mirror of
https://github.com/ruby/ruby.git
synced 2022-11-09 12:17:21 -05:00
4f364c6bf7
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@23346 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
297 lines
11 KiB
Ruby
Executable file
297 lines
11 KiB
Ruby
Executable file
require 'json/common'
|
|
# = json - JSON for Ruby
|
|
#
|
|
# == Description
|
|
#
|
|
# This is a implementation of the JSON specification according to RFC 4627
|
|
# (http://www.ietf.org/rfc/rfc4627.txt). Starting from version 1.0.0 on there
|
|
# will be two variants available:
|
|
#
|
|
# * A pure ruby variant, that relies on the iconv and the stringscan
|
|
# extensions, which are both part of the ruby standard library.
|
|
# * The quite a bit faster C extension variant, which is in parts implemented
|
|
# in C and comes with its own unicode conversion functions and a parser
|
|
# generated by the ragel state machine compiler
|
|
# (http://www.cs.queensu.ca/~thurston/ragel).
|
|
#
|
|
# Both variants of the JSON generator escape all non-ASCII an control
|
|
# characters with \uXXXX escape sequences, and support UTF-16 surrogate pairs
|
|
# in order to be able to generate the whole range of unicode code points. This
|
|
# means that generated JSON text is encoded as UTF-8 (because ASCII is a subset
|
|
# of UTF-8) and at the same time avoids decoding problems for receiving
|
|
# endpoints, that don't expect UTF-8 encoded texts. On the negative side this
|
|
# may lead to a bit longer strings than necessarry.
|
|
#
|
|
# All strings, that are to be encoded as JSON strings, should be UTF-8 byte
|
|
# sequences on the Ruby side. To encode raw binary strings, that aren't UTF-8
|
|
# encoded, please use the to_json_raw_object method of String (which produces
|
|
# an object, that contains a byte array) and decode the result on the receiving
|
|
# endpoint.
|
|
#
|
|
# == Author
|
|
#
|
|
# Florian Frank <mailto:flori@ping.de>
|
|
#
|
|
# == License
|
|
#
|
|
# This software is distributed under the same license as Ruby itself, see
|
|
# http://www.ruby-lang.org/en/LICENSE.txt.
|
|
#
|
|
# == Download
|
|
#
|
|
# The latest version of this library can be downloaded at
|
|
#
|
|
# * http://rubyforge.org/frs?group_id=953
|
|
#
|
|
# Online Documentation should be located at
|
|
#
|
|
# * http://json.rubyforge.org
|
|
#
|
|
# == Usage
|
|
#
|
|
# To use JSON you can
|
|
# require 'json'
|
|
# to load the installed variant (either the extension 'json' or the pure
|
|
# variant 'json_pure'). If you have installed the extension variant, you can
|
|
# pick either the extension variant or the pure variant by typing
|
|
# require 'json/ext'
|
|
# or
|
|
# require 'json/pure'
|
|
#
|
|
# You can choose to load a set of common additions to ruby core's objects if
|
|
# you
|
|
# require 'json/add/core'
|
|
#
|
|
# After requiring this you can, e. g., serialise/deserialise Ruby ranges:
|
|
#
|
|
# JSON JSON(1..10) # => 1..10
|
|
#
|
|
# To find out how to add JSON support to other or your own classes, read the
|
|
# Examples section below.
|
|
#
|
|
# To get the best compatibility to rails' JSON implementation, you can
|
|
# require 'json/add/rails'
|
|
#
|
|
# Both of the additions attempt to require 'json' (like above) first, if it has
|
|
# not been required yet.
|
|
#
|
|
# == Speed Comparisons
|
|
#
|
|
# I have created some benchmark results (see the benchmarks/data-p4-3Ghz
|
|
# subdir of the package) for the JSON-parser to estimate the speed up in the C
|
|
# extension:
|
|
#
|
|
# Comparing times (call_time_mean):
|
|
# 1 ParserBenchmarkExt#parser 900 repeats:
|
|
# 553.922304770 ( real) -> 21.500x
|
|
# 0.001805307
|
|
# 2 ParserBenchmarkYAML#parser 1000 repeats:
|
|
# 224.513358139 ( real) -> 8.714x
|
|
# 0.004454078
|
|
# 3 ParserBenchmarkPure#parser 1000 repeats:
|
|
# 26.755020642 ( real) -> 1.038x
|
|
# 0.037376163
|
|
# 4 ParserBenchmarkRails#parser 1000 repeats:
|
|
# 25.763381731 ( real) -> 1.000x
|
|
# 0.038814780
|
|
# calls/sec ( time) -> speed covers
|
|
# secs/call
|
|
#
|
|
# In the table above 1 is JSON::Ext::Parser, 2 is YAML.load with YAML
|
|
# compatbile JSON document, 3 is is JSON::Pure::Parser, and 4 is
|
|
# ActiveSupport::JSON.decode. The ActiveSupport JSON-decoder converts the
|
|
# input first to YAML and then uses the YAML-parser, the conversion seems to
|
|
# slow it down so much that it is only as fast as the JSON::Pure::Parser!
|
|
#
|
|
# If you look at the benchmark data you can see that this is mostly caused by
|
|
# the frequent high outliers - the median of the Rails-parser runs is still
|
|
# overall smaller than the median of the JSON::Pure::Parser runs:
|
|
#
|
|
# Comparing times (call_time_median):
|
|
# 1 ParserBenchmarkExt#parser 900 repeats:
|
|
# 800.592479481 ( real) -> 26.936x
|
|
# 0.001249075
|
|
# 2 ParserBenchmarkYAML#parser 1000 repeats:
|
|
# 271.002390644 ( real) -> 9.118x
|
|
# 0.003690004
|
|
# 3 ParserBenchmarkRails#parser 1000 repeats:
|
|
# 30.227910865 ( real) -> 1.017x
|
|
# 0.033082008
|
|
# 4 ParserBenchmarkPure#parser 1000 repeats:
|
|
# 29.722384421 ( real) -> 1.000x
|
|
# 0.033644676
|
|
# calls/sec ( time) -> speed covers
|
|
# secs/call
|
|
#
|
|
# I have benchmarked the JSON-Generator as well. This generated a few more
|
|
# values, because there are different modes that also influence the achieved
|
|
# speed:
|
|
#
|
|
# Comparing times (call_time_mean):
|
|
# 1 GeneratorBenchmarkExt#generator_fast 1000 repeats:
|
|
# 547.354332608 ( real) -> 15.090x
|
|
# 0.001826970
|
|
# 2 GeneratorBenchmarkExt#generator_safe 1000 repeats:
|
|
# 443.968212317 ( real) -> 12.240x
|
|
# 0.002252414
|
|
# 3 GeneratorBenchmarkExt#generator_pretty 900 repeats:
|
|
# 375.104545883 ( real) -> 10.341x
|
|
# 0.002665923
|
|
# 4 GeneratorBenchmarkPure#generator_fast 1000 repeats:
|
|
# 49.978706968 ( real) -> 1.378x
|
|
# 0.020008521
|
|
# 5 GeneratorBenchmarkRails#generator 1000 repeats:
|
|
# 38.531868759 ( real) -> 1.062x
|
|
# 0.025952543
|
|
# 6 GeneratorBenchmarkPure#generator_safe 1000 repeats:
|
|
# 36.927649925 ( real) -> 1.018x 7 (>=3859)
|
|
# 0.027079979
|
|
# 7 GeneratorBenchmarkPure#generator_pretty 1000 repeats:
|
|
# 36.272134441 ( real) -> 1.000x 6 (>=3859)
|
|
# 0.027569373
|
|
# calls/sec ( time) -> speed covers
|
|
# secs/call
|
|
#
|
|
# In the table above 1-3 are JSON::Ext::Generator methods. 4, 6, and 7 are
|
|
# JSON::Pure::Generator methods and 5 is the Rails JSON generator. It is now a
|
|
# bit faster than the generator_safe and generator_pretty methods of the pure
|
|
# variant but slower than the others.
|
|
#
|
|
# To achieve the fastest JSON text output, you can use the fast_generate
|
|
# method. Beware, that this will disable the checking for circular Ruby data
|
|
# structures, which may cause JSON to go into an infinite loop.
|
|
#
|
|
# Here are the median comparisons for completeness' sake:
|
|
#
|
|
# Comparing times (call_time_median):
|
|
# 1 GeneratorBenchmarkExt#generator_fast 1000 repeats:
|
|
# 708.258020939 ( real) -> 16.547x
|
|
# 0.001411915
|
|
# 2 GeneratorBenchmarkExt#generator_safe 1000 repeats:
|
|
# 569.105020353 ( real) -> 13.296x
|
|
# 0.001757145
|
|
# 3 GeneratorBenchmarkExt#generator_pretty 900 repeats:
|
|
# 482.825371244 ( real) -> 11.280x
|
|
# 0.002071142
|
|
# 4 GeneratorBenchmarkPure#generator_fast 1000 repeats:
|
|
# 62.717626652 ( real) -> 1.465x
|
|
# 0.015944481
|
|
# 5 GeneratorBenchmarkRails#generator 1000 repeats:
|
|
# 43.965681162 ( real) -> 1.027x
|
|
# 0.022745013
|
|
# 6 GeneratorBenchmarkPure#generator_safe 1000 repeats:
|
|
# 43.929073409 ( real) -> 1.026x 7 (>=3859)
|
|
# 0.022763968
|
|
# 7 GeneratorBenchmarkPure#generator_pretty 1000 repeats:
|
|
# 42.802514491 ( real) -> 1.000x 6 (>=3859)
|
|
# 0.023363113
|
|
# calls/sec ( time) -> speed covers
|
|
# secs/call
|
|
#
|
|
# == Examples
|
|
#
|
|
# To create a JSON text from a ruby data structure, you can call JSON.generate
|
|
# like that:
|
|
#
|
|
# json = JSON.generate [1, 2, {"a"=>3.141}, false, true, nil, 4..10]
|
|
# # => "[1,2,{\"a\":3.141},false,true,null,\"4..10\"]"
|
|
#
|
|
# To create a valid JSON text you have to make sure, that the output is
|
|
# embedded in either a JSON array [] or a JSON object {}. The easiest way to do
|
|
# this, is by putting your values in a Ruby Array or Hash instance.
|
|
#
|
|
# To get back a ruby data structure from a JSON text, you have to call
|
|
# JSON.parse on it:
|
|
#
|
|
# JSON.parse json
|
|
# # => [1, 2, {"a"=>3.141}, false, true, nil, "4..10"]
|
|
#
|
|
# Note, that the range from the original data structure is a simple
|
|
# string now. The reason for this is, that JSON doesn't support ranges
|
|
# or arbitrary classes. In this case the json library falls back to call
|
|
# Object#to_json, which is the same as #to_s.to_json.
|
|
#
|
|
# It's possible to add JSON support serialization to arbitrary classes by
|
|
# simply implementing a more specialized version of the #to_json method, that
|
|
# should return a JSON object (a hash converted to JSON with #to_json) like
|
|
# this (don't forget the *a for all the arguments):
|
|
#
|
|
# class Range
|
|
# def to_json(*a)
|
|
# {
|
|
# 'json_class' => self.class.name, # = 'Range'
|
|
# 'data' => [ first, last, exclude_end? ]
|
|
# }.to_json(*a)
|
|
# end
|
|
# end
|
|
#
|
|
# The hash key 'json_class' is the class, that will be asked to deserialise the
|
|
# JSON representation later. In this case it's 'Range', but any namespace of
|
|
# the form 'A::B' or '::A::B' will do. All other keys are arbitrary and can be
|
|
# used to store the necessary data to configure the object to be deserialised.
|
|
#
|
|
# If a the key 'json_class' is found in a JSON object, the JSON parser checks
|
|
# if the given class responds to the json_create class method. If so, it is
|
|
# called with the JSON object converted to a Ruby hash. So a range can
|
|
# be deserialised by implementing Range.json_create like this:
|
|
#
|
|
# class Range
|
|
# def self.json_create(o)
|
|
# new(*o['data'])
|
|
# end
|
|
# end
|
|
#
|
|
# Now it possible to serialise/deserialise ranges as well:
|
|
#
|
|
# json = JSON.generate [1, 2, {"a"=>3.141}, false, true, nil, 4..10]
|
|
# # => "[1,2,{\"a\":3.141},false,true,null,{\"json_class\":\"Range\",\"data\":[4,10,false]}]"
|
|
# JSON.parse json
|
|
# # => [1, 2, {"a"=>3.141}, false, true, nil, 4..10]
|
|
#
|
|
# JSON.generate always creates the shortest possible string representation of a
|
|
# ruby data structure in one line. This good for data storage or network
|
|
# protocols, but not so good for humans to read. Fortunately there's also
|
|
# JSON.pretty_generate (or JSON.pretty_generate) that creates a more
|
|
# readable output:
|
|
#
|
|
# puts JSON.pretty_generate([1, 2, {"a"=>3.141}, false, true, nil, 4..10])
|
|
# [
|
|
# 1,
|
|
# 2,
|
|
# {
|
|
# "a": 3.141
|
|
# },
|
|
# false,
|
|
# true,
|
|
# null,
|
|
# {
|
|
# "json_class": "Range",
|
|
# "data": [
|
|
# 4,
|
|
# 10,
|
|
# false
|
|
# ]
|
|
# }
|
|
# ]
|
|
#
|
|
# There are also the methods Kernel#j for generate, and Kernel#jj for
|
|
# pretty_generate output to the console, that work analogous to Core Ruby's p
|
|
# and the pp library's pp methods.
|
|
#
|
|
# The script tools/server.rb contains a small example if you want to test, how
|
|
# receiving a JSON object from a webrick server in your browser with the
|
|
# javasript prototype library (http://www.prototypejs.org) works.
|
|
#
|
|
module JSON
|
|
require 'json/version'
|
|
|
|
if VARIANT_BINARY
|
|
require 'json/ext'
|
|
else
|
|
begin
|
|
require 'json/ext'
|
|
rescue LoadError
|
|
require 'json/pure'
|
|
end
|
|
end
|
|
end
|