mirror of
https://github.com/prometheus/prometheus.git
synced 2024-11-18 03:24:05 -08:00
306 lines
8 KiB
Go
306 lines
8 KiB
Go
/*
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Copyright 2014 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package diff
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import (
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"bytes"
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"encoding/json"
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"fmt"
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"reflect"
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"sort"
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"strings"
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"text/tabwriter"
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"github.com/davecgh/go-spew/spew"
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"k8s.io/apimachinery/pkg/util/validation/field"
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)
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// StringDiff diffs a and b and returns a human readable diff.
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func StringDiff(a, b string) string {
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ba := []byte(a)
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bb := []byte(b)
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out := []byte{}
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i := 0
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for ; i < len(ba) && i < len(bb); i++ {
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if ba[i] != bb[i] {
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break
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}
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out = append(out, ba[i])
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}
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out = append(out, []byte("\n\nA: ")...)
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out = append(out, ba[i:]...)
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out = append(out, []byte("\n\nB: ")...)
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out = append(out, bb[i:]...)
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out = append(out, []byte("\n\n")...)
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return string(out)
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}
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// ObjectDiff writes the two objects out as JSON and prints out the identical part of
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// the objects followed by the remaining part of 'a' and finally the remaining part of 'b'.
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// For debugging tests.
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func ObjectDiff(a, b interface{}) string {
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ab, err := json.Marshal(a)
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if err != nil {
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panic(fmt.Sprintf("a: %v", err))
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}
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bb, err := json.Marshal(b)
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if err != nil {
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panic(fmt.Sprintf("b: %v", err))
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}
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return StringDiff(string(ab), string(bb))
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}
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// ObjectGoPrintDiff is like ObjectDiff, but uses go-spew to print the objects,
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// which shows absolutely everything by recursing into every single pointer
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// (go's %#v formatters OTOH stop at a certain point). This is needed when you
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// can't figure out why reflect.DeepEqual is returning false and nothing is
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// showing you differences. This will.
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func ObjectGoPrintDiff(a, b interface{}) string {
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s := spew.ConfigState{DisableMethods: true}
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return StringDiff(
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s.Sprintf("%#v", a),
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s.Sprintf("%#v", b),
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)
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}
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func ObjectReflectDiff(a, b interface{}) string {
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vA, vB := reflect.ValueOf(a), reflect.ValueOf(b)
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if vA.Type() != vB.Type() {
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return fmt.Sprintf("type A %T and type B %T do not match", a, b)
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}
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diffs := objectReflectDiff(field.NewPath("object"), vA, vB)
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if len(diffs) == 0 {
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return "<no diffs>"
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}
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out := []string{""}
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for _, d := range diffs {
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elidedA, elidedB := limit(d.a, d.b, 80)
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out = append(out,
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fmt.Sprintf("%s:", d.path),
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fmt.Sprintf(" a: %s", elidedA),
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fmt.Sprintf(" b: %s", elidedB),
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)
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}
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return strings.Join(out, "\n")
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}
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// limit:
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// 1. stringifies aObj and bObj
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// 2. elides identical prefixes if either is too long
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// 3. elides remaining content from the end if either is too long
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func limit(aObj, bObj interface{}, max int) (string, string) {
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elidedPrefix := ""
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elidedASuffix := ""
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elidedBSuffix := ""
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a, b := fmt.Sprintf("%#v", aObj), fmt.Sprintf("%#v", bObj)
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for {
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switch {
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case len(a) > max && len(a) > 4 && len(b) > 4 && a[:4] == b[:4]:
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// a is too long, b has data, and the first several characters are the same
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elidedPrefix = "..."
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a = a[2:]
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b = b[2:]
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case len(b) > max && len(b) > 4 && len(a) > 4 && a[:4] == b[:4]:
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// b is too long, a has data, and the first several characters are the same
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elidedPrefix = "..."
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a = a[2:]
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b = b[2:]
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case len(a) > max:
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a = a[:max]
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elidedASuffix = "..."
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case len(b) > max:
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b = b[:max]
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elidedBSuffix = "..."
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default:
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// both are short enough
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return elidedPrefix + a + elidedASuffix, elidedPrefix + b + elidedBSuffix
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}
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}
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}
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func public(s string) bool {
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if len(s) == 0 {
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return false
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}
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return s[:1] == strings.ToUpper(s[:1])
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}
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type diff struct {
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path *field.Path
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a, b interface{}
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}
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type orderedDiffs []diff
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func (d orderedDiffs) Len() int { return len(d) }
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func (d orderedDiffs) Swap(i, j int) { d[i], d[j] = d[j], d[i] }
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func (d orderedDiffs) Less(i, j int) bool {
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a, b := d[i].path.String(), d[j].path.String()
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if a < b {
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return true
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}
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return false
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}
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func objectReflectDiff(path *field.Path, a, b reflect.Value) []diff {
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switch a.Type().Kind() {
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case reflect.Struct:
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var changes []diff
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for i := 0; i < a.Type().NumField(); i++ {
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if !public(a.Type().Field(i).Name) {
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if reflect.DeepEqual(a.Interface(), b.Interface()) {
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continue
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}
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return []diff{{path: path, a: fmt.Sprintf("%#v", a), b: fmt.Sprintf("%#v", b)}}
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}
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if sub := objectReflectDiff(path.Child(a.Type().Field(i).Name), a.Field(i), b.Field(i)); len(sub) > 0 {
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changes = append(changes, sub...)
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}
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}
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return changes
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case reflect.Ptr, reflect.Interface:
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if a.IsNil() || b.IsNil() {
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switch {
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case a.IsNil() && b.IsNil():
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return nil
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case a.IsNil():
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return []diff{{path: path, a: nil, b: b.Interface()}}
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default:
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return []diff{{path: path, a: a.Interface(), b: nil}}
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}
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}
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return objectReflectDiff(path, a.Elem(), b.Elem())
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case reflect.Chan:
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if !reflect.DeepEqual(a.Interface(), b.Interface()) {
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return []diff{{path: path, a: a.Interface(), b: b.Interface()}}
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}
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return nil
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case reflect.Slice:
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lA, lB := a.Len(), b.Len()
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l := lA
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if lB < lA {
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l = lB
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}
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if lA == lB && lA == 0 {
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if a.IsNil() != b.IsNil() {
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return []diff{{path: path, a: a.Interface(), b: b.Interface()}}
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}
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return nil
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}
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var diffs []diff
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for i := 0; i < l; i++ {
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if !reflect.DeepEqual(a.Index(i), b.Index(i)) {
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diffs = append(diffs, objectReflectDiff(path.Index(i), a.Index(i), b.Index(i))...)
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}
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}
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for i := l; i < lA; i++ {
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diffs = append(diffs, diff{path: path.Index(i), a: a.Index(i), b: nil})
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}
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for i := l; i < lB; i++ {
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diffs = append(diffs, diff{path: path.Index(i), a: nil, b: b.Index(i)})
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}
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return diffs
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case reflect.Map:
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if reflect.DeepEqual(a.Interface(), b.Interface()) {
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return nil
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}
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aKeys := make(map[interface{}]interface{})
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for _, key := range a.MapKeys() {
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aKeys[key.Interface()] = a.MapIndex(key).Interface()
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}
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var missing []diff
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for _, key := range b.MapKeys() {
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if _, ok := aKeys[key.Interface()]; ok {
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delete(aKeys, key.Interface())
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if reflect.DeepEqual(a.MapIndex(key).Interface(), b.MapIndex(key).Interface()) {
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continue
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}
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missing = append(missing, objectReflectDiff(path.Key(fmt.Sprintf("%s", key.Interface())), a.MapIndex(key), b.MapIndex(key))...)
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continue
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}
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missing = append(missing, diff{path: path.Key(fmt.Sprintf("%s", key.Interface())), a: nil, b: b.MapIndex(key).Interface()})
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}
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for key, value := range aKeys {
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missing = append(missing, diff{path: path.Key(fmt.Sprintf("%s", key)), a: value, b: nil})
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}
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if len(missing) == 0 {
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missing = append(missing, diff{path: path, a: a.Interface(), b: b.Interface()})
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}
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sort.Sort(orderedDiffs(missing))
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return missing
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default:
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if reflect.DeepEqual(a.Interface(), b.Interface()) {
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return nil
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}
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if !a.CanInterface() {
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return []diff{{path: path, a: fmt.Sprintf("%#v", a), b: fmt.Sprintf("%#v", b)}}
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}
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return []diff{{path: path, a: a.Interface(), b: b.Interface()}}
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}
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}
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// ObjectGoPrintSideBySide prints a and b as textual dumps side by side,
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// enabling easy visual scanning for mismatches.
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func ObjectGoPrintSideBySide(a, b interface{}) string {
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s := spew.ConfigState{
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Indent: " ",
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// Extra deep spew.
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DisableMethods: true,
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}
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sA := s.Sdump(a)
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sB := s.Sdump(b)
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linesA := strings.Split(sA, "\n")
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linesB := strings.Split(sB, "\n")
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width := 0
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for _, s := range linesA {
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l := len(s)
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if l > width {
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width = l
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}
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}
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for _, s := range linesB {
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l := len(s)
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if l > width {
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width = l
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}
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}
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buf := &bytes.Buffer{}
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w := tabwriter.NewWriter(buf, width, 0, 1, ' ', 0)
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max := len(linesA)
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if len(linesB) > max {
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max = len(linesB)
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}
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for i := 0; i < max; i++ {
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var a, b string
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if i < len(linesA) {
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a = linesA[i]
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}
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if i < len(linesB) {
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b = linesB[i]
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}
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fmt.Fprintf(w, "%s\t%s\n", a, b)
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}
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w.Flush()
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return buf.String()
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}
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