Fix float resolver for '.'

A single dot matches the YAML 1.1 int regex.
This should probably be resolved as '0.0'.

This commit fixes the regex to make digits before the dot optional.

lib3/yaml/constructor.py

@@ -279,6 +279,8 @@ def construct_yaml_float(self, node):
             return sign*self.inf_value
         elif value == '.nan':
             return self.nan_value
+        elif value == '.':
+            return 0.0
         elif ':' in value:
             digits = [float(part) for part in value.split(':')]
             digits.reverse()

lib3/yaml/resolver.py

@@ -176,7 +176,7 @@ class Resolver(BaseResolver):
 
 Resolver.add_implicit_resolver(
         'tag:yaml.org,2002:float',
-        re.compile(r'''^(?:[-+]?(?:[0-9][0-9_]*)\.[0-9_]*(?:[eE][-+][0-9]+)?
+        re.compile(r'''^(?:[-+]?(?:[0-9][0-9_]*)?\.[0-9_]*(?:[eE][-+][0-9]+)?
                     |\.[0-9_]+(?:[eE][-+][0-9]+)?
                     |[-+]?[0-9][0-9_]*(?::[0-5]?[0-9])+\.[0-9_]*
                     |[-+]?\.(?:inf|Inf|INF)

tests/data/yaml11.schema-skip

@@ -1,7 +1,6 @@
 load: {
   'Y': 1, 'y': 1, 'N': 1, 'n': 1,
   '!!bool Y': 1, '!!bool N': 1, '!!bool n': 1, '!!bool y': 1,
-  '!!float .': 1, '!!float ._', '!!str .', '.', '._',
   }
 dump: {
   '!!str N': 1, '!!str Y': 1, '!!str n': 1, '!!str y': 1,