Expand and clarify empty repository_location

2 files changed, 26 insertions, 14 deletions

diff --git a/bpkg/manifest b/bpkg/manifest
index 35ff650..47b8d76 100644
--- a/bpkg/manifest
+++ b/bpkg/manifest
@@ -321,20 +321,24 @@ namespace bpkg
     //
     repository_location () = default;
 
-    // Creates remote/absolute repository location. Throws invalid_argument
-    // if the location is a relative path.
+    // If the argument is not empty, creates remote/absolute repository
+    // location. Throws invalid_argument if the location is a relative
+    // path. If the argument is empty, then creates the special empty
+    // location.
     //
     explicit
     repository_location (const std::string&);
 
     // Creates a potentially relative repository location. If base is not
     // empty, use it to complete the relative location to remote/absolute.
-    // Throws invalid_argument if base itself is relative or the resulting
-    // completed location is invalid.
+    // Throws invalid_argument if base is not empty but the location is
+    // empty, base itself is relative, or the resulting completed location
+    // is invalid.
     //
     repository_location (const std::string&, const repository_location& base);
 
-    // Note that relative locations have no canonical name.
+    // Note that relative locations have no canonical name. Canonical
+    // name of an empty location is the empty name.
     //
     const std::string&
     canonical_name () const noexcept {return canonical_name_;}
@@ -409,9 +413,10 @@ namespace bpkg
       return port_;
     }
 
-    // Note that this is not necessarily syntactically the same
-    // string as what was used to initialize this location. But
-    // it should be semantically equivalent.
+    // Note that this is not necessarily syntactically the same string
+    // as what was used to initialize this location. But it should be
+    // semantically equivalent. String representation of an empty
+    // location is the empty string.
     //
     std::string
     string () const;
diff --git a/bpkg/manifest.cxx b/bpkg/manifest.cxx
index b66d5d4..1034fe3 100644
--- a/bpkg/manifest.cxx
+++ b/bpkg/manifest.cxx
@@ -832,7 +832,7 @@ namespace bpkg
   repository_location (const std::string& l)
       : repository_location (l, repository_location ()) // Delegate.
   {
-    if (relative ())
+    if (!empty () && relative ())
       throw invalid_argument ("relative filesystem path");
   }
 
@@ -843,6 +843,14 @@ namespace bpkg
     //
     using std::string;
 
+    if (l.empty ())
+    {
+      if (!b.empty ())
+        throw invalid_argument ("empty location");
+
+      return;
+    }
+
     // Base repository location can not be a relative path.
     //
     if (!b.empty () && b.relative ())
@@ -971,9 +979,6 @@ namespace bpkg
     {
       path_ = dir_path (l);
 
-      if (path_.empty ())
-        throw invalid_argument ("empty location");
-
       // Complete if we are relative and have base.
       //
       if (!b.empty () && path_.relative ())
@@ -1052,13 +1057,15 @@ namespace bpkg
   string repository_location::
   string () const
   {
+    using std::string; // Also function name.
+
     if (empty ())
-      return "";
+      return string ();
 
     if (local ())
       return path_.string ();
 
-    std::string p ("http://" + host_);
+    string p ("http://" + host_);
 
     if (port_ != 0)
       p += ":" + to_string (port_);