90 lines
3 KiB
Go
90 lines
3 KiB
Go
// Copyright 2017, 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 provides common options for the cmp package.
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package cmpopts
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import (
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"math"
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"reflect"
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"github.com/google/go-cmp/cmp"
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)
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func equateAlways(_, _ interface{}) bool { return true }
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// EquateEmpty returns a Comparer option that determines all maps and slices
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// with a length of zero to be equal, regardless of whether they are nil.
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//
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// EquateEmpty can be used in conjuction with SortSlices and SortMaps.
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func EquateEmpty() cmp.Option {
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return cmp.FilterValues(isEmpty, cmp.Comparer(equateAlways))
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}
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func isEmpty(x, y interface{}) bool {
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vx, vy := reflect.ValueOf(x), reflect.ValueOf(y)
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return (x != nil && y != nil && vx.Type() == vy.Type()) &&
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(vx.Kind() == reflect.Slice || vx.Kind() == reflect.Map) &&
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(vx.Len() == 0 && vy.Len() == 0)
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}
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// EquateApprox returns a Comparer option that determines float32 or float64
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// values to be equal if they are within a relative fraction or absolute margin.
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// This option is not used when either x or y is NaN or infinite.
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//
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// The fraction determines that the difference of two values must be within the
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// smaller fraction of the two values, while the margin determines that the two
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// values must be within some absolute margin.
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// To express only a fraction or only a margin, use 0 for the other parameter.
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// The fraction and margin must be non-negative.
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//
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// The mathematical expression used is equivalent to:
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// |x-y| ≤ max(fraction*min(|x|, |y|), margin)
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//
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// EquateApprox can be used in conjuction with EquateNaNs.
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func EquateApprox(fraction, margin float64) cmp.Option {
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if margin < 0 || fraction < 0 || math.IsNaN(margin) || math.IsNaN(fraction) {
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panic("margin or fraction must be a non-negative number")
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}
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a := approximator{fraction, margin}
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return cmp.Options{
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cmp.FilterValues(areRealF64s, cmp.Comparer(a.compareF64)),
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cmp.FilterValues(areRealF32s, cmp.Comparer(a.compareF32)),
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}
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}
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type approximator struct{ frac, marg float64 }
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func areRealF64s(x, y float64) bool {
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return !math.IsNaN(x) && !math.IsNaN(y) && !math.IsInf(x, 0) && !math.IsInf(y, 0)
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}
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func areRealF32s(x, y float32) bool {
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return areRealF64s(float64(x), float64(y))
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}
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func (a approximator) compareF64(x, y float64) bool {
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relMarg := a.frac * math.Min(math.Abs(x), math.Abs(y))
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return math.Abs(x-y) <= math.Max(a.marg, relMarg)
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}
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func (a approximator) compareF32(x, y float32) bool {
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return a.compareF64(float64(x), float64(y))
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}
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// EquateNaNs returns a Comparer option that determines float32 and float64
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// NaN values to be equal.
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//
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// EquateNaNs can be used in conjuction with EquateApprox.
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func EquateNaNs() cmp.Option {
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return cmp.Options{
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cmp.FilterValues(areNaNsF64s, cmp.Comparer(equateAlways)),
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cmp.FilterValues(areNaNsF32s, cmp.Comparer(equateAlways)),
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}
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}
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func areNaNsF64s(x, y float64) bool {
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return math.IsNaN(x) && math.IsNaN(y)
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}
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func areNaNsF32s(x, y float32) bool {
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return areNaNsF64s(float64(x), float64(y))
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}
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