Add attribute syntax infrastructure

1 files changed, 15 insertions, 11 deletions

diff --git a/build2/lexer b/build2/lexer
index 001d52c..c856344 100644
--- a/build2/lexer
+++ b/build2/lexer
@@ -42,32 +42,31 @@ namespace build2
            void (*processor) (token&, const lexer&) = nullptr)
         : char_scanner (is), fail (name), processor_ (processor), sep_ (false)
     {
-      mode_.push (lexer_mode::normal);
+      mode (lexer_mode::normal);
     }
 
     const path&
     name () const {return fail.name_;}
 
-    // Note: sets mode for the next token. If mode is pairs, then
-    // the second argument specifies the separator character.
+    // Note: sets mode for the next token. If mode is pairs, then the second
+    // argument specifies the separator character.
     //
     void
-    mode (lexer_mode m, char pair_separator = '=')
+    mode (lexer_mode m, char pair_separator = '\0')
     {
-      mode_.push (m);
-      pair_separator_ = pair_separator;
+      state_.push (state{m, pair_separator});
     }
 
     // Expire the current mode early.
     //
     void
-    expire_mode () {mode_.pop ();}
+    expire_mode () {state_.pop ();}
 
     lexer_mode
-    mode () const {return mode_.top ();}
+    mode () const {return state_.top ().mode;}
 
     char
-    pair_separator () const {return pair_separator_;}
+    pair_separator () const {return state_.top ().pair_separator;}
 
     // Scanner. Note that it is ok to call next() again after getting eos.
     //
@@ -123,8 +122,13 @@ namespace build2
 
     void (*processor_) (token&, const lexer&);
 
-    std::stack<lexer_mode> mode_;
-    char pair_separator_;
+    struct state
+    {
+      lexer_mode mode;
+      char pair_separator;
+    };
+    std::stack<state> state_;
+
     bool sep_; // True if we skipped spaces in peek().
   };
 }