mirror of
https://github.com/appgurueu/modlib.git
synced 2024-08-20 05:14:10 +02:00
403 lines
10 KiB
Lua
403 lines
10 KiB
Lua
local modlib, setmetatable, pairs, assert, error, table, table_insert, table_concat, tonumber, tostring, math_huge, string, type, next
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= modlib, setmetatable, pairs, assert, error, table, table.insert, table.concat, tonumber, tostring, math.huge, string, type, next
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local _ENV = {}
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setfenv(1, _ENV)
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--! experimental
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-- See https://tools.ietf.org/id/draft-ietf-json-rfc4627bis-09.html#unichars and https://json.org
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-- Null
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-- TODO consider using userdata (for ex. by using newproxy)
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do
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local metatable = {}
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-- eq is not among the metamethods, len won't work on 5.1
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for _, metamethod in pairs{"add", "sub", "mul", "div", "mod", "pow", "unm", "concat", "len", "lt", "le", "index", "newindex", "call"} do
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metatable["__" .. metamethod] = function() return error("attempt to " .. metamethod .. " a null value") end
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end
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null = setmetatable({}, metatable)
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end
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local metatable = {__index = self}
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_ENV.metatable = metatable
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function new(self)
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return setmetatable(self, metatable)
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end
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local whitespace = modlib.table.set{"\t", "\r", "\n", " "}
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local decoding_escapes = {
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['"'] = '"',
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["\\"] = "\\",
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["/"] = "/",
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b = "\b",
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f = "\f",
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n = "\n",
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r = "\r",
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t = "\t"
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-- TODO is this complete?
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}
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-- Set up a DFA for number syntax validations
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local number_dfa
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do
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-- TODO proper DFA utilities
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local function set_transitions(state, transitions)
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for chars, next_state in pairs(transitions) do
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for char in chars:gmatch"." do
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state[char] = next_state
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end
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end
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end
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local onenine = "123456789"
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local digit = "0" .. onenine
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local e = "eE"
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local exponent = {final = true}
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set_transitions(exponent, {
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[digit] = exponent
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})
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local pre_exponent = {expected = "exponent"}
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set_transitions(pre_exponent, {
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[digit] = exponent
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})
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local exponent_sign = {expected = "exponent"}
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set_transitions(exponent_sign, {
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[digit] = exponent,
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["+"] = exponent,
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["-"] = exponent
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})
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local fraction_final = {final = true}
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set_transitions(fraction_final, {
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[digit] = fraction_final,
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[e] = exponent_sign
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})
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local fraction = {expected = "fraction"}
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set_transitions(fraction, {
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[digit] = fraction_final
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})
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local integer = {final = true}
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set_transitions(integer, {
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[digit] = integer,
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[e] = exponent_sign,
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["."] = fraction
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})
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local zero = {final = true}
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set_transitions(zero, {
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["."] = fraction
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})
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number_dfa = {}
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set_transitions(number_dfa, {
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[onenine] = integer,
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["0"] = zero
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})
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end
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local hex_digit_values = {}
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for i = 0, 9 do
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hex_digit_values[tostring(i)] = i
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end
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for i = 0, 5 do
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hex_digit_values[string.char(("a"):byte() + i)] = 10 + i
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hex_digit_values[string.char(("A"):byte() + i)] = 10 + i
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end
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-- TODO SAX vs DOM
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local utf8 = modlib.text.utf8
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function read(self, read_)
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local index = 0
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local char
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-- TODO support read functions which provide additional debug output (such as row:column)
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local function read()
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index = index + 1
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char = read_()
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return char
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end
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local function syntax_error(errmsg)
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-- TODO ensure the index isn't off
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error("syntax error: " .. index .. ": " .. errmsg)
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end
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local function syntax_assert(value, errmsg)
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if not value then
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syntax_error(errmsg or "assertion failed!")
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end
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return value
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end
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local function skip_whitespace()
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while whitespace[char] do
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read()
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end
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end
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-- Forward declaration
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local value
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local function number()
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local state = number_dfa
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local num = {}
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while true do
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-- Will work for nil too
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local next_state = state[char]
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if not next_state then
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if not state.final then
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if state == number_dfa then
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syntax_error"expected a number"
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end
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syntax_error("invalid number: expected " .. state.expected)
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end
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return assert(tonumber(table_concat(num)))
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end
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table_insert(num, char)
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state = next_state
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read()
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end
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end
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local function utf8_codepoint(codepoint)
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return syntax_assert(utf8(codepoint), "invalid codepoint")
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end
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local function string()
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local chars = {}
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local high_surrogate
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while true do
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local string_char, next_high_surrogate
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if char == '"' then
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if high_surrogate then
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table_insert(chars, utf8_codepoint(high_surrogate))
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end
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return table_concat(chars)
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end
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if char == "\\" then
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read()
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if char == "u" then
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local codepoint = 0
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for i = 3, 0, -1 do
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codepoint = syntax_assert(hex_digit_values[read()], "expected a hex digit") * (16 ^ i) + codepoint
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end
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if high_surrogate and codepoint >= 0xDC00 and codepoint <= 0xDFFF then
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-- TODO strict mode: throw an error for single surrogates
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codepoint = 0x10000 + (high_surrogate - 0xD800) * 0x400 + codepoint - 0xDC00
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-- Don't write the high surrogate
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high_surrogate = nil
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end
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if codepoint >= 0xD800 and codepoint <= 0xDBFF then
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next_high_surrogate = codepoint
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else
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string_char = utf8_codepoint(codepoint)
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end
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else
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string_char = syntax_assert(decoding_escapes[char], "invalid escape sequence")
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end
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else
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-- TODO check whether the character is one that must be escaped ("strict" mode)
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string_char = syntax_assert(char, "unclosed string")
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end
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if high_surrogate then
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table_insert(chars, utf8_codepoint(high_surrogate))
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end
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high_surrogate = next_high_surrogate
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if string_char then
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table_insert(chars, string_char)
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end
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read()
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end
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end
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local element
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local funcs = {
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['-'] = function()
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return -number()
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end,
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['"'] = string,
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["{"] = function()
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local dict = {}
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skip_whitespace()
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if char == "}" then return dict end
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while true do
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syntax_assert(char == '"', "key expected")
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read()
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local key = string()
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read()
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skip_whitespace()
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syntax_assert(char == ":", "colon expected, got " .. char)
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local val = element()
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dict[key] = val
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if char == "}" then return dict end
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syntax_assert(char == ",", "comma expected")
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read()
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skip_whitespace()
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end
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end,
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["["] = function()
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local list = {}
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skip_whitespace()
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if char == "]" then return list end
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while true do
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table_insert(list, value())
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skip_whitespace()
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if char == "]" then return list end
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syntax_assert(char == ",", "comma expected")
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read()
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skip_whitespace()
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end
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end,
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}
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local function expect_word(word, value)
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local msg = word .. " expected"
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funcs[word:sub(1, 1)] = function()
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syntax_assert(char == word:sub(2, 2), msg)
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for i = 3, #word do
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read()
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syntax_assert(char == word:sub(i, i), msg)
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end
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return value
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end
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end
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expect_word("true", true)
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expect_word("false", false)
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expect_word("null", self.null)
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function value()
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syntax_assert(char, "value expected")
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local func = funcs[char]
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if func then
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-- Advance after first char
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read()
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local val = func()
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-- Advance after last char
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read()
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return val
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end
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if char >= "0" and char <= "9" then
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return number()
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end
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syntax_error"value expected"
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end
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function element()
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read()
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skip_whitespace()
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local val = value()
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skip_whitespace()
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return val
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end
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-- TODO consider asserting EOF as read() == nil, perhaps controlled by a parameter
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return element()
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end
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local encoding_escapes = modlib.table.flip(decoding_escapes)
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-- Solidus does not need to be escaped
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encoding_escapes["/"] = nil
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-- Control characters. Note: U+0080 to U+009F and U+007F are not considered control characters.
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for byte = 0, 0x1F do
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encoding_escapes[string.char(byte)] = string.format("u%04X", byte)
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end
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modlib.table.map(encoding_escapes, function(str) return "\\" .. str end)
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local function escape(str)
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return str:gsub(".", encoding_escapes)
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end
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function write(self, value, write)
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local null = self.null
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local written_strings = self.cache_escaped_strings and setmetatable({}, {__index = function(self, str)
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local escaped_str = escape(str)
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self[str] = escaped_str
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return escaped_str
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end})
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local function string(str)
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write'"'
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write(written_strings and written_strings[str] or escape(str))
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return write'"'
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end
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local dump
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local function write_kv(key, value)
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assert(type(key) == "string", "not a dictionary")
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string(key)
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write":"
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dump(value)
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end
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function dump(value)
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if value == null then
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-- TODO improve null check (checking for equality doesn't allow using nan as null, for instance)
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return write"null"
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end
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if value == true then
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return write"true"
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end
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if value == false then
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return write"false"
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end
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local type_ = type(value)
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if type_ == "number" then
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assert(value == value, "unsupported number value: nan")
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assert(value ~= math_huge, "unsupported number value: inf")
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assert(value ~= -math_huge, "unsupported number value: -inf")
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return write(("%.17g"):format(value))
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end
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if type_ == "string" then
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return string(value)
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end
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if type_ == "table" then
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local table = value
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local len = #table
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if len == 0 then
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local first, value = next(table)
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write"{"
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if first ~= nil then
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write_kv(first, value)
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end
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for key, value in next, table, first do
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write","
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write_kv(key, value)
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end
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write"}"
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else
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assert(modlib.table.count(table) == len, "mixed list & hash part")
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write"["
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for i = 1, len - 1 do
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dump(table[i])
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write","
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end
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dump(table[len])
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write"]"
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end
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return
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end
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error("unsupported type: " .. type_)
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end
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dump(value)
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end
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-- TODO get rid of this paste of write_file and write_string (see modlib.luon)
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function write_file(self, value, file)
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return self:write(value, function(text)
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file:write(text)
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end)
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end
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function write_string(self, value)
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local rope = {}
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self:write(value, function(text)
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table_insert(rope, text)
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end)
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return table_concat(rope)
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end
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-- TODO read_path (for other serializers too)
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function read_file(self, file)
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local value = self:read(function()
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return file:read(1)
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end)
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-- TODO consider file:close()
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return value
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end
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function read_string(self, string)
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-- TODO move the string -> one char read func pattern to modlib.text
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local index = 0
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local value = self:read(function()
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index = index + 1
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if index > #string then
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return
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end
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return string:sub(index, index)
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end)
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-- We just expect EOF for strings
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assert(index > #string, "EOF expected")
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return value
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end
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return _ENV |