1 files changed, 49 insertions, 0 deletions
diff --git a/tool/ruby_vm/helpers/scanner.rb b/tool/ruby_vm/helpers/scanner.rb
new file mode 100644
index 0000000000..3dce6ffdfe
--- /dev/null
+++ b/tool/ruby_vm/helpers/scanner.rb
@@ -0,0 +1,49 @@
+#! /your/favourite/path/to/ruby
+# -*- mode: ruby; coding: utf-8; indent-tabs-mode: nil; ruby-indent-level: 2 -*-
+# -*- frozen_string_literal: true; -*-
+# -*- warn_indent: true; -*-
+#
+# Copyright (c) 2017 Urabe, Shyouhei.  All rights reserved.
+#
+# This file is  a part of the programming language  Ruby.  Permission is hereby
+# granted, to  either redistribute and/or  modify this file, provided  that the
+# conditions  mentioned in  the file  COPYING are  met.  Consult  the file  for
+# details.
+
+require 'pathname'
+require 'strscan'
+
+class RubyVM::Scanner
+  attr_reader :__FILE__
+  attr_reader :__LINE__
+
+  def initialize path
+    src       = Pathname.new __dir__
+    src      += path
+    @__LINE__ = 1
+    @__FILE__ = src.realpath.to_path
+    str       = src.read mode: 'rt:utf-8:utf-8'
+    @scanner  = StringScanner.new str
+  end
+
+  def eos?
+    @scanner.eos?
+  end
+
+  def scan re
+    ret   = @__LINE__
+    match = @scanner.scan re
+    return unless match
+    @__LINE__ += match.count "\n"
+    return ret
+  end
+
+  def scan! re
+    scan re or raise sprintf "parse error at %s:%d near:\n %s...", \
+        @__FILE__, @__LINE__, @scanner.peek(32)
+  end
+
+  def [] key
+    return @scanner[key]
+  end
+end