683 lines
11 KiB
Go
683 lines
11 KiB
Go
package jsonpatch
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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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"strconv"
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"strings"
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)
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const (
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eRaw = iota
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eDoc
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eAry
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)
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var SupportNegativeIndices bool = true
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type lazyNode struct {
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raw *json.RawMessage
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doc partialDoc
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ary partialArray
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which int
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}
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type operation map[string]*json.RawMessage
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// Patch is an ordered collection of operations.
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type Patch []operation
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type partialDoc map[string]*lazyNode
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type partialArray []*lazyNode
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type container interface {
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get(key string) (*lazyNode, error)
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set(key string, val *lazyNode) error
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add(key string, val *lazyNode) error
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remove(key string) error
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}
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func newLazyNode(raw *json.RawMessage) *lazyNode {
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return &lazyNode{raw: raw, doc: nil, ary: nil, which: eRaw}
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}
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func (n *lazyNode) MarshalJSON() ([]byte, error) {
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switch n.which {
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case eRaw:
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return json.Marshal(n.raw)
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case eDoc:
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return json.Marshal(n.doc)
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case eAry:
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return json.Marshal(n.ary)
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default:
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return nil, fmt.Errorf("Unknown type")
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}
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}
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func (n *lazyNode) UnmarshalJSON(data []byte) error {
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dest := make(json.RawMessage, len(data))
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copy(dest, data)
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n.raw = &dest
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n.which = eRaw
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return nil
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}
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func (n *lazyNode) intoDoc() (*partialDoc, error) {
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if n.which == eDoc {
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return &n.doc, nil
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}
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if n.raw == nil {
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return nil, fmt.Errorf("Unable to unmarshal nil pointer as partial document")
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}
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err := json.Unmarshal(*n.raw, &n.doc)
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if err != nil {
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return nil, err
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}
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n.which = eDoc
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return &n.doc, nil
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}
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func (n *lazyNode) intoAry() (*partialArray, error) {
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if n.which == eAry {
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return &n.ary, nil
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}
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if n.raw == nil {
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return nil, fmt.Errorf("Unable to unmarshal nil pointer as partial array")
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}
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err := json.Unmarshal(*n.raw, &n.ary)
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if err != nil {
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return nil, err
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}
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n.which = eAry
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return &n.ary, nil
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}
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func (n *lazyNode) compact() []byte {
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buf := &bytes.Buffer{}
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if n.raw == nil {
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return nil
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}
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err := json.Compact(buf, *n.raw)
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if err != nil {
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return *n.raw
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}
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return buf.Bytes()
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}
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func (n *lazyNode) tryDoc() bool {
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if n.raw == nil {
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return false
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}
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err := json.Unmarshal(*n.raw, &n.doc)
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if err != nil {
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return false
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}
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n.which = eDoc
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return true
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}
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func (n *lazyNode) tryAry() bool {
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if n.raw == nil {
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return false
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}
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err := json.Unmarshal(*n.raw, &n.ary)
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if err != nil {
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return false
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}
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n.which = eAry
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return true
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}
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func (n *lazyNode) equal(o *lazyNode) bool {
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if n.which == eRaw {
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if !n.tryDoc() && !n.tryAry() {
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if o.which != eRaw {
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return false
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}
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return bytes.Equal(n.compact(), o.compact())
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}
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}
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if n.which == eDoc {
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if o.which == eRaw {
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if !o.tryDoc() {
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return false
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}
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}
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if o.which != eDoc {
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return false
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}
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for k, v := range n.doc {
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ov, ok := o.doc[k]
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if !ok {
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return false
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}
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if v == nil && ov == nil {
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continue
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}
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if !v.equal(ov) {
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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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if o.which != eAry && !o.tryAry() {
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return false
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}
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if len(n.ary) != len(o.ary) {
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return false
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}
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for idx, val := range n.ary {
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if !val.equal(o.ary[idx]) {
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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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func (o operation) kind() string {
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if obj, ok := o["op"]; ok && obj != nil {
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var op string
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err := json.Unmarshal(*obj, &op)
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if err != nil {
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return "unknown"
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}
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return op
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}
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return "unknown"
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}
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func (o operation) path() string {
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if obj, ok := o["path"]; ok && obj != nil {
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var op string
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err := json.Unmarshal(*obj, &op)
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if err != nil {
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return "unknown"
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}
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return op
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}
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return "unknown"
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}
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func (o operation) from() string {
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if obj, ok := o["from"]; ok && obj != nil {
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var op string
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err := json.Unmarshal(*obj, &op)
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if err != nil {
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return "unknown"
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}
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return op
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}
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return "unknown"
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}
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func (o operation) value() *lazyNode {
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if obj, ok := o["value"]; ok {
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return newLazyNode(obj)
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}
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return nil
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}
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func isArray(buf []byte) bool {
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Loop:
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for _, c := range buf {
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switch c {
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case ' ':
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case '\n':
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case '\t':
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continue
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case '[':
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return true
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default:
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break Loop
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}
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}
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return false
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}
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func findObject(pd *container, path string) (container, string) {
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doc := *pd
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split := strings.Split(path, "/")
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if len(split) < 2 {
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return nil, ""
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}
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parts := split[1 : len(split)-1]
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key := split[len(split)-1]
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var err error
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for _, part := range parts {
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next, ok := doc.get(decodePatchKey(part))
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if next == nil || ok != nil {
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return nil, ""
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}
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if isArray(*next.raw) {
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doc, err = next.intoAry()
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if err != nil {
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return nil, ""
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}
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} else {
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doc, err = next.intoDoc()
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if err != nil {
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return nil, ""
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}
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}
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}
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return doc, decodePatchKey(key)
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}
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func (d *partialDoc) set(key string, val *lazyNode) error {
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(*d)[key] = val
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return nil
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}
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func (d *partialDoc) add(key string, val *lazyNode) error {
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(*d)[key] = val
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return nil
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}
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func (d *partialDoc) get(key string) (*lazyNode, error) {
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return (*d)[key], nil
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}
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func (d *partialDoc) remove(key string) error {
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_, ok := (*d)[key]
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if !ok {
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return fmt.Errorf("Unable to remove nonexistent key: %s", key)
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}
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delete(*d, key)
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return nil
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}
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func (d *partialArray) set(key string, val *lazyNode) error {
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if key == "-" {
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*d = append(*d, val)
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return nil
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}
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idx, err := strconv.Atoi(key)
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if err != nil {
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return err
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}
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sz := len(*d)
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if idx+1 > sz {
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sz = idx + 1
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}
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ary := make([]*lazyNode, sz)
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cur := *d
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copy(ary, cur)
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if idx >= len(ary) {
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return fmt.Errorf("Unable to access invalid index: %d", idx)
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}
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ary[idx] = val
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*d = ary
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return nil
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}
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func (d *partialArray) add(key string, val *lazyNode) error {
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if key == "-" {
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*d = append(*d, val)
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return nil
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}
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idx, err := strconv.Atoi(key)
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if err != nil {
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return err
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}
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ary := make([]*lazyNode, len(*d)+1)
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cur := *d
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if idx >= len(ary) {
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return fmt.Errorf("Unable to access invalid index: %d", idx)
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}
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if SupportNegativeIndices {
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if idx < -len(ary) {
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return fmt.Errorf("Unable to access invalid index: %d", idx)
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}
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if idx < 0 {
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idx += len(ary)
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}
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}
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copy(ary[0:idx], cur[0:idx])
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ary[idx] = val
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copy(ary[idx+1:], cur[idx:])
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*d = ary
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return nil
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}
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func (d *partialArray) get(key string) (*lazyNode, error) {
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idx, err := strconv.Atoi(key)
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if err != nil {
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return nil, err
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}
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if idx >= len(*d) {
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return nil, fmt.Errorf("Unable to access invalid index: %d", idx)
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}
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return (*d)[idx], nil
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}
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func (d *partialArray) remove(key string) error {
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idx, err := strconv.Atoi(key)
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if err != nil {
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return err
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}
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cur := *d
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if idx >= len(cur) {
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return fmt.Errorf("Unable to access invalid index: %d", idx)
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}
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if SupportNegativeIndices {
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if idx < -len(cur) {
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return fmt.Errorf("Unable to access invalid index: %d", idx)
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}
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if idx < 0 {
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idx += len(cur)
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}
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}
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ary := make([]*lazyNode, len(cur)-1)
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copy(ary[0:idx], cur[0:idx])
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copy(ary[idx:], cur[idx+1:])
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*d = ary
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return nil
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}
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func (p Patch) add(doc *container, op operation) error {
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path := op.path()
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con, key := findObject(doc, path)
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if con == nil {
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return fmt.Errorf("jsonpatch add operation does not apply: doc is missing path: \"%s\"", path)
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}
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return con.add(key, op.value())
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}
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func (p Patch) remove(doc *container, op operation) error {
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path := op.path()
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con, key := findObject(doc, path)
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if con == nil {
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return fmt.Errorf("jsonpatch remove operation does not apply: doc is missing path: \"%s\"", path)
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}
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return con.remove(key)
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}
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func (p Patch) replace(doc *container, op operation) error {
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path := op.path()
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con, key := findObject(doc, path)
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if con == nil {
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return fmt.Errorf("jsonpatch replace operation does not apply: doc is missing path: %s", path)
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}
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_, ok := con.get(key)
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if ok != nil {
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return fmt.Errorf("jsonpatch replace operation does not apply: doc is missing key: %s", path)
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}
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return con.set(key, op.value())
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}
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func (p Patch) move(doc *container, op operation) error {
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from := op.from()
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con, key := findObject(doc, from)
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if con == nil {
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return fmt.Errorf("jsonpatch move operation does not apply: doc is missing from path: %s", from)
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}
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val, err := con.get(key)
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if err != nil {
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return err
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}
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err = con.remove(key)
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if err != nil {
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return err
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}
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path := op.path()
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con, key = findObject(doc, path)
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if con == nil {
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return fmt.Errorf("jsonpatch move operation does not apply: doc is missing destination path: %s", path)
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}
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return con.set(key, val)
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}
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func (p Patch) test(doc *container, op operation) error {
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path := op.path()
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con, key := findObject(doc, path)
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if con == nil {
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return fmt.Errorf("jsonpatch test operation does not apply: is missing path: %s", path)
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}
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val, err := con.get(key)
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if err != nil {
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return err
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}
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if val == nil {
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if op.value().raw == nil {
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return nil
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}
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return fmt.Errorf("Testing value %s failed", path)
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} else if op.value() == nil {
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return fmt.Errorf("Testing value %s failed", path)
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}
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if val.equal(op.value()) {
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return nil
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}
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return fmt.Errorf("Testing value %s failed", path)
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}
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func (p Patch) copy(doc *container, op operation) error {
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from := op.from()
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con, key := findObject(doc, from)
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if con == nil {
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return fmt.Errorf("jsonpatch copy operation does not apply: doc is missing from path: %s", from)
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}
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val, err := con.get(key)
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if err != nil {
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return err
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}
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path := op.path()
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con, key = findObject(doc, path)
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if con == nil {
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return fmt.Errorf("jsonpatch copy operation does not apply: doc is missing destination path: %s", path)
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}
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return con.set(key, val)
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}
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// Equal indicates if 2 JSON documents have the same structural equality.
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func Equal(a, b []byte) bool {
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ra := make(json.RawMessage, len(a))
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copy(ra, a)
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la := newLazyNode(&ra)
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rb := make(json.RawMessage, len(b))
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copy(rb, b)
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lb := newLazyNode(&rb)
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return la.equal(lb)
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}
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// DecodePatch decodes the passed JSON document as an RFC 6902 patch.
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func DecodePatch(buf []byte) (Patch, error) {
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var p Patch
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err := json.Unmarshal(buf, &p)
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if err != nil {
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return nil, err
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}
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return p, nil
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}
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// Apply mutates a JSON document according to the patch, and returns the new
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// document.
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func (p Patch) Apply(doc []byte) ([]byte, error) {
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return p.ApplyIndent(doc, "")
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}
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// ApplyIndent mutates a JSON document according to the patch, and returns the new
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// document indented.
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func (p Patch) ApplyIndent(doc []byte, indent string) ([]byte, error) {
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var pd container
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if doc[0] == '[' {
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pd = &partialArray{}
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} else {
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pd = &partialDoc{}
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}
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err := json.Unmarshal(doc, pd)
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if err != nil {
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return nil, err
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}
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err = nil
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for _, op := range p {
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switch op.kind() {
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case "add":
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err = p.add(&pd, op)
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case "remove":
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err = p.remove(&pd, op)
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case "replace":
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err = p.replace(&pd, op)
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case "move":
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err = p.move(&pd, op)
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case "test":
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err = p.test(&pd, op)
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case "copy":
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err = p.copy(&pd, op)
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default:
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err = fmt.Errorf("Unexpected kind: %s", op.kind())
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}
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if err != nil {
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return nil, err
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}
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}
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if indent != "" {
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return json.MarshalIndent(pd, "", indent)
|
|
}
|
|
|
|
return json.Marshal(pd)
|
|
}
|
|
|
|
// 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 (
|
|
rfc6901Decoder = strings.NewReplacer("~1", "/", "~0", "~")
|
|
)
|
|
|
|
func decodePatchKey(k string) string {
|
|
return rfc6901Decoder.Replace(k)
|
|
}
|