class Psych::TreeBuilder

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.

Attributes

root[R]

Returns the root node for the built tree

Public Class Methods

new() click to toggle source

Create a new TreeBuilder instance

# File ext/psych/lib/psych/tree_builder.rb, line 22
def initialize
  @stack = []
  @last  = nil
  @root  = nil
end

Public Instance Methods

alias(anchor) click to toggle source
# 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?) click to toggle source

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

See Psych::Handler#start_document

# 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() click to toggle source
# File ext/psych/lib/psych/tree_builder.rb, line 71
def end_stream
  pop
end
scalar(value, anchor, tag, plain, quoted, style) click to toggle source
# 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) click to toggle source

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

See Psych::Handler#start_document

# 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) click to toggle source
# File ext/psych/lib/psych/tree_builder.rb, line 66
def start_stream encoding
  @root = Nodes::Stream.new(encoding)
  push @root
end

Private Instance Methods

pop() click to toggle source
# File ext/psych/lib/psych/tree_builder.rb, line 91
def pop
  x = @stack.pop
  @last = @stack.last
  x
end
push(value) click to toggle source
# File ext/psych/lib/psych/tree_builder.rb, line 86
def push value
  @stack.push value
  @last = value
end