ARSON is JSON, with a little bit of sugar: Comments, Commas, and Tags.
For example:
{
"numbers": +0123.0, # Can have leading zeros
"octal": 0o10, # Oh, and comments too
"hex": 0xFF, #
"binary": 0b1000_0001, # Number literals can have _'s
"lists": [1,2,3,], # Lists can have trailing commas
"strings": "At least \x61 \u0061 and \U00000061 work now",
"or": 'a string', # both "" and '' work.
"records": {
"a": 1, # Must have unique keys
"b": 2, # and the order must be kept
},
}
Along with some sugar atop JSON, ARSON supports tagging literals to represent types outside of JSON:
@datetime "2017-11-22T23:32:07.100497Z"
, a tagged RFC 3339 datestamp@duration 60
(a duration in seconds, float or int)@base64 "...=="
, a base64 encoded bytestring@set
,@dict
,@complex
,@bytestring
Use pip install arson
to get the latest copy of the python library. The arson
library
has two methods, parse
and dump
.
import arson
print(arson.parse(arson.dump([1,2,3])))
If you want to use your own tagged object types, you can create a custom Codec
:
import arson
class Example:
def __init__(self, value):
self.value = value
def __repr__(self):
return f"Example {self.value}"
def object_to_tagged(obj):
if isinstance(obj, Example):
return "Example", {"value": obj.value}
else:
raise NotImplementedError()
def tagged_to_object(name, value):
if name == "Example":
return Example(value['value'])
else:
raise NotImplementedError()
codec = arson.Codec(object_to_tagged, tagged_to_object)
print(codec.parse(codec.dump(Example(1))))
This library supports serializing and deserializing the following types
str
,int
,bool
float
(including Infinity and Nan)list
,tuple
(but will always return a list)dict
,set
,OrderedDict
(but will use dicts on 3.7+)datetime
,timedelta
(but will convert times to UTC)bytestring
,bytearray
(but will return a bytearray)complex
The fixed width numeric types are currently unsupported (Sorry).
- File MUST be utf-8, not cesu-8/utf-16/utf-32, without surrogate pairs.
- Use
#.... <end of line>
for comments - Byte Order Mark is treated as whitespace (along with
\x09
,\x0a
,\x0d
,\x20
) - ARSON Document is any ARSON Object, (i.e
1
is a valid ARSON file). - Lists are
[]
,[obj]
,[obj,]
,[obj, obj]
... (trailing comma optional) - Records are
{"key": value}
, keys must be unique, order must be preserved. - Built-ins:
true
,false
,null
"unicode strings"
with escapes\" \\ \/ \b \f \n \r \t \uFFFF \UFFFFFFFF
, no control codes unecaped, and''
can be used instead of""
.- int/float numbers (unary plus or minus, allowleading zeros, hex, octal, and binary integer liters)
- Tagged literals:
@name [1,2,3]
for any other type of value.
Errors are fatal. A record with duplicate keys, or a string too long, or a number too big to represent MUST cause the parse to fail outright.
ARSON has the following types of literals:
null
,true
,false
- Numbers (Floating Point, and integer literals: decimal, binary, octal, hex)
- Strings (using single or double quotes)
- Lists
- Records (a JSON object with ordering and without duplicate keys)
- Tagged Literal
ARSON has a number of built-in tags that map reasonably well to python types:
@bytestring
, or@base64
for bytestrings@set
for sets,@complex
for complex numbers@datetime
,@duration
for datetimes and timedeltas.