beta 2013.02.18 15:46

22 files changed, 172 insertions, 74 deletions

diff --git a/tex/context/base/cont-new.mkii b/tex/context/base/cont-new.mkii
index 02c90c61b..a982a819a 100644
--- a/tex/context/base/cont-new.mkii
+++ b/tex/context/base/cont-new.mkii
@@ -11,7 +11,7 @@
 %C therefore copyrighted by \PRAGMA. See mreadme.pdf for
 %C details.
 
-\newcontextversion{2013.02.13 18:06}
+\newcontextversion{2013.02.18 15:46}
 
 %D This file is loaded at runtime, thereby providing an
 %D excellent place for hacks, patches, extensions and new
diff --git a/tex/context/base/cont-new.mkiv b/tex/context/base/cont-new.mkiv
index c9781dc1b..6e45607a8 100644
--- a/tex/context/base/cont-new.mkiv
+++ b/tex/context/base/cont-new.mkiv
@@ -11,7 +11,7 @@
 %C therefore copyrighted by \PRAGMA. See mreadme.pdf for
 %C details.
 
-\newcontextversion{2013.02.13 18:06}
+\newcontextversion{2013.02.18 15:46}
 
 %D This file is loaded at runtime, thereby providing an excellent place for
 %D hacks, patches, extensions and new features.
diff --git a/tex/context/base/context-version.pdf b/tex/context/base/context-version.pdf
index efe94e504..8bf8163b4 100644
--- a/tex/context/base/context-version.pdf
+++ b/tex/context/base/context-version.pdf
diff --git a/tex/context/base/context-version.png b/tex/context/base/context-version.png
index 1aaafe23f..91c290491 100644
--- a/tex/context/base/context-version.png
+++ b/tex/context/base/context-version.png
diff --git a/tex/context/base/context.mkii b/tex/context/base/context.mkii
index 26687ca61..86748141b 100644
--- a/tex/context/base/context.mkii
+++ b/tex/context/base/context.mkii
@@ -20,7 +20,7 @@
 %D your styles an modules.
 
 \edef\contextformat {\jobname}
-\edef\contextversion{2013.02.13 18:06}
+\edef\contextversion{2013.02.18 15:46}
 
 %D For those who want to use this:
 
diff --git a/tex/context/base/context.mkiv b/tex/context/base/context.mkiv
index 9782937a5..f31e16ad4 100644
--- a/tex/context/base/context.mkiv
+++ b/tex/context/base/context.mkiv
@@ -25,7 +25,7 @@
 %D up and the dependencies are more consistent.
 
 \edef\contextformat {\jobname}
-\edef\contextversion{2013.02.13 18:06}
+\edef\contextversion{2013.02.18 15:46}
 
 %D For those who want to use this:
 
diff --git a/tex/context/base/l-file.lua b/tex/context/base/l-file.lua
index 3cc670f5e..1bde59522 100644
--- a/tex/context/base/l-file.lua
+++ b/tex/context/base/l-file.lua
@@ -12,6 +12,10 @@ file       = file or { }
 local file = file
 
 if not lfs then
+    lfs = optionalrequire("lfs")
+end
+
+if not lfs then
 
     lfs = {
         getcurrentdir = function()
diff --git a/tex/context/base/l-lua.lua b/tex/context/base/l-lua.lua
index b62b7b070..7c78a4031 100644
--- a/tex/context/base/l-lua.lua
+++ b/tex/context/base/l-lua.lua
@@ -41,12 +41,11 @@ end
 
 -- table:
 
--- Starting with version 5.2 Lua no longer provide ipairs, which makes
--- sense. As we already used the for loop and # in most places the
--- impact on ConTeXt was not that large; the remaining ipairs already
--- have been replaced. In a similar fashion we also hardly used pairs.
---
--- Hm, actually ipairs was retained, but we no longer use it anyway.
+-- At some point it was announced that i[pairs would be dropped, which makes
+-- sense. As we already used the for loop and # in most places the impact on
+-- ConTeXt was not that large; the remaining ipairs already have been replaced.
+-- Hm, actually ipairs was retained, but we no longer use it anyway (nor
+-- pairs).
 --
 -- Just in case, we provide the fallbacks as discussed in Programming
 -- in Lua (http://www.lua.org/pil/7.3.html):
@@ -137,3 +136,14 @@ function inspect(...) -- global function
         end
     end
 end
+
+--
+
+local dummy = function() end
+
+function optionalrequire(...)
+    local ok, result = xpcall(require,dummy,...)
+    if ok then
+        return result
+    end
+end
diff --git a/tex/context/base/l-md5.lua b/tex/context/base/l-md5.lua
index c19c8248d..01f17d924 100644
--- a/tex/context/base/l-md5.lua
+++ b/tex/context/base/l-md5.lua
@@ -8,6 +8,10 @@ if not modules then modules = { } end modules ['l-md5'] = {
 -- This also provides file checksums and checkers.
 
 if not md5 then
+    md5 = optionalrequire("md5")
+end
+
+if not md5 then
     md5 = {
         sum     = function(str) print("error: md5 is not loaded (sum     ignored)") return str end,
         sumhexa = function(str) print("error: md5 is not loaded (sumhexa ignored)") return str end,
diff --git a/tex/context/base/math-vfu.lua b/tex/context/base/math-vfu.lua
index 70d5e5514..418b9cc1b 100644
--- a/tex/context/base/math-vfu.lua
+++ b/tex/context/base/math-vfu.lua
@@ -605,7 +605,7 @@ function vfmath.define(specification,set,goodies)
         end
     end
     -- beware, loaded[1] is already passed to tex (we need to make a simple copy then .. todo)
-    local parent         = loaded[1] -- a text font
+    local parent         = loaded[1] or { } -- a text font
     local characters     = { }
     local parameters     = { }
     local mathparameters = { }
diff --git a/tex/context/base/meta-ini.mkiv b/tex/context/base/meta-ini.mkiv
index 0f474fefe..6e660bdb6 100644
--- a/tex/context/base/meta-ini.mkiv
+++ b/tex/context/base/meta-ini.mkiv
@@ -4,23 +4,61 @@
 %D          title=\METAPOST\ Graphics,
 %D       subtitle=Initialization,
 %D         author=Hans Hagen,
-%D           date=\currentdate,
+%D           date=\ currentdate,
 %D      copyright={PRAGMA ADE \& \CONTEXT\ Development Team}]
 %C
 %C This module is part of the \CONTEXT\ macro||package and is
 %C therefore copyrighted by \PRAGMA. See mreadme.pdf for
 %C details.
 
+% initializations:
+%
+% - pass settings from tex to mp (delayed expansion)
+% - used by context core (and modules)
+% - cummulative definitions
+% - flushed each graphic
+% - can be disabled per instance
+% - managed at the tex end
+%
+% extensions:
+%
+% - add mp functionality (immediate expansion)
+% - cummulative
+% - all instances or subset of instances
+% - can be disabled per instance
+% - managed at the lua/mp end
+% - could be managed at the tex end but no real reason and also messy
+%
+% definitions:
+%
+% - add mp functionality (delayed expansion)
+% - cummulative
+% - per instance
+% - managed at the tex end
+%
+% inclusions:
+%
+% - add mp functionality (delayed expansion)
+% - cummulative only when [+]
+% - per instance
+% - managed at the tex end
+%
+% order of execution:
+%
+%   definitions
+%   extensions
+%   inclusions
+%   beginfig
+%     initializations
+%     graphic
+%   endfig
+
 \writestatus{loading}{MetaPost Graphics / Initializations}
 
 \registerctxluafile{meta-ini}{1.001}
 
 \unprotect
 
-\newtoks \t_meta_extensions       % mp, once
-\newtoks \t_meta_initializations  % tex, each
-\newtoks \t_meta_userinclusions   % mp, user
-
 \newtoks \everyMPgraphic          % mp % public or not ?
 
 \appendtoks
@@ -33,11 +71,16 @@
 
 %installcorenamespace{graphicvariable} % todo
 \installcorenamespace{mpinstance}
-\installcorenamespace{mpinstancetokens}
+\installcorenamespace{mpinclusions}
+\installcorenamespace{mpdefinitions}
 \installcorenamespace{mpgraphic}
 \installcorenamespace{mpstaticgraphic}
 \installcorenamespace{mpclip}
 
+\newtoks \t_meta_initializations  % tex, each
+\def     \t_meta_inclusions     {\csname\??mpinclusions \currentMPinstance\endcsname} % token register
+\def     \t_meta_definitions    {\csname\??mpdefinitions\currentMPinstance\endcsname} % token register
+
 % The next command is, of course, dedicated to Mojca, who
 % needs it for gnuplot. Anyway, the whole multiple engine
 % mechanism is to keep her gnuplot from interfering.
@@ -56,8 +99,11 @@
 
 \let\stopMPdefinitions\relax
 
-\unexpanded\def\startMPextensions#1\stopMPextensions % for all instances, when enabled
-  {\global\t_meta_extensions\expandafter{\the\t_meta_extensions#1}}
+\unexpanded\def\startMPextensions
+  {\dosinglegroupempty\meta_start_extensions}
+
+\def\meta_start_extensions#1#2\stopMPextensions % we could use buffers instead
+  {\ctxlua{metapost.setextensions("#1",\!!bs#2\!!es)}}
 
 \let\stopMPextensions\relax
 
@@ -69,24 +115,42 @@
 \unexpanded\def\startMPinclusions
   {\dosingleempty\meta_start_inclusions}
 
-\def\meta_start_inclusions[#1]#2\stopMPinclusions
+\unexpanded\def\meta_start_inclusions[#1]%
   {\edef\m_meta_option{#1}%
+   \dosinglegroupempty\meta_start_inclusions_indeed}
+
+\def\meta_start_inclusions_indeed#1#2\stopMPinclusions
+  {\let\m_meta_saved_instance\currentMPinstance
+   \edef\currentMPinstance{#1}%
+   \ifx\currentMPinstance\empty
+     \let\currentMPinstance\defaultMPinstance
+   \fi
    \ifx\m_meta_option\!!plustoken \else
-     \global\t_meta_userinclusions\emptytoks
+     \global\t_meta_inclusions\emptytoks
    \fi
-   \global\t_meta_userinclusions\expandafter{\the\t_meta_userinclusions#2}}
+   \global\t_meta_inclusions\expandafter{\the\t_meta_inclusions#2}%
+   \let\currentMPinstance\m_meta_saved_instance}
 
 \let\stopMPinclusions\relax
 
 \unexpanded\def\MPinclusions
   {\dosingleempty\meta_inclusions}
 
-\def\meta_inclusions[#1]#2%
+\def\meta_inclusions[#1]%
   {\edef\m_meta_option{#1}%
+   \dosinglegroupempty\meta_inclusions_indeed}
+
+\def\meta_inclusions_indeed#1#2%
+  {\let\m_meta_saved_instance\currentMPinstance
+   \edef\currentMPinstance{#1}%
+   \ifx\currentMPinstance\empty
+     \let\currentMPinstance\defaultMPinstance
+   \fi
    \ifx\m_meta_option\!!plustoken \else
-     \global\t_meta_userinclusions\emptytoks
+     \global\t_meta_inclusions\emptytoks
    \fi
-   \global\t_meta_userinclusions\expandafter{\the\t_meta_userinclusions#2}}
+   \global\t_meta_inclusions\expandafter{\the\t_meta_inclusions#2}%
+   \let\currentMPinstance\m_meta_saved_instance}
 
 \def\meta_preset_definitions
   {\edef\overlaywidth    {\overlaywidth    \space}%
@@ -95,8 +159,6 @@
    \edef\currentwidth    {\the\hsize       \space}%
    \edef\currentheight   {\the\vsize       \space}}
 
-\def\t_meta_definitions{\csname\??mpinstancetokens\currentMPinstance\endcsname} % token register
-
 \installcommandhandler \??mpinstance {MPinstance} \??mpinstance
 
 \setupMPinstance
@@ -108,10 +170,14 @@
    \c!textcolor=]
 
 \appendtoks
-    \ifcsname\??mpinstancetokens\currentMPinstance\endcsname \else
-        \expandafter\newtoks\csname\??mpinstancetokens\currentMPinstance\endcsname
+    \ifcsname\??mpdefinitions\currentMPinstance\endcsname \else
+        \expandafter\newtoks\csname\??mpdefinitions\currentMPinstance\endcsname
+    \fi
+    \ifcsname\??mpinclusions\currentMPinstance\endcsname \else
+        \expandafter\newtoks\csname\??mpinclusions\currentMPinstance\endcsname
     \fi
     \t_meta_definitions\emptytoks % in case we redefine
+    \t_meta_inclusions \emptytoks % in case we redefine
 \to \everydefineMPinstance
 
 \unexpanded\def\resetMPinstance[#1]%
@@ -125,7 +191,7 @@
    \ifx\currentMPgraphicname\empty
      \edef\currentMPgraphicname{#1}%
      \let\currentMPinstance\defaultMPinstance
-   \else\ifcsname\??mpinstancetokens#1\endcsname
+   \else\ifcsname\??mpdefinitions#1\endcsname
      \edef\currentMPinstance{#1}%
    \else
      \let\currentMPinstance\defaultMPinstance
@@ -143,7 +209,6 @@
 \defineMPinstance[metapost]  [\s!format=mpost]
 \defineMPinstance[nofun]     [\s!format=mpost]
 
-\newconditional\c_meta_include_extensions
 \newconditional\c_meta_include_initializations
 
 \def\meta_begin_graphic_group#1%
@@ -161,44 +226,18 @@
    \fi
    \theMPrandomseed;}
 
-% \def\meta_flush_current_preamble
-%   {\ifconditional\c_meta_include_extensions
-%      \the\t_meta_extensions
-%      \the\t_meta_userinclusions
-%    \fi}
-
-\def\meta_flush_current_extensions
-  {\ifconditional\c_meta_include_extensions
-     \the\t_meta_extensions
-   \fi}
-
-\def\meta_flush_current_userinclusions
-  {\ifconditional\c_meta_include_extensions
-     \the\t_meta_userinclusions
-   \fi}
+\def\meta_flush_current_inclusions
+  {\the\t_meta_inclusions}
 
 \def\meta_flush_current_definitions
   {\the\t_meta_definitions}
 
-\def\meta_reset_current_preamble
-  {\ifconditional\c_meta_include_extensions
-     \global\t_meta_extensions\emptytoks
-   \fi}
-
 \def\meta_start_current_graphic
   {\begingroup
    \meta_enable_include
    \the\everyMPgraphic
    \meta_preset_definitions
    \setMPrandomseed % this has to change
-   % we need to preexpand the token lists
-   \edef\p_extensions{\MPinstanceparameter\s!extensions}%
-   \ifx\p_extensions\v!yes
-     \settrue \c_meta_include_extensions
-    %\global\letMPinstanceparameter\s!extensions\v!no % needs checking
-   \else
-     \setfalse\c_meta_include_extensions
-   \fi
    \edef\p_initializations{\MPinstanceparameter\s!initializations}%
    \ifx\p_initializations\v!yes
      \settrue \c_meta_include_initializations
@@ -213,6 +252,7 @@
 
 \def\meta_stop_current_graphic
   {\global\t_meta_definitions\emptytoks
+   \global\t_meta_inclusions\emptytoks
    \endgroup}
 
 \def\meta_process_graphic_start
@@ -231,14 +271,13 @@
        format          = "\currentMPformat",
        data            = \!!bs#1;\!!es,
        initializations = \!!bs\meta_flush_current_initializations\!!es,
-       extensions      = \!!bs\meta_flush_current_extensions\!!es,
-       inclusions      = \!!bs\meta_flush_current_userinclusions\!!es,
+       useextensions   = "\MPinstanceparameter\s!extensions",
+       inclusions      = \!!bs\meta_flush_current_inclusions\!!es,
        definitions     = \!!bs\meta_flush_current_definitions\!!es,
        figure          = "\MPaskedfigure",
        method          = "\MPinstanceparameter\c!method",
      }}}%
    \meta_process_graphic_stop
-   \meta_reset_current_preamble
    \meta_stop_current_graphic}
 
 \let\meta_process_graphic_figure_start\relax
@@ -339,12 +378,11 @@
             format          = "\currentMPformat",
             data            = \!!bs\getvalue{\??mpclip#1}\!!es,
             initializations = \!!bs\meta_flush_current_initializations\!!es,
-            extensions      = \!!bs\meta_flush_current_extensions\!!es,
-            inclusions      = \!!bs\meta_flush_current_userinclusions\!!es,
+            useextensions   = "\MPinstanceparameter\s!extensions",
+            inclusions      = \!!bs\meta_flush_current_inclusions\!!es,
             method          = "\MPinstanceparameter\c!method",
        }}}}%
      \meta_stop_current_graphic
-     \meta_reset_current_preamble
      \ifx\MPclippath\empty
        \xdef\MPclippath{#4}%
      \fi
diff --git a/tex/context/base/mlib-ctx.lua b/tex/context/base/mlib-ctx.lua
index 5d976d161..a795b0214 100644
--- a/tex/context/base/mlib-ctx.lua
+++ b/tex/context/base/mlib-ctx.lua
@@ -9,6 +9,7 @@ if not modules then modules = { } end modules ['mlib-ctx'] = {
 -- todo
 
 local format, concat = string.format, table.concat
+local settings_to_hash = utilities.parsers.settings_to_hash
 
 local report_metapost = logs.reporter("metapost")
 
@@ -19,6 +20,8 @@ local mplib = mplib
 metapost       = metapost or {}
 local metapost = metapost
 
+local v_no = interfaces.variables.no
+
 metapost.defaultformat   = "metafun"
 metapost.defaultinstance = "metafun"
 metapost.defaultmethod   = "default"
@@ -42,6 +45,38 @@ local function setmpsformat(specification)
     specification.mpx = metapost.format(instance,format,method)
 end
 
+local extensiondata    = metapost.extensiondata or storage.allocate { }
+metapost.extensiondata = extensiondata
+
+storage.register("metapost/extensiondata",extensiondata,"metapost.extensiondata")
+
+function metapost.setextensions(instances,data)
+    if data and data ~= "" then
+        extensiondata[#extensiondata+1] = {
+            usedinall  = not instances or instances == "",
+            instances  = settings_to_hash(instances or ""),
+            extensions = data,
+        }
+    end
+end
+
+function metapost.getextensions(instance,state)
+    if state and state == v_no then
+        return ""
+    else
+        local t = { }
+        for i=1,#extensiondata do
+            local e = extensiondata[i]
+            local status = e.instances[instance]
+            if (status ~= true) and (e.usedinall or status) then
+                t[#t+1] = e.extensions
+                e.instances[instance] = true
+            end
+        end
+        return concat(t," ")
+    end
+end
+
 function metapost.graphic(specification)
     setmpsformat(specification)
     metapost.graphic_base_pass(specification)
diff --git a/tex/context/base/mlib-pdf.mkiv b/tex/context/base/mlib-pdf.mkiv
index f000e9a10..f55888107 100644
--- a/tex/context/base/mlib-pdf.mkiv
+++ b/tex/context/base/mlib-pdf.mkiv
@@ -145,8 +145,8 @@
        format          = "\currentMPformat",
        data            = \!!bs#2;\!!es,
        initializations = \!!bs\meta_flush_current_initializations\!!es,
-       extensions      = \!!bs\meta_flush_current_extensions\!!es,
-       inclusions      = \!!bs\meta_flush_current_userinclusions\!!es,
+       useextensions   = "\MPinstanceparameter\s!extensions",
+       inclusions      = \!!bs\meta_flush_current_inclusions\!!es,
        definitions     = \!!bs\meta_flush_current_definitions\!!es,
        figure          = "all",
        method          = "\MPinstanceparameter\c!method",
diff --git a/tex/context/base/mlib-pps.lua b/tex/context/base/mlib-pps.lua
index 8e69066d0..c98bef8b8 100644
--- a/tex/context/base/mlib-pps.lua
+++ b/tex/context/base/mlib-pps.lua
@@ -539,7 +539,7 @@ function metapost.graphic_base_pass(specification)
     local mpx = specification.mpx -- mandate
     local data = specification.data or ""
     local definitions = specification.definitions or ""
-    local extensions = specification.extensions or ""
+    local extensions = metapost.getextensions(specification.instance,specification.useextensions) -- specification.extensions or ""
     local inclusions = specification.inclusions or ""
     local initializations = specification.initializations or ""
     local askedfig = specification.figure -- no default else no wrapper
diff --git a/tex/context/base/mlib-run.lua b/tex/context/base/mlib-run.lua
index 18abf5aae..35cbd40f5 100644
--- a/tex/context/base/mlib-run.lua
+++ b/tex/context/base/mlib-run.lua
@@ -302,7 +302,7 @@ else
             find_file   = finder,
             math_mode   = method,
         }
-report_metapost("initializing number mode %q",method)
+        report_metapost("initializing number mode %q",method)
         local result
         if not mpx then
             result = { status = 99, error = "out of memory"}
diff --git a/tex/context/base/status-files.pdf b/tex/context/base/status-files.pdf
index 4bf36f0f7..ce0c19c1f 100644
--- a/tex/context/base/status-files.pdf
+++ b/tex/context/base/status-files.pdf
diff --git a/tex/context/base/status-lua.pdf b/tex/context/base/status-lua.pdf
index 66c3581c1..a44b8d25e 100644
--- a/tex/context/base/status-lua.pdf
+++ b/tex/context/base/status-lua.pdf
diff --git a/tex/context/base/util-sql-imp-client.lua b/tex/context/base/util-sql-imp-client.lua
index b53bc2dda..d660a4a58 100644
--- a/tex/context/base/util-sql-imp-client.lua
+++ b/tex/context/base/util-sql-imp-client.lua
@@ -234,7 +234,7 @@ local booleanstring = string.booleanstring
 return function(data)
     for i=1,#data do
         local cells = data[i]
-        data[i] = {
+        data[%s] = {
             %s
         }
     end
diff --git a/tex/context/base/util-sql-imp-library.lua b/tex/context/base/util-sql-imp-library.lua
index 3167b95f5..a9983cbca 100644
--- a/tex/context/base/util-sql-imp-library.lua
+++ b/tex/context/base/util-sql-imp-library.lua
@@ -265,7 +265,7 @@ return function(result)
     local data = { }
     for i=1,nofrows do
         local cells = { result:fetch() }
-        data[i] = {
+        data[%s] = {
             %s
         }
     end
diff --git a/tex/context/base/util-sql-imp-swiglib.lua b/tex/context/base/util-sql-imp-swiglib.lua
index d923dec3d..d681ace13 100644
--- a/tex/context/base/util-sql-imp-swiglib.lua
+++ b/tex/context/base/util-sql-imp-swiglib.lua
@@ -406,7 +406,7 @@ return function(result)
      -- local len = mysql_fetch_lengths(result)
      -- local cells = util_unpackbytearray(row,noffields,len)
         local cells = util_mysql_fetch_fields_from_current_row(result)
-        data[i] = {
+        data[%s] = {
             %s
         }
     end
diff --git a/tex/context/base/util-sql.lua b/tex/context/base/util-sql.lua
index 5d57c22f5..42bf3dc88 100644
--- a/tex/context/base/util-sql.lua
+++ b/tex/context/base/util-sql.lua
@@ -125,6 +125,7 @@ sql.converters   = converters
 local function makeconverter(entries,celltemplate,wraptemplate)
     local shortcuts   = { }
     local assignments = { }
+    local key         = false
     for i=1,#entries do
         local entry = entries[i]
         local name  = entry.name
@@ -146,11 +147,14 @@ local function makeconverter(entries,celltemplate,wraptemplate)
             assignments[i] = format("[%q] = tab_%s[%s],",name,#converters,value)
         elseif kind == "deserialize" then
             assignments[i] = format("[%q] = deserialize(%s),",name,value)
+        elseif kind == "key" then
+            key = value -- hashed instead of indexed
         else
             assignments[i] = format("[%q] = %s,",name,value)
         end
     end
-    local code = format(wraptemplate,concat(shortcuts,"\n"),concat(assignments,"\n            "))
+    local code = format(wraptemplate,concat(shortcuts,"\n"),key or "i",concat(assignments,"\n            "))
+ -- print(code)
     local func = load(code)
     return func and func()
 end
diff --git a/tex/generic/context/luatex/luatex-fonts-merged.lua b/tex/generic/context/luatex/luatex-fonts-merged.lua
index 6b4b8709a..61dea0c9b 100644
--- a/tex/generic/context/luatex/luatex-fonts-merged.lua
+++ b/tex/generic/context/luatex/luatex-fonts-merged.lua
@@ -1,6 +1,6 @@
 -- merged file : luatex-fonts-merged.lua
 -- parent file : luatex-fonts.lua
--- merge date  : 02/13/13 18:06:17
+-- merge date  : 02/18/13 15:46:30
 
 do -- begin closure to overcome local limits and interference
 
@@ -1852,6 +1852,9 @@ if not modules then modules={} end modules ['l-file']={
 file=file or {}
 local file=file
 if not lfs then
+  lfs=optionalrequire("lfs")
+end
+if not lfs then
   lfs={
     getcurrentdir=function()
       return "."