Add support for configurable pair separator, use @ instead of = in buildspec

4 files changed, 42 insertions, 57 deletions

diff --git a/build/lexer b/build/lexer
index 98a1390..5f91dc4 100644
--- a/build/lexer
+++ b/build/lexer
@@ -20,8 +20,8 @@ namespace build
   // them in the variable values, e.g., 'foo = g++'. In contrast,
   // in the variable mode, we restrict certain character (e.g., /)
   // from appearing in the name. The pairs mode is just like value
-  // except that we split names separated by '='. The pairs mode must
-  // be set manually.
+  // except that we split names separated by the pair character.
+  // The pairs mode must be set manually.
   //
   enum class lexer_mode {normal, value, variable, pairs};
 
@@ -30,10 +30,15 @@ namespace build
   public:
     lexer (std::istream& is, const std::string& name): is_ (is), fail (name) {}
 
-    // Note: sets mode for the next token.
+    // Note: sets mode for the next token. If mode is pairs, then
+    // the second argument specifies the separator character.
     //
     void
-    mode (lexer_mode m) {next_mode_ = m;}
+    mode (lexer_mode m, char pair_separator = '=')
+    {
+      next_mode_ = m;
+      pair_separator_ = pair_separator;
+    }
 
     lexer_mode
     mode () const {return mode_;}
@@ -127,6 +132,7 @@ namespace build
 
     bool eos_ {false};
     lexer_mode mode_ {lexer_mode::normal};
+    char pair_separator_;
     lexer_mode next_mode_ {lexer_mode::normal}; // Switch to for next token.
     lexer_mode prev_mode_; // Return to after current mode expires.
   };
diff --git a/build/lexer.cxx b/build/lexer.cxx
index 9683567..4cd9cda 100644
--- a/build/lexer.cxx
+++ b/build/lexer.cxx
@@ -64,6 +64,11 @@ namespace build
       }
     }
 
+    // Handle pair separator.
+    //
+    if (mode_ == lexer_mode::pairs && c == pair_separator_)
+      return token (token_type::pair_separator, sep, ln, cn);
+
     // The following characters are not treated as special in the
     // value or pairs mode.
     //
@@ -85,26 +90,9 @@ namespace build
           next_mode_ = lexer_mode::value;
           return token (token_type::plus_equal, sep, ln, cn);
         }
-      }
-    }
-
-    // The following characters are not treated as special in the
-    // value mode.
-    //
-    if (mode_ != lexer_mode::value)
-    {
-      // NOTE: remember to update name() if adding new punctuations.
-      //
-      switch (c)
-      {
       case '=':
         {
-          // Unless we are already in the pairs mode, switch to the
-          // value mode.
-          //
-          if (next_mode_ != lexer_mode::pairs)
-            next_mode_ = lexer_mode::value;
-
+          next_mode_ = lexer_mode::value;
           return token (token_type::equal, sep, ln, cn);
         }
       }
@@ -126,6 +114,11 @@ namespace build
     {
       bool done (false);
 
+      // Handle pair separator.
+      //
+      if (mode_ == lexer_mode::pairs && c == pair_separator_)
+        break;
+
       // The following characters are not treated as special in the
       // value or pairs mode.
       //
@@ -135,23 +128,6 @@ namespace build
         {
         case ':':
         case '+':
-          {
-            done = true;
-            break;
-          }
-        }
-
-        if (done)
-          break;
-      }
-
-      // The following characters are not treated as special in the
-      // value mode.
-      //
-      if (mode_ != lexer_mode::value)
-      {
-        switch (c)
-        {
         case '=':
           {
             done = true;
diff --git a/build/parser.cxx b/build/parser.cxx
index b21dd6f..617f22b 100644
--- a/build/parser.cxx
+++ b/build/parser.cxx
@@ -976,7 +976,7 @@ namespace build
 
       // A pair separator (only in the pair mode).
       //
-      if (tt == type::equal && lexer_->mode () == lexer_mode::pairs)
+      if (tt == type::pair_separator)
       {
         if (pair != 0)
           fail (t) << "nested pair on the right hand side of a pair";
@@ -1043,9 +1043,10 @@ namespace build
     lexer_ = &l;
     scope_ = root_ = root_scope;
 
-    // Turn on pairs recognition (e.g., src_root/=out_root/exe{foo bar}).
+    // Turn on pairs recognition with '@' as the pair separator (e.g.,
+    // src_root/@out_root/exe{foo bar}).
     //
-    lexer_->mode (lexer_mode::pairs);
+    lexer_->mode (lexer_mode::pairs, '@');
 
     token t (type::eos, false, 0, 0);
     type tt;
@@ -1084,9 +1085,9 @@ namespace build
       // We always start with one or more names.
       //
       if (tt != type::name    &&
-          tt != type::lcbrace && // Untyped name group: '{foo ...'
-          tt != type::dollar  && // Variable expansion: '$foo ...'
-          tt != type::equal)     // Empty pair LHS: '=foo ...'
+          tt != type::lcbrace &&      // Untyped name group: '{foo ...'
+          tt != type::dollar  &&      // Variable expansion: '$foo ...'
+          tt != type::pair_separator) // Empty pair LHS: '=foo ...'
         fail (t) << "operation or target expected instead of " << t;
 
       location l (get_location (t, &path_)); // Start of names.
@@ -1296,17 +1297,18 @@ namespace build
   {
     switch (t.type ())
     {
-    case token_type::eos:        os << "<end-of-file>"; break;
-    case token_type::newline:    os << "<newline>"; break;
-    case token_type::colon:      os << ":"; break;
-    case token_type::lcbrace:    os << "{"; break;
-    case token_type::rcbrace:    os << "}"; break;
-    case token_type::equal:      os << "="; break;
-    case token_type::plus_equal: os << "+="; break;
-    case token_type::dollar:     os << "$"; break;
-    case token_type::lparen:     os << "("; break;
-    case token_type::rparen:     os << ")"; break;
-    case token_type::name:       os << t.name (); break;
+    case token_type::eos:            os << "<end-of-file>"; break;
+    case token_type::newline:        os << "<newline>"; break;
+    case token_type::pair_separator: os << "<pair separator>"; break;
+    case token_type::colon:          os << ":"; break;
+    case token_type::lcbrace:        os << "{"; break;
+    case token_type::rcbrace:        os << "}"; break;
+    case token_type::equal:          os << "="; break;
+    case token_type::plus_equal:     os << "+="; break;
+    case token_type::dollar:         os << "$"; break;
+    case token_type::lparen:         os << "("; break;
+    case token_type::rparen:         os << ")"; break;
+    case token_type::name:           os << t.name (); break;
     }
 
     return os;
diff --git a/build/token b/build/token
index 670207d..f7e45dc 100644
--- a/build/token
+++ b/build/token
@@ -18,6 +18,7 @@ namespace build
     eos,
     name,
     newline,
+    pair_separator,
     colon,
     lcbrace,
     rcbrace,
@@ -25,7 +26,7 @@ namespace build
     plus_equal,
     dollar,
     lparen,
-    rparen,
+    rparen
   };
 
   class token