[Feature #19741] Sync all files in yarp

This commit is the initial sync of all files from ruby/yarp
into ruby/ruby. Notably, it does the following:

* Sync all ruby/yarp/lib/ files to ruby/ruby/lib/yarp
* Sync all ruby/yarp/src/ files to ruby/ruby/yarp/
* Sync all ruby/yarp/test/ files to ruby/ruby/test/yarp

lib/yarp/ripper_compat.rb

@@ -0,0 +1,174 @@
+# frozen_string_literal: true
+
+require "ripper"
+
+module YARP
+  # This class is meant to provide a compatibility layer between YARP and
+  # Ripper. It functions by parsing the entire tree first and then walking it
+  # and executing each of the Ripper callbacks as it goes.
+  #
+  # This class is going to necessarily be slower than the native Ripper API. It
+  # is meant as a stopgap until developers migrate to using YARP. It is also
+  # meant as a test harness for the YARP parser.
+  class RipperCompat
+    # This class mirrors the ::Ripper::SexpBuilder subclass of ::Ripper that
+    # returns the arrays of [type, *children].
+    class SexpBuilder < RipperCompat
+      private
+
+      Ripper::PARSER_EVENTS.each do |event|
+        define_method(:"on_#{event}") do |*args|
+          [event, *args]
+        end
+      end
+
+      Ripper::SCANNER_EVENTS.each do |event|
+        define_method(:"on_#{event}") do |value|
+          [:"@#{event}", value, [lineno, column]]
+        end
+      end
+    end
+
+    # This class mirrors the ::Ripper::SexpBuilderPP subclass of ::Ripper that
+    # returns the same values as ::Ripper::SexpBuilder except with a couple of
+    # niceties that flatten linked lists into arrays.
+    class SexpBuilderPP < SexpBuilder
+      private
+
+      def _dispatch_event_new
+        []
+      end
+
+      def _dispatch_event_push(list, item)
+        list << item
+        list
+      end
+
+      Ripper::PARSER_EVENT_TABLE.each do |event, arity|
+        case event
+        when /_new\z/
+          alias :"on_#{event}" :_dispatch_event_new if arity == 0
+        when /_add\z/
+          alias :"on_#{event}" :_dispatch_event_push
+        end
+      end
+    end
+
+    attr_reader :source, :lineno, :column
+
+    def initialize(source)
+      @source = source
+      @result = nil
+      @lineno = nil
+      @column = nil
+    end
+
+    ############################################################################
+    # Public interface
+    ############################################################################
+
+    def error?
+      result.errors.any?
+    end
+
+    def parse
+      result.value.accept(self) unless error?
+    end
+
+    ############################################################################
+    # Visitor methods
+    ############################################################################
+
+    def visit(node)
+      node&.accept(self)
+    end
+
+    def visit_call_node(node)
+      if !node.opening_loc && node.arguments.arguments.length == 1
+        bounds(node.receiver.location)
+        left = visit(node.receiver)
+
+        bounds(node.arguments.arguments.first.location)
+        right = visit(node.arguments.arguments.first)
+
+        on_binary(left, source[node.message_loc.start_offset...node.message_loc.end_offset].to_sym, right)
+      else
+        raise NotImplementedError
+      end
+    end
+
+    def visit_integer_node(node)
+      bounds(node.location)
+      on_int(source[node.location.start_offset...node.location.end_offset])
+    end
+
+    def visit_statements_node(node)
+      bounds(node.location)
+      node.body.inject(on_stmts_new) do |stmts, stmt|
+        on_stmts_add(stmts, visit(stmt))
+      end
+    end
+
+    def visit_token(node)
+      bounds(node.location)
+
+      case node.type
+      when :MINUS
+        on_op(node.value)
+      when :PLUS
+        on_op(node.value)
+      else
+        raise NotImplementedError, "Unknown token: #{node.type}"
+      end
+    end
+
+    def visit_program_node(node)
+      bounds(node.location)
+      on_program(visit(node.statements))
+    end
+
+    ############################################################################
+    # Entrypoints for subclasses
+    ############################################################################
+
+    # This is a convenience method that runs the SexpBuilder subclass parser.
+    def self.sexp_raw(source)
+      SexpBuilder.new(source).parse
+    end
+
+    # This is a convenience method that runs the SexpBuilderPP subclass parser.
+    def self.sexp(source)
+      SexpBuilderPP.new(source).parse
+    end
+
+    private
+
+    # This method is responsible for updating lineno and column information
+    # to reflect the current node.
+    #
+    # This method could be drastically improved with some caching on the start
+    # of every line, but for now it's good enough.
+    def bounds(location)
+      start_offset = location.start_offset
+
+      @lineno = source[0..start_offset].count("\n") + 1
+      @column = start_offset - (source.rindex("\n", start_offset) || 0)
+    end
+
+    def result
+      @result ||= YARP.parse(source)
+    end
+
+    def _dispatch0; end
+    def _dispatch1(_); end
+    def _dispatch2(_, _); end
+    def _dispatch3(_, _, _); end
+    def _dispatch4(_, _, _, _); end
+    def _dispatch5(_, _, _, _, _); end
+    def _dispatch7(_, _, _, _, _, _, _); end
+
+    (Ripper::SCANNER_EVENT_TABLE.merge(Ripper::PARSER_EVENT_TABLE)).each do |event, arity|
+      alias :"on_#{event}" :"_dispatch#{arity}"
+    end
+  end
+end