Module:JSON

-- Module options: local always_try_using_lpeg = true local register_global_module_table = false local global_module_name = 'json'

--[==[

David Kolf's JSON module for Lua 5.1/5.2

Version 2.5

For the documentation see the corresponding readme.txt or visit .

You can contact the author by sending an e-mail to 'david' at the domain 'dkolf.de'.

Copyright (C) 2010-2013 David Heiko Kolf

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

--]==]

-- global dependencies: local pairs, type, tostring, tonumber, getmetatable, setmetatable, rawset = pairs, type, tostring, tonumber, getmetatable, setmetatable, rawset local error, require, pcall, select = error, require, pcall, select local floor, huge = math.floor, math.huge local strrep, gsub, strsub, strbyte, strchar, strfind, strlen, strformat = string.rep, string.gsub, string.sub, string.byte, string.char, string.find, string.len, string.format local strmatch = string.match local concat = table.concat

local json = { version = "dkjson 2.5" }

if register_global_module_table then _G[global_module_name] = json end

local _ENV = nil -- blocking globals in Lua 5.2

pcall (function -- Enable access to blocked metatables.  -- Don't worry, this module doesn't change anything in them.  local debmeta = require "debug".getmetatable  if debmeta then getmetatable = debmeta end end)

json.null = setmetatable ({}, { __tojson = function  return "null" end })

local function isarray (tbl) local max, n, arraylen = 0, 0, 0 for k,v in pairs (tbl) do   if k == 'n' and type(v) == 'number' then arraylen = v     if v > max then max = v     end else if type(k) ~= 'number' or k < 1 or floor(k) ~= k then return false end if k > max then max = k     end n = n + 1 end end if max > 10 and max > arraylen and max > n * 2 then return false -- don't create an array with too many holes end return true, max end

local escapecodes = { ["\""] = "\\\"", ["\\"] = "\\\\", ["\b"] = "\\b", ["\f"] = "\\f", ["\n"] = "\\n", ["\r"] = "\\r",  ["\t"] = "\\t" }

local function escapeutf8 (uchar) local value = escapecodes[uchar] if value then return value end local a, b, c, d = strbyte (uchar, 1, 4) a, b, c, d = a or 0, b or 0, c or 0, d or 0 if a <= 0x7f then value = a elseif 0xc0 <= a and a <= 0xdf and b >= 0x80 then value = (a - 0xc0) * 0x40 + b - 0x80 elseif 0xe0 <= a and a <= 0xef and b >= 0x80 and c >= 0x80 then value = ((a - 0xe0) * 0x40 + b - 0x80) * 0x40 + c - 0x80 elseif 0xf0 <= a and a <= 0xf7 and b >= 0x80 and c >= 0x80 and d >= 0x80 then value = (((a - 0xf0) * 0x40 + b - 0x80) * 0x40 + c - 0x80) * 0x40 + d - 0x80 else return "" end if value <= 0xffff then return strformat ("\\u%.4x", value) elseif value <= 0x10ffff then -- encode as UTF-16 surrogate pair value = value - 0x10000 local highsur, lowsur = 0xD800 + floor (value/0x400), 0xDC00 + (value % 0x400) return strformat ("\\u%.4x\\u%.4x", highsur, lowsur) else return "" end end

local function fsub (str, pattern, repl) -- gsub always builds a new string in a buffer, even when no match -- exists. First using find should be more efficient when most strings -- don't contain the pattern. if strfind (str, pattern) then return gsub (str, pattern, repl) else return str end end

local function quotestring (value) -- based on the regexp "escapable" in https://github.com/douglascrockford/JSON-js value = fsub (value, "[%z\1-\31\"\\\127]", escapeutf8) if strfind (value, "[\194\216\220\225\226\239]") then    value = fsub (value, "\194[\128-\159\173]", escapeutf8)    value = fsub (value, "\216[\128-\132]", escapeutf8)    value = fsub (value, "\220\143", escapeutf8)    value = fsub (value, "\225\158[\180\181]", escapeutf8)    value = fsub (value, "\226\128[\140-\143\168-\175]", escapeutf8)    value = fsub (value, "\226\129[\160-\175]", escapeutf8)    value = fsub (value, "\239\187\191", escapeutf8)    value = fsub (value, "\239\191[\176-\191]", escapeutf8)  end  return "\"" .. value .. "\"" end json.quotestring = quotestring

local function replace(str, o, n) local i, j = strfind (str, o, 1, true) if i then return strsub(str, 1, i-1) .. n .. strsub(str, j+1, -1) else return str end end

-- locale independent num2str and str2num functions local decpoint, numfilter

local function updatedecpoint decpoint = strmatch(tostring(0.5), "([^05+])") -- build a filter that can be used to remove group separators numfilter = "[^0-9%-%+eE" .. gsub(decpoint, "[%^%$%(%)%%%.%[%]%*%+%-%?]", "%%%0") .. "]+" end

updatedecpoint

local function num2str (num) return replace(fsub(tostring(num), numfilter, ""), decpoint, ".") end

local function str2num (str) local num = tonumber(replace(str, ".", decpoint)) if not num then updatedecpoint num = tonumber(replace(str, ".", decpoint)) end return num end

local function addnewline2 (level, buffer, buflen) buffer[buflen+1] = "\n" buffer[buflen+2] = strrep (" ", level) buflen = buflen + 2 return buflen end

function json.addnewline (state) if state.indent then state.bufferlen = addnewline2 (state.level or 0,                          state.buffer, state.bufferlen or #(state.buffer)) end end

local encode2 -- forward declaration

local function addpair (key, value, prev, indent, level, buffer, buflen, tables, globalorder, state) local kt = type (key) if kt ~= 'string' and kt ~= 'number' then return nil, "type '" .. kt .. "' is not supported as a key by JSON." end if prev then buflen = buflen + 1 buffer[buflen] = "," end if indent then buflen = addnewline2 (level, buffer, buflen) end buffer[buflen+1] = quotestring (key) buffer[buflen+2] = ":" return encode2 (value, indent, level, buffer, buflen + 2, tables, globalorder, state) end

local function appendcustom(res, buffer, state) local buflen = state.bufferlen if type (res) == 'string' then buflen = buflen + 1 buffer[buflen] = res end return buflen end

local function exception(reason, value, state, buffer, buflen, defaultmessage) defaultmessage = defaultmessage or reason local handler = state.exception if not handler then return nil, defaultmessage else state.bufferlen = buflen local ret, msg = handler (reason, value, state, defaultmessage) if not ret then return nil, msg or defaultmessage end return appendcustom(ret, buffer, state) end end

function json.encodeexception(reason, value, state, defaultmessage) return quotestring("<" .. defaultmessage .. ">") end

encode2 = function (value, indent, level, buffer, buflen, tables, globalorder, state) local valtype = type (value) local valmeta = getmetatable (value) valmeta = type (valmeta) == 'table' and valmeta -- only tables local valtojson = valmeta and valmeta.__tojson if valtojson then if tables[value] then return exception('reference cycle', value, state, buffer, buflen) end tables[value] = true state.bufferlen = buflen local ret, msg = valtojson (value, state) if not ret then return exception('custom encoder failed', value, state, buffer, buflen, msg) end tables[value] = nil buflen = appendcustom(ret, buffer, state) elseif value == nil then buflen = buflen + 1 buffer[buflen] = "null" elseif valtype == 'number' then local s   if value ~= value or value >= huge or -value >= huge then -- This is the behaviour of the original JSON implementation. s = "null" else s = num2str (value) end buflen = buflen + 1 buffer[buflen] = s elseif valtype == 'boolean' then buflen = buflen + 1 buffer[buflen] = value and "true" or "false" elseif valtype == 'string' then buflen = buflen + 1 buffer[buflen] = quotestring (value) elseif valtype == 'table' then if tables[value] then return exception('reference cycle', value, state, buffer, buflen) end tables[value] = true level = level + 1 local isa, n = isarray (value) if n == 0 and valmeta and valmeta.__jsontype == 'object' then isa = false end local msg if isa then -- JSON array buflen = buflen + 1 buffer[buflen] = "[" for i = 1, n do       buflen, msg = encode2 (value[i], indent, level, buffer, buflen, tables, globalorder, state) if not buflen then return nil, msg end if i < n then buflen = buflen + 1 buffer[buflen] = "," end end buflen = buflen + 1 buffer[buflen] = "]" else -- JSON object local prev = false buflen = buflen + 1 buffer[buflen] = "{" local order = valmeta and valmeta.__jsonorder or globalorder if order then local used = {} n = #order for i = 1, n do         local k = order[i] local v = value[k] if v then used[k] = true buflen, msg = addpair (k, v, prev, indent, level, buffer, buflen, tables, globalorder, state) prev = true -- add a seperator before the next element end end for k,v in pairs (value) do         if not used[k] then buflen, msg = addpair (k, v, prev, indent, level, buffer, buflen, tables, globalorder, state) if not buflen then return nil, msg end prev = true -- add a seperator before the next element end end else -- unordered for k,v in pairs (value) do         buflen, msg = addpair (k, v, prev, indent, level, buffer, buflen, tables, globalorder, state) if not buflen then return nil, msg end prev = true -- add a seperator before the next element end end if indent then buflen = addnewline2 (level - 1, buffer, buflen) end buflen = buflen + 1 buffer[buflen] = "}" end tables[value] = nil else return exception ('unsupported type', value, state, buffer, buflen,     "type '" .. valtype .. "' is not supported by JSON.") end return buflen end

function json.encode (value, state) state = state or {} local oldbuffer = state.buffer local buffer = oldbuffer or {} state.buffer = buffer updatedecpoint local ret, msg = encode2 (value, state.indent, state.level or 0,                  buffer, state.bufferlen or 0, state.tables or {}, state.keyorder, state) if not ret then error (msg, 2) elseif oldbuffer == buffer then state.bufferlen = ret return true else state.bufferlen = nil state.buffer = nil return concat (buffer) end end

local function loc (str, where) local line, pos, linepos = 1, 1, 0 while true do   pos = strfind (str, "\n", pos, true) if pos and pos < where then line = line + 1 linepos = pos pos = pos + 1 else break end end return "line " .. line .. ", column " .. (where - linepos) end

local function unterminated (str, what, where) return nil, strlen (str) + 1, "unterminated " .. what .. " at " .. loc (str, where) end

local function scanwhite (str, pos) while true do   pos = strfind (str, "%S", pos) if not pos then return nil end local sub2 = strsub (str, pos, pos + 1) if sub2 == "\239\187" and strsub (str, pos + 2, pos + 2) == "\191" then -- UTF-8 Byte Order Mark pos = pos + 3 elseif sub2 == "//" then pos = strfind (str, "[\n\r]", pos + 2) if not pos then return nil end elseif sub2 == "/*" then pos = strfind (str, "*/", pos + 2) if not pos then return nil end pos = pos + 2 else return pos end end end

local escapechars = { ["\""] = "\"", ["\\"] = "\\", ["/"] = "/", ["b"] = "\b", ["f"] = "\f", ["n"] = "\n", ["r"] = "\r", ["t"] = "\t" }

local function unichar (value) if value < 0 then return nil elseif value <= 0x007f then return strchar (value) elseif value <= 0x07ff then return strchar (0xc0 + floor(value/0x40),                   0x80 + (floor(value) % 0x40)) elseif value <= 0xffff then return strchar (0xe0 + floor(value/0x1000),                   0x80 + (floor(value/0x40) % 0x40),                    0x80 + (floor(value) % 0x40)) elseif value <= 0x10ffff then return strchar (0xf0 + floor(value/0x40000),                   0x80 + (floor(value/0x1000) % 0x40),                    0x80 + (floor(value/0x40) % 0x40),                    0x80 + (floor(value) % 0x40)) else return nil end end

local function scanstring (str, pos) local lastpos = pos + 1 local buffer, n = {}, 0 while true do   local nextpos = strfind (str, "[\"\\]", lastpos)    if not nextpos then      return unterminated (str, "string", pos)    end    if nextpos > lastpos then      n = n + 1      buffer[n] = strsub (str, lastpos, nextpos - 1)    end    if strsub (str, nextpos, nextpos) == "\"" then lastpos = nextpos + 1 break else local escchar = strsub (str, nextpos + 1, nextpos + 1) local value if escchar == "u" then value = tonumber (strsub (str, nextpos + 2, nextpos + 5), 16) if value then local value2 if 0xD800 <= value and value <= 0xDBff then -- we have the high surrogate of UTF-16. Check if there is a           -- low surrogate escaped nearby to combine them. if strsub (str, nextpos + 6, nextpos + 7) == "\\u" then value2 = tonumber (strsub (str, nextpos + 8, nextpos + 11), 16) if value2 and 0xDC00 <= value2 and value2 <= 0xDFFF then value = (value - 0xD800) * 0x400 + (value2 - 0xDC00) + 0x10000 else value2 = nil -- in case it was out of range for a low surrogate end end end value = value and unichar (value) if value then if value2 then lastpos = nextpos + 12 else lastpos = nextpos + 6 end end end end if not value then value = escapechars[escchar] or escchar lastpos = nextpos + 2 end n = n + 1 buffer[n] = value end end if n == 1 then return buffer[1], lastpos elseif n > 1 then return concat (buffer), lastpos else return "", lastpos end end

local scanvalue -- forward declaration

local function scantable (what, closechar, str, startpos, nullval, objectmeta, arraymeta) local len = strlen (str) local tbl, n = {}, 0 local pos = startpos + 1 if what == 'object' then setmetatable (tbl, objectmeta) else setmetatable (tbl, arraymeta) end while true do   pos = scanwhite (str, pos) if not pos then return unterminated (str, what, startpos) end local char = strsub (str, pos, pos) if char == closechar then return tbl, pos + 1 end local val1, err val1, pos, err = scanvalue (str, pos, nullval, objectmeta, arraymeta) if err then return nil, pos, err end pos = scanwhite (str, pos) if not pos then return unterminated (str, what, startpos) end char = strsub (str, pos, pos) if char == ":" then if val1 == nil then return nil, pos, "cannot use nil as table index (at " .. loc (str, pos) .. ")" end pos = scanwhite (str, pos + 1) if not pos then return unterminated (str, what, startpos) end local val2 val2, pos, err = scanvalue (str, pos, nullval, objectmeta, arraymeta) if err then return nil, pos, err end tbl[val1] = val2 pos = scanwhite (str, pos) if not pos then return unterminated (str, what, startpos) end char = strsub (str, pos, pos) else n = n + 1 tbl[n] = val1 end if char == "," then pos = pos + 1 end end end

scanvalue = function (str, pos, nullval, objectmeta, arraymeta) pos = pos or 1 pos = scanwhite (str, pos) if not pos then return nil, strlen (str) + 1, "no valid JSON value (reached the end)" end local char = strsub (str, pos, pos) if char == "{" then return scantable ('object', "}", str, pos, nullval, objectmeta, arraymeta) elseif char == "[" then return scantable ('array', "]", str, pos, nullval, objectmeta, arraymeta) elseif char == "\"" then   return scanstring (str, pos)  else    local pstart, pend = strfind (str, "^%-?[%d%.]+[eE]?[%+%-]?%d*", pos)    if pstart then      local number = str2num (strsub (str, pstart, pend))      if number then        return number, pend + 1      end    end    pstart, pend = strfind (str, "^%a%w*", pos)    if pstart then      local name = strsub (str, pstart, pend)      if name == "true" then        return true, pend + 1      elseif name == "false" then        return false, pend + 1      elseif name == "null" then        return nullval, pend + 1      end    end    return nil, pos, "no valid JSON value at " .. loc (str, pos)  end end

local function optionalmetatables(...) if select("#", ...) > 0 then return ... else return {__jsontype = 'object'}, {__jsontype = 'array'} end end

function json.decode (str, pos, nullval, ...) local objectmeta, arraymeta = optionalmetatables(...) return scanvalue (str, pos, nullval, objectmeta, arraymeta) end

function json.use_lpeg local g = require ("lpeg")

if g.version == "0.11" then error "due to a bug in LPeg 0.11, it cannot be used for JSON matching" end

local pegmatch = g.match local P, S, R = g.P, g.S, g.R

local function ErrorCall (str, pos, msg, state) if not state.msg then state.msg = msg .. " at " .. loc (str, pos) state.pos = pos end return false end

local function Err (msg) return g.Cmt (g.Cc (msg) * g.Carg (2), ErrorCall) end

local SingleLineComment = P"//" * (1 - S"\n\r")^0 local MultiLineComment = P"/*" * (1 - P"*/")^0 * P"*/" local Space = (S" \n\r\t" + P"\239\187\191" + SingleLineComment + MultiLineComment)^0

local PlainChar = 1 - S"\"\\\n\r" local EscapeSequence = (P"\\" * g.C (S"\"\\/bfnrt" + Err "unsupported escape sequence")) / escapechars local HexDigit = R("09", "af", "AF") local function UTF16Surrogate (match, pos, high, low) high, low = tonumber (high, 16), tonumber (low, 16) if 0xD800 <= high and high <= 0xDBff and 0xDC00 <= low and low <= 0xDFFF then return true, unichar ((high - 0xD800) * 0x400 + (low - 0xDC00) + 0x10000) else return false end end local function UTF16BMP (hex) return unichar (tonumber (hex, 16)) end local U16Sequence = (P"\\u" * g.C (HexDigit * HexDigit * HexDigit * HexDigit)) local UnicodeEscape = g.Cmt (U16Sequence * U16Sequence, UTF16Surrogate) + U16Sequence/UTF16BMP local Char = UnicodeEscape + EscapeSequence + PlainChar local String = P"\"" * g.Cs (Char ^ 0) * (P"\"" + Err "unterminated string") local Integer = P"-"^(-1) * (P"0" + (R"19" * R"09"^0)) local Fractal = P"." * R"09"^0 local Exponent = (S"eE") * (S"+-")^(-1) * R"09"^1 local Number = (Integer * Fractal^(-1) * Exponent^(-1))/str2num local Constant = P"true" * g.Cc (true) + P"false" * g.Cc (false) + P"null" * g.Carg (1) local SimpleValue = Number + String + Constant local ArrayContent, ObjectContent

-- The functions parsearray and parseobject parse only a single value/pair -- at a time and store them directly to avoid hitting the LPeg limits. local function parsearray (str, pos, nullval, state) local obj, cont local npos local t, nt = {}, 0 repeat obj, cont, npos = pegmatch (ArrayContent, str, pos, nullval, state) if not npos then break end pos = npos nt = nt + 1 t[nt] = obj until cont == 'last' return pos, setmetatable (t, state.arraymeta) end

local function parseobject (str, pos, nullval, state) local obj, key, cont local npos local t = {} repeat key, obj, cont, npos = pegmatch (ObjectContent, str, pos, nullval, state) if not npos then break end pos = npos t[key] = obj until cont == 'last' return pos, setmetatable (t, state.objectmeta) end

local Array = P"[" * g.Cmt (g.Carg(1) * g.Carg(2), parsearray) * Space * (P"]" + Err "']' expected") local Object = P"{" * g.Cmt (g.Carg(1) * g.Carg(2), parseobject) * Space * (P"}" + Err "'}' expected") local Value = Space * (Array + Object + SimpleValue) local ExpectedValue = Value + Space * Err "value expected" ArrayContent = Value * Space * (P"," * g.Cc'cont' + g.Cc'last') * g.Cp local Pair = g.Cg (Space * String * Space * (P":" + Err "colon expected") * ExpectedValue) ObjectContent = Pair * Space * (P"," * g.Cc'cont' + g.Cc'last') * g.Cp local DecodeValue = ExpectedValue * g.Cp

function json.decode (str, pos, nullval, ...) local state = {} state.objectmeta, state.arraymeta = optionalmetatables(...) local obj, retpos = pegmatch (DecodeValue, str, pos, nullval, state) if state.msg then return nil, state.pos, state.msg else return obj, retpos end end

-- use this function only once: json.use_lpeg = function return json end

json.using_lpeg = true

return json -- so you can get the module using json = require "dkjson".use_lpeg end

if always_try_using_lpeg then pcall (json.use_lpeg) end

return json