Add the new ArtifactResolver class.

This class takes a CacheKeyComputer and a SourcePool, analyses the
sources and their dependencies and creates a list of artifacts
(represented by Artifact objects) that would be created when
building sources in the pool.

1 files changed, 116 insertions, 0 deletions

diff --git a/morphlib/artifactresolver.py b/morphlib/artifactresolver.py
new file mode 100644
index 00000000..5ad6dcac
--- /dev/null
+++ b/morphlib/artifactresolver.py
@@ -0,0 +1,116 @@
+# Copyright (C) 2012  Codethink Limited
+# 
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; version 2 of the License.
+# 
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+# 
+# You should have received a copy of the GNU General Public License along
+# with this program; if not, write to the Free Software Foundation, Inc.,
+# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+
+import cliapp
+import collections
+
+import morphlib
+
+
+class UndefinedChunkArtifactError(cliapp.AppException):
+
+    '''Exception raised when non-existent artifacts are referenced.
+    
+    Usually, this will only occur when a stratum refers to a chunk
+    artifact that is not defined in a chunk.
+    
+    '''
+
+    def __init__(self, parent, reference):
+        cliapp.AppException.__init__(
+                self, 'Undefined chunk artifact "%s" referenced in %s' %
+                    (reference, parent))
+
+
+class ArtifactResolver(object):
+
+    '''Resolves sources into artifacts that would be build from the sources.
+    
+    This class takes a CacheKeyComputer and a SourcePool, analyses the
+    sources and their dependencies and creates a list of artifacts
+    (represented by Artifact objects) that are involved in building the
+    sources in the pool.
+    
+    '''
+
+    def __init__(self, cache_key_computer):
+        self.cache_key_computer = cache_key_computer
+
+    def resolve_artifacts(self, source_pool):
+        artifacts = []
+        roots = [x for x in source_pool if not x.dependents]
+        queue = collections.deque(roots)
+        while queue:
+            source = queue.popleft()
+            cache_key = self.cache_key_computer.compute_key(source)
+            if source.morphology['kind'] == 'system':
+                artifact = morphlib.artifact.Artifact(
+                        source, source.morphology['name'], cache_key)
+                artifacts.append(artifact)
+                for dependency in source.dependencies:
+                    queue.append(dependency)
+            elif source.morphology['kind'] == 'stratum':
+                artifact = morphlib.artifact.Artifact(
+                        source, source.morphology['name'], cache_key)
+                artifacts.append(artifact)
+                for dependency in source.dependencies:
+                    if dependency.morphology['kind'] == 'stratum':
+                        queue.append(dependency)
+                    elif dependency.morphology['kind'] == 'chunk':
+                        chunk_artifacts = self._find_required_chunk_artifacts(
+                                source, dependency, source_pool)
+                        artifacts.extend(chunk_artifacts)
+            elif source.morphology['kind'] == 'chunk':
+                names = self._chunk_artifact_names(source)
+                for name in names:
+                    artifact = morphlib.artifact.Artifact(
+                            source, name, cache_key)
+                    artifacts.append(artifact)
+
+        return artifacts
+
+    def _find_required_chunk_artifacts(self, stratum, chunk, source_pool):
+        artifacts = []
+        for source in stratum.morphology['sources']:
+            if self._source_matches_chunk(stratum, source, chunk, source_pool):
+                cache_key = self.cache_key_computer.compute_key(chunk)
+                artifact = morphlib.artifact.Artifact(
+                        chunk, source['name'], cache_key)
+                artifacts.append(artifact)
+        return artifacts
+
+    def _source_matches_chunk(self, stratum, source, chunk, source_pool):
+        source_from_pool = source_pool.lookup(
+                source['repo'],
+                source['ref'],
+                '%s.morph' % source['morph'])
+
+        if source_from_pool is not chunk:
+            return False
+
+        chunk_names = self._chunk_artifact_names(chunk)
+        
+        if source['name'] not in chunk_names:
+            raise UndefinedChunkArtifactError(stratum, source['name'])
+
+        return True
+
+    def _chunk_artifact_names(self, chunk):
+        if 'artifacts' in chunk.morphology:
+            return sorted(chunk.morphology['artifacts'].keys())
+        else:
+            return [chunk.morphology['name']]
+