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