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|
# frozen_string_literal: true
require_relative 'handler'
module Psych
###
# 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.
class TreeBuilder < Psych::Handler
# Returns the root node for the built tree
attr_reader :root
# Create a new TreeBuilder instance
def initialize
@stack = []
@last = nil
@root = nil
@start_line = nil
@start_column = nil
@end_line = nil
@end_column = nil
end
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
%w{
Sequence
Mapping
}.each do |node|
class_eval <<~RUBY, __FILE__, __LINE__ + 1
def start_#{node.downcase}(anchor, tag, implicit, style)
n = Nodes::#{node}.new(anchor, tag, implicit, style)
set_start_location(n)
@last.children << n
push n
end
def end_#{node.downcase}
n = pop
set_end_location(n)
n
end
RUBY
end
###
# Handles start_document events with +version+, +tag_directives+,
# and +implicit+ styling.
#
# See Psych::Handler#start_document
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
###
# Handles end_document events with +version+, +tag_directives+,
# and +implicit+ styling.
#
# See Psych::Handler#start_document
def end_document implicit_end = !streaming?
@last.implicit_end = implicit_end
n = pop
set_end_location(n)
n
end
def start_stream encoding
@root = Nodes::Stream.new(encoding)
set_start_location(@root)
push @root
end
def end_stream
n = pop
set_end_location(n)
n
end
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
def alias anchor
a = Nodes::Alias.new(anchor)
set_location(a)
@last.children << a
a
end
private
def push value
@stack.push value
@last = value
end
def pop
x = @stack.pop
@last = @stack.last
x
end
def set_location(node)
set_start_location(node)
set_end_location(node)
end
def set_start_location(node)
node.start_line = @start_line
node.start_column = @start_column
end
def set_end_location(node)
node.end_line = @end_line
node.end_column = @end_column
end
end
end
|
