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 21
def initialize
  @stack = []
  @last  = nil
  @root  = nil

  @start_line   = nil
  @start_column = nil
  @end_line     = nil
  @end_column   = nil
end

Public Instance Methods

alias(anchor) click to toggle source

# File ext/psych/lib/psych/tree_builder.rb, line 102
def alias anchor
  a = Nodes::Alias.new(anchor)
  set_location(a)
  @last.children << a
  a
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 76
def end_document implicit_end = !streaming?
  @last.implicit_end = implicit_end
  n = pop
  set_end_location(n)
  n
end

end_stream() click to toggle source

# File ext/psych/lib/psych/tree_builder.rb, line 89
def end_stream
  n = pop
  set_end_location(n)
  n
end

event_location(start_line, start_column, end_line, end_column) click to toggle source

# File ext/psych/lib/psych/tree_builder.rb, line 32
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) click to toggle source

# File ext/psych/lib/psych/tree_builder.rb, line 95
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) 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 64
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) click to toggle source

# File ext/psych/lib/psych/tree_builder.rb, line 83
def start_stream encoding
  @root = Nodes::Stream.new(encoding)
  set_start_location(@root)
  push @root
end

Private Instance Methods

pop() click to toggle source

# File ext/psych/lib/psych/tree_builder.rb, line 115
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 110
def push value
  @stack.push value
  @last = value
end

set_end_location(node) click to toggle source

# File ext/psych/lib/psych/tree_builder.rb, line 131
def set_end_location(node)
  node.end_line   = @end_line
  node.end_column = @end_column
end

set_location(node) click to toggle source

# File ext/psych/lib/psych/tree_builder.rb, line 121
def set_location(node)
  set_start_location(node)
  set_end_location(node)
end

set_start_location(node) click to toggle source

# File ext/psych/lib/psych/tree_builder.rb, line 126
def set_start_location(node)
  node.start_line   = @start_line
  node.start_column = @start_column
end