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

#initialize ⇒ TreeBuilder

Create a new TreeBuilder instance



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# File '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 ⇒ Object (readonly)

Returns the root node for the built tree



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

def root
  @root
end

Instance Method Details

#alias(anchor) ⇒ Object 



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# File '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?) ⇒ 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 77

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

#end_stream ⇒ Object 



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# File '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) ⇒ Object 



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# File '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

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



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# File '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

#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 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) ⇒ Object 



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

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