Implement automatic subproject discovery

Currently we only capture their directories without the project
names. We will need project names when we hook import search into
this.

1 files changed, 27 insertions, 2 deletions

diff --git a/build/variable.cxx b/build/variable.cxx
index 6a40bc7..d00fcf6 100644
--- a/build/variable.cxx
+++ b/build/variable.cxx
@@ -15,6 +15,17 @@ namespace build
   // value_proxy
   //
   template <>
+  string& value_proxy::
+  as<string&> () const
+  {
+    list_value& lv (as<list_value&> ());
+    assert (lv.size () == 1);
+    name& n (lv.front ());
+    assert (n.simple ());
+    return n.value;
+  }
+
+  template <>
   const string& value_proxy::
   as<const string&> () const
   {
@@ -26,11 +37,22 @@ namespace build
 
     const name& n (lv.front ());
 
-    assert (n.type.empty () && n.dir.empty ());
+    assert (n.simple ());
     return n.value;
   }
 
   template <>
+  dir_path& value_proxy::
+  as<dir_path&> () const
+  {
+    list_value& lv (as<list_value&> ());
+    assert (lv.size () == 1);
+    name& n (lv.front ());
+    assert (n.directory ());
+    return n.dir;
+  }
+
+  template <>
   const dir_path& value_proxy::
   as<const dir_path&> () const
   {
@@ -42,7 +64,10 @@ namespace build
 
     const name& n (lv.front ());
 
-    assert (n.type.empty () && n.value.empty ());
+    if (n.empty ())
+      return empty_dir_path;
+
+    assert (n.directory ());
     return n.dir;
   }
 }