Handle cross junction elements in workspaces.

Workspaces are now index by colon separated junction path. This
now allows to create workspaces for elements in external projects.

Workspaces are owned by context instead of root project. However
it is initialized once top-level project is registered as we need
to resolve paths relatively to this top-level project.

Part of #359.

1 files changed, 7 insertions, 0 deletions

diff --git a/buildstream/_context.py b/buildstream/_context.py
index c0d49b245..114ac9e86 100644
--- a/buildstream/_context.py
+++ b/buildstream/_context.py
@@ -30,6 +30,7 @@ from ._exceptions import LoadError, LoadErrorReason, BstError
 from ._message import Message, MessageType
 from ._profile import Topics, profile_start, profile_end
 from ._artifactcache import ArtifactCache
+from ._workspaces import Workspaces
 
 
 # Context()
@@ -113,6 +114,7 @@ class Context():
         self._message_depth = deque()
         self._projects = []
         self._project_overrides = {}
+        self._workspaces = None
 
     # load()
     #
@@ -219,6 +221,8 @@ class Context():
     #    project (Project): The project to add
     #
     def add_project(self, project):
+        if not self._projects:
+            self._workspaces = Workspaces(project)
         self._projects.append(project)
 
     # get_projects():
@@ -242,6 +246,9 @@ class Context():
     def get_toplevel_project(self):
         return self._projects[0]
 
+    def get_workspaces(self):
+        return self._workspaces
+
     # get_overrides():
     #
     # Fetch the override dictionary for the active project. This returns