Make '*' optional for io.read() and io.lines().

Author: siffiejoe

compat53/module.lua

@@ -9,8 +9,11 @@ if lua_version < "5.3" then
    -- cache globals in upvalues
    local error, ipairs, pairs, pcall, require, select, setmetatable, type =
          error, ipairs, pairs, pcall, require, select, setmetatable, type
-   local debug, math, package, string, table =
-         debug, math, package, string, table
+   local debug, io, math, package, string, table =
+         debug, io, math, package, string, table
+   local io_lines = io.lines
+   local io_read = io.read
+   local unpack = lua_version == "5.1" and unpack or table.unpack
 
    -- create module table
    M = {}
@@ -21,6 +24,7 @@ if lua_version < "5.3" then
    setmetatable(M, M_meta)
 
    -- create subtables
+   M.io = setmetatable({}, { __index = io })
    M.math = setmetatable({}, { __index = math })
    M.string = setmetatable({}, { __index = string })
    M.table = setmetatable({}, { __index = table })
@@ -148,15 +152,13 @@ if lua_version < "5.3" then
 
 
    -- assert should allow non-string error objects
-   do
-      function M.assert(cond, ...)
-         if cond then
-            return cond, ...
-         elseif select('#', ...) > 0 then
-            error((...), 0)
-         else
-            error("assertion failed!", 0)
-         end
+   function M.assert(cond, ...)
+      if cond then
+         return cond, ...
+      elseif select('#', ...) > 0 then
+         error((...), 0)
+      else
+         error("assertion failed!", 0)
       end
    end
 
@@ -180,13 +182,63 @@ if lua_version < "5.3" then
    end
 
 
+   -- make '*' optional for io.read and io.lines
+   do
+      local function addasterisk(fmt)
+         if type(fmt) == "string" and fmt:sub(1, 1) ~= "*" then
+            return "*"..fmt
+         else
+            return fmt
+         end
+      end
+
+      function M.io.read(...)
+         local n = select('#', ...)
+         for i = 1, n do
+            local a = select(i, ...)
+            local b = addasterisk(a)
+            -- as an optimization we only allocate a table for the
+            -- modified format arguments when we have a '*' somewhere.
+            if a ~= b then
+               local args = { ... }
+               args[i] = b
+               for j = i+1, n do
+                  args[j] = addasterisk(args[j])
+               end
+               return io_read(unpack(args, 1, n))
+            end
+         end
+         return io_read(...)
+      end
+
+      -- PUC-Rio Lua 5.1 uses a different implementation for io.lines!
+      function M.io.lines(...)
+         local n = select('#', ...)
+         for i = 2, n do
+            local a = select(i, ...)
+            local b = addasterisk(a)
+            -- as an optimization we only allocate a table for the
+            -- modified format arguments when we have a '*' somewhere.
+            if a ~= b then
+               local args = { ... }
+               args[i] = b
+               for j = i+1, n do
+                  args[j] = addasterisk(args[j])
+               end
+               return io_lines(unpack(args, 1, n))
+            end
+         end
+         return io_lines(...)
+      end
+   end
+
+
    -- update table library (if C module not available)
    if not table_ok then
       local table_concat = table.concat
       local table_insert = table.insert
       local table_remove = table.remove
       local table_sort = table.sort
-      local table_unpack = lua_version == "5.1" and unpack or table.unpack
 
       function M.table.concat(list, sep, i, j)
          local mt = gmt(list)
@@ -344,7 +396,7 @@ if lua_version < "5.3" then
             i, j = i or 1, j or (has_len and mt.__len(list)) or #list
             return unpack_helper(list, i, j)
          else
-            return table_unpack(list, i, j)
+            return unpack(list, i, j)
          end
       end
    end -- update table library
@@ -358,9 +410,9 @@ if lua_version < "5.3" then
         #setmetatable({}, { __len = function() return 1 end }) == 1
 
       -- cache globals in upvalues
-      local load, loadfile, loadstring, setfenv, unpack, xpcall =
-            load, loadfile, loadstring, setfenv, unpack, xpcall
-      local coroutine, io, os = coroutine, io, os
+      local load, loadfile, loadstring, setfenv, xpcall =
+            load, loadfile, loadstring, setfenv, xpcall
+      local coroutine, os = coroutine, os
       local coroutine_create = coroutine.create
       local coroutine_resume = coroutine.resume
       local coroutine_running = coroutine.running
@@ -382,7 +434,6 @@ if lua_version < "5.3" then
 
       -- create subtables
       M.coroutine = setmetatable({}, { __index = coroutine })
-      M.io = setmetatable({}, { __index = io })
       M.os = setmetatable({}, { __index = os })
       M.package = setmetatable({}, { __index = package })
 
@@ -734,8 +785,6 @@ if lua_version < "5.3" then
             return helper(st, st.f:read(unpack(st, 1, st.n)))
          end
 
-         local valid_format = { ["*l"] = true, ["*n"] = true, ["*a"] = true }
-
          function M.io.lines(fname, ...)
             local doclose, file, msg
             if fname ~= nil then
@@ -746,8 +795,15 @@ if lua_version < "5.3" then
             end
             local st = { f=file, doclose=doclose, n=select('#', ...), ... }
             for i = 1, st.n do
-               if type(st[i]) ~= "number" and not valid_format[st[i]] then
-                 error("bad argument #"..(i+1).." to 'for iterator' (invalid format)", 2)
+               local t = type(st[i])
+               if t == "string" then
+                  local fmt = st[i]:match("^%*?([aln])")
+                  if not fmt then
+                     error("bad argument #"..(i+1).." to 'for iterator' (invalid format)", 2)
+                  end
+                  st[i] = "*"..fmt
+               elseif t ~= "number" then
+                  error("bad argument #"..(i+1).." to 'for iterator' (invalid format)", 2)
                end
             end
             return lines_iterator, st

tests/test.lua

@@ -537,6 +537,18 @@ do
 end
 
 
+___''
+do
+   writefile("data.txt", "123 18.8 hello world\ni'm here\n")
+   io.input("data.txt")
+   print(io.read("*n", "*number", "*l", "*a"))
+   io.input("data.txt")
+   print(io.read("n", "number", "l", "a"))
+   io.input(io.stdin)
+   os.remove("data.txt")
+end
+
+
 ___''
 do
    writefile("data.txt", "123 18.8 hello world\ni'm here\n")
@@ -548,7 +560,7 @@ do
       print("io.lines()", l)
       break
    end
-   for n1,n2,rest in io.lines("data.txt", "*n", "*n", "*a") do
+   for n1,n2,rest in io.lines("data.txt", "*n", "n", "*a") do
       print("io.lines()", n1, n2, rest)
    end
    for l in io.lines("data.txt") do