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|
-- Prosody IM
-- Copyright (C) 2008-2009 Matthew Wild
-- Copyright (C) 2008-2009 Waqas Hussain
--
-- This project is MIT/X11 licensed. Please see the
-- COPYING file in the source package for more information.
--
local file = nil;
local last = nil;
local function read(expected)
local ch;
if last then
ch = last; last = nil;
else ch = file:read(1); end
if expected and ch ~= expected then error("expected: "..expected.."; got: "..(ch or "nil")); end
return ch;
end
local function pushback(ch)
if last then error(); end
last = ch;
end
local function peek()
if not last then last = read(); end
return last;
end
local _A, _a, _Z, _z, _0, _9, __, _at, _space = string.byte("AaZz09@_ ", 1, 9);
local function isLowerAlpha(ch)
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);
end
local function isAtom(ch)
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";
return ch <= _space;
end
local escapes = {["\\b"]="\b", ["\\d"]="\d", ["\\e"]="\e", ["\\f"]="\f", ["\\n"]="\n", ["\\r"]="\r", ["\\s"]="\s", ["\\t"]="\t", ["\\v"]="\v", ["\\\""]="\"", ["\\'"]="'", ["\\\\"]="\\"};
local function readString()
read("\""); -- skip quote
local slash = nil;
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];
slash = nil;
elseif ch == "\"" then
break;
elseif ch == "\\" then
slash = ch;
else
str = str..ch;
end
end
return str;
end
local function readAtom1()
local var = read();
while isAtom(peek()) do
var = var..read();
end
return var;
end
local function readAtom2()
local str = read("'");
local slash = nil;
while true do
local ch = read();
str = str..ch;
if ch == "'" and not slash then break; end
end
return str;
end
local function readNumber()
local num = read();
while isNumeric(peek()) do
num = num..read();
end
return tonumber(num);
end
local readItem = nil;
local function readTuple()
local t = {};
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
s = nil;
elseif s then
s = s..string.char(item);
end
table.insert(t, item);
end
read(); -- read }, or ], or >
if s and s ~= "" then
return s
else
return t
end;
end
local function readBinary()
read("<"); -- read <
local t = readTuple();
read(">") -- read >
local ch = peek();
if type(t) == type("") then
-- binary is a list of integers
return t;
elseif type(t) == type({}) then
if t[1] then
-- binary contains string
return t[1];
else
-- binary is empty
return "";
end;
else
error();
end
end
readItem = function()
local ch = peek();
if ch == nil then return nil end
if ch == "{" or ch == "[" then
return readTuple();
elseif isLowerAlpha(ch) then
return readAtom1();
elseif ch == "'" then
return readAtom2();
elseif isNumeric(ch) then
return readNumber();
elseif ch == "\"" then
return readString();
elseif ch == "<" then
return readBinary();
elseif isSpace(ch) or ch == "," or ch == "|" then
read();
return readItem();
else
--print("Unknown char: "..ch);
return nil;
end
end
local function readChunk()
local x = readItem();
if x then read("."); end
return x;
end
local function readFile(filename)
file = io.open(filename);
if not file then error("File not found: "..filename); os.exit(0); end
return function()
local x = readChunk();
if not x and peek() then error("Invalid char: "..peek()); end
return x;
end;
end
module "erlparse"
function parseFile(file)
return readFile(file);
end
return _M;
|
