Downlaod: Add "<<" and ">>" operators.

"<<" and ">>" are like "<=" and ">=" except they select the
closest value and accept "Infinity" for integer comparisons.

slapos/libnetworkcache.py

@@ -477,14 +477,15 @@ class NetworkcacheClient(object):
 
 class NetworkcacheFilter(object):
 
-  special_word_mapping = {"max":max, "min":max}
-  parse_criterion = re.compile("([<>]=?|==|:)").split
+  parse_criterion = re.compile("(<<|>>|[<>]=?|==)").split
   operator_mapping = {
         ">=": operator.ge,
         "<=": operator.le,
         ">": operator.gt,
         "<": operator.lt,
         "==": operator.eq,
+        ">>": operator.ge,
+        "<<": operator.le,
         }
 
   def __init__(self, criterion_list=()):
@@ -500,42 +501,41 @@ class NetworkcacheFilter(object):
           raise NetworkcacheException(
             'Could not parse criterion: missing or invalid separator (%s)'
             % criterion)
-        if parsed_criterion[1] != ':':
-          parsed_criterion[2] = json.loads(parsed_criterion[2])
-        elif parsed_criterion[2] not in self.special_word_mapping:
-          raise NetworkcacheException('Unknown special word %r'
-                                      % parsed_criterion[2])
+        parsed_criterion[2] = json.loads(parsed_criterion[2])
         parsed_criterion_list.append(parsed_criterion)
       self.criterion_list = parsed_criterion_list
     else:
       raise NetworkcacheException('Invalid criteria: %s' % criterion_list)
 
-  def __call__(self, data_dict_iterator):
+  def __call__(self, data_dict_list):
     ''' Return a list of shadir entries that match given criteria
     '''
-    # converting generator into list because the min/max case whould exhaust it
-    data_dict_list = list(data_dict_iterator)
+    def safe_op(data_dict):
+      try:
+        return _op(data_dict[key], value)
+      except TypeError:
+        logger.info('Comparison failed: %s %s %s with types: %s %s',
+                    data_dict[key], op, value,
+                    type(data_dict[key]), type(value))
     for key, op, value in self.criterion_list:
-      data_dict_list = [data_dict for data_dict in data_dict_list if key in data_dict]
+      data_dict_list = [data_dict for data_dict in data_dict_list
+                                  if key in data_dict]
       if not data_dict_list:
         break
-      if op == ":":
-        extremum = self.special_word_mapping[value](
-            data_dict[key] for data_dict in data_dict_list)
-        data_dict_list = [data_dict for data_dict in data_dict_list
-                                    if data_dict[key] == extremum]
-      else:
+      _op = self.operator_mapping[op]
+      if op in ("<<", ">>"):
         filtered_data_dict_list = []
         for data_dict in data_dict_list:
-          try:
-            if self.operator_mapping[op](data_dict[key], value):
+          if safe_op(data_dict):
+            if filtered_data_dict_list and _op(filtered_data_dict_list[0][key], data_dict[key]):
+              filtered_data_dict_list = [data_dict]
+            elif filtered_data_dict_list and filtered_data_dict_list[0][key] == data_dict[key]:
+              filtered_data_dict_list.append(data_dict)
+            elif not filtered_data_dict_list:
               filtered_data_dict_list.append(data_dict)
-          except TypeError:
-            logger.info('Comparison failed: %s %s %s'
-                        ' with types: %s %s',
-                        data_dict[key], op, value,
-                        type(data_dict[key]), type(value))
         data_dict_list = filtered_data_dict_list
+      else:
+        data_dict_list = list(filter(safe_op, data_dict_list))
     return data_dict_list
 
 class NetworkcacheException(Exception):
@@ -610,8 +610,8 @@ def cmd_upload(*args):
 
 def cmd_download(*args):
   parser = _newArgumentParser("URL of data to download.", key_help, True)
-  parser.add_argument('meta', nargs='*', metavar='KEY{>=,<=,==,<,>,:}VALUE',
-    help='Filter metadata. Each argument represents a filter with a comparison condition. The filters will be applied one by one with the arguments processed in the order of appearance.VALUE is expected to be a json dump of a comparable object in Python (strings included), except when the separator is ":" (in this case VALUE must be min or max).')
+  parser.add_argument('meta', nargs='*', metavar='KEY{>=,<=,==,<,>,>>,<<}VALUE',
+    help='Filter metadata. Each argument represents a filter with a comparison condition. The filters will be applied one by one with the arguments processed in the order of appearance. VALUE is expected to be a json dump of a comparable object in Python (strings included). "<<" and ">>" return the highest (resp. lowest) values lower (resp.higher) than the given value They accept "Infinity" and "-Infinity" for number comparisons.')
   args = parser.parse_args(args or sys.argv[1:])
   nc = NetworkcacheClient(args.config)
   if args.key: