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diff --git a/doc-main.txt b/doc-main.txt index debe535..8a0bc55 100644 --- a/doc-main.txt +++ b/doc-main.txt @@ -1,283 +1,283 @@ -# = 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. -# +== json - JSON Implementation 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. + |