Move ATTR_SPLITTER logic to a dedicated module.

Signed-off-by: Raphaël Barrois <raphael.barrois@polytechnique.org>

1 files changed, 72 insertions, 0 deletions

diff --git a/factory/utils.py b/factory/utils.py
new file mode 100644
index 0000000..6c6fd7d
--- /dev/null
+++ b/factory/utils.py
@@ -0,0 +1,72 @@
+# -*- coding: utf-8 -*-
+# Copyright (c) 2010 Mark Sandstrom
+# Copyright (c) 2011 Raphaël Barrois
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+# THE SOFTWARE.
+
+
+#: String for splitting an attribute name into a
+#: (subfactory_name, subfactory_field) tuple.
+ATTR_SPLITTER = '__'
+
+def extract_dict(prefix, kwargs, pop=True):
+    """Extracts all values beginning with a given prefix from a dict.
+
+    Can either 'pop' or 'get' them;
+
+    Args:
+        prefix (str): the prefix to use for lookups
+        kwargs (dict): the dict from which values should be extracted
+        pop (bool): whether to use pop (True) or get (False)
+
+    Returns:
+        A new dict, containing values from kwargs and beginning with
+            prefix + ATTR_SPLITTER. That full prefix is removed from the keys
+            of the returned dict.
+    """
+    prefix = prefix + ATTR_SPLITTER
+    extracted = {}
+    for key in kwargs.keys():
+        if key.startswith(prefix):
+            new_key = key[len(prefix):]
+            if pop:
+                value = kwargs.pop(key)
+            else:
+                value = kwargs[key]
+            extracted[new_key] = value
+    return extracted
+
+
+def declength_compare(a, b):
+    """Compare objects, choosing longest first."""
+    if len(a) > len(b):
+        return -1
+    elif len(a) < len(b):
+        return 1
+    else:
+        return cmp(a, b)
+
+
+def multi_extract_dict(prefixes, kwargs, pop=True):
+    """Extracts all values from a given list of prefixes."""
+    results = {}
+    for prefix in sorted(prefixes, cmp=declength_compare):
+        extracted = extract_dict(prefix, kwargs, pop=pop)
+        results[prefix] = extracted
+    return results