - Load Lualibs from package
      - Set up the logger routines
      - Load Fontloader
          - as package specified in configuration
          - from Context install
          - (optional: from raw unpackaged files distributed with
            Luaotfload)

  The initialization of the Lualibs may be made configurable in the
  future as well allowing to load both the files and the merged package
  depending on a configuration setting. However, this would require
  separating out the configuration parser into a self-contained
  package, which might be problematic due to its current dependency on
  the Lualibs itself.

--doc]]--

config                          = config or { }
local config                    = config
config.luaotfload               = config.luaotfload or { }

config.lualibs                  = config.lualibs or { }
config.lualibs.verbose          = false
config.lualibs.prefer_merged    = true
config.lualibs.load_extended    = true

require "lualibs"

if not lualibs    then error("this module requires Luaotfload") end
if not luaotfload then error("this module requires Luaotfload") end

local load_luaotfload_module = luaotfload.loaders.luaotfload
local load_fontloader_module = luaotfload.loaders.fontloader

--[[doc--

    The logger needs to be in place prior to loading the fontloader due
    to order of initialization being crucial for the logger functions
    that are swapped.

--doc]]--

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)

return {
  init = function ()
    init_prepare ()
    init_main ()
    init_cleanup ()
  end
}