Use delete_prefix instead of `sub(/\Afixed-pattern/, '')`

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66189 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 2 insertions, 2 deletions

diff --git a/ext/ripper/lib/ripper/lexer.rb b/ext/ripper/lib/ripper/lexer.rb
index ece71dd466..344328482b 100644
--- a/ext/ripper/lib/ripper/lexer.rb
+++ b/ext/ripper/lib/ripper/lexer.rb
@@ -207,14 +207,14 @@ class Ripper
     end
 
     def map_tokens(tokens)
-      tokens.map {|pos,type,str| map_token(type.to_s.sub(/\Aon_/,'')) }.join
+      tokens.map {|pos,type,str| map_token(type.to_s.delete_prefix('on_')) }.join
     end
 
     MAP = {}
     seed = ('a'..'z').to_a + ('A'..'Z').to_a + ('0'..'9').to_a
     SCANNER_EVENT_TABLE.each do |ev, |
       raise CompileError, "[RIPPER FATAL] too many system token" if seed.empty?
-      MAP[ev.to_s.sub(/\Aon_/,'')] = seed.shift
+      MAP[ev.to_s.delete_prefix('on_')] = seed.shift
     end
 
     def map_token(tok)