1 files changed, 50 insertions, 0 deletions
diff --git a/tools/build/v2/util/sequence.py b/tools/build/v2/util/sequence.py
new file mode 100644
index 0000000000..1d32efd2e3
--- /dev/null
+++ b/tools/build/v2/util/sequence.py
@@ -0,0 +1,50 @@
+#  (C) Copyright David Abrahams 2002. 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.
+
+import operator
+
+def unique (values, stable=False):
+    if stable:
+        s = set()
+        r = []
+        for v in values:
+            if not v in s:
+                r.append(v)
+                s.add(v)
+        return r
+    else:
+        return list(set(values))
+
+def max_element (elements, ordered = None):
+    """ Returns the maximum number in 'elements'. Uses 'ordered' for comparisons,
+        or '<' is none is provided.
+    """
+    if not ordered: ordered = operator.lt
+
+    max = elements [0]
+    for e in elements [1:]:
+        if ordered (max, e):
+            max = e
+
+    return max
+
+def select_highest_ranked (elements, ranks):
+    """ Returns all of 'elements' for which corresponding element in parallel
+        list 'rank' is equal to the maximum value in 'rank'.
+    """
+    if not elements:
+        return []
+
+    max_rank = max_element (ranks)
+
+    result = []
+    while elements:
+        if ranks [0] == max_rank:
+            result.append (elements [0])
+
+        elements = elements [1:]
+        ranks = ranks [1:]
+
+    return result