Add JSON Patch go package

util/diff/diff.go

@@ -0,0 +1,238 @@
+// 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 diff
+
+import (
+	"fmt"
+	"reflect"
+	"sort"
+	"strings"
+
+	"github.com/fatih/structs"
+	"github.com/sergi/go-diff/diffmatchpatch"
+)
+
+type Operation struct {
+	Op     string      `cork:"op,omietmpty" json:"op,omietmpty" structs:"op,omitempty"`
+	From   string      `cork:"from,omitempty" json:"from,omitempty" structs:"from,omitempty"`
+	Path   string      `cork:"path,omitempty" json:"path,omitempty" structs:"path,omitempty"`
+	Value  interface{} `cork:"value,omitempty" json:"value,omitempty" structs:"value,omitempty"`
+	Before interface{} `cork:"-" json:"-" structs:"-"`
+}
+
+type Operations struct {
+	Ops []*Operation
+}
+
+func Diff(old, now map[string]interface{}) (ops *Operations) {
+
+	ops = &Operations{}
+
+	ops.diff(old, now, "")
+
+	return
+
+}
+
+func (o *Operations) Patch(old map[string]interface{}) (now map[string]interface{}, err error) {
+	return nil, nil
+}
+
+func (o *Operations) Rebase(other *Operations) (ops *Operations, err error) {
+	return nil, nil
+}
+
+func (o *Operations) Out() (ops []map[string]interface{}) {
+
+	for _, v := range o.Ops {
+		ops = append(ops, structs.Map(v))
+	}
+
+	return
+
+}
+
+func route(path string, part interface{}) string {
+	if path == "" {
+		return fmt.Sprintf("/%v", part)
+	} else {
+		if strings.HasSuffix(path, "/") {
+			return path + fmt.Sprintf("%v", part)
+		} else {
+			return path + fmt.Sprintf("/%v", part)
+		}
+	}
+}
+
+func (o *Operations) op(op, from, path string, before, after interface{}) {
+
+	o.Ops = append(o.Ops, &Operation{
+		Op:     op,
+		From:   from,
+		Path:   path,
+		Value:  after,
+		Before: before,
+	})
+
+}
+
+func (o *Operations) diff(old, now map[string]interface{}, path string) {
+
+	for key, after := range now {
+
+		p := route(path, key)
+
+		// Check if the value existed
+		before, ok := old[key]
+
+		// Value did not previously exist
+		if !ok {
+			o.op("add", "", p, nil, after)
+			continue
+		}
+
+		// Data type is now completely different
+		if reflect.TypeOf(after) != reflect.TypeOf(before) {
+			o.op("replace", "", p, before, after)
+			continue
+		}
+
+		// Check whether the values have changed
+		o.vals(before, after, p)
+
+	}
+
+	for key, before := range old {
+
+		p := route(path, key)
+
+		// Check if the value exists
+		after, ok := now[key]
+
+		// Value now no longer exists
+		if !ok {
+			o.op("remove", "", p, before, after)
+			continue
+		}
+
+	}
+
+	var used []int
+
+	for i := len(o.Ops) - 1; i >= 0; i-- {
+		if iv := o.Ops[i]; !isIn(i, used) && iv.Op == "add" {
+			for j := len(o.Ops) - 1; j >= 0; j-- {
+				if jv := o.Ops[j]; !isIn(j, used) && jv.Op == "remove" {
+					if reflect.DeepEqual(iv.Value, jv.Before) {
+						used = append(used, []int{i, j}...)
+						o.op("move", jv.Path, iv.Path, nil, nil)
+					}
+				}
+			}
+		}
+	}
+
+	sort.Sort(sort.Reverse(sort.IntSlice(used)))
+
+	for _, i := range used {
+		o.Ops = append(o.Ops[:i], o.Ops[i+1:]...)
+	}
+
+}
+
+func isIn(a int, list []int) bool {
+	for _, b := range list {
+		if b == a {
+			return true
+		}
+	}
+	return false
+}
+
+func (o *Operations) text(old, now string, path string) {
+
+	dmp := diffmatchpatch.New()
+
+	dif := dmp.DiffMain(old, now, false)
+
+	txt := dmp.DiffToDelta(dif)
+
+	o.op("change", "", path, old, txt)
+
+}
+
+func (o *Operations) vals(old, now interface{}, path string) {
+
+	if reflect.TypeOf(old) != reflect.TypeOf(now) {
+		o.op("replace", "", path, old, now)
+		return
+	}
+
+	switch ov := old.(type) {
+	default:
+		if !reflect.DeepEqual(old, now) {
+			o.op("replace", "", path, old, now)
+		}
+	case bool:
+		if ov != now.(bool) {
+			o.op("replace", "", path, old, now)
+		}
+	case int64:
+		if ov != now.(int64) {
+			o.op("replace", "", path, old, now)
+		}
+	case float64:
+		if ov != now.(float64) {
+			o.op("replace", "", path, old, now)
+		}
+	case string:
+		if ov != now.(string) {
+			o.text(ov, now.(string), path)
+		}
+	case nil:
+		switch now.(type) {
+		case nil:
+		default:
+			o.op("replace", "", path, old, now)
+		}
+	case map[string]interface{}:
+		o.diff(ov, now.(map[string]interface{}), path)
+	case []interface{}:
+		o.arrs(ov, now.([]interface{}), path)
+	}
+
+}
+
+func (o *Operations) arrs(old, now []interface{}, path string) {
+
+	var i int
+
+	for i = 0; i < len(old) && i < len(now); i++ {
+		o.vals(old[i], now[i], route(path, i))
+	}
+
+	for j := i; j < len(now); j++ {
+		if j >= len(old) || !reflect.DeepEqual(now[j], old[j]) {
+			o.op("add", "", route(path, j), nil, now[j])
+		}
+	}
+
+	for j := i; j < len(old); j++ {
+		if j >= len(now) || !reflect.DeepEqual(old[j], now[j]) {
+			o.op("remove", "", route(path, j), old[j], nil)
+		}
+	}
+
+}