1 files changed, 56 insertions, 0 deletions
diff --git a/tex/context/base/mkiv/data-dec.lua b/tex/context/base/mkiv/data-dec.lua
new file mode 100644
index 000000000..2a62b7dd9
--- /dev/null
+++ b/tex/context/base/mkiv/data-dec.lua
@@ -0,0 +1,56 @@
+if not modules then modules = { } end modules ['data-dec'] = {
+    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"
+}
+
+local loaddata = io.loaddata
+local suffix   = file.suffix
+local resultof = os.resultof
+
+local decompressors     = { }
+resolvers.decompressors = decompressors
+
+local decompresslzma = nil
+local decompressgzip = gzip.decompress
+
+local function decompressed(k)
+    local s = suffix(k)
+    if s == "xz" then
+        if decompresslzma == nil then
+            local lzma = require(resolvers.findfile("libs-imp-lzma.lmt"))
+            if lzma then
+                local decompress = lzma.decompress
+                decompresslzma = function(name)
+                    return decompress(loaddata(k))
+                end
+            else
+                decompresslzma = function(name)
+                    -- todo: use a proper runner
+                    return resultof("xz -d -c -q -q " .. name)
+                end
+            end
+        end
+        return decompresslzma(k)
+    elseif s == "gz" then
+        return decompressgzip(loaddata(k))
+    end
+end
+
+local cache = table.setmetatableindex(function(t,k)
+    local v = decompressed(k) or false
+    t[k] = v
+    return v
+end)
+
+decompressors.decompress = decompress
+
+function decompressors.register(filename)
+    return cache[filename]
+end
+
+function decompressors.unregister(filename)
+    cache[filename] = nil
+end