Merge pull request #280 from phi-gamma/master

refactor main a bit further; fix  #278

1 files changed, 256 insertions, 0 deletions

diff --git a/src/luaotfload-resolvers.lua b/src/luaotfload-resolvers.lua
new file mode 100644
index 0000000..42ea2fd
--- /dev/null
+++ b/src/luaotfload-resolvers.lua
@@ -0,0 +1,256 @@
+#!/usr/bin/env texlua
+-----------------------------------------------------------------------
+--         FILE:  luaotfload-resolvers.lua
+--        USAGE:  ./luaotfload-resolvers.lua 
+--  DESCRIPTION:  Resolvers for hooking into the fontloader
+-- REQUIREMENTS:  Luaotfload and a decent bit of courage
+--       AUTHOR:  Philipp Gesang (Phg), <phg@phi-gamma.net>
+--      VERSION:  1.0
+--      CREATED:  2015-07-23 07:31:50+0200
+-----------------------------------------------------------------------
+--
+--- The bare fontloader uses a set of simplistic file name resolvers
+--- that must be overloaded by the user (i. e. us).
+
+if not lualibs    then error "this module requires Luaotfload" end
+if not luaotfload then error "this module requires Luaotfload" end
+
+--[[doc--
+
+    Relying on the \verb|name:| resolver for everything has been the
+    source of permanent trouble with the database.
+    With the introduction of the new syntax parser we now have enough
+    granularity to distinguish between the \XETEX emulation layer and
+    the genuine \verb|name:| and \verb|file:| lookups of \LUATEX-Fonts.
+    Another benefit is that we can now easily plug in or replace new
+    lookup behaviors if necessary.
+    The name resolver remains untouched, but it calls
+    \luafunction{fonts.names.resolve()} internally anyways (see
+    \fileent{luaotfload-database.lua}).
+
+--doc]]--
+
+local next                = next
+local kpsefind_file       = kpse.find_file
+local lfsisfile           = lfs.isfile
+local stringlower         = string.lower
+local stringformat        = string.format
+local filesuffix          = file.suffix
+local fileremovesuffix    = file.removesuffix
+local formats             = fonts.formats
+local names               = fonts.names
+local encodings           = fonts.encodings
+local luatexbase          = luatexbase
+local logreport           = luaotfload.log.report
+
+formats.ofm               = "type1"
+encodings.known           = encodings.known or { }
+
+--[[doc--
+
+    \identifier{luaotfload} promises easy access to system fonts.
+    Without additional precautions, this cannot be achieved by
+    \identifier{kpathsea} alone, because it searches only the
+    \fileent{texmf} directories by default.
+    Although it is possible for \identifier{kpathsea} to include extra
+    paths by adding them to the \verb|OSFONTDIR| environment variable,
+    this is still short of the goal »\emphasis{it just works!}«.
+    When building the font database \identifier{luaotfload} scans
+    system font directories anyways, so we already have all the
+    information for looking sytem fonts.
+    With the release version 2.2 the file names are indexed in the
+    database as well and we are ready to resolve \verb|file:| lookups
+    this way.
+    Thus we no longer need to call the \identifier{kpathsea} library in
+    most cases when looking up font files, only when generating the
+    database, and when verifying the existence of a file in the
+    \fileent{texmf} tree.
+
+--doc]]--
+
+local resolve_file
+resolve_file = function (specification)
+    local name   = names.lookup_font_file (specification.name)
+    local suffix = filesuffix (name)
+    if formats[suffix] then
+        specification.forced      = stringlower (suffix)
+        specification.forcedname  = fileremovesuffix(name)
+    else
+        specification.name = name
+    end
+end
+
+--[[doc--
+
+    Prior to version 2.2, \identifier{luaotfload} did not distinguish
+    \verb|file:| and \verb|path:| lookups, causing complications with
+    the resolver.
+    Now we test if the requested name is an absolute path in the file
+    system, otherwise we fall back to the \verb|file:| lookup.
+
+--doc]]--
+
+local resolve_path
+resolve_path = function (specification)
+    local name       = specification.name
+    local exists, _  = lfsisfile(name)
+    if not exists then -- resort to file: lookup
+        logreport ("log", 0, "load",
+                   "path lookup of %q unsuccessful, falling back to file:",
+                   name)
+        resolve_file (specification)
+    else
+        local suffix = filesuffix (name)
+        if formats[suffix] then
+            specification.forced      = stringlower (suffix)
+            specification.name        = fileremovesuffix(name)
+            specification.forcedname  = name
+        else
+            specification.name = name
+        end
+    end
+end
+
+--[[doc--
+
+    The \verb|name:| resolver.
+
+--doc]]--
+
+--- fonts.names.resolvers.name -- Customized version of the
+--- generic name resolver.
+
+local resolve_name
+resolve_name = function (specification)
+    local resolver = names.lookup_font_name_cached
+    if config.luaotfload.run.resolver == "normal" then
+        resolver = names.lookup_font_name
+    end
+    local resolved, subfont = resolver (specification)
+    if resolved then
+        logreport ("log", 0, "load", "Lookup/name: %q -> \"%s%s\"",
+                   specification.name,
+                   resolved,
+                   subfont and stringformat ("(%d)", subfont) or "")
+        specification.resolved   = resolved
+        specification.sub        = subfont
+        specification.forced     = stringlower (filesuffix (resolved) or "")
+        specification.forcedname = resolved
+        specification.name       = fileremovesuffix (resolved)
+    else
+        resolve_file (specification)
+    end
+end
+
+--[[doc--
+
+    We classify as \verb|anon:| those requests that have neither a
+    prefix nor brackets. According to Khaled\footnote{%
+        % XXX dead link‽
+        \url{https://github.com/phi-gamma/luaotfload/issues/4#issuecomment-17090553}.
+    }
+    they are the \XETEX equivalent of a \verb|name:| request, so we
+    will be treating them as such or, at least, in a similar fashion.
+
+    Not distinguishing between “anon” and “name” requests has a serious
+    drawback: The syntax is overloaded for requesting fonts in
+    \identifier{Type1} (\abbrev{tfm}, \abbrev{ofm}) format.
+    These are essentially \verb|file:| lookups and must be caught
+    before the \verb|name:| resolver kicks in, lest they cause the
+    database to update.
+    Even if we were to require the \verb|file:| prefix for all
+    \identifier{Type1} requests, tests have shown that certain fonts
+    still include further fonts (e.~g. \fileent{omlgcb.ofm} will ask
+    for \fileent{omsecob.tfm}) \emphasis{using the old syntax}.
+    For this reason, we introduce an extra check with an early return.
+
+--doc]]--
+
+local type1_formats = { "tfm", "ofm", "TFM", "OFM", }
+
+local resolve_anon
+resolve_anon = function (specification)
+    local name = specification.name
+    for i=1, #type1_formats do
+        local format = type1_formats[i]
+        local suffix = filesuffix (name)
+        if resolvers.findfile(name, format) then
+            local usename = suffix == format and fileremovesuffix (name) or name
+            specification.forcedname = file.addsuffix (usename, format)
+            specification.forced     = format
+            return
+        end
+    end
+    --- under some weird circumstances absolute paths get
+    --- passed to the definer; we have to catch them
+    --- before the name: resolver misinterprets them.
+    name = specification.specification
+    local exists, _ = lfsisfile(name)
+    if exists then --- garbage; we do this because we are nice,
+                   --- not because it is correct
+        logreport ("log", 1, "load", "file %q exists", name)
+        logreport ("log", 1, "load",
+                   "... overriding borked anon: lookup with path: lookup")
+        specification.name = name
+        resolve_path (specification)
+        return
+    end
+    resolve_name (specification)
+end
+
+--[[doc--
+
+    {\bfseries EXPERIMENTAL}:
+    \identifier{kpse}-only resolver, for those who can do without
+    system fonts.
+
+--doc]]--
+
+local resolve_kpse
+resolve_kpse = function (specification)
+    local name       = specification.name
+    local suffix     = filesuffix (name)
+    if suffix and formats[suffix] then
+        name = fileremovesuffix (name)
+        if resolvers.findfile (name, suffix) then
+            specification.forced       = stringlower (suffix)
+            specification.forcedname   = name
+            return
+        end
+    end
+    for t, format in next, formats do --- brute force
+        if kpsefind_file (name, format) then
+            specification.forced = t
+            specification.name   = name
+            return
+        end
+    end
+end
+
+--[[doc--
+
+    Also {\bfseries EXPERIMENTAL}: custom file resolvers via callback.
+
+--doc]]--
+
+local resolve_my = function (specification)
+    luatexbase.call_callback ("luaotfload.resolve_font", specification)
+end
+
+return {
+    install = function ( )
+        luatexbase.create_callback ("luaotfload.resolve_font", "simple", function () end)
+        logreport ("log", 5, "resolvers", "installing font resolvers", name)
+        local request_resolvers = fonts.definers.resolvers
+        request_resolvers.file = resolve_file
+        request_resolvers.name = resolve_name
+        request_resolvers.anon = resolve_anon
+        request_resolvers.path = resolve_path
+        request_resolvers.kpse = resolve_kpse
+        request_resolvers.my   = resolve_my
+        return true
+    end, --- [.install]
+}
+
+--- vim:ft=lua:ts=8:sw=4:et
+