-
Notifications
You must be signed in to change notification settings - Fork 209
/
sort.go
146 lines (137 loc) · 4.97 KB
/
sort.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
// Copyright 2017, 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 (
"fmt"
"reflect"
"github.com/google/go-cmp/cmp"
"github.com/google/go-cmp/cmp/internal/function"
)
// SortSlices returns a Transformer option that sorts all []V.
// The less function must be of the form "func(T, T) bool" which is used to
// sort any slice with element type V that is assignable to T.
//
// The less function must be:
// • Deterministic: less(x, y) == less(x, y)
// • Irreflexive: !less(x, x)
// • Transitive: if !less(x, y) and !less(y, z), then !less(x, z)
//
// The less function does not have to be "total". That is, if !less(x, y) and
// !less(y, x) for two elements x and y, their relative order is maintained.
//
// SortSlices can be used in conjunction with EquateEmpty.
func SortSlices(less interface{}) cmp.Option {
vf := reflect.ValueOf(less)
if !function.IsType(vf.Type(), function.Less) || vf.IsNil() {
panic(fmt.Sprintf("invalid less function: %T", less))
}
ss := sliceSorter{vf.Type().In(0), vf}
return cmp.FilterValues(ss.filter, cmp.Transformer("Sort", ss.sort))
}
type sliceSorter struct {
in reflect.Type // T
fnc reflect.Value // func(T, T) bool
}
func (ss sliceSorter) filter(x, y interface{}) bool {
vx, vy := reflect.ValueOf(x), reflect.ValueOf(y)
if !(x != nil && y != nil && vx.Type() == vy.Type()) ||
!(vx.Kind() == reflect.Slice && vx.Type().Elem().AssignableTo(ss.in)) ||
(vx.Len() <= 1 && vy.Len() <= 1) {
return false
}
// Check whether the slices are already sorted to avoid an infinite
// recursion cycle applying the same transform to itself.
ok1 := sliceIsSorted(x, func(i, j int) bool { return ss.less(vx, i, j) })
ok2 := sliceIsSorted(y, func(i, j int) bool { return ss.less(vy, i, j) })
return !ok1 || !ok2
}
func (ss sliceSorter) sort(x interface{}) interface{} {
src := reflect.ValueOf(x)
dst := reflect.MakeSlice(src.Type(), src.Len(), src.Len())
for i := 0; i < src.Len(); i++ {
dst.Index(i).Set(src.Index(i))
}
sortSliceStable(dst.Interface(), func(i, j int) bool { return ss.less(dst, i, j) })
ss.checkSort(dst)
return dst.Interface()
}
func (ss sliceSorter) checkSort(v reflect.Value) {
start := -1 // Start of a sequence of equal elements.
for i := 1; i < v.Len(); i++ {
if ss.less(v, i-1, i) {
// Check that first and last elements in v[start:i] are equal.
if start >= 0 && (ss.less(v, start, i-1) || ss.less(v, i-1, start)) {
panic(fmt.Sprintf("incomparable values detected: want equal elements: %v", v.Slice(start, i)))
}
start = -1
} else if start == -1 {
start = i
}
}
}
func (ss sliceSorter) less(v reflect.Value, i, j int) bool {
vx, vy := v.Index(i), v.Index(j)
return ss.fnc.Call([]reflect.Value{vx, vy})[0].Bool()
}
// SortMaps returns a Transformer option that flattens map[K]V types to be a
// sorted []struct{K, V}. The less function must be of the form
// "func(T, T) bool" which is used to sort any map with key K that is
// assignable to T.
//
// Flattening the map into a slice has the property that cmp.Equal is able to
// use Comparers on K or the K.Equal method if it exists.
//
// The less function must be:
// • Deterministic: less(x, y) == less(x, y)
// • Irreflexive: !less(x, x)
// • Transitive: if !less(x, y) and !less(y, z), then !less(x, z)
// • Total: if x != y, then either less(x, y) or less(y, x)
//
// SortMaps can be used in conjunction with EquateEmpty.
func SortMaps(less interface{}) cmp.Option {
vf := reflect.ValueOf(less)
if !function.IsType(vf.Type(), function.Less) || vf.IsNil() {
panic(fmt.Sprintf("invalid less function: %T", less))
}
ms := mapSorter{vf.Type().In(0), vf}
return cmp.FilterValues(ms.filter, cmp.Transformer("Sort", ms.sort))
}
type mapSorter struct {
in reflect.Type // T
fnc reflect.Value // func(T, T) bool
}
func (ms mapSorter) filter(x, y interface{}) bool {
vx, vy := reflect.ValueOf(x), reflect.ValueOf(y)
return (x != nil && y != nil && vx.Type() == vy.Type()) &&
(vx.Kind() == reflect.Map && vx.Type().Key().AssignableTo(ms.in)) &&
(vx.Len() != 0 || vy.Len() != 0)
}
func (ms mapSorter) sort(x interface{}) interface{} {
src := reflect.ValueOf(x)
outType := mapEntryType(src.Type())
dst := reflect.MakeSlice(reflect.SliceOf(outType), src.Len(), src.Len())
for i, k := range src.MapKeys() {
v := reflect.New(outType).Elem()
v.Field(0).Set(k)
v.Field(1).Set(src.MapIndex(k))
dst.Index(i).Set(v)
}
sortSlice(dst.Interface(), func(i, j int) bool { return ms.less(dst, i, j) })
ms.checkSort(dst)
return dst.Interface()
}
func (ms mapSorter) checkSort(v reflect.Value) {
for i := 1; i < v.Len(); i++ {
if !ms.less(v, i-1, i) {
panic(fmt.Sprintf("partial order detected: want %v < %v", v.Index(i-1), v.Index(i)))
}
}
}
func (ms mapSorter) less(v reflect.Value, i, j int) bool {
vx, vy := v.Index(i).Field(0), v.Index(j).Field(0)
if !hasReflectStructOf {
vx, vy = vx.Elem(), vy.Elem()
}
return ms.fnc.Call([]reflect.Value{vx, vy})[0].Bool()
}