From ab8fef3cdb2bf5c6393ed841f74baf2bfc5a1a23 Mon Sep 17 00:00:00 2001
From: Florian Bruhin <git@the-compiler.org>
Date: Thu, 20 Feb 2014 19:50:17 +0100
Subject: [PATCH] Add new NeighborList datatype

---
 qutebrowser/utils/types.py     | 113 +++++++++++++++++++++++++++++++++
 qutebrowser/widgets/browser.py |   1 +
 2 files changed, 114 insertions(+)
 create mode 100644 qutebrowser/utils/types.py

diff --git a/qutebrowser/utils/types.py b/qutebrowser/utils/types.py
new file mode 100644
index 000000000..328515d8b
--- /dev/null
+++ b/qutebrowser/utils/types.py
@@ -0,0 +1,113 @@
+# Copyright 2014 Florian Bruhin (The Compiler) <mail@qutebrowser.org>
+#
+# This file is part of qutebrowser.
+#
+# qutebrowser 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, either version 3 of the License, or
+# (at your option) any later version.
+#
+# qutebrowser 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 qutebrowser.  If not, see <http://www.gnu.org/licenses/>.
+
+"""Custom useful datatypes."""
+
+# Used as default argument in the constructor so default can be None.
+_UNSET = object()
+
+
+class NeighborList:
+
+    """A list of items which saves it current position.
+
+    Attributes:
+        BLOCK/WRAP/RAISE: Modes, see constructor documentation.
+        _items: A list of all items, accessed through item property.
+        idx: The current position in the list.
+        _mode: The current mode.
+
+    """
+
+    BLOCK = 0
+    WRAP = 1
+    RAISE = 2
+
+    def __init__(self, items, default=_UNSET, mode=BLOCK):
+        """Constructor.
+
+        Args:
+            items: The list of items to iterate in.
+            _default: The initially selected value.
+            _mode: Behaviour when the first/last item is reached.
+                   BLOCK: Stay on the selected item
+                   WRAP: Wrap around to the other end
+                   RAISE: Raise an IndexError.
+
+        """
+        self._items = items
+        self._default = default
+        if default is not _UNSET:
+            self.idx = self._items.index(default)
+        self._mode = mode
+
+    @property
+    def items(self):
+        """Getter for items, which should not be set."""
+        return self._items
+
+    def getitem(self, offset):
+        """Get the item with a relative position.
+
+        Args:
+            offset: The offset of the current item, relative to the last one.
+
+        Return:
+            The new item.
+
+        Raise:
+            IndexError if the border of the list is reached and mode is RAISE.
+
+        """
+        # FIXME - zooming somehow wraps...
+        try:
+            if self.idx + offset > 0:
+                new = self._items[self.idx + offset]
+            else:
+                raise IndexError
+        except IndexError:
+            if self._mode == self.BLOCK:
+                new = self.curitem()
+            elif self._mode == self.WRAP:
+                self.idx += offset
+                self.idx %= len(self.items)
+                new = self.curitem()
+            elif self._mode == self.RAISE:
+                raise
+        else:
+            self.idx += offset
+        return new
+
+    def curitem(self):
+        """Get the current item in the list."""
+        return self._items[self.idx]
+
+    def nextitem(self):
+        """Get the next item in the list."""
+        return self.getitem(1)
+
+    def previtem(self):
+        """Get the previous item in the list."""
+        return self.getitem(-1)
+
+    def reset(self):
+        """Reset the position to the default."""
+        if self._default is _UNSET:
+            raise ValueError("No default set!")
+        else:
+            self.idx = self._items.index(self._default)
+            return self.curitem()
diff --git a/qutebrowser/widgets/browser.py b/qutebrowser/widgets/browser.py
index a1c842a3f..66e9a6ea6 100644
--- a/qutebrowser/widgets/browser.py
+++ b/qutebrowser/widgets/browser.py
@@ -40,6 +40,7 @@ import qutebrowser.utils.config as config
 from qutebrowser.widgets.tabbar import TabWidget
 from qutebrowser.utils.signals import SignalCache, dbg_signal
 from qutebrowser.utils.misc import read_file
+from qutebrowser.utils.types import NeighborList
 
 
 class TabbedBrowser(TabWidget):