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patch.go
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package jsonpatch
import (
"bytes"
"encoding/json"
"fmt"
"strconv"
"strings"
"github.com/pkg/errors"
)
const (
eRaw = iota
eDoc
eAry
)
// Hello from Floobits editor
var (
// SupportNegativeIndices decides whether to support non-standard practice of
// allowing negative indices to mean indices starting at the end of an array.
// Default to true.
SupportNegativeIndices bool = true
// AccumulatedCopySizeLimit limits the total size increase in bytes caused by
// "copy" operations in a patch.
AccumulatedCopySizeLimit int64 = 0
)
var (
ErrTestFailed = errors.New("test failed")
ErrMissing = errors.New("missing value")
ErrUnknownType = errors.New("unknown object type")
ErrInvalid = errors.New("invalid state detected")
ErrInvalidIndex = errors.New("invalid index referenced")
)
type lazyNode struct {
raw *json.RawMessage
doc partialDoc
ary partialArray
which int
}
// Operation is a single JSON-Patch step, such as a single 'add' operation.
type Operation map[string]*json.RawMessage
// Patch is an ordered collection of Operations.
type Patch []Operation
type partialDoc map[string]*lazyNode
type partialArray []*lazyNode
type container interface {
get(key string) (*lazyNode, error)
set(key string, val *lazyNode) error
add(key string, val *lazyNode) error
remove(key string) error
}
func newLazyNode(raw *json.RawMessage) *lazyNode {
return &lazyNode{raw: raw, doc: nil, ary: nil, which: eRaw}
}
func (n *lazyNode) MarshalJSON() ([]byte, error) {
switch n.which {
case eRaw:
return json.Marshal(n.raw)
case eDoc:
return json.Marshal(n.doc)
case eAry:
return json.Marshal(n.ary)
default:
return nil, ErrUnknownType
}
}
func (n *lazyNode) UnmarshalJSON(data []byte) error {
dest := make(json.RawMessage, len(data))
copy(dest, data)
n.raw = &dest
n.which = eRaw
return nil
}
func deepCopy(src *lazyNode) (*lazyNode, int, error) {
if src == nil {
return nil, 0, nil
}
a, err := src.MarshalJSON()
if err != nil {
return nil, 0, err
}
sz := len(a)
ra := make(json.RawMessage, sz)
copy(ra, a)
return newLazyNode(&ra), sz, nil
}
func (n *lazyNode) intoDoc() (*partialDoc, error) {
if n.which == eDoc {
return &n.doc, nil
}
if n.raw == nil {
return nil, ErrInvalid
}
err := json.Unmarshal(*n.raw, &n.doc)
if err != nil {
return nil, err
}
n.which = eDoc
return &n.doc, nil
}
func (n *lazyNode) intoAry() (*partialArray, error) {
if n.which == eAry {
return &n.ary, nil
}
if n.raw == nil {
return nil, ErrInvalid
}
err := json.Unmarshal(*n.raw, &n.ary)
if err != nil {
return nil, err
}
n.which = eAry
return &n.ary, nil
}
func (n *lazyNode) compact() []byte {
buf := &bytes.Buffer{}
if n.raw == nil {
return nil
}
err := json.Compact(buf, *n.raw)
if err != nil {
return *n.raw
}
return buf.Bytes()
}
func (n *lazyNode) tryDoc() bool {
if n.raw == nil {
return false
}
err := json.Unmarshal(*n.raw, &n.doc)
if err != nil {
return false
}
n.which = eDoc
return true
}
func (n *lazyNode) tryAry() bool {
if n.raw == nil {
return false
}
err := json.Unmarshal(*n.raw, &n.ary)
if err != nil {
return false
}
n.which = eAry
return true
}
func (n *lazyNode) equal(o *lazyNode) bool {
if n.which == eRaw {
if !n.tryDoc() && !n.tryAry() {
if o.which != eRaw {
return false
}
return bytes.Equal(n.compact(), o.compact())
}
}
if n.which == eDoc {
if o.which == eRaw {
if !o.tryDoc() {
return false
}
}
if o.which != eDoc {
return false
}
if len(n.doc) != len(o.doc) {
return false
}
for k, v := range n.doc {
ov, ok := o.doc[k]
if !ok {
return false
}
if v == nil && ov == nil {
continue
}
if !v.equal(ov) {
return false
}
}
return true
}
if o.which != eAry && !o.tryAry() {
return false
}
if len(n.ary) != len(o.ary) {
return false
}
for idx, val := range n.ary {
if !val.equal(o.ary[idx]) {
return false
}
}
return true
}
// Kind reads the "op" field of the Operation.
func (o Operation) Kind() string {
if obj, ok := o["op"]; ok && obj != nil {
var op string
err := json.Unmarshal(*obj, &op)
if err != nil {
return "unknown"
}
return op
}
return "unknown"
}
// Path reads the "path" field of the Operation.
func (o Operation) Path() (string, error) {
if obj, ok := o["path"]; ok && obj != nil {
var op string
err := json.Unmarshal(*obj, &op)
if err != nil {
return "unknown", err
}
return op, nil
}
return "unknown", errors.Wrapf(ErrMissing, "operation missing path field")
}
// From reads the "from" field of the Operation.
func (o Operation) From() (string, error) {
if obj, ok := o["from"]; ok && obj != nil {
var op string
err := json.Unmarshal(*obj, &op)
if err != nil {
return "unknown", err
}
return op, nil
}
return "unknown", errors.Wrapf(ErrMissing, "operation, missing from field")
}
func (o Operation) value() *lazyNode {
if obj, ok := o["value"]; ok {
return newLazyNode(obj)
}
return nil
}
// ValueInterface decodes the operation value into an interface.
func (o Operation) ValueInterface() (interface{}, error) {
if obj, ok := o["value"]; ok && obj != nil {
var v interface{}
err := json.Unmarshal(*obj, &v)
if err != nil {
return nil, err
}
return v, nil
}
return nil, errors.Wrapf(ErrMissing, "operation, missing value field")
}
func isArray(buf []byte) bool {
Loop:
for _, c := range buf {
switch c {
case ' ':
case '\n':
case '\t':
continue
case '[':
return true
default:
break Loop
}
}
return false
}
func findObject(pd *container, path string) (container, string) {
doc := *pd
split := strings.Split(path, "/")
if len(split) < 2 {
return nil, ""
}
parts := split[1 : len(split)-1]
key := split[len(split)-1]
var err error
for _, part := range parts {
next, ok := doc.get(decodePatchKey(part))
if next == nil || ok != nil {
return nil, ""
}
if isArray(*next.raw) {
doc, err = next.intoAry()
if err != nil {
return nil, ""
}
} else {
doc, err = next.intoDoc()
if err != nil {
return nil, ""
}
}
}
return doc, decodePatchKey(key)
}
func (d *partialDoc) set(key string, val *lazyNode) error {
(*d)[key] = val
return nil
}
func (d *partialDoc) add(key string, val *lazyNode) error {
(*d)[key] = val
return nil
}
func (d *partialDoc) get(key string) (*lazyNode, error) {
v, ok := (*d)[key]
if !ok {
return v, errors.Wrapf(ErrMissing, "unable to get nonexistent key: %s", key)
}
return v, nil
}
func (d *partialDoc) remove(key string) error {
_, ok := (*d)[key]
if !ok {
return errors.Wrapf(ErrMissing, "unable to remove nonexistent key: %s", key)
}
delete(*d, key)
return nil
}
// set should only be used to implement the "replace" operation, so "key" must
// be an already existing index in "d".
func (d *partialArray) set(key string, val *lazyNode) error {
idx, err := strconv.Atoi(key)
if err != nil {
return err
}
(*d)[idx] = val
return nil
}
func (d *partialArray) add(key string, val *lazyNode) error {
if key == "-" {
*d = append(*d, val)
return nil
}
idx, err := strconv.Atoi(key)
if err != nil {
return errors.Wrapf(err, "value was not a proper array index: '%s'", key)
}
sz := len(*d) + 1
ary := make([]*lazyNode, sz)
cur := *d
if idx >= len(ary) {
return errors.Wrapf(ErrInvalidIndex, "Unable to access invalid index: %d", idx)
}
if idx < 0 {
if !SupportNegativeIndices {
return errors.Wrapf(ErrInvalidIndex, "Unable to access invalid index: %d", idx)
}
if idx < -len(ary) {
return errors.Wrapf(ErrInvalidIndex, "Unable to access invalid index: %d", idx)
}
idx += len(ary)
}
copy(ary[0:idx], cur[0:idx])
ary[idx] = val
copy(ary[idx+1:], cur[idx:])
*d = ary
return nil
}
func (d *partialArray) get(key string) (*lazyNode, error) {
idx, err := strconv.Atoi(key)
if err != nil {
return nil, err
}
if idx >= len(*d) {
return nil, errors.Wrapf(ErrInvalidIndex, "Unable to access invalid index: %d", idx)
}
return (*d)[idx], nil
}
func (d *partialArray) remove(key string) error {
idx, err := strconv.Atoi(key)
if err != nil {
return err
}
cur := *d
if idx >= len(cur) {
return errors.Wrapf(ErrInvalidIndex, "Unable to access invalid index: %d", idx)
}
if idx < 0 {
if !SupportNegativeIndices {
return errors.Wrapf(ErrInvalidIndex, "Unable to access invalid index: %d", idx)
}
if idx < -len(cur) {
return errors.Wrapf(ErrInvalidIndex, "Unable to access invalid index: %d", idx)
}
idx += len(cur)
}
ary := make([]*lazyNode, len(cur)-1)
copy(ary[0:idx], cur[0:idx])
copy(ary[idx:], cur[idx+1:])
*d = ary
return nil
}
func (p Patch) add(doc *container, op Operation) error {
path, err := op.Path()
if err != nil {
return errors.Wrapf(ErrMissing, "add operation failed to decode path")
}
con, key := findObject(doc, path)
if con == nil {
return errors.Wrapf(ErrMissing, "add operation does not apply: doc is missing path: \"%s\"", path)
}
err = con.add(key, op.value())
if err != nil {
return errors.Wrapf(err, "error in add for path: '%s'", path)
}
return nil
}
func (p Patch) remove(doc *container, op Operation) error {
path, err := op.Path()
if err != nil {
return errors.Wrapf(ErrMissing, "remove operation failed to decode path")
}
con, key := findObject(doc, path)
if con == nil {
return errors.Wrapf(ErrMissing, "remove operation does not apply: doc is missing path: \"%s\"", path)
}
err = con.remove(key)
if err != nil {
return errors.Wrapf(err, "error in remove for path: '%s'", path)
}
return nil
}
func (p Patch) replace(doc *container, op Operation) error {
path, err := op.Path()
if err != nil {
return errors.Wrapf(err, "replace operation failed to decode path")
}
con, key := findObject(doc, path)
if con == nil {
return errors.Wrapf(ErrMissing, "replace operation does not apply: doc is missing path: %s", path)
}
_, ok := con.get(key)
if ok != nil {
return errors.Wrapf(ErrMissing, "replace operation does not apply: doc is missing key: %s", path)
}
err = con.set(key, op.value())
if err != nil {
return errors.Wrapf(err, "error in remove for path: '%s'", path)
}
return nil
}
func (p Patch) move(doc *container, op Operation) error {
from, err := op.From()
if err != nil {
return errors.Wrapf(err, "move operation failed to decode from")
}
con, key := findObject(doc, from)
if con == nil {
return errors.Wrapf(ErrMissing, "move operation does not apply: doc is missing from path: %s", from)
}
val, err := con.get(key)
if err != nil {
return errors.Wrapf(err, "error in move for path: '%s'", key)
}
err = con.remove(key)
if err != nil {
return errors.Wrapf(err, "error in move for path: '%s'", key)
}
path, err := op.Path()
if err != nil {
return errors.Wrapf(err, "move operation failed to decode path")
}
con, key = findObject(doc, path)
if con == nil {
return errors.Wrapf(ErrMissing, "move operation does not apply: doc is missing destination path: %s", path)
}
err = con.add(key, val)
if err != nil {
return errors.Wrapf(err, "error in move for path: '%s'", path)
}
return nil
}
func (p Patch) test(doc *container, op Operation) error {
path, err := op.Path()
if err != nil {
return errors.Wrapf(err, "test operation failed to decode path")
}
con, key := findObject(doc, path)
if con == nil {
return errors.Wrapf(ErrMissing, "test operation does not apply: is missing path: %s", path)
}
val, err := con.get(key)
if err != nil && errors.Cause(err) != ErrMissing {
return errors.Wrapf(err, "error in test for path: '%s'", path)
}
if val == nil {
if op.value().raw == nil {
return nil
}
return errors.Wrapf(ErrTestFailed, "testing value %s failed", path)
} else if op.value() == nil {
return errors.Wrapf(ErrTestFailed, "testing value %s failed", path)
}
if val.equal(op.value()) {
return nil
}
return errors.Wrapf(ErrTestFailed, "testing value %s failed", path)
}
func (p Patch) copy(doc *container, op Operation, accumulatedCopySize *int64) error {
from, err := op.From()
if err != nil {
return errors.Wrapf(err, "copy operation failed to decode from")
}
con, key := findObject(doc, from)
if con == nil {
return errors.Wrapf(ErrMissing, "copy operation does not apply: doc is missing from path: %s", from)
}
val, err := con.get(key)
if err != nil {
return errors.Wrapf(err, "error in copy for from: '%s'", from)
}
path, err := op.Path()
if err != nil {
return errors.Wrapf(ErrMissing, "copy operation failed to decode path")
}
con, key = findObject(doc, path)
if con == nil {
return errors.Wrapf(ErrMissing, "copy operation does not apply: doc is missing destination path: %s", path)
}
valCopy, sz, err := deepCopy(val)
if err != nil {
return errors.Wrapf(err, "error while performing deep copy")
}
(*accumulatedCopySize) += int64(sz)
if AccumulatedCopySizeLimit > 0 && *accumulatedCopySize > AccumulatedCopySizeLimit {
return NewAccumulatedCopySizeError(AccumulatedCopySizeLimit, *accumulatedCopySize)
}
err = con.add(key, valCopy)
if err != nil {
return errors.Wrapf(err, "error while adding value during copy")
}
return nil
}
// Equal indicates if 2 JSON documents have the same structural equality.
func Equal(a, b []byte) bool {
ra := make(json.RawMessage, len(a))
copy(ra, a)
la := newLazyNode(&ra)
rb := make(json.RawMessage, len(b))
copy(rb, b)
lb := newLazyNode(&rb)
return la.equal(lb)
}
// DecodePatch decodes the passed JSON document as an RFC 6902 patch.
func DecodePatch(buf []byte) (Patch, error) {
var p Patch
err := json.Unmarshal(buf, &p)
if err != nil {
return nil, err
}
return p, nil
}
// Apply mutates a JSON document according to the patch, and returns the new
// document.
func (p Patch) Apply(doc []byte) ([]byte, error) {
return p.ApplyIndent(doc, "")
}
// ApplyIndent mutates a JSON document according to the patch, and returns the new
// document indented.
func (p Patch) ApplyIndent(doc []byte, indent string) ([]byte, error) {
var pd container
if doc[0] == '[' {
pd = &partialArray{}
} else {
pd = &partialDoc{}
}
err := json.Unmarshal(doc, pd)
if err != nil {
return nil, err
}
err = nil
var accumulatedCopySize int64
for _, op := range p {
switch op.Kind() {
case "add":
err = p.add(&pd, op)
case "remove":
err = p.remove(&pd, op)
case "replace":
err = p.replace(&pd, op)
case "move":
err = p.move(&pd, op)
case "test":
err = p.test(&pd, op)
case "copy":
err = p.copy(&pd, op, &accumulatedCopySize)
default:
err = fmt.Errorf("Unexpected kind: %s", op.Kind())
}
if err != nil {
return nil, err
}
}
if indent != "" {
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)
}