--[==[
David Kolf's JSON module for Lua 5.1/5.2
========================================
*Version 2.1*
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 2.1"`.
`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.
<!-- This documentation can be parsed using Markdown to generate HTML.
The source code is enclosed in a HTML comment so it won't be displayed
by browsers, but it should be removed from the final HTML file as
it isn't a valid HTML comment (and wastes space).
-->
<!--]==]
-- 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 2.1" }
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 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*", pos)
if pstart then
local number = tonumber (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
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" + R"\176\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 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, 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
-->
