------------------------------------------------------------------------
-- David Kolf's JSON module for Lua 5.1/5.2
-- Version 2.0
--
-- This module writes no global values, not even the module table.
-- Import it using
-- json = require ("dkjson")
--
-- Exported functions and values:
--
-- json.encode (object [, state])
-- Create a string representing the object. 'Object' can be a table,
-- a string, a number, a boolean, nil, json.null or any object with
-- a function __tojson in its metatable. A table can only use strings
-- and numbers as keys and its values have to be valid objects as
-- well. It raises an error for any invalid data types or reference
-- cycles.
--
-- 'state' is an optional table with the following fields:
-- - indent
-- When 'indent' (a boolean) is set, the created string will contain
-- newlines and indentations. Otherwise it will be one long line.
-- - keyorder
-- 'keyorder' is an array to specify the ordering of keys in the
-- encoded output. If an object has keys which are not in this array
-- they are written after the sorted keys.
-- - level
-- This is the initial level of indentation used when 'indent' is
-- set. For each level two spaces are added. When absent it is set
-- to 0.
-- - buffer
-- 'buffer' is an array to store the strings for the result so they
-- can be concatenated at once. When it isn't given, the encode
-- function will create it temporary and will return the
-- concatenated result.
-- - bufferlen
-- When 'bufferlen' is set, it has to be the index of the last
-- element of 'buffer'.
-- - tables
-- 'tables' is a set to detect reference cycles. It is created
-- temporary when absent. Every table that is currently processed
-- is used as key, the value is 'true'.
--
-- When state.buffer was set, the return value will be true on
-- success. Without state.buffer the return value will be a string.
--
-- json.decode (string [, position [, null]])
-- Decode 'string' starting at 'position' or at 1 if 'position' was
-- omitted.
--
-- 'null' is an optional value to be returned for null values. The
-- default is 'nil', but you could set it to json.null or any other
-- value.
--
-- The return values are the object or nil, the position of the next
-- character that doesn't belong to the object, and in case of errors
-- an error message.
--
-- Two metatables are created. Every array or object that is decoded gets
-- a metatable with the __jsontype field set to either 'array' or
-- 'object'. If you want to provide your own metatables use the syntax
-- json.decode (string, position, null, objectmeta, arraymeta)
--
-- <metatable>.__jsonorder
-- __jsonorder can overwrite the 'keyorder' for a specific table.
-- <metatable>.__jsontype
-- __jsontype can be either 'array' or 'object'. This is mainly useful
-- for tables that can be empty. (The default for empty tables is
-- 'array').
-- <metatable>.__tojson (self, state)
-- You can provide your own __tojson function in a metatable. In this
-- function you can either add directly to the buffer and return true,
-- or you can return a string. On errors nil and a message should be
-- returned.
--
-- json.null
-- You can use this value for setting explicit 'null' values.
--
-- json.version
-- Set to "dkjson 2.0".
--
-- json.quotestring (string)
-- Quote a UTF-8 string and escape critical characters using JSON
-- escape sequences. This function is only necessary when you build
-- your own __tojson functions.
--
-- json.addnewline (state)
-- When state.indent is set, add a newline to state.buffer and spaces
-- according to state.level.
--
-- LPeg support: When the local configuration variable
-- 'always_try_using_lpeg' is set, this module tries to load LPeg to
-- replace the functions 'quotestring' and 'decode'. The speed increase
-- is significant. You can get the LPeg module at
-- <http://www.inf.puc-rio.br/~roberto/lpeg/>.
-- When LPeg couldn't be loaded, the pure Lua functions stay active.
-- In case you don't want this module to require LPeg on its own,
-- disable this option:
local always_try_using_lpeg = true
-- In this case you can later load LPeg support using
--
-- json.use_lpeg ()
-- Require the LPeg module and replace the functions 'quotestring' and
-- and 'decode' with functions that use LPeg patterns.
-- This function returns the module table, so you can load the module
-- using:
-- json = require "dkjson".use_lpeg()
-- Alternatively you can use pcall so the JSON module still works when
-- LPeg isn't found.
-- json = require "dkjson"
-- pcall (json.use_lpeg)
--
-- json.using_lpeg
-- This variable is set to true when LPeg was loaded successfully.
--
-- You can contact the author by sending an e-mail to 'kolf' at the
-- e-mail provider 'gmx.de'.
--
-- Copyright (C) 2010, 2011 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 = error, require, pcall
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 concat = table.concat
if _VERSION == 'Lua 5.1' then
local function noglobals (s,k,v) error ("global access: " .. k, 2) end
setfenv (1, setmetatable ({}, { __index = noglobals, __newindex = noglobals }))
end
local _ENV = nil -- blocking globals in Lua 5.2
local json = { version = "dkjson 2.0" }
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[\190\191]", escapeutf8)
end
return "\"" .. value .. "\""
end
json.quotestring = quotestring
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)
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)
end
encode2 = function (value, indent, level, buffer, buflen, tables, globalorder)
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 nil, "reference cycle"
end
tables[value] = true
local state = {
indent = indent, level = level, buffer = buffer,
bufferlen = buflen, tables = tables, keyorder = globalorder
}
local ret, msg = valtojson (value, state)
if not ret then return nil, msg end
tables[value] = nil
buflen = state.bufferlen
if type (ret) == 'string' then
buflen = buflen + 1
buffer[buflen] = ret
end
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 = tostring (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 nil, "reference cycle"
end
tables[value] = true
level = level + 1
local metatype = valmeta and valmeta.__jsontype
local isa, n
if metatype == 'array' then
isa = true
n = value.n or #value
elseif metatype == 'object' then
isa = false
else
isa, n = isarray (value)
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)
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)
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)
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)
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 nil, "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 {}
local ret, msg = encode2 (value, state.indent, state.level or 0,
buffer, state.bufferlen or 0, state.tables or {}, state.keyorder)
if not ret then
error (msg, 2)
elseif oldbuffer then
state.bufferlen = ret
return true
else
return concat (buffer)
end
end
local function loc (str, where)
local line, pos, linepos = 1, 1, 1
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
if strsub (str, pos, pos + 2) == "\239\187\191" then
-- UTF-8 Byte Order Mark
pos = pos + 3
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*%W", pos)
if pstart then
local number = tonumber (strsub (str, pstart, pend - 1))
if number then
return number, pend
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
function json.decode (str, pos, nullval, objectmeta, arraymeta)
objectmeta = objectmeta or {__jsontype = 'object'}
arraymeta = arraymeta or {__jsontype = 'array'}
return scanvalue (str, pos, nullval, objectmeta, arraymeta)
end
function json.use_lpeg ()
local g = require ("lpeg")
local pegmatch = g.match
local P, S, R, V = g.P, g.S, g.R, g.V
local SpecialChars = (R"\0\31" + S"\"\\\127" +
P"\194" * (R"\128\159" + P"\173") +
P"\216" * R"\128\132" +
P"\220\132" +
P"\225\158" * S"\180\181" +
P"\226\128" * (R"\140\143" + S"\168\175") +
P"\226\129" * R"\160\175" +
P"\239\187\191" +
P"\229\191" + S"\190\191") / escapeutf8
local QuoteStr = g.Cs (g.Cc "\"" * (SpecialChars + 1)^0 * g.Cc "\"")
quotestring = function (str)
return pegmatch (QuoteStr, str)
end
json.quotestring = quotestring
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 Space = (S" \n\r\t" + P"\239\187\191")^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))/tonumber
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 recursion is done in the functions parsearray and parseobject instead of
-- in a grammar to avoid the "too many pending calls/choices" error.
local function parsearray (str, pos, nullval, state)
local obj, retpos = pegmatch (ArrayContent, str, pos, nullval, state)
if obj then
return retpos, setmetatable (obj, state.arraymeta)
else
return nil
end
end
local function parseobject (str, pos, nullval, state)
local obj, retpos = pegmatch (ObjectContent, str, pos, nullval, state)
if obj then
return retpos, setmetatable (obj, state.objectmeta)
else
return nil
end
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 = g.Ct ((Value * (Space * P"," * ExpectedValue)^0)^(-1)) * g.Cp()
local Pair = g.Cg (Space * String * Space * (P":" + Err "colon expected") * ExpectedValue)
ObjectContent = g.Cf (g.Ct ("") * (Pair * (Space * P"," * (Pair +
Err "key string expected"))^0)^(-1), rawset) * g.Cp()
local DecodeValue = ExpectedValue * g.Cp ()
function json.decode (str, pos, nullval, objectmeta, arraymeta)
local state = {
objectmeta = objectmeta or {__jsontype = 'object'},
arraymeta = arraymeta or {__jsontype = 'array'}
}
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