1 files changed, 209 insertions, 0 deletions
diff --git a/system/apis/json.lua b/system/apis/json.lua
new file mode 100644
index 0000000..3bef482
--- /dev/null
+++ b/system/apis/json.lua
@@ -0,0 +1,209 @@
+------------------------------------------------------------------ utils
+local controls = {["\n"]="\\n", ["\r"]="\\r", ["\t"]="\\t", ["\b"]="\\b", ["\f"]="\\f", ["\""]="\\\"", ["\\"]="\\\\"}
+
+local function isArray(t)
+	local max = 0
+	for k,v in pairs(t) do
+		if type(k) ~= "number" then
+			return false
+		elseif k > max then
+			max = k
+		end
+	end
+	return max == #t
+end
+
+local whites = {['\n']=true; ['\r']=true; ['\t']=true; [' ']=true; [',']=true; [':']=true}
+function removeWhite(str)
+	while whites[str:sub(1, 1)] do
+		str = str:sub(2)
+	end
+	return str
+end
+
+------------------------------------------------------------------ encoding
+
+local function encodeCommon(val, pretty, tabLevel, tTracking)
+	local str = ""
+
+	-- Tabbing util
+	local function tab(s)
+		str = str .. ("\t"):rep(tabLevel) .. s
+	end
+
+	local function arrEncoding(val, bracket, closeBracket, iterator, loopFunc)
+		str = str .. bracket
+		if pretty then
+			str = str .. "\n"
+			tabLevel = tabLevel + 1
+		end
+		for k,v in iterator(val) do
+			tab("")
+			loopFunc(k,v)
+			str = str .. ","
+			if pretty then str = str .. "\n" end
+		end
+		if pretty then
+			tabLevel = tabLevel - 1
+		end
+		if str:sub(-2) == ",\n" then
+			str = str:sub(1, -3) .. "\n"
+		elseif str:sub(-1) == "," then
+			str = str:sub(1, -2)
+		end
+		tab(closeBracket)
+	end
+
+	-- Table encoding
+	if type(val) == "table" then
+		assert(not tTracking[val], "Cannot encode a table holding itself recursively")
+		tTracking[val] = true
+		if isArray(val) then
+			arrEncoding(val, "[", "]", ipairs, function(k,v)
+				str = str .. encodeCommon(v, pretty, tabLevel, tTracking)
+			end)
+		else
+			arrEncoding(val, "{", "}", pairs, function(k,v)
+				assert(type(k) == "string", "JSON object keys must be strings", 2)
+				str = str .. encodeCommon(k, pretty, tabLevel, tTracking)
+				str = str .. (pretty and ": " or ":") .. encodeCommon(v, pretty, tabLevel, tTracking)
+			end)
+		end
+	-- String encoding
+	elseif type(val) == "string" then
+		str = '"' .. val:gsub("[%c\"\\]", controls) .. '"'
+	-- Number encoding
+	elseif type(val) == "number" or type(val) == "boolean" then
+		str = tostring(val)
+	else
+		error("JSON only supports arrays, objects, numbers, booleans, and strings", 2)
+	end
+	return str
+end
+
+function encode(val)
+	return encodeCommon(val, false, 0, {})
+end
+
+function encodePretty(val)
+	return encodeCommon(val, true, 0, {})
+end
+
+------------------------------------------------------------------ decoding
+
+local decodeControls = {}
+for k,v in pairs(controls) do
+	decodeControls[v] = k
+end
+
+function parseBoolean(str)
+	if str:sub(1, 4) == "true" then
+		return true, removeWhite(str:sub(5))
+	else
+		return false, removeWhite(str:sub(6))
+	end
+end
+
+function parseNull(str)
+	return nil, removeWhite(str:sub(5))
+end
+
+local numChars = {['e']=true; ['E']=true; ['+']=true; ['-']=true; ['.']=true}
+function parseNumber(str)
+	local i = 1
+	while numChars[str:sub(i, i)] or tonumber(str:sub(i, i)) do
+		i = i + 1
+	end
+	local val = tonumber(str:sub(1, i - 1))
+	str = removeWhite(str:sub(i))
+	return val, str
+end
+
+function parseString(str)
+	str = str:sub(2)
+	local s = ""
+	while str:sub(1,1) ~= "\"" do
+		local next = str:sub(1,1)
+		str = str:sub(2)
+		assert(next ~= "\n", "Unclosed string")
+
+		if next == "\\" then
+			local escape = str:sub(1,1)
+			str = str:sub(2)
+
+			next = assert(decodeControls[next..escape], "Invalid escape character")
+		end
+
+		s = s .. next
+	end
+	return s, removeWhite(str:sub(2))
+end
+
+function parseArray(str)
+	str = removeWhite(str:sub(2))
+
+	local val = {}
+	local i = 1
+	while str:sub(1, 1) ~= "]" do
+		local v = nil
+		v, str = parseValue(str)
+		val[i] = v
+		i = i + 1
+		str = removeWhite(str)
+	end
+	str = removeWhite(str:sub(2))
+	return val, str
+end
+
+function parseObject(str)
+	str = removeWhite(str:sub(2))
+
+	local val = {}
+	while str:sub(1, 1) ~= "}" do
+		local k, v = nil, nil
+		k, v, str = parseMember(str)
+		val[k] = v
+		str = removeWhite(str)
+	end
+	str = removeWhite(str:sub(2))
+	return val, str
+end
+
+function parseMember(str)
+	local k = nil
+	k, str = parseValue(str)
+	local val = nil
+	val, str = parseValue(str)
+	return k, val, str
+end
+
+function parseValue(str)
+	local fchar = str:sub(1, 1)
+	if fchar == "{" then
+		return parseObject(str)
+	elseif fchar == "[" then
+		return parseArray(str)
+	elseif tonumber(fchar) ~= nil or numChars[fchar] then
+		return parseNumber(str)
+	elseif str:sub(1, 4) == "true" or str:sub(1, 5) == "false" then
+		return parseBoolean(str)
+	elseif fchar == "\"" then
+		return parseString(str)
+	elseif str:sub(1, 4) == "null" then
+		return parseNull(str)
+	end
+	return nil
+end
+
+function decode(str)
+	str = removeWhite(str)
+	t = parseValue(str)
+	return t
+end
+
+function decodeFromFile(path)
+	local file = assert(fs.open(path, "r"))
+	local decoded = decode(file.readAll())
+	file.close()
+	return decoded
+end
+\ No newline at end of file