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8a974dc83c
This change fixes an incorrect `#` position in the API documentation of the `JSON` module. https://github.com/flori/json/commit/dc4b62424f
583 lines
19 KiB
Ruby
583 lines
19 KiB
Ruby
#frozen_string_literal: false
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require 'json/common'
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##
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# = JavaScript \Object Notation (\JSON)
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#
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# \JSON is a lightweight data-interchange format.
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#
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# A \JSON value is one of the following:
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# - Double-quoted text: <tt>"foo"</tt>.
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# - Number: +1+, +1.0+, +2.0e2+.
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# - Boolean: +true+, +false+.
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# - Null: +null+.
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# - \Array: an ordered list of values, enclosed by square brackets:
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# ["foo", 1, 1.0, 2.0e2, true, false, null]
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#
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# - \Object: a collection of name/value pairs, enclosed by curly braces;
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# each name is double-quoted text;
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# the values may be any \JSON values:
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# {"a": "foo", "b": 1, "c": 1.0, "d": 2.0e2, "e": true, "f": false, "g": null}
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#
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# A \JSON array or object may contain nested arrays, objects, and scalars
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# to any depth:
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# {"foo": {"bar": 1, "baz": 2}, "bat": [0, 1, 2]}
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# [{"foo": 0, "bar": 1}, ["baz", 2]]
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#
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# == Using \Module \JSON
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#
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# To make module \JSON available in your code, begin with:
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# require 'json'
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#
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# All examples here assume that this has been done.
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#
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# === Parsing \JSON
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#
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# You can parse a \String containing \JSON data using
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# either of two methods:
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# - <tt>JSON.parse(source, opts)</tt>
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# - <tt>JSON.parse!(source, opts)</tt>
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#
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# where
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# - +source+ is a Ruby object.
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# - +opts+ is a \Hash object containing options
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# that control both input allowed and output formatting.
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#
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# The difference between the two methods
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# is that JSON.parse! omits some checks
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# and may not be safe for some +source+ data;
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# use it only for data from trusted sources.
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# Use the safer method JSON.parse for less trusted sources.
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#
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# ==== Parsing \JSON Arrays
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#
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# When +source+ is a \JSON array, JSON.parse by default returns a Ruby \Array:
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# json = '["foo", 1, 1.0, 2.0e2, true, false, null]'
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# ruby = JSON.parse(json)
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# ruby # => ["foo", 1, 1.0, 200.0, true, false, nil]
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# ruby.class # => Array
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#
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# The \JSON array may contain nested arrays, objects, and scalars
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# to any depth:
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# json = '[{"foo": 0, "bar": 1}, ["baz", 2]]'
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# JSON.parse(json) # => [{"foo"=>0, "bar"=>1}, ["baz", 2]]
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#
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# ==== Parsing \JSON \Objects
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#
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# When the source is a \JSON object, JSON.parse by default returns a Ruby \Hash:
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# json = '{"a": "foo", "b": 1, "c": 1.0, "d": 2.0e2, "e": true, "f": false, "g": null}'
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# ruby = JSON.parse(json)
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# ruby # => {"a"=>"foo", "b"=>1, "c"=>1.0, "d"=>200.0, "e"=>true, "f"=>false, "g"=>nil}
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# ruby.class # => Hash
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#
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# The \JSON object may contain nested arrays, objects, and scalars
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# to any depth:
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# json = '{"foo": {"bar": 1, "baz": 2}, "bat": [0, 1, 2]}'
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# JSON.parse(json) # => {"foo"=>{"bar"=>1, "baz"=>2}, "bat"=>[0, 1, 2]}
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#
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# ==== Parsing \JSON Scalars
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#
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# When the source is a \JSON scalar (not an array or object),
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# JSON.parse returns a Ruby scalar.
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#
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# \String:
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# ruby = JSON.parse('"foo"')
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# ruby # => 'foo'
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# ruby.class # => String
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# \Integer:
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# ruby = JSON.parse('1')
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# ruby # => 1
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# ruby.class # => Integer
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# \Float:
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# ruby = JSON.parse('1.0')
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# ruby # => 1.0
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# ruby.class # => Float
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# ruby = JSON.parse('2.0e2')
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# ruby # => 200
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# ruby.class # => Float
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# Boolean:
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# ruby = JSON.parse('true')
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# ruby # => true
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# ruby.class # => TrueClass
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# ruby = JSON.parse('false')
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# ruby # => false
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# ruby.class # => FalseClass
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# Null:
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# ruby = JSON.parse('null')
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# ruby # => nil
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# ruby.class # => NilClass
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#
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# ==== Parsing Options
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#
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# ====== Input Options
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#
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# Option +max_nesting+ (\Integer) specifies the maximum nesting depth allowed;
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# defaults to +100+; specify +false+ to disable depth checking.
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#
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# With the default, +false+:
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# source = '[0, [1, [2, [3]]]]'
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# ruby = JSON.parse(source)
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# ruby # => [0, [1, [2, [3]]]]
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# Too deep:
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# # Raises JSON::NestingError (nesting of 2 is too deep):
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# JSON.parse(source, {max_nesting: 1})
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# Bad value:
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# # Raises TypeError (wrong argument type Symbol (expected Fixnum)):
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# JSON.parse(source, {max_nesting: :foo})
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#
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# ---
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#
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# Option +allow_nan+ (boolean) specifies whether to allow
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# NaN, Infinity, and MinusInfinity in +source+;
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# defaults to +false+.
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#
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# With the default, +false+:
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# # Raises JSON::ParserError (225: unexpected token at '[NaN]'):
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# JSON.parse('[NaN]')
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# # Raises JSON::ParserError (232: unexpected token at '[Infinity]'):
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# JSON.parse('[Infinity]')
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# # Raises JSON::ParserError (248: unexpected token at '[-Infinity]'):
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# JSON.parse('[-Infinity]')
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# Allow:
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# source = '[NaN, Infinity, -Infinity]'
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# ruby = JSON.parse(source, {allow_nan: true})
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# ruby # => [NaN, Infinity, -Infinity]
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#
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# ====== Output Options
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#
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# Option +symbolize_names+ (boolean) specifies whether returned \Hash keys
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# should be Symbols;
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# defaults to +false+ (use Strings).
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#
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# With the default, +false+:
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# source = '{"a": "foo", "b": 1.0, "c": true, "d": false, "e": null}'
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# ruby = JSON.parse(source)
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# ruby # => {"a"=>"foo", "b"=>1.0, "c"=>true, "d"=>false, "e"=>nil}
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# Use Symbols:
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# ruby = JSON.parse(source, {symbolize_names: true})
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# ruby # => {:a=>"foo", :b=>1.0, :c=>true, :d=>false, :e=>nil}
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#
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# ---
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#
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# Option +object_class+ (\Class) specifies the Ruby class to be used
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# for each \JSON object;
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# defaults to \Hash.
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#
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# With the default, \Hash:
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# source = '{"a": "foo", "b": 1.0, "c": true, "d": false, "e": null}'
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# ruby = JSON.parse(source)
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# ruby.class # => Hash
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# Use class \OpenStruct:
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# ruby = JSON.parse(source, {object_class: OpenStruct})
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# ruby # => #<OpenStruct a="foo", b=1.0, c=true, d=false, e=nil>
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#
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# ---
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#
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# Option +array_class+ (\Class) specifies the Ruby class to be used
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# for each \JSON array;
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# defaults to \Array.
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#
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# With the default, \Array:
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# source = '["foo", 1.0, true, false, null]'
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# ruby = JSON.parse(source)
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# ruby.class # => Array
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# Use class \Set:
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# ruby = JSON.parse(source, {array_class: Set})
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# ruby # => #<Set: {"foo", 1.0, true, false, nil}>
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#
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# ---
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#
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# Option +create_additions+ (boolean) specifies whether to use \JSON additions in parsing.
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# See {\JSON Additions}[#module-JSON-label-JSON+Additions].
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#
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# === Generating \JSON
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#
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# To generate a Ruby \String containing \JSON data,
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# use method <tt>JSON.generate(source, opts)</tt>, where
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# - +source+ is a Ruby object.
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# - +opts+ is a \Hash object containing options
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# that control both input allowed and output formatting.
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#
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# ==== Generating \JSON from Arrays
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#
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# When the source is a Ruby \Array, JSON.generate returns
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# a \String containing a \JSON array:
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# ruby = [0, 's', :foo]
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# json = JSON.generate(ruby)
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# json # => '[0,"s","foo"]'
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#
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# The Ruby \Array array may contain nested arrays, hashes, and scalars
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# to any depth:
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# ruby = [0, [1, 2], {foo: 3, bar: 4}]
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# json = JSON.generate(ruby)
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# json # => '[0,[1,2],{"foo":3,"bar":4}]'
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#
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# ==== Generating \JSON from Hashes
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#
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# When the source is a Ruby \Hash, JSON.generate returns
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# a \String containing a \JSON object:
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# ruby = {foo: 0, bar: 's', baz: :bat}
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# json = JSON.generate(ruby)
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# json # => '{"foo":0,"bar":"s","baz":"bat"}'
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#
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# The Ruby \Hash array may contain nested arrays, hashes, and scalars
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# to any depth:
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# ruby = {foo: [0, 1], bar: {baz: 2, bat: 3}, bam: :bad}
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# json = JSON.generate(ruby)
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# json # => '{"foo":[0,1],"bar":{"baz":2,"bat":3},"bam":"bad"}'
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#
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# ==== Generating \JSON from Other Objects
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#
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# When the source is neither an \Array nor a \Hash,
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# the generated \JSON data depends on the class of the source.
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#
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# When the source is a Ruby \Integer or \Float, JSON.generate returns
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# a \String containing a \JSON number:
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# JSON.generate(42) # => '42'
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# JSON.generate(0.42) # => '0.42'
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#
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# When the source is a Ruby \String, JSON.generate returns
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# a \String containing a \JSON string (with double-quotes):
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# JSON.generate('A string') # => '"A string"'
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#
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# When the source is +true+, +false+ or +nil+, JSON.generate returns
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# a \String containing the corresponding \JSON token:
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# JSON.generate(true) # => 'true'
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# JSON.generate(false) # => 'false'
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# JSON.generate(nil) # => 'null'
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#
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# When the source is none of the above, JSON.generate returns
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# a \String containing a \JSON string representation of the source:
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# JSON.generate(:foo) # => '"foo"'
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# JSON.generate(Complex(0, 0)) # => '"0+0i"'
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# JSON.generate(Dir.new('.')) # => '"#<Dir>"'
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#
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# ==== Generating Options
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#
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# ====== Input Options
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#
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# Option +allow_nan+ (boolean) specifies whether
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# +NaN+, +Infinity+, and <tt>-Infinity</tt> may be generated;
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# defaults to +false+.
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#
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# With the default, +false+:
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# # Raises JSON::GeneratorError (920: NaN not allowed in JSON):
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# JSON.generate(JSON::NaN)
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# # Raises JSON::GeneratorError (917: Infinity not allowed in JSON):
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# JSON.generate(JSON::Infinity)
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# # Raises JSON::GeneratorError (917: -Infinity not allowed in JSON):
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# JSON.generate(JSON::MinusInfinity)
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#
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# Allow:
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# ruby = [Float::NaN, Float::Infinity, Float::MinusInfinity]
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# JSON.generate(ruby, allow_nan: true) # => '[NaN,Infinity,-Infinity]'
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#
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# ---
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#
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# Option +max_nesting+ (\Integer) specifies the maximum nesting depth
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# in +obj+; defaults to +100+.
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#
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# With the default, +100+:
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# obj = [[[[[[0]]]]]]
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# JSON.generate(obj) # => '[[[[[[0]]]]]]'
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#
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# Too deep:
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# # Raises JSON::NestingError (nesting of 2 is too deep):
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# JSON.generate(obj, max_nesting: 2)
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#
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# ====== Output Options
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#
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# The default formatting options generate the most compact
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# \JSON data, all on one line and with no whitespace.
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#
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# You can use these formatting options to generate
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# \JSON data in a more open format, using whitespace.
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# See also JSON.pretty_generate.
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#
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# - Option +array_nl+ (\String) specifies a string (usually a newline)
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# to be inserted after each \JSON array; defaults to the empty \String, <tt>''</tt>.
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# - Option +object_nl+ (\String) specifies a string (usually a newline)
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# to be inserted after each \JSON object; defaults to the empty \String, <tt>''</tt>.
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# - Option +indent+ (\String) specifies the string (usually spaces) to be
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# used for indentation; defaults to the empty \String, <tt>''</tt>;
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# defaults to the empty \String, <tt>''</tt>;
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# has no effect unless options +array_nl+ or +object_nl+ specify newlines.
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# - Option +space+ (\String) specifies a string (usually a space) to be
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# inserted after the colon in each \JSON object's pair;
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# defaults to the empty \String, <tt>''</tt>.
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# - Option +space_before+ (\String) specifies a string (usually a space) to be
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# inserted before the colon in each \JSON object's pair;
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# defaults to the empty \String, <tt>''</tt>.
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#
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# In this example, +obj+ is used first to generate the shortest
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# \JSON data (no whitespace), then again with all formatting options
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# specified:
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#
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# obj = {foo: [:bar, :baz], bat: {bam: 0, bad: 1}}
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# json = JSON.generate(obj)
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# puts 'Compact:', json
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# opts = {
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# array_nl: "\n",
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# object_nl: "\n",
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# indent: ' ',
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# space_before: ' ',
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# space: ' '
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# }
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# puts 'Open:', JSON.generate(obj, opts)
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#
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# Output:
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# Compact:
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# {"foo":["bar","baz"],"bat":{"bam":0,"bad":1}}
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# Open:
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# {
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# "foo" : [
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# "bar",
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# "baz"
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# ],
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# "bat" : {
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# "bam" : 0,
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# "bad" : 1
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# }
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# }
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#
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# == \JSON Additions
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#
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# When you "round trip" a non-\String object from Ruby to \JSON and back,
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# you have a new \String, instead of the object you began with:
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# ruby0 = Range.new(0, 2)
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# json = JSON.generate(ruby0)
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# json # => '0..2"'
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# ruby1 = JSON.parse(json)
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# ruby1 # => '0..2'
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# ruby1.class # => String
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#
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# You can use \JSON _additions_ to preserve the original object.
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# The addition is an extension of a ruby class, so that:
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# - \JSON.generate stores more information in the \JSON string.
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# - \JSON.parse, called with option +create_additions+,
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# uses that information to create a proper Ruby object.
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#
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# This example shows a \Range being generated into \JSON
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# and parsed back into Ruby, both without and with
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# the addition for \Range:
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# ruby = Range.new(0, 2)
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# # This passage does not use the addition for Range.
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# json0 = JSON.generate(ruby)
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# ruby0 = JSON.parse(json0)
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# # This passage uses the addition for Range.
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# require 'json/add/range'
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# json1 = JSON.generate(ruby)
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# ruby1 = JSON.parse(json1, create_additions: true)
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# # Make a nice display.
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# display = <<EOT
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# Generated JSON:
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# Without addition: #{json0} (#{json0.class})
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# With addition: #{json1} (#{json1.class})
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# Parsed JSON:
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# Without addition: #{ruby0.inspect} (#{ruby0.class})
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# With addition: #{ruby1.inspect} (#{ruby1.class})
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# EOT
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# puts display
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#
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# This output shows the different results:
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# Generated JSON:
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# Without addition: "0..2" (String)
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# With addition: {"json_class":"Range","a":[0,2,false]} (String)
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# Parsed JSON:
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# Without addition: "0..2" (String)
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# With addition: 0..2 (Range)
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#
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# The \JSON module includes additions for certain classes.
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# You can also craft custom additions.
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# See {Custom \JSON Additions}[#module-JSON-label-Custom+JSON+Additions].
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#
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# === Built-in Additions
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#
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# The \JSON module includes additions for certain classes.
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# To use an addition, +require+ its source:
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# - BigDecimal: <tt>require 'json/add/bigdecimal'</tt>
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# - Complex: <tt>require 'json/add/complex'</tt>
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# - Date: <tt>require 'json/add/date'</tt>
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# - DateTime: <tt>require 'json/add/date_time'</tt>
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# - Exception: <tt>require 'json/add/exception'</tt>
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# - OpenStruct: <tt>require 'json/add/ostruct'</tt>
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# - Range: <tt>require 'json/add/range'</tt>
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# - Rational: <tt>require 'json/add/rational'</tt>
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# - Regexp: <tt>require 'json/add/regexp'</tt>
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# - Set: <tt>require 'json/add/set'</tt>
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# - Struct: <tt>require 'json/add/struct'</tt>
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# - Symbol: <tt>require 'json/add/symbol'</tt>
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# - Time: <tt>require 'json/add/time'</tt>
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#
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# To reduce punctuation clutter, the examples below
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# show the generated \JSON via +puts+, rather than the usual +inspect+,
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#
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# \BigDecimal:
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# require 'json/add/bigdecimal'
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# ruby0 = BigDecimal(0) # 0.0
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# json = JSON.generate(ruby0) # {"json_class":"BigDecimal","b":"27:0.0"}
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# ruby1 = JSON.parse(json, create_additions: true) # 0.0
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# ruby1.class # => BigDecimal
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#
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# \Complex:
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# require 'json/add/complex'
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# ruby0 = Complex(1+0i) # 1+0i
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# json = JSON.generate(ruby0) # {"json_class":"Complex","r":1,"i":0}
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# ruby1 = JSON.parse(json, create_additions: true) # 1+0i
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# ruby1.class # Complex
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#
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# \Date:
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# require 'json/add/date'
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# ruby0 = Date.today # 2020-05-02
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# json = JSON.generate(ruby0) # {"json_class":"Date","y":2020,"m":5,"d":2,"sg":2299161.0}
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# ruby1 = JSON.parse(json, create_additions: true) # 2020-05-02
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# ruby1.class # Date
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#
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# \DateTime:
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# require 'json/add/date_time'
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# ruby0 = DateTime.now # 2020-05-02T10:38:13-05:00
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# json = JSON.generate(ruby0) # {"json_class":"DateTime","y":2020,"m":5,"d":2,"H":10,"M":38,"S":13,"of":"-5/24","sg":2299161.0}
|
|
# ruby1 = JSON.parse(json, create_additions: true) # 2020-05-02T10:38:13-05:00
|
|
# ruby1.class # DateTime
|
|
#
|
|
# \Exception (and its subclasses including \RuntimeError):
|
|
# require 'json/add/exception'
|
|
# ruby0 = Exception.new('A message') # A message
|
|
# json = JSON.generate(ruby0) # {"json_class":"Exception","m":"A message","b":null}
|
|
# ruby1 = JSON.parse(json, create_additions: true) # A message
|
|
# ruby1.class # Exception
|
|
# ruby0 = RuntimeError.new('Another message') # Another message
|
|
# json = JSON.generate(ruby0) # {"json_class":"RuntimeError","m":"Another message","b":null}
|
|
# ruby1 = JSON.parse(json, create_additions: true) # Another message
|
|
# ruby1.class # RuntimeError
|
|
#
|
|
# \OpenStruct:
|
|
# require 'json/add/ostruct'
|
|
# ruby0 = OpenStruct.new(name: 'Matz', language: 'Ruby') # #<OpenStruct name="Matz", language="Ruby">
|
|
# json = JSON.generate(ruby0) # {"json_class":"OpenStruct","t":{"name":"Matz","language":"Ruby"}}
|
|
# ruby1 = JSON.parse(json, create_additions: true) # #<OpenStruct name="Matz", language="Ruby">
|
|
# ruby1.class # OpenStruct
|
|
#
|
|
# \Range:
|
|
# require 'json/add/range'
|
|
# ruby0 = Range.new(0, 2) # 0..2
|
|
# json = JSON.generate(ruby0) # {"json_class":"Range","a":[0,2,false]}
|
|
# ruby1 = JSON.parse(json, create_additions: true) # 0..2
|
|
# ruby1.class # Range
|
|
#
|
|
# \Rational:
|
|
# require 'json/add/rational'
|
|
# ruby0 = Rational(1, 3) # 1/3
|
|
# json = JSON.generate(ruby0) # {"json_class":"Rational","n":1,"d":3}
|
|
# ruby1 = JSON.parse(json, create_additions: true) # 1/3
|
|
# ruby1.class # Rational
|
|
#
|
|
# \Regexp:
|
|
# require 'json/add/regexp'
|
|
# ruby0 = Regexp.new('foo') # (?-mix:foo)
|
|
# json = JSON.generate(ruby0) # {"json_class":"Regexp","o":0,"s":"foo"}
|
|
# ruby1 = JSON.parse(json, create_additions: true) # (?-mix:foo)
|
|
# ruby1.class # Regexp
|
|
#
|
|
# \Set:
|
|
# require 'json/add/set'
|
|
# ruby0 = Set.new([0, 1, 2]) # #<Set: {0, 1, 2}>
|
|
# json = JSON.generate(ruby0) # {"json_class":"Set","a":[0,1,2]}
|
|
# ruby1 = JSON.parse(json, create_additions: true) # #<Set: {0, 1, 2}>
|
|
# ruby1.class # Set
|
|
#
|
|
# \Struct:
|
|
# require 'json/add/struct'
|
|
# Customer = Struct.new(:name, :address) # Customer
|
|
# ruby0 = Customer.new("Dave", "123 Main") # #<struct Customer name="Dave", address="123 Main">
|
|
# json = JSON.generate(ruby0) # {"json_class":"Customer","v":["Dave","123 Main"]}
|
|
# ruby1 = JSON.parse(json, create_additions: true) # #<struct Customer name="Dave", address="123 Main">
|
|
# ruby1.class # Customer
|
|
#
|
|
# \Symbol:
|
|
# require 'json/add/symbol'
|
|
# ruby0 = :foo # foo
|
|
# json = JSON.generate(ruby0) # {"json_class":"Symbol","s":"foo"}
|
|
# ruby1 = JSON.parse(json, create_additions: true) # foo
|
|
# ruby1.class # Symbol
|
|
#
|
|
# \Time:
|
|
# require 'json/add/time'
|
|
# ruby0 = Time.now # 2020-05-02 11:28:26 -0500
|
|
# json = JSON.generate(ruby0) # {"json_class":"Time","s":1588436906,"n":840560000}
|
|
# ruby1 = JSON.parse(json, create_additions: true) # 2020-05-02 11:28:26 -0500
|
|
# ruby1.class # Time
|
|
#
|
|
#
|
|
# === Custom \JSON Additions
|
|
#
|
|
# In addition to the \JSON additions provided,
|
|
# you can craft \JSON additions of your own,
|
|
# either for Ruby built-in classes or for user-defined classes.
|
|
#
|
|
# Here's a user-defined class +Foo+:
|
|
# class Foo
|
|
# attr_accessor :bar, :baz
|
|
# def initialize(bar, baz)
|
|
# self.bar = bar
|
|
# self.baz = baz
|
|
# end
|
|
# end
|
|
#
|
|
# Here's the \JSON addition for it:
|
|
# # Extend class Foo with JSON addition.
|
|
# class Foo
|
|
# # Serialize Foo object with its class name and arguments
|
|
# def to_json(*args)
|
|
# {
|
|
# JSON.create_id => self.class.name,
|
|
# 'a' => [ bar, baz ]
|
|
# }.to_json(*args)
|
|
# end
|
|
# # Deserialize JSON string by constructing new Foo object with arguments.
|
|
# def self.json_create(object)
|
|
# new(*object['a'])
|
|
# end
|
|
# end
|
|
#
|
|
# Demonstration:
|
|
# require 'json'
|
|
# # This Foo object has no custom addition.
|
|
# foo0 = Foo.new(0, 1)
|
|
# json0 = JSON.generate(foo0)
|
|
# obj0 = JSON.parse(json0)
|
|
# # Lood the custom addition.
|
|
# require_relative 'foo_addition'
|
|
# # This foo has the custom addition.
|
|
# foo1 = Foo.new(0, 1)
|
|
# json1 = JSON.generate(foo1)
|
|
# obj1 = JSON.parse(json1, create_additions: true)
|
|
# # Make a nice display.
|
|
# display = <<EOT
|
|
# Generated JSON:
|
|
# Without custom addition: #{json0} (#{json0.class})
|
|
# With custom addition: #{json1} (#{json1.class})
|
|
# Parsed JSON:
|
|
# Without custom addition: #{obj0.inspect} (#{obj0.class})
|
|
# With custom addition: #{obj1.inspect} (#{obj1.class})
|
|
# EOT
|
|
# puts display
|
|
#
|
|
# Output:
|
|
#
|
|
# Generated JSON:
|
|
# Without custom addition: "#<Foo:0x0000000006534e80>" (String)
|
|
# With custom addition: {"json_class":"Foo","a":[0,1]} (String)
|
|
# Parsed JSON:
|
|
# Without custom addition: "#<Foo:0x0000000006534e80>" (String)
|
|
# With custom addition: #<Foo:0x0000000006473bb8 @bar=0, @baz=1> (Foo)
|
|
#
|
|
module JSON
|
|
require 'json/version'
|
|
|
|
begin
|
|
require 'json/ext'
|
|
rescue LoadError
|
|
require 'json/pure'
|
|
end
|
|
end
|