view mod_couchdb/couchdb/json.lib.lua @ 737:e4ea03b060ed

mod_archive: switch from/to The XEP-0136 is not very explicit about the meening of <from> and <to> elements, but the examples are clear: <from> means it comes from the user in the 'with' attribute of the collection. That is the opposite of what is currently implemented in that module. So for better compatibility with complient clients, this switch the 'from' and 'to' fields
author Olivier Goffart <ogoffart@woboq.com>
date Wed, 04 Jul 2012 14:08:43 +0200
parents 316d7c8e1fb0
children
line wrap: on
line source


local type = type;
local t_insert, t_concat, t_remove = table.insert, table.concat, table.remove;
local s_char = string.char;
local tostring, tonumber = tostring, tonumber;
local pairs, ipairs = pairs, ipairs;
local next = next;
local error = error;
local newproxy, getmetatable = newproxy, getmetatable;
local print = print;

--module("json")
local _M = {};

local null = newproxy and newproxy(true) or {};
if getmetatable and getmetatable(null) then
	getmetatable(null).__tostring = function() return "null"; end;
end
_M.null = null;

local escapes = {
	["\""] = "\\\"", ["\\"] = "\\\\", ["\b"] = "\\b",
	["\f"] = "\\f", ["\n"] = "\\n", ["\r"] = "\\r", ["\t"] = "\\t"};
local unescapes = {
	["\""] = "\"", ["\\"] = "\\", ["/"] = "/",
	b = "\b", f = "\f", n = "\n", r = "\r", t = "\t"};
for i=0,31 do
	local ch = s_char(i);
	if not escapes[ch] then escapes[ch] = ("\\u%.4X"):format(i); end
end

local valid_types = {
	number  = true,
	string  = true,
	table   = true,
	boolean = true
};
local special_keys = {
	__array = true;
	__hash  = true;
};

local simplesave, tablesave, arraysave, stringsave;

function stringsave(o, buffer)
	-- FIXME do proper utf-8 and binary data detection
	t_insert(buffer, "\""..(o:gsub(".", escapes)).."\"");
end

function arraysave(o, buffer)
	t_insert(buffer, "[");
	if next(o) then
		for i,v in ipairs(o) do
			simplesave(v, buffer);
			t_insert(buffer, ",");
		end
		t_remove(buffer);
	end
	t_insert(buffer, "]");
end

function tablesave(o, buffer)
	local __array = {};
	local __hash = {};
	local hash = {};
	for i,v in ipairs(o) do
		__array[i] = v;
	end
	for k,v in pairs(o) do
		local ktype, vtype = type(k), type(v);
		if valid_types[vtype] or v == null then
			if ktype == "string" and not special_keys[k] then
				hash[k] = v;
			elseif (valid_types[ktype] or k == null) and __array[k] == nil then
				__hash[k] = v;
			end
		end
	end
	if next(__hash) ~= nil or next(hash) ~= nil or next(__array) == nil then
		t_insert(buffer, "{");
		local mark = #buffer;
		for k,v in pairs(hash) do
			stringsave(k, buffer);
			t_insert(buffer, ":");
			simplesave(v, buffer);
			t_insert(buffer, ",");
		end
		if next(__hash) ~= nil then
			t_insert(buffer, "\"__hash\":[");
			for k,v in pairs(__hash) do
				simplesave(k, buffer);
				t_insert(buffer, ",");
				simplesave(v, buffer);
				t_insert(buffer, ",");
			end
			t_remove(buffer);
			t_insert(buffer, "]");
			t_insert(buffer, ",");
		end
		if next(__array) then
			t_insert(buffer, "\"__array\":");
			arraysave(__array, buffer);
			t_insert(buffer, ",");
		end
		if mark ~= #buffer then t_remove(buffer); end
		t_insert(buffer, "}");
	else
		arraysave(__array, buffer);
	end
end

function simplesave(o, buffer)
	local t = type(o);
	if t == "number" then
		t_insert(buffer, tostring(o));
	elseif t == "string" then
		stringsave(o, buffer);
	elseif t == "table" then
		tablesave(o, buffer);
	elseif t == "boolean" then
		t_insert(buffer, (o and "true" or "false"));
	else
		t_insert(buffer, "null");
	end
end

function _M.encode(obj)
	local t = {};
	simplesave(obj, t);
	return t_concat(t);
end

-----------------------------------


function _M.decode(json)
	local pos = 1;
	local current = {};
	local stack = {};
	local ch, peek;
	local function next()
		ch = json:sub(pos, pos);
		pos = pos+1;
		peek = json:sub(pos, pos);
		return ch;
	end
	
	local function skipwhitespace()
		while ch and (ch == "\r" or ch == "\n" or ch == "\t" or ch == " ") do
			next();
		end
	end
	local function skiplinecomment()
		repeat next(); until not(ch) or ch == "\r" or ch == "\n";
		skipwhitespace();
	end
	local function skipstarcomment()
		next(); next(); -- skip '/', '*'
		while peek and ch ~= "*" and peek ~= "/" do next(); end
		if not peek then error("eof in star comment") end
		next(); next(); -- skip '*', '/'
		skipwhitespace();
	end
	local function skipstuff()
		while true do
			skipwhitespace();
			if ch == "/" and peek == "*" then
				skipstarcomment();
			elseif ch == "/" and peek == "*" then
				skiplinecomment();
			else
				return;
			end
		end
	end
	
	local readvalue;
	local function readarray()
		local t = {};
		next(); -- skip '['
		skipstuff();
		if ch == "]" then next(); return t; end
		t_insert(t, readvalue());
		while true do
			skipstuff();
			if ch == "]" then next(); return t; end
			if not ch then error("eof while reading array");
			elseif ch == "," then next();
			elseif ch then error("unexpected character in array, comma expected"); end
			if not ch then error("eof while reading array"); end 
			t_insert(t, readvalue());
		end
	end
	
	local function checkandskip(c)
		local x = ch or "eof";
		if x ~= c then error("unexpected "..x..", '"..c.."' expected"); end
		next();
	end
	local function readliteral(lit, val)
		for c in lit:gmatch(".") do
			checkandskip(c);
		end
		return val;
	end
	local function readstring()
		local s = "";
		checkandskip("\"");
		while ch do
			while ch and ch ~= "\\" and ch ~= "\"" do
				s = s..ch; next();
			end
			if ch == "\\" then
				next();
				if unescapes[ch] then
					s = s..unescapes[ch];
					next();
				elseif ch == "u" then
					local seq = "";
					for i=1,4 do
						next();
						if not ch then error("unexpected eof in string"); end
						if not ch:match("[0-9a-fA-F]") then error("invalid unicode escape sequence in string"); end
						seq = seq..ch;
					end
					s = s..s.char(tonumber(seq, 16)); -- FIXME do proper utf-8
					next();
				else error("invalid escape sequence in string"); end
			end
			if ch == "\"" then
				next();
				return s;
			end
		end
		error("eof while reading string");
	end
	local function readnumber()
		local s = "";
		if ch == "-" then
			s = s..ch; next();
			if not ch:match("[0-9]") then error("number format error"); end
		end
		if ch == "0" then
			s = s..ch; next();
			if ch:match("[0-9]") then error("number format error"); end
		else
			while ch and ch:match("[0-9]") do
				s = s..ch; next();
			end
		end
		if ch == "." then
			s = s..ch; next();
			if not ch:match("[0-9]") then error("number format error"); end
			while ch and ch:match("[0-9]") do
				s = s..ch; next();
			end
			if ch == "e" or ch == "E" then
				s = s..ch; next();
				if ch == "+" or ch == "-" then
					s = s..ch; next();
					if not ch:match("[0-9]") then error("number format error"); end
					while ch and ch:match("[0-9]") do
						s = s..ch; next();
					end
				end
			end
		end
		return tonumber(s);
	end
	local function readmember(t)
		local k = readstring();
		checkandskip(":");
		t[k] = readvalue();
	end
	local function fixobject(obj)
		local __array = obj.__array;
		if __array then
			obj.__array = nil;
			for i,v in ipairs(__array) do
				t_insert(obj, v);
			end
		end
		local __hash = obj.__hash;
		if __hash then
			obj.__hash = nil;
			local k;
			for i,v in ipairs(__hash) do
				if k ~= nil then
					obj[k] = v; k = nil;
				else
					k = v;
				end
			end
		end
		return obj;
	end
	local function readobject()
		local t = {};
		next(); -- skip '{'
		skipstuff();
		if ch == "}" then next(); return t; end
		if not ch then error("eof while reading object"); end
		readmember(t);
		while true do
			skipstuff();
			if ch == "}" then next(); return fixobject(t); end
			if not ch then error("eof while reading object");
			elseif ch == "," then next();
			elseif ch then error("unexpected character in object, comma expected"); end
			if not ch then error("eof while reading object"); end
			readmember(t);
		end
	end
	
	function readvalue()
		skipstuff();
		while ch do
			if ch == "{" then
				return readobject();
			elseif ch == "[" then
				return readarray();
			elseif ch == "\"" then
				return readstring();
			elseif ch:match("[%-0-9%.]") then
				return readnumber();
			elseif ch == "n" then
				return readliteral("null", null);
			elseif ch == "t" then
				return readliteral("true", true);
			elseif ch == "f" then
				return readliteral("false", false);
			end
		end
		error("eof while reading value");
	end
	next();
	return readvalue();
end

function _M.test(object)
	local encoded = encode(object);
	local decoded = decode(encoded);
	local recoded = encode(decoded);
	if encoded ~= recoded then
		print("FAILED");
		print("encoded:", encoded);
		print("recoded:", recoded);
	else
		print(encoded);
	end
	return encoded ~= recoded;
end

return _M;