[meld] Update recent files handling to use a enum for type

[Kai Willadsen <kaiw src gnome org>]

commit 0b66cd807572e69f0483c66674cac82e01601391
Author: Kai Willadsen <kai willadsen gmail com>
Date:   Fri Nov 17 06:14:48 2017 +1000

    Update recent files handling to use a enum for type
    
    From a user POV this should be a no-op, but it makes reasoning about
    the values in use easier, and allows typing.

 meld/dirdiff.py    |    4 ++--
 meld/filediff.py   |    4 ++--
 meld/filemerge.py  |    4 ++--
 meld/melddoc.py    |    3 ++-
 meld/meldwindow.py |   24 ++++++++++--------------
 meld/recent.py     |   21 +++++++++++++--------
 meld/vcview.py     |    4 ++--
 7 files changed, 33 insertions(+), 31 deletions(-)
---
diff --git a/meld/dirdiff.py b/meld/dirdiff.py
index ab1ade1..68f95d4 100644
--- a/meld/dirdiff.py
+++ b/meld/dirdiff.py
@@ -36,7 +36,6 @@ from gi.repository import Gtk
 from . import melddoc
 from . import tree
 from . import misc
-from . import recent
 from .ui import gnomeglade
 from .ui import emblemcellrenderer
 
@@ -45,6 +44,7 @@ from decimal import Decimal
 
 from meld.conf import _
 from meld.misc import all_same
+from meld.recent import RecentType
 from meld.settings import bind_settings, meldsettings, settings
 
 
@@ -645,7 +645,7 @@ class DirDiff(melddoc.MeldDoc, gnomeglade.Component):
                     for d in self.model.value_paths(root)]
         else:
             uris = []
-        return recent.TYPE_FOLDER, uris
+        return RecentType.Folder, uris
 
     def recursively_update( self, path ):
         """Recursively update from tree path 'path'.
diff --git a/meld/filediff.py b/meld/filediff.py
index 0fbb20f..ca36cdd 100644
--- a/meld/filediff.py
+++ b/meld/filediff.py
@@ -30,7 +30,6 @@ from meld.conf import _
 from . import meldbuffer
 from . import melddoc
 from . import misc
-from . import recent
 from . import undo
 from .ui import gnomeglade
 
@@ -39,6 +38,7 @@ from meld.matchers.diffutil import Differ, merged_chunk_order
 from meld.matchers.helpers import CachedSequenceMatcher
 from meld.matchers.merge import Merger
 from meld.patchdialog import PatchDialog
+from meld.recent import RecentType
 from meld.settings import bind_settings, meldsettings
 from meld.sourceview import LanguageManager, get_custom_encoding_candidates
 from meld.ui.findbar import FindBar
@@ -1070,7 +1070,7 @@ class FileDiff(melddoc.MeldDoc, gnomeglade.Component):
 
     def get_comparison(self):
         uris = [b.data.gfile for b in self.textbuffer[:self.num_panes]]
-        return recent.TYPE_FILE, uris
+        return RecentType.File, uris
 
     def file_loaded(self, loader, result, user_data):
 
diff --git a/meld/filemerge.py b/meld/filemerge.py
index 6777ba4..57e3b6e 100644
--- a/meld/filemerge.py
+++ b/meld/filemerge.py
@@ -17,7 +17,7 @@
 from meld.conf import _
 from . import filediff
 from meld.matchers import merge
-from . import recent
+from meld.recent import RecentType
 
 
 class FileMerge(filediff.FileDiff):
@@ -31,7 +31,7 @@ class FileMerge(filediff.FileDiff):
 
     def get_comparison(self):
         comp = filediff.FileDiff.get_comparison(self)
-        return recent.TYPE_MERGE, comp[1]
+        return RecentType.Merge, comp[1]
 
     def _merge_files(self):
         yield _("[%s] Merging files") % self.label_text
diff --git a/meld/melddoc.py b/meld/melddoc.py
index 723e2f3..e36c9ab 100644
--- a/meld/melddoc.py
+++ b/meld/melddoc.py
@@ -31,6 +31,7 @@ from . import task
 
 from meld.conf import _
 from meld.settings import settings
+from meld.recent import RecentType
 
 log = logging.getLogger(__name__)
 
@@ -106,7 +107,7 @@ class MeldDoc(LabeledObjectMixin, GObject.GObject):
         self.emit('state-changed', self._state, value)
         self._state = value
 
-    def get_comparison(self):
+    def get_comparison(self) -> RecentType:
         """Get the comparison type and URI(s) being compared"""
         pass
 
diff --git a/meld/meldwindow.py b/meld/meldwindow.py
index 7f97af8..4987131 100644
--- a/meld/meldwindow.py
+++ b/meld/meldwindow.py
@@ -14,8 +14,6 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-import os
-
 from gi.repository import Gdk
 from gi.repository import Gio
 from gi.repository import GLib
@@ -27,14 +25,13 @@ from . import filediff
 from . import filemerge
 from . import melddoc
 from . import newdifftab
-from . import recent
 from . import task
 from . import vcview
 from .ui import gnomeglade
 from .ui import notebooklabel
 
 from meld.conf import _
-from meld.recent import recent_comparisons
+from meld.recent import RecentType, recent_comparisons
 from meld.settings import interface_settings, settings
 from meld.windowstate import SavedWindowState
 
@@ -623,7 +620,8 @@ class MeldWindow(gnomeglade.Component):
     def append_vcview(self, location, auto_compare=False):
         doc = vcview.VcView()
         self._append_page(doc, "meld-version-control")
-        location = location[0] if isinstance(location, list) else location
+        if isinstance(location, (list, tuple)):
+            location = location[0]
         doc.set_location(location.get_path())
         if auto_compare:
             doc.scheduler.add_task(doc.auto_compare)
@@ -631,15 +629,13 @@ class MeldWindow(gnomeglade.Component):
 
     def append_recent(self, uri):
         comparison_type, gfiles, flags = recent_comparisons.read(uri)
-        if comparison_type == recent.TYPE_MERGE:
-            tab = self.append_filemerge(gfiles)
-        elif comparison_type == recent.TYPE_FOLDER:
-            tab = self.append_dirdiff(gfiles)
-        elif comparison_type == recent.TYPE_VC:
-            # Files should be a single-element iterable
-            tab = self.append_vcview(gfiles[0])
-        else:  # comparison_type == recent.TYPE_FILE:
-            tab = self.append_filediff(gfiles)
+        comparison_method = {
+            RecentType.File: self.append_filediff,
+            RecentType.Folder: self.append_dirdiff,
+            RecentType.Merge: self.append_filemerge,
+            RecentType.VersionControl: self.append_vcview,
+        }
+        tab = comparison_method[comparison_type](gfiles)
         self.notebook.set_current_page(self.notebook.page_num(tab.widget))
         recent_comparisons.add(tab)
         return tab
diff --git a/meld/recent.py b/meld/recent.py
index dfdee4e..c52acf7 100644
--- a/meld/recent.py
+++ b/meld/recent.py
@@ -25,6 +25,7 @@ infrastructure that that's actually what we opened.
 """
 
 import configparser
+import enum
 import os
 import sys
 import tempfile
@@ -37,11 +38,12 @@ import meld.misc
 
 from meld.conf import _
 
-TYPE_FILE = "File"
-TYPE_FOLDER = "Folder"
-TYPE_VC = "Version control"
-TYPE_MERGE = "Merge"
-COMPARISON_TYPES = (TYPE_FILE, TYPE_FOLDER, TYPE_VC, TYPE_MERGE)
+
+class RecentType(enum.Enum):
+    File = "File"
+    Folder = "Folder"
+    VersionControl = "Version control"
+    Merge = "Merge"
 
 
 def unicodeify(s):
@@ -81,7 +83,7 @@ class RecentFiles(object):
         The passed flags are currently ignored. In the future these are to be
         used for extra initialisation not captured by the tab itself.
         """
-        comp_type, gfiles = tab.get_comparison()
+        recent_type, gfiles = tab.get_comparison()
 
         # While Meld handles comparisons including None, recording these as
         # recently-used comparisons just isn't that sane.
@@ -90,6 +92,7 @@ class RecentFiles(object):
 
         uris = [f.get_uri() for f in gfiles]
         names = [f.get_parse_name() for f in gfiles]
+        comp_type = recent_type.value
 
         # If a (type, uris) comparison is already registered, then re-add
         # the corresponding comparison file
@@ -146,7 +149,9 @@ class RecentFiles(object):
             raise ValueError("Invalid recent comparison file")
 
         comp_type = config.get("Comparison", "type")
-        if comp_type not in COMPARISON_TYPES:
+        try:
+            recent_type = RecentType(comp_type)
+        except ValueError:
             raise ValueError("Invalid recent comparison file")
 
         if config.has_option("Comparison", "uris"):
@@ -157,7 +162,7 @@ class RecentFiles(object):
                 for p in tuple(config.get("Comparison", "paths").split(";"))])
         flags = tuple()
 
-        return comp_type, gfiles, flags
+        return recent_type, gfiles, flags
 
     def _write_recent_file(self, comp_type, uris):
         # TODO: Use GKeyFile instead, and return a Gio.File. This is why we're
diff --git a/meld/vcview.py b/meld/vcview.py
index 2aa853b..fef033d 100644
--- a/meld/vcview.py
+++ b/meld/vcview.py
@@ -34,13 +34,13 @@ from gi.repository import Pango
 
 from meld import melddoc
 from meld import misc
-from meld import recent
 from meld import tree
 from meld import vc
 from meld.ui import gnomeglade
 from meld.ui import vcdialogs
 
 from meld.conf import _
+from meld.recent import RecentType
 from meld.settings import settings, bind_settings
 from meld.vc import _null
 from meld.vc._vc import Entry
@@ -326,7 +326,7 @@ class VcView(melddoc.MeldDoc, gnomeglade.Component):
 
     def get_comparison(self):
         uris = [Gio.File.new_for_path(self.location)]
-        return recent.TYPE_VC, uris
+        return RecentType.VersionControl, uris
 
     def recompute_label(self):
         self.label_text = os.path.basename(self.location)