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0b396d5880
* Rely on encoding tags to determine if string should be dumped as binary.
8949a47b8c
* Specify "frozen_string_literal: true".
* Support to binary release for mingw32 platform.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59327 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
78 lines
2.4 KiB
Ruby
78 lines
2.4 KiB
Ruby
# frozen_string_literal: true
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require 'psych/nodes/node'
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require 'psych/nodes/stream'
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require 'psych/nodes/document'
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require 'psych/nodes/sequence'
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require 'psych/nodes/scalar'
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require 'psych/nodes/mapping'
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require 'psych/nodes/alias'
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module Psych
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###
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# = Overview
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#
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# When using Psych.load to deserialize a YAML document, the document is
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# translated to an intermediary AST. That intermediary AST is then
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# translated in to a Ruby object graph.
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#
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# In the opposite direction, when using Psych.dump, the Ruby object graph is
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# translated to an intermediary AST which is then converted to a YAML
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# document.
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#
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# Psych::Nodes contains all of the classes that make up the nodes of a YAML
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# AST. You can manually build an AST and use one of the visitors (see
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# Psych::Visitors) to convert that AST to either a YAML document or to a
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# Ruby object graph.
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#
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# Here is an example of building an AST that represents a list with one
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# scalar:
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#
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# # Create our nodes
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# stream = Psych::Nodes::Stream.new
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# doc = Psych::Nodes::Document.new
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# seq = Psych::Nodes::Sequence.new
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# scalar = Psych::Nodes::Scalar.new('foo')
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#
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# # Build up our tree
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# stream.children << doc
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# doc.children << seq
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# seq.children << scalar
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#
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# The stream is the root of the tree. We can then convert the tree to YAML:
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#
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# stream.to_yaml => "---\n- foo\n"
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#
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# Or convert it to Ruby:
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#
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# stream.to_ruby => [["foo"]]
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#
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# == YAML AST Requirements
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#
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# A valid YAML AST *must* have one Psych::Nodes::Stream at the root. A
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# Psych::Nodes::Stream node must have 1 or more Psych::Nodes::Document nodes
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# as children.
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#
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# Psych::Nodes::Document nodes must have one and *only* one child. That child
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# may be one of:
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#
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# * Psych::Nodes::Sequence
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# * Psych::Nodes::Mapping
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# * Psych::Nodes::Scalar
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#
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# Psych::Nodes::Sequence and Psych::Nodes::Mapping nodes may have many
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# children, but Psych::Nodes::Mapping nodes should have an even number of
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# children.
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#
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# All of these are valid children for Psych::Nodes::Sequence and
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# Psych::Nodes::Mapping nodes:
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#
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# * Psych::Nodes::Sequence
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# * Psych::Nodes::Mapping
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# * Psych::Nodes::Scalar
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# * Psych::Nodes::Alias
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#
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# Psych::Nodes::Scalar and Psych::Nodes::Alias are both terminal nodes and
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# should not have any children.
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module Nodes
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end
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end
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