Bump google.golang.org/api

vendor/github.com/google/go-cmp/cmp/cmpopts/xform.go

@@ -0,0 +1,35 @@
+// Copyright 2018, The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE.md file.
+
+package cmpopts
+
+import (
+	"github.com/google/go-cmp/cmp"
+)
+
+type xformFilter struct{ xform cmp.Option }
+
+func (xf xformFilter) filter(p cmp.Path) bool {
+	for _, ps := range p {
+		if t, ok := ps.(cmp.Transform); ok && t.Option() == xf.xform {
+			return false
+		}
+	}
+	return true
+}
+
+// AcyclicTransformer returns a Transformer with a filter applied that ensures
+// that the transformer cannot be recursively applied upon its own output.
+//
+// An example use case is a transformer that splits a string by lines:
+//	AcyclicTransformer("SplitLines", func(s string) []string{
+//		return strings.Split(s, "\n")
+//	})
+//
+// Had this been an unfiltered Transformer instead, this would result in an
+// infinite cycle converting a string to []string to [][]string and so on.
+func AcyclicTransformer(name string, xformFunc interface{}) cmp.Option {
+	xf := xformFilter{cmp.Transformer(name, xformFunc)}
+	return cmp.FilterPath(xf.filter, xf.xform)
+}