Faster string.split implementation.

diff --git a/builtin/common/misc_helpers.lua b/builtin/common/misc_helpers.lua
index 713555109cad1ac4e792e52e3c874c64af6c3e1e..2ee990e5c0cdaa3b455cab746d01875b35cc03c4 100644 (file)
--- a/builtin/common/misc_helpers.lua
+++ b/builtin/common/misc_helpers.lua
@@ -155,33 +155,33 @@ function dump(o, indent, nested, level)
 end
 
 --------------------------------------------------------------------------------
-function string.split(str, delim, include_empty, max_splits)
+-- Localize functions to avoid table lookups (better performance).
+local table_insert = table.insert
+local str_sub, str_find = string.sub, string.find
+function string.split(str, delim, include_empty, max_splits, sep_is_pattern)
        delim = delim or ","
-       max_splits = max_splits or 0
-       local fields = {}
-       local num_splits = 0
-       local last_pos = 0
-       for part, pos in str:gmatch("(.-)[" .. delim .. "]()") do
-               last_pos = pos
-               if include_empty or part ~= "" then
-                       num_splits = num_splits + 1
-                       fields[num_splits] = part
-                       if max_splits > 0 and num_splits + 1 >= max_splits then
-                               break
-                       end
+       max_splits = max_splits or -1
+       local items = {}
+       local pos, len, seplen = 1, #str, #delim
+       local plain = not sep_is_pattern
+       max_splits = max_splits + 1
+       repeat
+               local np, npe = str_find(str, delim, pos, plain)
+               np, npe = (np or (len+1)), (npe or (len+1))
+               if (not np) or (max_splits == 1) then
+                       np = len + 1
+                       npe = np
                end
-       end
-       -- Handle the last field
-       if max_splits <= 0 or num_splits <= max_splits then
-               local last_part = str:sub(last_pos)
-               if include_empty or last_part ~= "" then
-                       fields[num_splits + 1] = last_part
+               local s = str_sub(str, pos, np - 1)
+               if include_empty or (s ~= "") then
+                       max_splits = max_splits - 1
+                       table_insert(items, s)
                end
-       end
-       return fields
+               pos = npe + 1
+       until (max_splits == 0) or (pos > len)
+       return items
 end
 
-
 --------------------------------------------------------------------------------
 function file_exists(filename)
        local f = io.open(filename, "r")