From d5faeeab1d2115c02a330ac9c95d63ba225faabc Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Wed, 10 Jun 2020 10:00:55 +0200
Subject: Handle special variable names in base lexer via mode data

---
 .../test/script/lexer+variable.test.testscript     |  3 +-
 libbuild2/test/script/lexer.cxx                    | 46 ++++++++++------------
 2 files changed, 22 insertions(+), 27 deletions(-)

(limited to 'libbuild2/test')

diff --git a/libbuild2/test/script/lexer+variable.test.testscript b/libbuild2/test/script/lexer+variable.test.testscript
index ac7d6be..5993c37 100644
--- a/libbuild2/test/script/lexer+variable.test.testscript
+++ b/libbuild2/test/script/lexer+variable.test.testscript
@@ -64,6 +64,7 @@ test.arguments = variable
   : multi-digit
   :
   $* <"10" 2>>EOE != 0
-  <stdin>:1:1: error: multi-digit special variable name
+  <stdin>:1:2: error: multi-digit special variable name
+    info: use '($*[NN])' to access elements beyond 9
   EOE
 }
diff --git a/libbuild2/test/script/lexer.cxx b/libbuild2/test/script/lexer.cxx
index e895d4a..c23dea4 100644
--- a/libbuild2/test/script/lexer.cxx
+++ b/libbuild2/test/script/lexer.cxx
@@ -92,16 +92,16 @@ namespace build2
           }
         default:
           {
-            // Make sure pair separators are only enabled where we expect
-            // them.
+            // Recognize special variable names ($*, $N, $~, $@). See also an
+            // extra check in word() below.
             //
-            // @@ Should we disable pair separators in the eval mode?
-            //
-            assert (ps == '\0' ||
-                    m == lexer_mode::eval ||
-                    m == lexer_mode::attribute_value);
+            if (m == lexer_mode::variable)
+            {
+              assert (data == 0);
+              data = reinterpret_cast<uintptr_t> ("*~@0123456789");
+            }
 
-            base_lexer::mode (m, ps, esc);
+            base_lexer::mode (m, ps, esc, data);
             return;
           }
         }
@@ -335,27 +335,21 @@ namespace build2
       {
         lexer_mode m (st.mode);
 
-        // Customized implementation that handles special variable names ($*,
-        // $N, $~, $@).
-        //
-        if (m != lexer_mode::variable)
-          return base_lexer::word (st, sep);
-
-        xchar c (peek ());
-
-        if (c != '*' && c != '~' && c != '@' && !digit (c))
-          return base_lexer::word (st, sep);
+        token r (base_lexer::word (st, sep));
 
-        get ();
+        if (m == lexer_mode::variable)
+        {
+          if (r.value.size () == 1 && digit (r.value[0])) // $N
+          {
+            xchar c (peek ());
 
-        if (digit (c) && digit (peek ()))
-          fail (c) << "multi-digit special variable name";
+            if (digit (c)) // $NN
+              fail (c) << "multi-digit special variable name" <<
+                info << "use '($*[NN])' to access elements beyond 9";
+          }
+        }
 
-        state_.pop (); // Expire the variable mode.
-        return token (string (1, c),
-                      sep,
-                      quote_type::unquoted, false,
-                      c.line, c.column);
+        return r;
       }
     }
   }
-- 
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