Add a MorphologySet class, for changing many morphologies

Various parts of Morph need to change a set of morphologies at once,
particularly for petrification and unpetrification. This is easiest
done by loading all the morphologies into memory at once, and changing
them there, then saving again.

1 files changed, 158 insertions, 0 deletions

diff --git a/morphlib/morphset.py b/morphlib/morphset.py
new file mode 100644
index 00000000..98a4b8f9
--- /dev/null
+++ b/morphlib/morphset.py
@@ -0,0 +1,158 @@
+# Copyright (C) 2013  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.
+#
+# =*= License: GPL-2 =*=
+
+
+import morphlib
+
+
+class StratumNotInSystemError(morphlib.Error):
+
+    def __init__(self, system_name, stratum_name):
+        self.msg = (
+            'System %s does not contain %s' % (system_name, stratum_name))
+
+
+class StratumNotInSetError(morphlib.Error):
+
+    def __init__(self, stratum_name):
+        self.msg = 'Stratum %s is not in MorphologySet' % stratum_name
+
+
+class ChunkNotInStratumError(morphlib.Error):
+
+    def __init__(self, stratum_name, chunk_name):
+        self.msg = (
+            'Stratum %s does not contain %s' % (stratum_name, chunk_name))
+
+
+class MorphologySet(object):
+
+    '''Store and manipulate a set of Morphology objects.'''
+
+    def __init__(self):
+        self.morphologies = []
+
+    def add_morphology(self, morphology):
+        '''Add a morphology object to the set, unless it's there already.'''
+
+        triplet = (
+            morphology.repo_url,
+            morphology.ref,
+            morphology.filename
+        )
+        for existing in self.morphologies:
+            existing_triplet = (
+                existing.repo_url,
+                existing.ref,
+                existing.filename
+            )
+            if existing_triplet == triplet:
+                return
+
+        self.morphologies.append(morphology)
+
+    def has(self, repo_url, ref, filename):
+        '''Does the set have a morphology for the given triplet?'''
+        return self._get_morphology(repo_url, ref, filename) is not None
+
+    def _get_morphology(self, repo_url, ref, filename):
+        for m in self.morphologies:
+            if (m.repo_url == repo_url and
+                m.ref == ref and
+                m.filename == filename):
+                return m
+        return None
+
+    def _find_spec(self, specs, wanted_name):
+        for spec in specs:
+            name = spec.get('morph', spec.get('name'))
+            if name == wanted_name:
+                return spec['repo'], spec['ref'], name
+        return None, None, None
+
+    def get_stratum_in_system(self, system_morph, stratum_name):
+        '''Return morphology for a stratum that is in a system.
+
+        If the stratum is not in the system, raise StratumNotInSystemError.
+        If the stratum morphology has not been added to the set,
+        raise StratumNotInSetError.
+
+        '''
+
+        repo_url, ref, morph = self._find_spec(
+            system_morph['strata'], stratum_name)
+        if repo_url is None:
+            raise StratumNotInSystemError(system_morph['name'], stratum_name)
+        m = self._get_morphology(repo_url, ref, '%s.morph' % morph)
+        if m is None:
+            raise StratumNotInSetError(stratum_name)
+        return m
+
+    def get_chunk_triplet(self, stratum_morph, chunk_name):
+        '''Return the repo url, ref, morph name triplet for a chunk.
+
+        Given a stratum morphology, find the triplet used to refer to
+        a given chunk. Note that because of how the chunk may be
+        referred to using either name or morph fields in the morphology,
+        the morph field (or its computed value) is always returned.
+        Note also that the morph field, not the filename, is returned.
+
+        Raise ChunkNotInStratumError if the chunk is not found in the
+        stratum.
+
+        '''
+
+        repo_url, ref, morph = self._find_spec(
+            stratum_morph['chunks'], chunk_name)
+        if repo_url is None:
+            raise ChunkNotInStratumError(stratum_morph['name'], chunk_name)
+        return repo_url, ref, morph
+
+    def change_ref(self, repo_url, orig_ref, morph_filename, new_ref):
+        '''Change a triplet's ref to a new one in all morphologies in a ref.
+
+        Change orig_ref to new_ref in any morphology that references the
+        original triplet. This includes stratum build-dependencies.
+
+        '''
+
+        def wanted_spec(spec):
+            return (spec['repo'] == repo_url and
+                    spec['ref'] == orig_ref and
+                    spec['morph'] + '.morph' == morph_filename)
+
+        def change_specs(specs):
+            for spec in specs:
+                if wanted_spec(spec):
+                    spec['ref'] = new_ref
+                    m.dirty = True
+
+        def change(m):
+            if m['kind'] == 'system':
+                change_specs(m['strata'])
+            elif m['kind'] == 'stratum':
+                change_specs(m['chunks'])
+                change_specs(m['build-depends'])
+
+        for m in self.morphologies:
+            change(m)
+
+        m = self._get_morphology(repo_url, orig_ref, morph_filename)
+        if m and m.ref != new_ref:
+            m.ref = new_ref
+            m.dirty = True
+