beta 2013.04.01 14:16

1 files changed, 146 insertions, 0 deletions

diff --git a/tex/context/base/util-lib.lua b/tex/context/base/util-lib.lua
new file mode 100644
index 000000000..c987bdde3
--- /dev/null
+++ b/tex/context/base/util-lib.lua
@@ -0,0 +1,146 @@
+if not modules then modules = { } end modules ['util-lib'] = {
+    version   = 1.001,
+    comment   = "companion to luat-lib.mkiv",
+    author    = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
+    copyright = "PRAGMA ADE / ConTeXt Development Team",
+    license   = "see context related readme files",
+}
+
+-- This is experimental code for Hans and Luigi. Don't depend on it! There
+-- will be a plain variant.
+
+--[[
+
+The problem with library bindings is manyfold. They are of course platform
+dependent and while a binary with its directly related libraries are often
+easy to maintain and load, additional libraries can each have their demands.
+
+One important aspect is that loading additional libraries from within the
+loaded one is also operating system dependent. There can be shared libraries
+elsewhere on the system and as there can be multiple libraries with the same
+name but different usage and versioning there can be clashes. So there has to
+be some logic in where to look for these sublibraries.
+
+We found out that for instance on windows libraries are by default sought on
+the parents path and then on the binary paths and these of course can be in
+an out of our control, thereby enlarging the changes on a clash. A rather
+safe solution for that to load the library on the path where it sits.
+
+Another aspect is initialization. When you ask for a library t.e.x it will
+try to initialize luaopen_t_e_x no matter if such an inializer is present.
+However, because loading is configurable and in the case of luatex is already
+partly under out control, this is easy to deal with. We only have to make
+sure that we inform the loader that the library has been loaded so that
+it won't load it twice.
+
+In swiglib we have chosen for a clear organization and although one can use
+variants normally in the tex directory structure predictability is more or
+less the standard. For instance:
+
+..../tex/texmf-mswin/bin/swiglib/gmwand
+
+]]--
+
+local savedrequire = require
+local loaded = package.loaded
+local gsub, find = string.gsub, string.find
+
+--[[
+
+A request for t.e.x is converted to t/e/x.dll or t/e/x.so depending on the
+platform. Then we use the regular finder to locate the file in the tex
+directory structure. Once located we goto the path where it sits, load the
+file and return to the original path. We register as t.e.x in order to
+prevent reloading and also because the base name is seldom unique.
+
+]]--
+
+local function requireswiglib(required)
+    local library = loaded[required]
+    if not library then
+        local name = gsub(required,"%.","/") .. "." .. os.libsuffix
+        local full = resolvers.findfile(name,"lib")
+   --   local full = resolvers.findfile(name)
+        if not full or full == "" then
+            -- We can consider alternatives but we cannot load yet ... I
+            -- need to extent l-lua with a helper if we really want that.
+            --
+            -- package.helpers.trace = true
+            -- package.extraclibpath(environment.ownpath)
+        end
+        local path = file.pathpart(full)
+        local base = file.nameonly(full)
+        dir.push(path)
+     -- if false then
+     --     local savedlibrary = loaded[base]
+     --     library = savedrequire(base)
+     --     loaded[base] = savedlibrary
+     -- else
+            library = package.loadlib(full,"luaopen_" .. base)
+            if type(library) == "function" then
+                library = library()
+            else
+                -- some error
+            end
+     -- end
+        dir.pop()
+        loaded[required] = library
+    end
+    return library
+end
+
+--[[
+
+For convenience we make the require loader function swiglib aware. Alternatively
+we could put the specific loader in the global namespace.
+
+]]--
+
+function require(name,...) -- this might disappear or change
+    if find(name,"^swiglib%.") then
+        return requireswiglib(name,...)
+    else
+        return savedrequire(name,...)
+    end
+end
+
+--[[
+
+At the cost of some overhead we provide a specific loader so that we can keep
+track of swiglib usage which is handy for development.
+
+]]--
+
+local report_swiglib = logs.reporter("swiglib")
+
+local swiglibs = { }
+
+function swiglib(name)
+    local library = swiglibs[name]
+    if not library then
+        statistics.starttiming(swiglibs)
+        report_swiglib("loading %a",name)
+        library = requireswiglib("swiglib." .. name)
+        swiglibs[name] = library
+        statistics.stoptiming(swiglibs)
+    end
+    return library
+end
+
+statistics.register("used swiglibs", function()
+    if next(swiglibs) then
+        return string.format("%s, initial load time %s seconds",table.concat(table.sortedkeys(swiglibs)," "),statistics.elapsedtime(swiglibs))
+    end
+end)
+
+--[[
+
+So, we now have:
+
+----- gm = requireswiglib("swiglib.gmwand.core") -- most bare method (not public in context)
+local gm = require("swiglib.gmwand.core")        -- nicer integrated (maybe not in context)
+local gm = swiglib("gmwand.core")                -- the context way
+
+Watch out, the last one is less explicit and lacks the swiglib prefix.
+
+]]--