| // 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 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 [cmp.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 [cmp.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) |
| } |