1 files changed, 74 insertions, 0 deletions
diff --git a/webapp/django/utils/itercompat.py b/webapp/django/utils/itercompat.py
new file mode 100644
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+++ b/webapp/django/utils/itercompat.py
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+"""
+Providing iterator functions that are not in all version of Python we support.
+Where possible, we try to use the system-native version and only fall back to
+these implementations if necessary.
+"""
+
+import itertools
+
+def compat_tee(iterable):
+    """
+    Return two independent iterators from a single iterable.
+
+    Based on http://www.python.org/doc/2.3.5/lib/itertools-example.html
+    """
+    # Note: Using a dictionary and a list as the default arguments here is
+    # deliberate and safe in this instance.
+    def gen(next, data={}, cnt=[0]):
+        dpop = data.pop
+        for i in itertools.count():
+            if i == cnt[0]:
+                item = data[i] = next()
+                cnt[0] += 1
+            else:
+                item = dpop(i)
+            yield item
+    next = iter(iterable).next
+    return gen(next), gen(next)
+
+def groupby(iterable, keyfunc=None):
+    """
+    Taken from http://docs.python.org/lib/itertools-functions.html
+    """
+    if keyfunc is None:
+        keyfunc = lambda x:x
+    iterable = iter(iterable)
+    l = [iterable.next()]
+    lastkey = keyfunc(l[0])
+    for item in iterable:
+        key = keyfunc(item)
+        if key != lastkey:
+            yield lastkey, l
+            lastkey = key
+            l = [item]
+        else:
+            l.append(item)
+    yield lastkey, l
+
+# Not really in itertools, since it's a builtin in Python 2.4 and later, but it
+# does operate as an iterator.
+def reversed(data):
+    for index in xrange(len(data)-1, -1, -1):
+        yield data[index]
+
+if hasattr(itertools, 'tee'):
+    tee = itertools.tee
+else:
+    tee = compat_tee
+if hasattr(itertools, 'groupby'):
+    groupby = itertools.groupby
+
+def is_iterable(x):
+    "A implementation independent way of checking for iterables"
+    try:
+        iter(x)
+    except TypeError:
+        return False
+    else:
+        return True
+
+def sorted(in_value):
+    "A naive implementation of sorted"
+    out_value = in_value[:]
+    out_value.sort()
+    return out_value