Refactor subpackages

structdiff/diff.go

@@ -0,0 +1,113 @@
+package structdiff
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"reflect"
+	"strings"
+	"sync"
+)
+
+var bufPool = sync.Pool{
+	New: func() interface{} {
+		return new(bytes.Buffer)
+	},
+}
+
+var builderPool = sync.Pool{
+	New: func() interface{} {
+		return new(strings.Builder)
+	},
+}
+
+type Entry struct {
+	Name  string
+	Value interface{}
+}
+
+type Entries []Entry
+
+func (d Entries) String() string {
+	buf := builderPool.Get().(*strings.Builder)
+	last := len(d) - 1
+
+	buf.Reset()
+
+	for i, e := range d {
+		buf.WriteString(e.Name)
+		buf.WriteString(": ")
+
+		if dd, ok := e.Value.(Entries); ok {
+			buf.WriteByte('{')
+			buf.WriteString(dd.String())
+			buf.WriteByte('}')
+		} else {
+			fmt.Fprint(buf, e.Value)
+		}
+
+		if i != last {
+			buf.WriteString("; ")
+		}
+	}
+
+	return buf.String()
+}
+
+func (d Entries) MarshalJSON() ([]byte, error) {
+	buf := bufPool.Get().(*bytes.Buffer)
+	last := len(d) - 1
+
+	buf.Reset()
+
+	buf.WriteByte('{')
+
+	for i, e := range d {
+		j, err := json.Marshal(e.Value)
+		if err != nil {
+			return nil, err
+		}
+
+		fmt.Fprintf(buf, "%q:%s", e.Name, j)
+
+		if i != last {
+			buf.WriteByte(',')
+		}
+	}
+
+	buf.WriteByte('}')
+
+	return buf.Bytes(), nil
+}
+
+func Diff(a, b interface{}) Entries {
+	valA := reflect.Indirect(reflect.ValueOf(a))
+	valB := reflect.Indirect(reflect.ValueOf(b))
+
+	d := make(Entries, 0, valA.NumField())
+
+	if valA.Type() != valB.Type() {
+		return d
+	}
+
+	for i := 0; i < valA.NumField(); i++ {
+		fieldA := valA.Field(i)
+		fieldB := valB.Field(i)
+
+		intA := fieldA.Interface()
+		intB := fieldB.Interface()
+
+		if !reflect.DeepEqual(intA, intB) {
+			name := valB.Type().Field(i).Name
+			value := intB
+
+			if fieldB.Kind() == reflect.Struct {
+				value = Diff(intA, intB)
+			}
+
+			d = append(d, Entry{name, value})
+		}
+	}
+
+	return d
+}