1 files changed, 42 insertions, 0 deletions
diff --git a/tools/build/src/util/set.py b/tools/build/src/util/set.py
new file mode 100644
index 000000000..dc7cf3282
--- /dev/null
+++ b/tools/build/src/util/set.py
@@ -0,0 +1,42 @@
+#  (C) Copyright David Abrahams 2001. Permission to copy, use, modify, sell and
+#  distribute this software is granted provided this copyright notice appears in
+#  all copies. This software is provided "as is" without express or implied
+#  warranty, and with no claim as to its suitability for any purpose.
+
+from utility import to_seq
+
+def difference (b, a):
+    """ Returns the elements of B that are not in A.
+    """
+    result = []
+    for element in b:
+        if not element in a:
+            result.append (element)
+
+    return result
+
+def intersection (set1, set2):
+    """ Removes from set1 any items which don't appear in set2 and returns the result.
+    """
+    result = []
+    for v in set1:
+        if v in set2:
+            result.append (v)
+    return result
+
+def contains (small, large):
+    """ Returns true iff all elements of 'small' exist in 'large'.
+    """
+    small = to_seq (small)
+    large = to_seq (large)
+
+    for s in small:
+        if not s in large:
+            return False
+    return True
+
+def equal (a, b):
+    """ Returns True iff 'a' contains the same elements as 'b', irrespective of their order.
+        # TODO: Python 2.4 has a proper set class.
+    """
+    return contains (a, b) and contains (b, a)