v0.0.32

dataext/structHash.go

@@ -0,0 +1,254 @@
+package dataext
+
+import (
+	"bytes"
+	"crypto/sha256"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"gogs.mikescher.com/BlackForestBytes/goext/langext"
+	"hash"
+	"io"
+	"reflect"
+	"sort"
+)
+
+type StructHashOptions struct {
+	HashAlgo    hash.Hash
+	Tag         *string
+	SkipChannel bool
+	SkipFunc    bool
+}
+
+func StructHash(dat any, opt ...StructHashOptions) (r []byte, err error) {
+	defer func() {
+		if rec := recover(); rec != nil {
+			r = nil
+			err = errors.New(fmt.Sprintf("recovered panic: %v", rec))
+		}
+	}()
+
+	shopt := StructHashOptions{}
+	if len(opt) > 1 {
+		return nil, errors.New("multiple options supplied")
+	} else if len(opt) == 1 {
+		shopt = opt[0]
+	}
+
+	if shopt.HashAlgo == nil {
+		shopt.HashAlgo = sha256.New()
+	}
+
+	writer := new(bytes.Buffer)
+
+	if langext.IsNil(dat) {
+		shopt.HashAlgo.Reset()
+		shopt.HashAlgo.Write(writer.Bytes())
+		res := shopt.HashAlgo.Sum(nil)
+		return res, nil
+	}
+
+	err = binarize(writer, reflect.ValueOf(dat), shopt)
+	if err != nil {
+		return nil, err
+	}
+
+	shopt.HashAlgo.Reset()
+	shopt.HashAlgo.Write(writer.Bytes())
+	res := shopt.HashAlgo.Sum(nil)
+
+	return res, nil
+}
+
+func writeBinarized(writer io.Writer, dat any) error {
+	tmp := bytes.Buffer{}
+	err := binary.Write(&tmp, binary.LittleEndian, dat)
+	if err != nil {
+		return err
+	}
+	err = binary.Write(writer, binary.LittleEndian, uint64(tmp.Len()))
+	if err != nil {
+		return err
+	}
+	_, err = writer.Write(tmp.Bytes())
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func binarize(writer io.Writer, dat reflect.Value, opt StructHashOptions) error {
+	var err error
+
+	err = binary.Write(writer, binary.LittleEndian, uint8(dat.Kind()))
+	switch dat.Kind() {
+	case reflect.Ptr, reflect.Map, reflect.Array, reflect.Chan, reflect.Slice, reflect.Interface:
+		if dat.IsNil() {
+			err = binary.Write(writer, binary.LittleEndian, uint64(0))
+			if err != nil {
+				return err
+			}
+			return nil
+		}
+	}
+
+	err = binary.Write(writer, binary.LittleEndian, uint64(len(dat.Type().String())))
+	if err != nil {
+		return err
+	}
+	_, err = writer.Write([]byte(dat.Type().String()))
+	if err != nil {
+		return err
+	}
+
+	switch dat.Type().Kind() {
+	case reflect.Invalid:
+		return errors.New("cannot binarize value of kind <Invalid>")
+	case reflect.Bool:
+		return writeBinarized(writer, dat.Bool())
+	case reflect.Int:
+		return writeBinarized(writer, int64(dat.Int()))
+	case reflect.Int8:
+		fallthrough
+	case reflect.Int16:
+		fallthrough
+	case reflect.Int32:
+		fallthrough
+	case reflect.Int64:
+		return writeBinarized(writer, dat.Interface())
+	case reflect.Uint:
+		return writeBinarized(writer, uint64(dat.Int()))
+	case reflect.Uint8:
+		fallthrough
+	case reflect.Uint16:
+		fallthrough
+	case reflect.Uint32:
+		fallthrough
+	case reflect.Uint64:
+		return writeBinarized(writer, dat.Interface())
+	case reflect.Uintptr:
+		return errors.New("cannot binarize value of kind <Uintptr>")
+	case reflect.Float32:
+		fallthrough
+	case reflect.Float64:
+		return writeBinarized(writer, dat.Interface())
+	case reflect.Complex64:
+		return errors.New("cannot binarize value of kind <Complex64>")
+	case reflect.Complex128:
+		return errors.New("cannot binarize value of kind <Complex128>")
+	case reflect.Slice:
+		fallthrough
+	case reflect.Array:
+		return binarizeArrayOrSlice(writer, dat, opt)
+	case reflect.Chan:
+		if opt.SkipChannel {
+			return nil
+		}
+		return errors.New("cannot binarize value of kind <Chan>")
+	case reflect.Func:
+		if opt.SkipFunc {
+			return nil
+		}
+		return errors.New("cannot binarize value of kind <Func>")
+	case reflect.Interface:
+		return binarize(writer, dat.Elem(), opt)
+	case reflect.Map:
+		return binarizeMap(writer, dat, opt)
+	case reflect.Pointer:
+		return binarize(writer, dat.Elem(), opt)
+	case reflect.String:
+		v := dat.String()
+		err = binary.Write(writer, binary.LittleEndian, uint64(len(v)))
+		if err != nil {
+			return err
+		}
+		_, err = writer.Write([]byte(v))
+		if err != nil {
+			return err
+		}
+		return nil
+	case reflect.Struct:
+		return binarizeStruct(writer, dat, opt)
+	case reflect.UnsafePointer:
+		return errors.New("cannot binarize value of kind <UnsafePointer>")
+	default:
+		return errors.New("cannot binarize value of unknown kind <" + dat.Type().Kind().String() + ">")
+	}
+}
+
+func binarizeStruct(writer io.Writer, dat reflect.Value, opt StructHashOptions) error {
+	err := binary.Write(writer, binary.LittleEndian, uint64(dat.NumField()))
+	if err != nil {
+		return err
+	}
+
+	for i := 0; i < dat.NumField(); i++ {
+
+		if opt.Tag != nil {
+			if _, ok := dat.Type().Field(i).Tag.Lookup(*opt.Tag); !ok {
+				continue
+			}
+		}
+
+		err = binary.Write(writer, binary.LittleEndian, uint64(len(dat.Type().Field(i).Name)))
+		if err != nil {
+			return err
+		}
+		_, err = writer.Write([]byte(dat.Type().Field(i).Name))
+		if err != nil {
+			return err
+		}
+
+		err = binarize(writer, dat.Field(i), opt)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func binarizeArrayOrSlice(writer io.Writer, dat reflect.Value, opt StructHashOptions) error {
+	err := binary.Write(writer, binary.LittleEndian, uint64(dat.Len()))
+	if err != nil {
+		return err
+	}
+
+	for i := 0; i < dat.Len(); i++ {
+		err := binarize(writer, dat.Index(i), opt)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func binarizeMap(writer io.Writer, dat reflect.Value, opt StructHashOptions) error {
+	err := binary.Write(writer, binary.LittleEndian, uint64(dat.Len()))
+	if err != nil {
+		return err
+	}
+
+	sub := make([][]byte, 0, dat.Len())
+
+	for _, k := range dat.MapKeys() {
+		tmp := bytes.Buffer{}
+		err = binarize(&tmp, dat.MapIndex(k), opt)
+		if err != nil {
+			return err
+		}
+		sub = append(sub, tmp.Bytes())
+	}
+
+	sort.Slice(sub, func(i1, i2 int) bool { return bytes.Compare(sub[i1], sub[i2]) < 0 })
+
+	for _, v := range sub {
+		_, err = writer.Write(v)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}