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Class: Psych::TreeBuilder

Relationships & Source Files
Extension / Inclusion / Inheritance Descendants
Subclasses:
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.
#event_location

Called before each event with line/column information.
#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

.new ⇒ TreeBuilder

Create a new TreeBuilder instance

[ GitHub ] 

  


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



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

  @start_line   = nil
  @start_column = nil
  @end_line     = nil
  @end_column   = 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 103



def alias anchor
  a = Nodes::Alias.new(anchor)
  set_location(a)
  @last.children << a
  a
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 77



def end_document implicit_end = !streaming?
  @last.implicit_end = implicit_end
  n = pop
  set_end_location(n)
  n
end


  








  

    #end_stream  
  

  [ GitHub ]


  

  


# File 'ext/psych/lib/psych/tree_builder.rb', line 90



def end_stream
  n = pop
  set_end_location(n)
  n
end


  








  

    #event_location(start_line, start_column, end_line, end_column)  
  

  [ GitHub ]


  

  


# File 'ext/psych/lib/psych/tree_builder.rb', line 33



def event_location(start_line, start_column, end_line, end_column)
  @start_line   = start_line
  @start_column = start_column
  @end_line     = end_line
  @end_column   = end_column
end


  








  

    #pop   (private)
  

  [ GitHub ]


  

  


# File 'ext/psych/lib/psych/tree_builder.rb', line 116



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


  








  

    #push(value)   (private)
  

  [ GitHub ]


  

  


# File 'ext/psych/lib/psych/tree_builder.rb', line 111



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 96



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


  








  

    #set_end_location(node)   (private)
  

  [ GitHub ]


  

  


# File 'ext/psych/lib/psych/tree_builder.rb', line 132



def set_end_location(node)
  node.end_line   = @end_line
  node.end_column = @end_column
end


  








  

    #set_location(node)   (private)
  

  [ GitHub ]


  

  


# File 'ext/psych/lib/psych/tree_builder.rb', line 122



def set_location(node)
  set_start_location(node)
  set_end_location(node)
end


  








  

    #set_start_location(node)   (private)
  

  [ GitHub ]


  

  


# File 'ext/psych/lib/psych/tree_builder.rb', line 127



def set_start_location(node)
  node.start_line   = @start_line
  node.start_column = @start_column
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 65



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


  








  

    #start_stream(encoding)  
  

  [ GitHub ]


  

  


# File 'ext/psych/lib/psych/tree_builder.rb', line 84



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