tool/ruby_vm support for pre-2.1 BASERUBY

as requested by devs, support for BASERUBY prior to 2.1

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@61786 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

2 files changed, 73 insertions, 68 deletions

diff --git a/tool/ruby_vm/helpers/dumper.rb b/tool/ruby_vm/helpers/dumper.rb
index 8f14d90d1f..3ba7310f56 100644
--- a/tool/ruby_vm/helpers/dumper.rb
+++ b/tool/ruby_vm/helpers/dumper.rb
@@ -16,67 +16,69 @@ require_relative 'c_escape'
 
 class RubyVM::Dumper
   include RubyVM::CEscape
+  private
+
+  def new_binding
+    # This `eval 'binding'` does not return the current binding
+    # but creates one on top of it.
+    return eval 'binding'
+  end
+
+  def new_erb spec
+    path  = Pathname.new __dir__
+    path += '../views'
+    path += spec
+    src   = path.read mode: 'rt:utf-8:utf-8'
+  rescue Errno::ENOENT
+    raise "don't know how to generate #{path}"
+  else
+    erb = ERB.new src, nil, '%-'
+    erb.filename = path.realpath.to_path
+    return erb
+  end
 
-  # I learned this handy "super-private" maneuver from @a_matsuda
-  # cf: https://github.com/rails/rails/pull/27363/files
-  using Module.new {
-    refine RubyVM::Dumper do
-      private
-
-      def new_binding
-        # This `eval 'binding'` does not return the current binding
-        # but creates one on top of it.
-        return eval 'binding'
-      end
-
-      def new_erb spec
-        path  = Pathname.new __dir__
-        path += '../views'
-        path += spec
-        src   = path.read mode: 'rt:utf-8:utf-8'
-      rescue Errno::ENOENT
-        raise "don't know how to generate #{path}"
-      else
-        erb = ERB.new src, nil, '%-'
-        erb.filename = path.realpath.to_path
-        return erb
-      end
-
-      def finderb spec
-        return @erb.fetch spec do |k|
-          erb = new_erb k
-          @erb[k] = erb
-        end
-      end
-
-      def replace_pragma_line str, lineno
-        if str == "#pragma RubyVM reset source\n" then
-          return "#line #{lineno + 2} #{@file}\n"
-        else
-          return str
-        end
-      end
-
-      public
-
-      def do_render source, locals
-        erb = finderb source
-        bnd = @empty.dup
-        locals.each_pair do |k, v|
-          bnd.local_variable_set k, v
-        end
-        return erb.result bnd
-      end
-
-      def replace_pragma str
-        return str                                 \
-          . each_line                              \
-          . with_index                             \
-          . map {|i, j| replace_pragma_line i, j } \
-          . join
-      end
+  def finderb spec
+    return @erb.fetch spec do |k|
+      erb = new_erb k
+      @erb[k] = erb
     end
-  }
+  end
+
+  def replace_pragma_line str, lineno
+    if str == "#pragma RubyVM reset source\n" then
+      return "#line #{lineno + 2} #{@file}\n"
+    else
+      return str
+    end
+  end
+
+  def local_variable_set bnd, var, val
+    eval '__locals__ ||= {}', bnd
+    locals = eval '__locals__', bnd
+    locals[var] = val
+    eval "#{var} = __locals__[:#{var}]", bnd
+    test = eval "#{var}", bnd
+    raise unless test == val
+  end
+
+  public
+
+  def do_render source, locals
+    erb = finderb source
+    bnd = @empty.dup
+    locals.each_pair do |k, v|
+      local_variable_set bnd, k, v
+    end
+    return erb.result bnd
+  end
+
+  def replace_pragma str
+    return str                                 \
+      . each_line                              \
+      . with_index                             \
+      . map {|i, j| replace_pragma_line i, j } \
+      . join
+  end
 
   def initialize path
     @erb   = {}
diff --git a/tool/ruby_vm/helpers/scanner.rb b/tool/ruby_vm/helpers/scanner.rb
index 3dce6ffdfe..5ae1363480 100644
--- a/tool/ruby_vm/helpers/scanner.rb
+++ b/tool/ruby_vm/helpers/scanner.rb
@@ -11,8 +11,10 @@
 # details.
 
 require 'pathname'
-require 'strscan'
 
+# Poor man's StringScanner.
+# Sadly  https://bugs.ruby-lang.org/issues/8343 is  not backported  to 2.0.  We
+# have to do it by hand.
 class RubyVM::Scanner
   attr_reader :__FILE__
   attr_reader :__LINE__
@@ -22,28 +24,29 @@ class RubyVM::Scanner
     src      += path
     @__LINE__ = 1
     @__FILE__ = src.realpath.to_path
-    str       = src.read mode: 'rt:utf-8:utf-8'
-    @scanner  = StringScanner.new str
+    @str      = src.read mode: 'rt:utf-8:utf-8'
+    @pos      = 0
   end
 
   def eos?
-    @scanner.eos?
+    return @pos >= @str.length
   end
 
   def scan re
     ret   = @__LINE__
-    match = @scanner.scan re
-    return unless match
-    @__LINE__ += match.count "\n"
+    @last_match = @str.match re, @pos
+    return unless @last_match
+    @__LINE__ += @last_match.to_s.count "\n"
+    @pos = @last_match.end 0
     return ret
   end
 
   def scan! re
     scan re or raise sprintf "parse error at %s:%d near:\n %s...", \
-        @__FILE__, @__LINE__, @scanner.peek(32)
+        @__FILE__, @__LINE__, @str[pos, 32]
   end
 
   def [] key
-    return @scanner[key]
+    return @last_match[key]
   end
 end