Move find() and friends to reusable module.

[fulbank.git] / fulbank / util.py

diff --git a/fulbank/util.py b/fulbank/util.py
new file mode 100644 (file)
index 0000000..eaf1249
--- /dev/null
+++ b/fulbank/util.py
@@ -0,0 +1,37 @@
+import operator
+
+def pfxmatch(pfx, item):
+    return str(item)[:len(pfx)] == pfx
+
+def ipfxmatch(pfx, item):
+    return str(item).upper()[:len(pfx)] == pfx.upper()
+
+class ambiguous(LookupError):
+    def __init__(self, a, b):
+        super().__init__("ambigous match: %s and %s" % (a, b))
+        self.a = a
+        self.b = b
+
+def find(seq, *, item=None, test=None, match=None, key=None, default=LookupError):
+    if key is None:
+        key = lambda o: o
+    if match is None and item is not None:
+        match = lambda o: test(item, o)
+    if test is None:
+        test = operator.eq
+    found = None
+    for thing in seq:
+        if match(key(thing)):
+            if found is None:
+                found = thing
+            else:
+                if default is LookupError:
+                    raise ambiguous(key(found), key(thing))
+                else:
+                    return default
+    if found is not None:
+        return found
+    if default is LookupError:
+        raise LookupError()
+    else:
+        return default