1 files changed, 108 insertions, 0 deletions
diff --git a/morphlib/defaults.py b/morphlib/defaults.py
new file mode 100644
index 00000000..9e695a90
--- /dev/null
+++ b/morphlib/defaults.py
@@ -0,0 +1,108 @@
+# Copyright (C) 2015  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, see <http://www.gnu.org/licenses/>.
+#
+# =*= License: GPL-2 =*=
+
+
+import cliapp
+import jsonschema
+import yaml
+
+import os
+
+import morphlib
+
+
+class Defaults(object):
+    '''Represents predefined default values specific to Baserock definitions.
+
+    The DEFAULTS file was added in definitions format version 7, which lets
+    users set these defaults. The text of DEFAULTS file can be passed in as
+    'text', and will be validated and parsed if definitions_version >= 7.
+
+    Prior to version 7, the defaults were hardcoded in Morph. These defaults
+    will be returned if definitions_version < 7.
+
+    '''
+    def __init__(self, definitions_version, text=None):
+        self._build_systems = {}
+        self._split_rules = {}
+
+        schema_path = os.path.join(morphlib.util.schemas_directory(),
+                                   'defaults.json-schema')
+        with open(schema_path) as f:
+            self.schema = yaml.load(f)
+
+        if definitions_version >= 7:
+            if text:
+                self._build_systems, self._split_rules = self._parse(text)
+        else:
+            self._build_systems, self._split_rules = self._builtins()
+
+    def _parse(self, text):
+        build_systems = {}
+        split_rules = {}
+
+        # This reports errors against <string> rather than the actual filename,
+        # which is sad.
+        data = yaml.safe_load(text)
+
+        if data is None:
+            # It's OK to be empty, I guess.
+            return build_systems, split_rules
+
+        try:
+            # It would be nice if this could give line numbers when it spotted
+            # errors. Seems tricky.
+            jsonschema.validate(data, self.schema)
+        except jsonschema.ValidationError as e:
+            raise cliapp.AppException('Invalid DEFAULTS file: %s' % e.message)
+
+        build_system_data = data.get('build-systems', {})
+        for name, commands in build_system_data.items():
+            build_system = morphlib.buildsystem.BuildSystem()
+            build_system.from_dict(name, commands)
+            build_systems[name] = build_system
+
+        # It would make sense to create artifactsplitrule.SplitRule instances
+        # here, instead of an unlabelled data structure. That would need some
+        # changes to source.make_sources() and the 'artifactsplitrule' module.
+        split_rules_data = data.get('split-rules', {})
+        for kind, rules in split_rules_data.items():
+            split_rules[kind] = []
+            for rule in rules:
+                rule_unlabelled = (rule['artifact'], rule['include'])
+                split_rules[kind].append(rule_unlabelled)
+
+        return build_systems, split_rules
+
+    def _builtins(self):
+        build_systems = {}
+        split_rules = {}
+
+        for build_system in morphlib.buildsystem.build_systems:
+            build_systems[build_system.name] = build_system
+
+        split_rules['chunk'] = \
+            morphlib.artifactsplitrule.DEFAULT_CHUNK_RULES
+        split_rules['stratum'] = \
+            morphlib.artifactsplitrule.DEFAULT_STRATUM_RULES
+
+        return build_systems, split_rules
+
+    def build_systems(self):
+        return self._build_systems
+
+    def split_rules(self):
+        return self._split_rules