From b35bd94bd2b01853b0096dea6e3bf5404d79b1e9 Mon Sep 17 00:00:00 2001
From: Tristan Maat <tristan.maat@codethink.co.uk>
Date: Wed, 8 Nov 2017 15:18:02 +0000
Subject: Remove DummyElement hack

---
 buildstream/_pipeline.py | 28 ++++++++++------------------
 buildstream/element.py   | 42 +++++++++++++++++++++++++-----------------
 2 files changed, 35 insertions(+), 35 deletions(-)

diff --git a/buildstream/_pipeline.py b/buildstream/_pipeline.py
index febadbcc7..9820880f6 100644
--- a/buildstream/_pipeline.py
+++ b/buildstream/_pipeline.py
@@ -195,24 +195,16 @@ class Pipeline():
     # also iterate over sources.
     #
     def dependencies(self, scope, include_sources=False):
-        # Create a dummy element (can't use namedtuple because of the
-        # '__' prefix).
-        class DummyElement(object):
-            def __init__(self, build_dependencies, runtime_dependencies):
-                self.name = ''
-                self._Element__build_dependencies = build_dependencies
-                self._Element__runtime_dependencies = runtime_dependencies
-        dummy = DummyElement(self.targets, self.targets)
-
-        for element in Element.dependencies(dummy, scope):
-            # We don't actually want to find the dummy element
-            if isinstance(element, DummyElement):
-                continue
-
-            if include_sources:
-                for source in element.sources():
-                    yield source
-            yield element
+        # Keep track of 'visited' in this scope, so that all targets
+        # share the same context.
+        visited = {}
+
+        for target in self.targets:
+            for element in target.dependencies(scope, visited=visited):
+                if include_sources:
+                    for source in element.sources():
+                        yield source
+                yield element
 
     # Asserts that the pipeline is in a consistent state, that
     # is to say that all sources are consistent and can at least
diff --git a/buildstream/element.py b/buildstream/element.py
index 22a2ebdbb..b76ef688f 100644
--- a/buildstream/element.py
+++ b/buildstream/element.py
@@ -179,7 +179,7 @@ class Element(Plugin):
         for source in self.__sources:
             yield source
 
-    def dependencies(self, scope, recurse=True, visited=None):
+    def dependencies(self, scope, recurse=True, visited=None, recursed=False):
         """dependencies(scope, recurse=True)
 
         A generator function which yields the dependencies of the given element.
@@ -197,36 +197,44 @@ class Element(Plugin):
         Yields:
            (:class:`.Element`): The dependencies in `scope`, in deterministic staging order
         """
-        did_recurse = False
         if visited is None:
-            visited = []
-        else:
-            did_recurse = True
+            visited = {}
+
+        scope_set = set((Scope.BUILD, Scope.RUN)) if scope == Scope.ALL else set((scope,))
 
-        if self.name in visited:
+        if self.name in visited and scope_set.issubset(visited[self.name]):
             return
-        visited.append(self.name)
 
-        if recurse or not did_recurse:
+        should_yield = False
+        if self.name not in visited:
+            visited[self.name] = scope_set
+            should_yield = True
+        else:
+            visited[self.name] |= scope_set
+
+        if recurse or not recursed:
             if scope == Scope.ALL:
                 for dep in self.__build_dependencies:
-                    for elt in dep.dependencies(Scope.ALL, recurse=recurse, visited=visited):
-                        yield elt
+                    yield from dep.dependencies(Scope.ALL, recurse=recurse,
+                                                visited=visited, recursed=True)
+
                 for dep in self.__runtime_dependencies:
                     if dep not in self.__build_dependencies:
-                        for elt in dep.dependencies(Scope.ALL, recurse=recurse, visited=visited):
-                            yield elt
+                        yield from dep.dependencies(Scope.ALL, recurse=recurse,
+                                                    visited=visited, recursed=True)
+
             elif scope == Scope.BUILD:
                 for dep in self.__build_dependencies:
-                    for elt in dep.dependencies(Scope.RUN, recurse=recurse, visited=visited):
-                        yield elt
+                    yield from dep.dependencies(Scope.RUN, recurse=recurse,
+                                                visited=visited, recursed=True)
+
             elif scope == Scope.RUN:
                 for dep in self.__runtime_dependencies:
-                    for elt in dep.dependencies(Scope.RUN, recurse=recurse, visited=visited):
-                        yield elt
+                    yield from dep.dependencies(Scope.RUN, recurse=recurse,
+                                                visited=visited, recursed=True)
 
         # Yeild self only at the end, after anything needed has been traversed
-        if (recurse or did_recurse) and (scope == Scope.ALL or scope == Scope.RUN):
+        if should_yield and (recurse or recursed) and (scope == Scope.ALL or scope == Scope.RUN):
             yield self
 
     def search(self, scope, name):
-- 
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