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Class: Psych::TreeBuilder

Relationships & Source Files
Extension / Inclusion / Inheritance Descendants
Subclasses:
Psych::Handlers::DocumentStream, JSON::TreeBuilder
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, Handler
Instance Chain:
self, Handler
Inherits: Psych::Handler
Defined in: ext/psych/lib/psych/tree_builder.rb

Overview

This class works in conjunction with 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 Handler for documentation on the event methods used in this class.

Constant Summary

Handler - Inherited

EVENTS, OPTIONS

Class Method Summary

Instance Attribute Summary

  • #root readonly

    Returns the root node for the built tree.

Handler - Inherited

#streaming?

Is this handler a streaming handler?

Instance Method Summary

Handler - Inherited

#alias

Called when an alias is found to anchor.

#empty

Called when an empty event happens.

#end_document

Called with the document ends.

#end_mapping

Called when a map ends.

#end_sequence

Called when a sequence ends.

#end_stream

Called when the YAML stream ends.

#scalar

Called when a scalar value is found.

#start_document

Called when the document starts with the declared version, tag_directives, if the document is implicit.

#start_mapping

Called when a map starts.

#start_sequence

Called when a sequence is started.

#start_stream

Called with encoding when the YAML stream starts.

Constructor Details

.newTreeBuilder

Create a new TreeBuilder instance

[ GitHub ]

  
# File 'ext/psych/lib/psych/tree_builder.rb', line 22

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

Instance Attribute Details

#root (readonly)

Returns the root node for the built tree

[ GitHub ]

  
# File 'ext/psych/lib/psych/tree_builder.rb', line 19

attr_reader :root

Instance Method Details

#alias(anchor)

[ GitHub ]

  
# File 'ext/psych/lib/psych/tree_builder.rb', line 81

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

#end_document(implicit_end = !streaming?)

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

See Handler#start_document

[ GitHub ]

  
# File 'ext/psych/lib/psych/tree_builder.rb', line 61

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

#end_stream

[ GitHub ]

  
# File 'ext/psych/lib/psych/tree_builder.rb', line 71

def end_stream
  pop
end

#pop (private)

[ GitHub ]

  
# File 'ext/psych/lib/psych/tree_builder.rb', line 91

def pop
  x = @stack.pop
  @last = @stack.last
  x
end

#push(value) (private)

[ GitHub ]

  
# File 'ext/psych/lib/psych/tree_builder.rb', line 86

def push value
  @stack.push value
  @last = value
end

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

[ GitHub ]

  
# File 'ext/psych/lib/psych/tree_builder.rb', line 75

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)

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

See Handler#start_document

[ GitHub ]

  
# File 'ext/psych/lib/psych/tree_builder.rb', line 50

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

#start_stream(encoding)

[ GitHub ]

  
# File 'ext/psych/lib/psych/tree_builder.rb', line 66

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