Implement shortcut config add/create versions

Now:

$ bdep init -C ../hello-clang @clang ...

Can be rewritten as:

$ bdep init -C @clang ...

3 files changed, 41 insertions, 2 deletions

diff --git a/bdep/bdep.cli b/bdep/bdep.cli
index 595e9d9..a4e8c41 100644
--- a/bdep/bdep.cli
+++ b/bdep/bdep.cli
@@ -188,8 +188,17 @@ namespace bdep
          $ bdep init -A ../hello-clang @clang
          \
 
-         We can now use the \l{bdep-status(1)} command to examine the status
-         of our project in its configurations:
+         If the configuration directory is next to the project and its name is
+         in the \c{\i{prj-name}\b{-}\i{cfg-name}} form, then the shortcut
+         version of the \c{init} can be used instead:
+
+         \
+         $ bdep init -C @gcc cc config.cxx=g++
+         $ bdep init -A @clang
+         \
+
+         After initialization we can use the \l{bdep-status(1)} command to
+         examine the status of our project in its configurations:
 
          \
          $ bdep status -a
diff --git a/bdep/config.cli b/bdep/config.cli
index 0a5dd74..e087693 100644
--- a/bdep/config.cli
+++ b/bdep/config.cli
@@ -80,6 +80,11 @@ namespace bdep
          such names as a more convenient way to specify build configurations
          (see \l{bdep-projects-configs(1)} for details).
 
+         As a shortcut, if \ci{cfg-name} is not specified and \ci{cfg-dir} is
+         a simple path that starts with \cb{@}, then it is treated as the name
+         and the configuration directory is assumed to be
+         \c{\i{prj-dir}\b{-}\i{cfg-name}}.
+
          Unless the \cb{--no-default} option is specified, the first added or
          created build configuration is designated as the default. Several
          \cb{bdep} commands use such a configuration by default if no
diff --git a/bdep/config.cxx b/bdep/config.cxx
index 45cba1f..28289fb 100644
--- a/bdep/config.cxx
+++ b/bdep/config.cxx
@@ -12,6 +12,27 @@ using namespace std;
 
 namespace bdep
 {
+  // Translate the configuration directory that is actually a name (@foo) to
+  // the real directory (prj-foo) and name (@foo).
+  //
+  static inline void
+  translate_path_name (const dir_path& prj,
+                       dir_path& path,
+                       optional<string> name)
+  {
+    if (name || !path.simple () || path.string ().front () != '@')
+      return;
+
+    string n (move (path).string ()); // Move out.
+    n.erase (0, 1);                   // Remove leading '@'.
+
+    path  = prj;
+    path += '-';
+    path += n;
+
+    name = move (n);
+  }
+
   shared_ptr<configuration>
   cmd_config_add (const configuration_add_options& ao,
                   const dir_path&                  prj,
@@ -21,6 +42,8 @@ namespace bdep
                   optional<uint64_t>               id,
                   const char*                      what)
   {
+    translate_path_name (prj, path, name);
+
     if (!exists (path))
       fail << "configuration directory " << path << " does not exist";
 
@@ -142,6 +165,8 @@ namespace bdep
                      optional<string>                 name,
                      optional<uint64_t>               id)
   {
+    translate_path_name (prj, path, name);
+
     // Call bpkg to create the configuration.
     //
     {