tools/erlparse: Optimisations aplenty for faster processing of large files

diff --git a/tools/erlparse.lua b/tools/erlparse.lua
index 387ffbe6aa0c670085e589f6176c0482e1f8e028..fdef7e8c6de8afe8c991e54e689f2b287b6f56f4 100644 (file)
--- a/tools/erlparse.lua
+++ b/tools/erlparse.lua
@@ -6,7 +6,9 @@
 -- COPYING file in the source package for more information.
 --
 
-
+local string_byte, string_char = string.byte, string.char;
+local t_concat, t_insert = table.concat, table.insert;
+local type, tonumber, tostring = type, tonumber, tostring;
 
 local file = nil;
 local last = nil;
@@ -27,21 +29,21 @@ local function peek()
        return last;
 end
 
-local _A, _a, _Z, _z, _0, _9, __, _at, _space = string.byte("AaZz09@_ ", 1, 9);
+local _A, _a, _Z, _z, _0, _9, __, _at, _space, _minus = string_byte("AaZz09@_ -", 1, 10);
 local function isLowerAlpha(ch)
-       ch = string.byte(ch) or 0;
+       ch = string_byte(ch) or 0;
        return (ch >= _a and ch <= _z);
 end
 local function isNumeric(ch)
-       ch = string.byte(ch) or 0;
-       return (ch >= _0 and ch <= _9);
+       ch = string_byte(ch) or 0;
+       return (ch >= _0 and ch <= _9) or ch == _minus;
 end
 local function isAtom(ch)
-       ch = string.byte(ch) or 0;
+       ch = string_byte(ch) or 0;
        return (ch >= _A and ch <= _Z) or (ch >= _a and ch <= _z) or (ch >= _0 and ch <= _9) or ch == __ or ch == _at;
 end
 local function isSpace(ch)
-       ch = string.byte(ch) or "x";
+       ch = string_byte(ch) or "x";
        return ch <= _space;
 end
 
@@ -49,66 +51,66 @@ local escapes = {["\\b"]="\b", ["\\d"]="\d", ["\\e"]="\e", ["\\f"]="\f", ["\\n"]
 local function readString()
        read("\""); -- skip quote
        local slash = nil;
-       local str = "";
+       local str = {};
        while true do
                local ch = read();
                if slash then
                        slash = slash..ch;
                        if not escapes[slash] then error("Unknown escape sequence: "..slash); end
-                       str = str..escapes[slash];
+                       str[#str+1] = escapes[slash];
                        slash = nil;
                elseif ch == "\"" then
                        break;
                elseif ch == "\\" then
                        slash = ch;
                else
-                       str = str..ch;
+                       str[#str+1] = ch;
                end
        end
-       return str;
+       return t_concat(str);
 end
 local function readAtom1()
-       local var = read();
+       local var = { read() };
        while isAtom(peek()) do
-               var = var..read();
+               var[#var+1] = read();
        end
-       return var;
+       return t_concat(var);
 end
 local function readAtom2()
-       local str = read("'");
+       local str = { read("'") };
        local slash = nil;
        while true do
                local ch = read();
-               str = str..ch;
+               str[#str+1] = ch;
                if ch == "'" and not slash then break; end
        end
-       return str;
+       return t_concat(str);
 end
 local function readNumber()
-       local num = read();
+       local num = { read() };
        while isNumeric(peek()) do
-               num = num..read();
+               num[#num+1] = read();
        end
-       return tonumber(num);
+       return tonumber(t_concat(num));
 end
 local readItem = nil;
 local function readTuple()
        local t = {};
-       local s = ""; -- string representation
+       local s = {}; -- string representation
        read(); -- read {, or [, or <
        while true do
                local item = readItem();
                if not item then break; end
-               if type(item) ~= type(0) or item > 255 then
+               if type(item) ~= "number" or item > 255 then
                        s = nil;
                elseif s then
-                       s = s..string.char(item);
+                       s[#s+1] = string_char(item);
                end
-               table.insert(t, item);
+               t_insert(t, item);
        end
        read(); -- read }, or ], or >
-       if s and s ~= "" then
-               return s
+       if s and #s > 0  then
+               return t_concat(s)
        else
                return t
        end;
@@ -118,10 +120,10 @@ local function readBinary()
        local t = readTuple();
        read(">") -- read >
        local ch = peek();
-       if type(t) == type("") then
+       if type(t) == "string" then
                -- binary is a list of integers
                return t;
-       elseif type(t) == type({}) then
+       elseif type(t) == "table" then
                if t[1] then
                        -- binary contains string
                        return t[1];