Class: Psych::TreeBuilder

Inherits:
Handler show all
Defined in:
lib/psych/tree_builder.rb

Overview

This class works in conjunction with Psych::Parser to build an in-memory parse tree that represents a YAML document.

Example

parser = Psych::Parser.new Psych::TreeBuilder.new
parser.parse('--- foo')
tree = parser.handler.root

See Psych::Handler for documentation on the event methods used in this class.

Direct Known Subclasses

Handlers::DocumentStream, JSON::TreeBuilder

Constant Summary

Constants inherited from Handler

Handler::EVENTS, Handler::OPTIONS

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods inherited from Handler

#empty, #end_mapping, #end_sequence, #start_mapping, #start_sequence, #streaming?

Constructor Details

#initializeTreeBuilder

Create a new TreeBuilder instance


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# File 'lib/psych/tree_builder.rb', line 21

def initialize
  @stack = []
  @last  = nil
  @root  = nil
end

Instance Attribute Details

#rootObject (readonly)

Returns the root node for the built tree


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# File 'lib/psych/tree_builder.rb', line 18

def root
  @root
end

Instance Method Details

#alias(anchor) ⇒ Object


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# File 'lib/psych/tree_builder.rb', line 80

def alias anchor
  @last.children << Nodes::Alias.new(anchor)
end

#end_document(implicit_end = !streaming?) ⇒ Object

Handles end_document events with version, tag_directives, and implicit styling.

See Psych::Handler#start_document


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# File 'lib/psych/tree_builder.rb', line 60

def end_document implicit_end = !streaming?
  @last.implicit_end = implicit_end
  pop
end

#end_streamObject


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# File 'lib/psych/tree_builder.rb', line 70

def end_stream
  pop
end

#scalar(value, anchor, tag, plain, quoted, style) ⇒ Object


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# File 'lib/psych/tree_builder.rb', line 74

def scalar value, anchor, tag, plain, quoted, style
  s = Nodes::Scalar.new(value,anchor,tag,plain,quoted,style)
  @last.children << s
  s
end

#start_document(version, tag_directives, implicit) ⇒ Object

Handles start_document events with version, tag_directives, and implicit styling.

See Psych::Handler#start_document


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# File 'lib/psych/tree_builder.rb', line 49

def start_document version, tag_directives, implicit
  n = Nodes::Document.new version, tag_directives, implicit
  @last.children << n
  push n
end

#start_stream(encoding) ⇒ Object


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# File 'lib/psych/tree_builder.rb', line 65

def start_stream encoding
  @root = Nodes::Stream.new(encoding)
  push @root
end