surrealpatch/util/json/merge.go
2016-10-14 23:02:01 +01:00

321 lines
6.8 KiB
Go
Executable file

// Copyright © 2016 Abcum Ltd
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package json
/*import (
"encoding/json"
"fmt"
"reflect"
"strings"
)
func merge(cur, patch *lazyNode) *lazyNode {
curDoc, err := cur.intoDoc()
if err != nil {
pruneNulls(patch)
return patch
}
patchDoc, err := patch.intoDoc()
if err != nil {
return patch
}
mergeDocs(curDoc, patchDoc)
return cur
}
func mergeDocs(doc, patch *partialDoc) {
for k, v := range *patch {
k := decodePatchKey(k)
if v == nil {
delete(*doc, k)
} else {
cur, ok := (*doc)[k]
if !ok || cur == nil {
pruneNulls(v)
(*doc)[k] = v
} else {
(*doc)[k] = merge(cur, v)
}
}
}
}
func pruneNulls(n *lazyNode) {
sub, err := n.intoDoc()
if err == nil {
pruneDocNulls(sub)
} else {
ary, err := n.intoAry()
if err == nil {
pruneAryNulls(ary)
}
}
}
func pruneDocNulls(doc *partialDoc) *partialDoc {
for k, v := range *doc {
if v == nil {
delete(*doc, k)
} else {
pruneNulls(v)
}
}
return doc
}
func pruneAryNulls(ary *partialArray) *partialArray {
newAry := []*lazyNode{}
for _, v := range *ary {
if v != nil {
pruneNulls(v)
newAry = append(newAry, v)
}
}
*ary = newAry
return ary
}
var errBadJSONDoc = fmt.Errorf("Invalid JSON Document")
var errBadJSONPatch = fmt.Errorf("Invalid JSON Patch")
// MergePatch merges the patchData into the docData.
func MergePatch(docData, patchData []byte) ([]byte, error) {
doc := &partialDoc{}
docErr := json.Unmarshal(docData, doc)
patch := &partialDoc{}
patchErr := json.Unmarshal(patchData, patch)
if _, ok := docErr.(*json.SyntaxError); ok {
return nil, errBadJSONDoc
}
if _, ok := patchErr.(*json.SyntaxError); ok {
return nil, errBadJSONPatch
}
if docErr == nil && *doc == nil {
return nil, errBadJSONDoc
}
if patchErr == nil && *patch == nil {
return nil, errBadJSONPatch
}
if docErr != nil || patchErr != nil {
// Not an error, just not a doc, so we turn straight into the patch
if patchErr == nil {
doc = pruneDocNulls(patch)
} else {
patchAry := &partialArray{}
patchErr = json.Unmarshal(patchData, patchAry)
if patchErr != nil {
return nil, errBadJSONPatch
}
pruneAryNulls(patchAry)
out, patchErr := json.Marshal(patchAry)
if patchErr != nil {
return nil, errBadJSONPatch
}
return out, nil
}
} else {
mergeDocs(doc, patch)
}
return json.Marshal(doc)
}
// CreateMergePatch creates a merge patch as specified in http://tools.ietf.org/html/draft-ietf-appsawg-json-merge-patch-07
//
// 'a' is original, 'b' is the modified document. Both are to be given as json encoded content.
// The function will return a mergeable json document with differences from a to b.
//
// An error will be returned if any of the two documents are invalid.
func CreateMergePatch(a, b []byte) ([]byte, error) {
aI := map[string]interface{}{}
bI := map[string]interface{}{}
err := json.Unmarshal(a, &aI)
if err != nil {
return nil, errBadJSONDoc
}
err = json.Unmarshal(b, &bI)
if err != nil {
return nil, errBadJSONDoc
}
dest, err := getDiff(aI, bI)
if err != nil {
return nil, err
}
return json.Marshal(dest)
}
// Returns true if the array matches (must be json types).
// As is idiomatic for go, an empty array is not the same as a nil array.
func matchesArray(a, b []interface{}) bool {
if len(a) != len(b) {
return false
}
if (a == nil && b != nil) || (a != nil && b == nil) {
return false
}
for i := range a {
if !matchesValue(a[i], b[i]) {
return false
}
}
return true
}
// Returns true if the values matches (must be json types)
// The types of the values must match, otherwise it will always return false
// If two map[string]interface{} are given, all elements must match.
func matchesValue(av, bv interface{}) bool {
if reflect.TypeOf(av) != reflect.TypeOf(bv) {
return false
}
switch at := av.(type) {
case string:
bt := bv.(string)
if bt == at {
return true
}
case float64:
bt := bv.(float64)
if bt == at {
return true
}
case bool:
bt := bv.(bool)
if bt == at {
return true
}
case map[string]interface{}:
bt := bv.(map[string]interface{})
for key := range at {
if !matchesValue(at[key], bt[key]) {
return false
}
}
for key := range bt {
if !matchesValue(at[key], bt[key]) {
return false
}
}
return true
case []interface{}:
bt := bv.([]interface{})
return matchesArray(at, bt)
}
return false
}
// getDiff returns the (recursive) difference between a and b as a map[string]interface{}.
func getDiff(a, b map[string]interface{}) (map[string]interface{}, error) {
into := map[string]interface{}{}
for key, bv := range b {
escapedKey := encodePatchKey(key)
av, ok := a[key]
// value was added
if !ok {
into[escapedKey] = bv
continue
}
// If types have changed, replace completely
if reflect.TypeOf(av) != reflect.TypeOf(bv) {
into[escapedKey] = bv
continue
}
// Types are the same, compare values
switch at := av.(type) {
case map[string]interface{}:
bt := bv.(map[string]interface{})
dst := make(map[string]interface{}, len(bt))
dst, err := getDiff(at, bt)
if err != nil {
return nil, err
}
if len(dst) > 0 {
into[escapedKey] = dst
}
case string, float64, bool:
if !matchesValue(av, bv) {
into[escapedKey] = bv
}
case []interface{}:
bt := bv.([]interface{})
if !matchesArray(at, bt) {
into[escapedKey] = bv
}
case nil:
switch bv.(type) {
case nil:
// Both nil, fine.
default:
into[escapedKey] = bv
}
default:
panic(fmt.Sprintf("Unknown type:%T in key %s", av, key))
}
}
// Now add all deleted values as nil
for key := range a {
_, found := b[key]
if !found {
into[key] = nil
}
}
return into, nil
}
// From http://tools.ietf.org/html/rfc6901#section-4 :
//
// Evaluation of each reference token begins by decoding any escaped
// character sequence. This is performed by first transforming any
// occurrence of the sequence '~1' to '/', and then transforming any
// occurrence of the sequence '~0' to '~'.
var (
rfc6901Encoder = strings.NewReplacer("~", "~0", "/", "~1")
rfc6901Decoder = strings.NewReplacer("~1", "/", "~0", "~")
)
func decodePatchKey(k string) string {
return rfc6901Decoder.Replace(k)
}
func encodePatchKey(k string) string {
return rfc6901Encoder.Replace(k)
}
*/