Software /
code /
prosody
File
util/json.lua @ 12518:73ee3855f970
mod_smacks: Factor out some convenience functions
Those lines are long and the risk of mistakes if another one needs to be
added seems high, but lower when factored out like this.
author | Kim Alvefur <zash@zash.se> |
---|---|
date | Fri, 11 Feb 2022 16:09:42 +0100 |
parent | 9329:19bc3ec13f07 |
child | 12792:997f3ca90628 |
line wrap: on
line source
-- Prosody IM -- Copyright (C) 2008-2010 Matthew Wild -- Copyright (C) 2008-2010 Waqas Hussain -- -- This project is MIT/X11 licensed. Please see the -- COPYING file in the source package for more information. -- 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, spairs = pairs, ipairs, require "util.iterators".sorted_pairs; local next = next; local getmetatable, setmetatable = getmetatable, setmetatable; local print = print; local has_array, array = pcall(require, "util.array"); local array_mt = has_array and getmetatable(array()) or {}; --module("json") local module = {}; local null = setmetatable({}, { __tostring = function() return "null"; end; }); module.null = null; local escapes = { ["\""] = "\\\"", ["\\"] = "\\\\", ["\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 function codepoint_to_utf8(code) if code < 0x80 then return s_char(code); end local bits0_6 = code % 64; if code < 0x800 then local bits6_5 = (code - bits0_6) / 64; return s_char(0x80 + 0x40 + bits6_5, 0x80 + bits0_6); end local bits0_12 = code % 4096; local bits6_6 = (bits0_12 - bits0_6) / 64; local bits12_4 = (code - bits0_12) / 4096; return s_char(0x80 + 0x40 + 0x20 + bits12_4, 0x80 + bits6_6, 0x80 + bits0_6); 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 _, 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; local _pairs = buffer.ordered and spairs or pairs; 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 o == null then t_insert(buffer, "null"); elseif t == "number" then t_insert(buffer, tostring(o)); elseif t == "string" then stringsave(o, buffer); elseif t == "table" then local mt = getmetatable(o); if mt == array_mt then arraysave(o, buffer); else tablesave(o, buffer); end elseif t == "boolean" then t_insert(buffer, (o and "true" or "false")); else t_insert(buffer, "null"); end end function module.encode(obj) local t = {}; simplesave(obj, t); return t_concat(t); end function module.encode_ordered(obj) local t = { ordered = true }; simplesave(obj, t); return t_concat(t); end function module.encode_array(obj) local t = {}; arraysave(obj, t); return t_concat(t); end ----------------------------------- local function _skip_whitespace(json, index) return json:find("[^ \t\r\n]", index) or index; -- no need to check \r\n, we converted those to \t end local function _fixobject(obj) local __array = obj.__array; if __array then obj.__array = nil; for _, v in ipairs(__array) do t_insert(obj, v); end end local __hash = obj.__hash; if __hash then obj.__hash = nil; local k; for _, v in ipairs(__hash) do if k ~= nil then obj[k] = v; k = nil; else k = v; end end end return obj; end local _readvalue, _readstring; local function _readobject(json, index) local o = {}; while true do local key, val; index = _skip_whitespace(json, index + 1); if json:byte(index) ~= 0x22 then -- "\"" if json:byte(index) == 0x7d then return o, index + 1; end -- "}" return nil, "key expected"; end key, index = _readstring(json, index); if key == nil then return nil, index; end index = _skip_whitespace(json, index); if json:byte(index) ~= 0x3a then return nil, "colon expected"; end -- ":" val, index = _readvalue(json, index + 1); if val == nil then return nil, index; end o[key] = val; index = _skip_whitespace(json, index); local b = json:byte(index); if b == 0x7d then return _fixobject(o), index + 1; end -- "}" if b ~= 0x2c then return nil, "object eof"; end -- "," end end local function _readarray(json, index) local a = {}; local oindex = index; while true do local val; val, index = _readvalue(json, index + 1); if val == nil then if json:byte(oindex + 1) == 0x5d then return setmetatable(a, array_mt), oindex + 2; end -- "]" return val, index; end t_insert(a, val); index = _skip_whitespace(json, index); local b = json:byte(index); if b == 0x5d then return setmetatable(a, array_mt), index + 1; end -- "]" if b ~= 0x2c then return nil, "array eof"; end -- "," end end local _unescape_error; local function _unescape_surrogate_func(x) local lead, trail = tonumber(x:sub(3, 6), 16), tonumber(x:sub(9, 12), 16); local codepoint = lead * 0x400 + trail - 0x35FDC00; local a = codepoint % 64; codepoint = (codepoint - a) / 64; local b = codepoint % 64; codepoint = (codepoint - b) / 64; local c = codepoint % 64; codepoint = (codepoint - c) / 64; return s_char(0xF0 + codepoint, 0x80 + c, 0x80 + b, 0x80 + a); end local function _unescape_func(x) x = x:match("%x%x%x%x", 3); if x then local codepoint = tonumber(x, 16) if codepoint >= 0xD800 and codepoint <= 0xDFFF then _unescape_error = true; end -- bad surrogate pair return codepoint_to_utf8(codepoint); end _unescape_error = true; end function _readstring(json, index) index = index + 1; local endindex = json:find("\"", index, true); if endindex then local s = json:sub(index, endindex - 1); --if s:find("[%z-\31]") then return nil, "control char in string"; end -- FIXME handle control characters _unescape_error = nil; s = s:gsub("\\u[dD][89abAB]%x%x\\u[dD][cdefCDEF]%x%x", _unescape_surrogate_func); -- FIXME handle escapes beyond BMP s = s:gsub("\\u.?.?.?.?", _unescape_func); if _unescape_error then return nil, "invalid escape"; end return s, endindex + 1; end return nil, "string eof"; end local function _readnumber(json, index) local m = json:match("[0-9%.%-eE%+]+", index); -- FIXME do strict checking return tonumber(m), index + #m; end local function _readnull(json, index) local a, b, c = json:byte(index + 1, index + 3); if a == 0x75 and b == 0x6c and c == 0x6c then return null, index + 4; end return nil, "null parse failed"; end local function _readtrue(json, index) local a, b, c = json:byte(index + 1, index + 3); if a == 0x72 and b == 0x75 and c == 0x65 then return true, index + 4; end return nil, "true parse failed"; end local function _readfalse(json, index) local a, b, c, d = json:byte(index + 1, index + 4); if a == 0x61 and b == 0x6c and c == 0x73 and d == 0x65 then return false, index + 5; end return nil, "false parse failed"; end function _readvalue(json, index) index = _skip_whitespace(json, index); local b = json:byte(index); -- TODO try table lookup instead of if-else? if b == 0x7B then -- "{" return _readobject(json, index); elseif b == 0x5B then -- "[" return _readarray(json, index); elseif b == 0x22 then -- "\"" return _readstring(json, index); elseif b ~= nil and b >= 0x30 and b <= 0x39 or b == 0x2d then -- "0"-"9" or "-" return _readnumber(json, index); elseif b == 0x6e then -- "n" return _readnull(json, index); elseif b == 0x74 then -- "t" return _readtrue(json, index); elseif b == 0x66 then -- "f" return _readfalse(json, index); else return nil, "value expected"; end end local first_escape = { ["\\\""] = "\\u0022"; ["\\\\"] = "\\u005c"; ["\\/" ] = "\\u002f"; ["\\b" ] = "\\u0008"; ["\\f" ] = "\\u000C"; ["\\n" ] = "\\u000A"; ["\\r" ] = "\\u000D"; ["\\t" ] = "\\u0009"; ["\\u" ] = "\\u"; }; function module.decode(json) json = json:gsub("\\.", first_escape) -- get rid of all escapes except \uXXXX, making string parsing much simpler --:gsub("[\r\n]", "\t"); -- \r\n\t are equivalent, we care about none of them, and none of them can be in strings -- TODO do encoding verification local val, index = _readvalue(json, 1); if val == nil then return val, index; end if json:find("[^ \t\r\n]", index) then return nil, "garbage at eof"; end return val; end function module.test(object) local encoded = module.encode(object); local decoded = module.decode(encoded); local recoded = module.encode(decoded); if encoded ~= recoded then print("FAILED"); print("encoded:", encoded); print("recoded:", recoded); else print(encoded); end return encoded == recoded; end return module;