package jsonpatch import ( "bytes" "encoding/json" "fmt" "strconv" "strings" ) const ( eRaw = iota eDoc eAry ) type lazyNode struct { raw *json.RawMessage doc partialDoc ary partialArray which int } 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, fmt.Errorf("Unknown type") } } 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 (n *lazyNode) intoDoc() (*partialDoc, error) { if n.which == eDoc { return &n.doc, nil } if n.raw == nil { return nil, fmt.Errorf("Unable to unmarshal nil pointer as partial document") } 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, fmt.Errorf("Unable to unmarshal nil pointer as partial array") } 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 } 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 } func (o operation) kind() string { if obj, ok := o["op"]; ok { var op string err := json.Unmarshal(*obj, &op) if err != nil { return "unknown" } return op } return "unknown" } func (o operation) path() string { if obj, ok := o["path"]; ok { var op string err := json.Unmarshal(*obj, &op) if err != nil { return "unknown" } return op } return "unknown" } func (o operation) from() string { if obj, ok := o["from"]; ok { var op string err := json.Unmarshal(*obj, &op) if err != nil { return "unknown" } return op } return "unknown" } func (o operation) value() *lazyNode { if obj, ok := o["value"]; ok { return newLazyNode(obj) } return nil } 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) { return (*d)[key], nil } func (d *partialDoc) remove(key string) error { _, ok := (*d)[key] if !ok { return fmt.Errorf("Unable to remove nonexistent key: %s", key) } delete(*d, key) return nil } func (d *partialArray) set(key string, val *lazyNode) error { if key == "-" { *d = append(*d, val) return nil } idx, err := strconv.Atoi(key) if err != nil { return err } sz := len(*d) if idx+1 > sz { sz = idx + 1 } ary := make([]*lazyNode, sz) cur := *d copy(ary, cur) if idx >= len(ary) { return fmt.Errorf("Unable to access invalid index: %d", idx) } ary[idx] = val *d = ary 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 err } ary := make([]*lazyNode, len(*d)+1) cur := *d if idx < 0 { idx *= -1 if idx > len(ary) { return fmt.Errorf("Unable to access invalid index: %d", idx) } idx = len(ary) - idx } 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, fmt.Errorf("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 fmt.Errorf("Unable to remove invalid index: %d", idx) } 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 := op.path() con, key := findObject(doc, path) if con == nil { return fmt.Errorf("jsonpatch add operation does not apply: doc is missing path: %s", path) } return con.add(key, op.value()) } func (p Patch) remove(doc *container, op operation) error { path := op.path() con, key := findObject(doc, path) if con == nil { return fmt.Errorf("jsonpatch remove operation does not apply: doc is missing path: %s", path) } return con.remove(key) } func (p Patch) replace(doc *container, op operation) error { path := op.path() con, key := findObject(doc, path) if con == nil { return fmt.Errorf("jsonpatch replace operation does not apply: doc is missing path: %s", path) } val, ok := con.get(key) if val == nil || ok != nil { return fmt.Errorf("jsonpatch replace operation does not apply: doc is missing key: %s", path) } return con.set(key, op.value()) } func (p Patch) move(doc *container, op operation) error { from := op.from() con, key := findObject(doc, from) if con == nil { return fmt.Errorf("jsonpatch move operation does not apply: doc is missing from path: %s", from) } val, err := con.get(key) if err != nil { return err } err = con.remove(key) if err != nil { return err } path := op.path() con, key = findObject(doc, path) if con == nil { return fmt.Errorf("jsonpatch move operation does not apply: doc is missing destination path: %s", path) } return con.set(key, val) } func (p Patch) test(doc *container, op operation) error { path := op.path() con, key := findObject(doc, path) if con == nil { return fmt.Errorf("jsonpatch test operation does not apply: is missing path: %s", path) } val, err := con.get(key) if err != nil { return err } if val == nil { if op.value().raw == nil { return nil } return fmt.Errorf("Testing value %s failed", path) } if val.equal(op.value()) { return nil } return fmt.Errorf("Testing value %s failed", path) } func (p Patch) copy(doc *container, op operation) error { from := op.from() con, key := findObject(doc, from) if con == nil { return fmt.Errorf("jsonpatch copy operation does not apply: doc is missing from path: %s", from) } val, err := con.get(key) if err != nil { return err } path := op.path() con, key = findObject(doc, path) if con == nil { return fmt.Errorf("jsonpatch copy operation does not apply: doc is missing destination path: %s", path) } return con.set(key, val) } // 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 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) 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) }