Use a hash table for the lexer keywords

lily/lily-lexer.cc

 /*
   This file is part of LilyPond, the GNU music typesetter.
 
   Copyright (C) 1997--2020 Han-Wen Nienhuys <hanwen@xs4all.nl>
 
   LilyPond is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.
 
   LilyPond is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
 
   You should have received a copy of the GNU General Public License
   along with LilyPond.  If not, see <http://www.gnu.org/licenses/>.
 */
 
 #include "lily-lexer.hh"
-
-#include <cctype>
-#include <sstream>
 
 #include "context.hh" // for nested_property_alist
 #include "international.hh"
 #include "interval.hh"
 #include "main.hh"
 #include "moment.hh"
 #include "parser.hh"
 #include "scm-hash.hh"
 #include "source-file.hh"
 #include "warn.hh"
 #include "program-option.hh"
 #include "lily-parser.hh"
 #include "ly-module.hh"
 
+#include <cctype>
+#include <sstream>
+#include <unordered_map>
+
 using std::string;
 
-class Keyword_ent
-{
-public:
-  char const *name_;
-  int tokcode_;
-};
-
-static Keyword_ent the_key_tab[]
-=
-{
+static std::unordered_map<std::string, int> keytable{
   {"accepts", ACCEPTS},
   {"addlyrics", ADDLYRICS},
   {"alias", ALIAS},
   {"alternative", ALTERNATIVE},
   {"book", BOOK},
   {"bookpart", BOOKPART},
   {"change", CHANGE},
   {"chordmode", CHORDMODE},
   {"chords", CHORDS},
   {"consists", CONSISTS},
@@ skipping 25 matching lines @@
   {"rest", REST},
   {"revert", REVERT},
   {"score", SCORE},
   {"sequential", SEQUENTIAL},
   {"set", SET},
   {"simultaneous", SIMULTANEOUS},
   {"tempo", TEMPO},
   {"type", TYPE},
   {"unset", UNSET},
   {"with", WITH},
-  {0, 0}
 };
 
 Lily_lexer::Lily_lexer (Sources *sources, Lily_parser *parser)
 {
   parser_ = parser;
-
-  Keyword_ent *tab = the_key_tab;
-  while (tab->name_)
-    keytable_[tab->name_] = tab->tokcode_;
 
   chordmodifier_tab_ = SCM_EOL;
   pitchname_tab_stack_ = SCM_EOL;
   sources_ = sources;
   scopes_ = SCM_EOL;
   error_level_ = 0;
   is_main_input_ = false;
   main_input_level_ = 0;
   start_module_ = SCM_EOL;
   extra_tokens_ = SCM_EOL;
@@ skipping 65 matching lines @@
     scm_set_current_module (scm_car (scopes_));
   else
     scm_set_current_module (start_module_);
 
   return old;
 }
 
 int
 Lily_lexer::lookup_keyword (const string &s)
 {
-  auto const &it = keytable_.find (s);
-  if (it == keytable_.end ())
+  auto const &it = keytable.find (s);
+  if (it == keytable.end ())
     {
       return -1;
     }
   return it->second;
 }
 
 SCM
 Lily_lexer::lookup_identifier_symbol (SCM sym)
 {
   for (SCM s = scopes_; scm_is_pair (s); s = scm_cdr (s))
@@ skipping 173 matching lines @@
   scm_display (scopes_, port);
   scm_puts (" >", port);
   return 1;
 }
 
 bool
 Lily_lexer::is_clean () const
 {
   return include_stack_.empty ();
 }