Parse floats correctly and fix mistake from go-yaml/yaml#171

The regular expression is copy & pasted form the one in the spec.
The change suggested in go-yaml/yaml#171 and integrated was improper.

Closes go-yaml/yaml#290

(cherry-pick of go-yaml/yaml@7b8349a)

Signed-off-by: John Ryan <jtigger@infosysengr.com>

pkg/yamlmeta/internal/yaml.v2/decode_test.go

@@ -694,13 +694,13 @@ var unmarshalTests = []struct {
 		M{"ñoño": "very yes 🟔"},
 	},
 
-	// YAML Float regex shouldn't match this
+	// This *is* in fact a float number, per the spec. #171 was a mistake.
 	{
 		"a: 123456e1\n",
-		M{"a": "123456e1"},
+		M{"a": 123456e1},
 	}, {
 		"a: 123456E1\n",
-		M{"a": "123456E1"},
+		M{"a": 123456E1},
 	},
 	// yaml-test-suite 3GZX: Spec Example 7.1. Alias Nodes
 	{

pkg/yamlmeta/internal/yaml.v2/resolve.go

@@ -84,7 +84,7 @@ func resolvableTag(tag string) bool {
 	return false
 }
 
-var yamlStyleFloat = regexp.MustCompile(`^[-+]?[0-9]*\.?[0-9]+([eE][-+][0-9]+)?$`)
+var yamlStyleFloat = regexp.MustCompile(`^[-+]?(\.[0-9]+|[0-9]+(\.[0-9]*)?)([eE][-+]?[0-9]+)?$`)
 
 func resolve(tag string, in string) (rtag string, out interface{}) {
 	if !resolvableTag(tag) {