JSON Parser in lua

json.lua

function jsonParse(str)
	if not str then return nil end
	str = str:match("^%s*(.-)%s*$")
	if #str == 0 then return nil end
	local t = str:sub(1, 1)
	str = str:sub(2, -2):match("^%s*(.-)%s*$") .. ','
	
	local obj = {}
	local depth = 0
	local last = 0
	local insideString = false
	for i=1, #str do
		local c = str:sub(i, i)
		
		if c == '[' or c == '{' then
			depth = depth + 1
		elseif c == ']' or c == '}' then
			depth = depth - 1
		elseif c == '\"' and str:sub(i-1, i-1) ~= '\\' then
			insideString = not insideString
		end
		
		if c == ',' and depth == 0 and not insideString then
			local segment = str:sub(last, i-1)
			last = i+1
			
			local key, value
			if t == '{' then
				key, value = segment:match('"(.-)"%s*:%s*(.+)')
				if not value then value = "" end
				if not key then key = -1 end
			elseif t == '[' then
				value = segment:match("^%s*(.-)%s*$")
			end
			
			local valueType = value:sub(1, 1)
			if valueType == '\"' then
				value = value:match('^"(.-)"$')
			elseif valueType == '{' or valueType == '[' then
				value = jsonParse(value)
			else
				if value == "true" then
					value = true
				elseif value == "false" then
					value = false
				elseif value == "null" then
					value = nil
				else
					value = tonumber(value) or value
				end
			end
			
			if t == '{' then
				obj[key] = value
			elseif t == '[' then
				table.insert(obj, value)
			end
		end
	end
	
	return obj
end