From 5d1cb5619ea720968e01ec9a63422b2cc30295ef Mon Sep 17 00:00:00 2001
From: Determinant <ted.sybil@gmail.com>
Date: Sun, 24 May 2015 19:11:59 +0800
Subject: add utils.lua from Penlight

---
 pl/compat.lua | 137 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 137 insertions(+)
 create mode 100644 pl/compat.lua

(limited to 'pl/compat.lua')

diff --git a/pl/compat.lua b/pl/compat.lua
new file mode 100644
index 0000000..7959ac3
--- /dev/null
+++ b/pl/compat.lua
@@ -0,0 +1,137 @@
+----------------
+--- Lua 5.1/5.2 compatibility
+-- Ensures that `table.pack` and `package.searchpath` are available
+-- for Lua 5.1 and LuaJIT.
+-- The exported function `load` is Lua 5.2 compatible.
+-- `compat.setfenv` and `compat.getfenv` are available for Lua 5.2, although
+-- they are not always guaranteed to work.
+-- @module pl.compat
+
+local compat = {}
+
+compat.lua51 = _VERSION == 'Lua 5.1'
+
+--- execute a shell command.
+-- This is a compatibility function that returns the same for Lua 5.1 and Lua 5.2
+-- @param cmd a shell command
+-- @return true if successful
+-- @return actual return code
+function compat.execute (cmd)
+    local res1,res2,res2 = os.execute(cmd)
+    if compat.lua51 then
+        return res1==0,res1
+    else
+        return not not res1,res2
+    end
+end
+
+----------------
+-- Load Lua code as a text or binary chunk.
+-- @param ld code string or loader
+-- @param[opt] source name of chunk for errors
+-- @param[opt] mode 'b', 't' or 'bt'
+-- @param[opt] env environment to load the chunk in
+-- @function compat.load
+
+---------------
+-- Get environment of a function.
+-- With Lua 5.2, may return nil for a function with no global references!
+-- Based on code by [Sergey Rozhenko](http://lua-users.org/lists/lua-l/2010-06/msg00313.html)
+-- @param f a function or a call stack reference
+-- @function compat.setfenv
+
+---------------
+-- Set environment of a function
+-- @param f a function or a call stack reference
+-- @param env a table that becomes the new environment of `f`
+-- @function compat.setfenv
+
+if compat.lua51 then -- define Lua 5.2 style load()
+    if not tostring(assert):match 'builtin' then -- but LuaJIT's load _is_ compatible
+        local lua51_load = load
+        function compat.load(str,src,mode,env)
+            local chunk,err
+            if type(str) == 'string' then
+                if str:byte(1) == 27 and not (mode or 'bt'):find 'b' then
+                    return nil,"attempt to load a binary chunk"
+                end
+                chunk,err = loadstring(str,src)
+            else
+                chunk,err = lua51_load(str,src)
+            end
+            if chunk and env then setfenv(chunk,env) end
+            return chunk,err
+        end
+    else
+        compat.load = load
+    end
+    compat.setfenv, compat.getfenv = setfenv, getfenv
+else
+    compat.load = load
+    -- setfenv/getfenv replacements for Lua 5.2
+    -- by Sergey Rozhenko
+    -- http://lua-users.org/lists/lua-l/2010-06/msg00313.html
+    -- Roberto Ierusalimschy notes that it is possible for getfenv to return nil
+    -- in the case of a function with no globals:
+    -- http://lua-users.org/lists/lua-l/2010-06/msg00315.html
+    function compat.setfenv(f, t)
+        f = (type(f) == 'function' and f or debug.getinfo(f + 1, 'f').func)
+        local name
+        local up = 0
+        repeat
+            up = up + 1
+            name = debug.getupvalue(f, up)
+        until name == '_ENV' or name == nil
+        if name then
+            debug.upvaluejoin(f, up, function() return name end, 1) -- use unique upvalue
+            debug.setupvalue(f, up, t)
+        end
+        if f ~= 0 then return f end
+    end
+
+    function compat.getfenv(f)
+        local f = f or 0
+        f = (type(f) == 'function' and f or debug.getinfo(f + 1, 'f').func)
+        local name, val
+        local up = 0
+        repeat
+            up = up + 1
+            name, val = debug.getupvalue(f, up)
+        until name == '_ENV' or name == nil
+        return val
+    end
+end
+
+--- Lua 5.2 Functions Available for 5.1
+-- @section lua52
+
+--- pack an argument list into a table.
+-- @param ... any arguments
+-- @return a table with field n set to the length
+-- @return the length
+-- @function table.pack
+if not table.pack then
+    function table.pack (...)
+        return {n=select('#',...); ...}
+    end
+end
+
+------
+-- return the full path where a Lua module name would be matched.
+-- @param mod module name, possibly dotted
+-- @param path a path in the same form as package.path or package.cpath
+-- @see path.package_path
+-- @function package.searchpath
+if not package.searchpath then
+    local sep = package.config:sub(1,1)
+    function package.searchpath (mod,path)
+        mod = mod:gsub('%.',sep)
+        for m in path:gmatch('[^;]+') do
+            local nm = m:gsub('?',mod)
+            local f = io.open(nm,'r')
+            if f then f:close(); return nm end
+        end
+    end
+end
+
+return compat
-- 
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