Enable pair recognition in the normal and eval lexer modes

We need this for the out-qualified target syntax:

h{config}@./: install = false

2 files changed, 17 insertions, 8 deletions

diff --git a/build2/lexer b/build2/lexer
index 7e59ff1..827d141 100644
--- a/build2/lexer
+++ b/build2/lexer
@@ -24,7 +24,8 @@ namespace build2
   // eval mode is used in the evaluation context. Quoted is an internal mode
   // and should not be set explicitly.
   //
-  // Note that the value mode splits names separated by the pair character.
+  // Note that the normal, value, and eval modes split names separated by the
+  // pair character (to disable pairs one can pass '\0' as a pair character).
   //
   // The alternnative modes must be set manually. The value mode is
   // automatically reset after the end of the line. The variable mode is reset
diff --git a/build2/lexer.cxx b/build2/lexer.cxx
index 6b599fd..8124765 100644
--- a/build2/lexer.cxx
+++ b/build2/lexer.cxx
@@ -35,7 +35,6 @@ namespace build2
   next_impl ()
   {
     lexer_mode m (state_.top ().mode);
-    char ps (state_.top ().pair_separator);
 
     // For some modes we have dedicated imlementations of next().
     //
@@ -54,6 +53,12 @@ namespace build2
     if (eos (c))
       return token (type::eos, sep, ln, cn);
 
+    // Handle pair separator.
+    //
+    if ((m == lexer_mode::normal || m == lexer_mode::value) &&
+        c == state_.top ().pair_separator)
+      return token (type::pair_separator, sep, ln, cn);
+
     switch (c)
     {
       // NOTE: remember to update name(), next_eval() if adding new
@@ -77,11 +82,6 @@ namespace build2
     case ')': return token (type::rparen, sep, ln, cn);
     }
 
-    // Handle pair separator.
-    //
-    if (m == lexer_mode::value && c == ps)
-      return token (type::pair_separator, sep, ln, cn);
-
     // The following characters are not treated as special in the value mode.
     //
     if (m != lexer_mode::value)
@@ -133,6 +133,12 @@ namespace build2
     // This mode is quite a bit like the value mode when it comes to special
     // characters, except that we have some of our own.
     //
+
+    // Handle pair separator.
+    //
+    if (c == state_.top ().pair_separator)
+      return token (type::pair_separator, sep, ln, cn);
+
     // Note: we don't treat [ and ] as special here. Maybe can use them for
     // something later.
     //
@@ -224,7 +230,9 @@ namespace build2
 
       // Handle the pair separator.
       //
-      if (m == lexer_mode::value && c == ps)
+      if ((m == lexer_mode::normal ||
+           m == lexer_mode::value  ||
+           m == lexer_mode::eval)  && c == ps)
         break;
 
       // The following characters are only special in the normal and