From bd32ea47fd8f720b54f81a769dc007d1fdb4e5c1 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Tue, 23 Aug 2016 09:05:54 +0200
Subject: Reverse empty simple values as an empty names sequence rather than
 empty name

This way we get:

config.import.foo =

Rather than:

config.import.foo = {}
---
 build2/variable.txx | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

(limited to 'build2/variable.txx')

diff --git a/build2/variable.txx b/build2/variable.txx
index f1335b4..95e4f0a 100644
--- a/build2/variable.txx
+++ b/build2/variable.txx
@@ -148,7 +148,21 @@ namespace build2
   names_view
   simple_reverse (const value& v, names& s)
   {
-    s.emplace_back (value_traits<T>::reverse (v.as<T> ()));
+    const T& x (v.as<T> ());
+
+    // Represent an empty simple value as empty name sequence rather than
+    // a single empty name. This way, for example, during serialization we
+    // end up with a much saner looking:
+    //
+    // config.import.foo =
+    //
+    // Rather than:
+    //
+    // config.import.foo = {}
+    //
+    if (!value_traits<T>::empty (x))
+      s.emplace_back (value_traits<T>::reverse (x));
+
     return s;
   }
 
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