1 files changed, 103 insertions, 0 deletions
diff --git a/pokemontools/interval_map.py b/pokemontools/interval_map.py
new file mode 100644
index 0000000..daf22cd
--- /dev/null
+++ b/pokemontools/interval_map.py
@@ -0,0 +1,103 @@
+# -*- coding: utf-8 -*-
+
+from bisect import bisect_left, bisect_right
+from itertools import izip
+
+class IntervalMap(object):
+    """
+    This class maps a set of intervals to a set of values.
+
+    >>> i = IntervalMap()
+    >>> i[0:5] = "hello world"
+    >>> i[6:10] = "hello cruel world"
+    >>> print i[4]
+    "hello world"
+    """
+
+    def __init__(self):
+        """initializes an empty IntervalMap"""
+        self._bounds = []
+        self._items = []
+        self._upperitem = None
+
+    def __setitem__(self, _slice, _value):
+        """sets an interval mapping"""
+        assert isinstance(_slice, slice), 'The key must be a slice object'
+
+        if _slice.start is None:
+            start_point = -1
+        else:
+            start_point = bisect_left(self._bounds, _slice.start)
+
+        if _slice.stop is None:
+            end_point = -1
+        else:
+            end_point = bisect_left(self._bounds, _slice.stop)
+
+        if start_point>=0:
+            if start_point < len(self._bounds) and self._bounds[start_point]<_slice.start:
+                start_point += 1
+
+            if end_point>=0:
+                self._bounds[start_point:end_point] = [_slice.start, _slice.stop]
+                if start_point < len(self._items):
+                    self._items[start_point:end_point] = [self._items[start_point], _value]
+                else:
+                    self._items[start_point:end_point] = [self._upperitem, _value]
+            else:
+                self._bounds[start_point:] = [_slice.start]
+                if start_point < len(self._items):
+                    self._items[start_point:] = [self._items[start_point], _value]
+                else:
+                    self._items[start_point:] = [self._upperitem]
+                self._upperitem = _value
+        else:
+            if end_point>=0:
+                self._bounds[:end_point] = [_slice.stop]
+                self._items[:end_point] = [_value]
+            else:
+                self._bounds[:] = []
+                self._items[:] = []
+                self._upperitem = _value
+
+    def __getitem__(self,_point):
+        """gets a value from the mapping"""
+        assert not isinstance(_point, slice), 'The key cannot be a slice object'
+
+        index = bisect_right(self._bounds, _point)
+        if index < len(self._bounds):
+            return self._items[index]
+        else:
+            return self._upperitem
+
+    def items(self):
+        """returns an iterator with each item being
+        ((low_bound, high_bound), value)
+        these items are returned in order"""
+        previous_bound = None
+        for (b, v) in izip(self._bounds, self._items):
+            if v is not None:
+                yield (previous_bound, b), v
+            previous_bound = b
+        if self._upperitem is not None:
+            yield (previous_bound, None), self._upperitem
+
+    def values(self):
+        """returns an iterator with each item being a stored value
+        the items are returned in order"""
+        for v in self._items:
+            if v is not None:
+                yield v
+        if self._upperitem is not None:
+            yield self._upperitem
+
+    def __repr__(self):
+        s = []
+        for b,v in self.items():
+            if v is not None:
+                s.append('[%r, %r] => %r'%(
+                    b[0],
+                    b[1],
+                    v
+                ))
+        return '{'+', '.join(s)+'}'