1 files changed, 53 insertions, 0 deletions
diff --git a/libbe/cmdutil.py b/libbe/cmdutil.py
index dcd4ca9..b892bde 100644
--- a/libbe/cmdutil.py
+++ b/libbe/cmdutil.py
@@ -217,6 +217,59 @@ def underlined(instring):
     
     return "%s\n%s" % (instring, "="*len(instring))
 
+def select_values(string, possible_values, name="unkown"):
+    """
+    This function allows the user to select values from a list of
+    possible values.  The default is to select all the values:
+
+    >>> select_values(None, ['abc', 'def', 'hij'])
+    ['abc', 'def', 'hij']
+
+    The user selects values with a comma-separated limit_string.
+    Prepending a minus sign to such a list denotes blacklist mode:
+
+    >>> select_values('-abc,hij', ['abc', 'def', 'hij'])
+    ['def']
+
+    Without the leading -, the selection is in whitelist mode:
+
+    >>> select_values('abc,hij', ['abc', 'def', 'hij'])
+    ['abc', 'hij']
+
+    In either case, appropriate errors are raised if on of the
+    user-values is not in the list of possible values.  The name
+    parameter lets you make the error message more clear:
+
+    >>> select_values('-xyz,hij', ['abc', 'def', 'hij'], name="foobar")
+    Traceback (most recent call last):
+      ...
+    UserError: Invalid foobar xyz
+      ['abc', 'def', 'hij']
+    >>> select_values('xyz,hij', ['abc', 'def', 'hij'], name="foobar")
+    Traceback (most recent call last):
+      ...
+    UserError: Invalid foobar xyz
+      ['abc', 'def', 'hij']
+    """
+    possible_values = list(possible_values) # don't alter the original
+    if string == None:
+        pass
+    elif string.startswith('-'):
+        blacklisted_values = set(string[1:].split(','))
+        for value in blacklisted_values:
+            if value not in possible_values:
+                raise UserError('Invalid %s %s\n  %s'
+                                % (name, value, possible_values))
+            possible_values.remove(value)
+    else:
+        whitelisted_values = string.split(',')
+        for value in whitelisted_values:
+            if value not in possible_values:
+                raise UserError('Invalid %s %s\n  %s'
+                                % (name, value, possible_values))
+        possible_values = whitelisted_values
+    return possible_values
+
 def restrict_file_access(bugdir, path):
     """
     Check that the file at path is inside bugdir.root.  This is