This is the documentation for dkjson, a JSON module written in Lua (5.1 to 5.4).
Version 2.8
In the default configuration this module writes no global values, not even the module table. Import it using
json = require ("dkjson")
In environments where require or a similiar function are not available
and you cannot receive the return value of the module, you can set the
option register_global_module_table to true. The module table will
then be saved in the global variable with the name given by the option
global_module_name.
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 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 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 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.exception exception is given, it will be called whenever the encoder
cannot encode a given value. reason, value, state and defaultmessage.
reason is either "reference cycle", "custom encoder failed" or
"unsupported type". value is the original value that caused the
exception, state is this state table, defaultmessage is the message
of the error that would usually be raised. true and add directly to the buffer or you can
return the string directly. To keep raising an error return nil and
the desired error message. json.encodeexception.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)
To prevent the assigning of metatables pass nil:
json.decode (string, position, null, nil)
<metatable>.__jsonorder__jsonorder can overwrite the keyorder for a specific table.
<metatable>.__jsontype__jsontype can be either "array" or "object". This value is only
checked for empty tables. (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.nullYou can use this value for setting explicit null values.
json.versionSet to "dkjson 2.8".
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.
json.encodeexception (reason, value, state, defaultmessage)This function can be used as value to the exception option. Instead of
raising an error this function encodes the error message as a string. This
can help to debug malformed input data.
x = json.encode(value, { exception = json.encodeexception })
When the local configuration variable always_use_lpeg is set,
this module tries to load LPeg to replace the decode function. The
speed increase is significant. You can get the LPeg module at
http://www.inf.puc-rio.br/~roberto/lpeg/.
Without changing the module configuration you can get LPeg support by
calling the function use_lpeg:
json.use_lpeg ()Require the LPeg module and return a copy of the module table where the
decode function was replaced by a version that uses LPeg:
json = require "dkjson".use_lpeg()
Without the configuration to always use LPEG the original module table is unchanged and still available by calls to
json = require "dkjson"
json.using_lpegThis variable is set to true in the copy of the module table that uses
LPeg support.
You can contact the author by sending an e-mail to 'david' at the domain 'dkolf.de'.
Copyright (C) 2010-2024 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.