Preserve sort order of morphologies, so they can be edited by Morph

3 files changed, 128 insertions, 33 deletions

diff --git a/morphlib/morph2.py b/morphlib/morph2.py
index d99e4a9e..0eca6fed 100644
--- a/morphlib/morph2.py
+++ b/morphlib/morph2.py
@@ -14,7 +14,10 @@
 # 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 
 
+import collections
+import copy
 import json
+import re
 
 
 class Morphology(object):
@@ -50,8 +53,15 @@ class Morphology(object):
         ]
     }
 
+    @staticmethod
+    def _order_keys(pairs):
+        result = collections.OrderedDict()
+        for k,v in pairs:
+            result[k] = v
+        return result
+
     def __init__(self, text):
-        self._dict = json.loads(text)
+        self._dict = json.loads(text, object_pairs_hook=self._order_keys)
         self._set_defaults()
         self._validate_children()
 
@@ -105,19 +115,8 @@ class Morphology(object):
 
         if 'disk-size' in self:
             size = self['disk-size']
-            if isinstance(size, basestring):
-                size = size.lower()
-                if size.endswith('g'):
-                    size = int(size[:-1]) * 1024 ** 3
-                elif size.endswith('m'):  # pragma: no cover
-                    size = int(size[:-1]) * 1024 ** 2
-                elif size.endswith('k'):  # pragma: no cover
-                    size = int(size[:-1]) * 1024
-                else:  # pragma: no cover
-                    size = int(size)
-            else: # pragma: no cover
-                size = int(size)
-            self._dict['disk-size'] = size
+            self._dict['_disk-size'] = size
+            self._dict['disk-size'] = self._parse_size(size)
 
         for name, value in self.static_defaults[self['kind']]:
             if name not in self._dict:
@@ -134,3 +133,38 @@ class Morphology(object):
                 source['morph'] = source['name']
             if 'build-depends' not in source:
                 source['build-depends'] = None
+
+    def _parse_size(self, size):
+        if isinstance(size, basestring):
+            size = size.lower()
+            if size.endswith('g'):
+                return int(size[:-1]) * 1024 ** 3
+            elif size.endswith('m'):  # pragma: no cover
+                return int(size[:-1]) * 1024 ** 2
+            elif size.endswith('k'):  # pragma: no cover
+                return int(size[:-1]) * 1024
+        return int(size)
+
+    def write_to_file(self, f):
+        # Recreate dict without the empty default values, with a few kind
+        # specific hacks to try and edit standard morphologies as
+        # non-destructively as possible
+        as_dict = collections.OrderedDict()
+        for key in self.keys():
+            if self['kind'] == 'stratum' and key == 'chunks':
+                value = copy.copy(self[key])
+                for chunk in value:
+                    if chunk["morph"] == chunk["name"]:
+                        del chunk["morph"]
+            if self['kind'] == 'system' and key == 'disk-size':
+                # Use human-readable value (assumes we never programmatically
+                # change this value within morph)
+                value = self['_disk-size']
+            else:
+                value = self[key]
+            if value and key[0] != '_':
+                as_dict[key] = value
+        text = json.dumps(as_dict, indent=4)
+        text = re.sub(" \n", "\n", text)
+        f.write(text)
+        f.write('\n')
diff --git a/morphlib/morph2_tests.py b/morphlib/morph2_tests.py
index 60917537..142b5949 100644
--- a/morphlib/morph2_tests.py
+++ b/morphlib/morph2_tests.py
@@ -14,6 +14,7 @@
 # 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 
 
+import StringIO
 import unittest
 
 from morphlib.morph2 import Morphology
@@ -197,3 +198,78 @@ class MorphologyTests(unittest.TestCase):
         self.assertRaises(ValueError,
                           Morphology,
                           text)
+
+    def test_writing_preserves_field_order(self):
+        text = '''{
+    "kind": "system",
+    "disk-size": 1073741824,
+    "description": "Some text",
+    "arch": "x86_64",
+    "system-kind": "syslinux-disk",
+    "strata": [
+        {
+            "morph": "foundation",
+            "repo": "morphs",
+            "ref": "ref"
+        },
+        {
+            "morph": "devel",
+            "repo": "morphs",
+            "ref": "ref"
+        }
+    ]
+}'''
+        morphology = Morphology(text)
+        output = StringIO.StringIO()
+        morphology.write_to_file(output)
+
+        text_lines = text.splitlines()
+        output_lines = output.getvalue().splitlines()
+
+        # Verify that input and output are equal.
+        self.assertEqual(text_lines, output_lines)
+
+    def test_writing_stratum_morphology_preserves_chunk_order(self):
+        text = '''{
+    "kind": "stratum",
+    "chunks": [
+        {
+            "name": "foo",
+            "repo": "morphs",
+            "ref": "ref",
+            "build-depends": []
+        },
+        {
+            "name": "bar",
+            "repo": "morphs",
+            "ref": "ref",
+            "build-depends": []
+        }
+    ]
+}'''
+        morphology = Morphology(text)
+        output = StringIO.StringIO()
+        morphology.write_to_file(output)
+
+        text_lines = text.splitlines()
+        output_lines = output.getvalue().splitlines()
+
+        # Verify that input and output are equal.
+        self.assertEqual(text_lines, output_lines)
+
+    def test_writing_preserves_disk_size(self):
+        text = '''{
+    "kind": "system",
+    "disk-size": "1g",
+    "arch": "x86_64",
+    "system-kind": "syslinux-disk"
+}'''
+        morphology = Morphology(text)
+        output = StringIO.StringIO()
+        morphology.write_to_file(output)
+
+        text_lines = text.splitlines()
+        output_lines = output.getvalue().splitlines()
+
+        # Verify that in- and output are the same.
+        self.assertEqual(text_lines, output_lines)
diff --git a/morphlib/plugins/branch_and_merge_plugin.py b/morphlib/plugins/branch_and_merge_plugin.py
index 5e5ce0c1..d6485c2b 100644
--- a/morphlib/plugins/branch_and_merge_plugin.py
+++ b/morphlib/plugins/branch_and_merge_plugin.py
@@ -234,14 +234,9 @@ class BranchAndMergePlugin(cliapp.Plugin):
             filename = name
         else:
             filename = os.path.join(repo_dir, name)
-        as_dict = {}
-        for key in morphology.keys():
-            value = morphology[key]
-            if value:
-                as_dict[key] = value
+        filename = os.path.join(repo_dir, '%s' % name)
         with morphlib.savefile.SaveFile(filename, 'w') as f:
-            json.dump(as_dict, fp=f, indent=4, sort_keys=True)
-            f.write('\n')
+            morphology.write_to_file(f)
 
     @staticmethod
     def get_edit_info(morphology_name, morphology, name, collection='strata'):
@@ -258,17 +253,6 @@ class BranchAndMergePlugin(cliapp.Plugin):
                         (name, morphology_name))
 
     @staticmethod
-    def write_morphology(filename, morphology):
-        as_dict = {}
-        for key in morphology.keys():
-            value = morphology[key]
-            if value:
-                as_dict[key] = value
-        with morphlib.savefile.SaveFile(filename, 'w') as f:
-            json.dump(as_dict, fp=f, indent=4, sort_keys=True)
-            f.write('\n')
-
-    @staticmethod
     def convert_uri_to_path(uri):
         parts = urlparse.urlparse(uri)
 
@@ -357,7 +341,8 @@ class BranchAndMergePlugin(cliapp.Plugin):
                 repo = cache.get_repo(reponame)
                 source['ref'], tree = repo.resolve_ref(ref)
 
-            self.write_morphology(filename, morph)
+            with morphlib.savefile.SaveFile(filename, 'w') as f:
+                morph.write_to_file(f)
 
     def init(self, args):
         '''Initialize a workspace directory.'''