feat: add null type

convert.go

@@ -0,0 +1,356 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Type conversions for Scan.
+
+package datatypes
+
+import (
+ "bytes"
+ "database/sql"
+ "database/sql/driver"
+ "errors"
+ "fmt"
+ "reflect"
+ "strconv"
+ "time"
+)
+
+var errNilPtr = errors.New("destination pointer is nil") // embedded in descriptive error
+
+// convertAssign is the same as convertAssignRows, but without the optional
+// rows argument.
+func convertAssign(dest, src any) error {
+ return convertAssignRows(dest, src, nil)
+}
+
+// convertAssignRows copies to dest the value in src, converting it if possible.
+// An error is returned if the copy would result in loss of information.
+// dest should be a pointer type. If rows is passed in, the rows will
+// be used as the parent for any cursor values converted from a
+// driver.Rows to a *Rows.
+func convertAssignRows(dest, src any, rows *sql.Rows) error {
+ // Common cases, without reflect.
+ switch s := src.(type) {
+ case string:
+ switch d := dest.(type) {
+ case *string:
+ if d == nil {
+ return errNilPtr
+ }
+ *d = s
+ return nil
+ case *[]byte:
+ if d == nil {
+ return errNilPtr
+ }
+ *d = []byte(s)
+ return nil
+ case *RawBytes:
+ if d == nil {
+ return errNilPtr
+ }
+ *d = append((*d)[:0], s...)
+ return nil
+ }
+ case []byte:
+ switch d := dest.(type) {
+ case *string:
+ if d == nil {
+ return errNilPtr
+ }
+ *d = string(s)
+ return nil
+ case *any:
+ if d == nil {
+ return errNilPtr
+ }
+ *d = bytes.Clone(s)
+ return nil
+ case *[]byte:
+ if d == nil {
+ return errNilPtr
+ }
+ *d = bytes.Clone(s)
+ return nil
+ case *RawBytes:
+ if d == nil {
+ return errNilPtr
+ }
+ *d = s
+ return nil
+ }
+ case time.Time:
+ switch d := dest.(type) {
+ case *time.Time:
+ *d = s
+ return nil
+ case *string:
+ *d = s.Format(time.RFC3339Nano)
+ return nil
+ case *[]byte:
+ if d == nil {
+ return errNilPtr
+ }
+ *d = []byte(s.Format(time.RFC3339Nano))
+ return nil
+ case *RawBytes:
+ if d == nil {
+ return errNilPtr
+ }
+ *d = s.AppendFormat((*d)[:0], time.RFC3339Nano)
+ return nil
+ }
+ case decimalDecompose:
+ switch d := dest.(type) {
+ case decimalCompose:
+ return d.Compose(s.Decompose(nil))
+ }
+ case nil:
+ switch d := dest.(type) {
+ case *any:
+ if d == nil {
+ return errNilPtr
+ }
+ *d = nil
+ return nil
+ case *[]byte:
+ if d == nil {
+ return errNilPtr
+ }
+ *d = nil
+ return nil
+ case *RawBytes:
+ if d == nil {
+ return errNilPtr
+ }
+ *d = nil
+ return nil
+ }
+ // The driver is returning a cursor the client may iterate over.
+ case driver.Rows:
+ switch d := dest.(type) {
+ case *sql.Rows:
+ if d == nil {
+ return errNilPtr
+ }
+ if rows == nil {
+ return errors.New("invalid context to convert cursor rows, missing parent *Rows")
+ }
+ rows.closemu.Lock()
+ *d = sql.Rows{
+ dc: rows.dc,
+ releaseConn: func(error) {},
+ rowsi: s,
+ }
+ // Chain the cancel function.
+ parentCancel := rows.cancel
+ rows.cancel = func() {
+ // When Rows.cancel is called, the closemu will be locked as well.
+ // So we can access rs.lasterr.
+ d.close(rows.lasterr)
+ if parentCancel != nil {
+ parentCancel()
+ }
+ }
+ rows.closemu.Unlock()
+ return nil
+ }
+ }
+
+ var sv reflect.Value
+
+ switch d := dest.(type) {
+ case *string:
+ sv = reflect.ValueOf(src)
+ switch sv.Kind() {
+ case reflect.Bool,
+ reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
+ reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64,
+ reflect.Float32, reflect.Float64:
+ *d = asString(src)
+ return nil
+ }
+ case *[]byte:
+ sv = reflect.ValueOf(src)
+ if b, ok := asBytes(nil, sv); ok {
+ *d = b
+ return nil
+ }
+ case *RawBytes:
+ sv = reflect.ValueOf(src)
+ if b, ok := asBytes([]byte(*d)[:0], sv); ok {
+ *d = RawBytes(b)
+ return nil
+ }
+ case *bool:
+ bv, err := driver.Bool.ConvertValue(src)
+ if err == nil {
+ *d = bv.(bool)
+ }
+ return err
+ case *any:
+ *d = src
+ return nil
+ }
+
+ if scanner, ok := dest.(sql.Scanner); ok {
+ return scanner.Scan(src)
+ }
+
+ dpv := reflect.ValueOf(dest)
+ if dpv.Kind() != reflect.Pointer {
+ return errors.New("destination not a pointer")
+ }
+ if dpv.IsNil() {
+ return errNilPtr
+ }
+
+ if !sv.IsValid() {
+ sv = reflect.ValueOf(src)
+ }
+
+ dv := reflect.Indirect(dpv)
+ if sv.IsValid() && sv.Type().AssignableTo(dv.Type()) {
+ switch b := src.(type) {
+ case []byte:
+ dv.Set(reflect.ValueOf(bytes.Clone(b)))
+ default:
+ dv.Set(sv)
+ }
+ return nil
+ }
+
+ if dv.Kind() == sv.Kind() && sv.Type().ConvertibleTo(dv.Type()) {
+ dv.Set(sv.Convert(dv.Type()))
+ return nil
+ }
+
+ // The following conversions use a string value as an intermediate representation
+ // to convert between various numeric types.
+ //
+ // This also allows scanning into user defined types such as "type Int int64".
+ // For symmetry, also check for string destination types.
+ switch dv.Kind() {
+ case reflect.Pointer:
+ if src == nil {
+ dv.SetZero()
+ return nil
+ }
+ dv.Set(reflect.New(dv.Type().Elem()))
+ return convertAssignRows(dv.Interface(), src, rows)
+ case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+ if src == nil {
+ return fmt.Errorf("converting NULL to %s is unsupported", dv.Kind())
+ }
+ s := asString(src)
+ i64, err := strconv.ParseInt(s, 10, dv.Type().Bits())
+ if err != nil {
+ err = strconvErr(err)
+ return fmt.Errorf("converting driver.Value type %T (%q) to a %s: %v", src, s, dv.Kind(), err)
+ }
+ dv.SetInt(i64)
+ return nil
+ case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+ if src == nil {
+ return fmt.Errorf("converting NULL to %s is unsupported", dv.Kind())
+ }
+ s := asString(src)
+ u64, err := strconv.ParseUint(s, 10, dv.Type().Bits())
+ if err != nil {
+ err = strconvErr(err)
+ return fmt.Errorf("converting driver.Value type %T (%q) to a %s: %v", src, s, dv.Kind(), err)
+ }
+ dv.SetUint(u64)
+ return nil
+ case reflect.Float32, reflect.Float64:
+ if src == nil {
+ return fmt.Errorf("converting NULL to %s is unsupported", dv.Kind())
+ }
+ s := asString(src)
+ f64, err := strconv.ParseFloat(s, dv.Type().Bits())
+ if err != nil {
+ err = strconvErr(err)
+ return fmt.Errorf("converting driver.Value type %T (%q) to a %s: %v", src, s, dv.Kind(), err)
+ }
+ dv.SetFloat(f64)
+ return nil
+ case reflect.String:
+ if src == nil {
+ return fmt.Errorf("converting NULL to %s is unsupported", dv.Kind())
+ }
+ switch v := src.(type) {
+ case string:
+ dv.SetString(v)
+ return nil
+ case []byte:
+ dv.SetString(string(v))
+ return nil
+ }
+ }
+
+ return fmt.Errorf("unsupported Scan, storing driver.Value type %T into type %T", src, dest)
+}
+
+func strconvErr(err error) error {
+ if ne, ok := err.(*strconv.NumError); ok {
+ return ne.Err
+ }
+ return err
+}
+
+func asString(src any) string {
+ switch v := src.(type) {
+ case string:
+ return v
+ case []byte:
+ return string(v)
+ }
+ rv := reflect.ValueOf(src)
+ switch rv.Kind() {
+ case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+ return strconv.FormatInt(rv.Int(), 10)
+ case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+ return strconv.FormatUint(rv.Uint(), 10)
+ case reflect.Float64:
+ return strconv.FormatFloat(rv.Float(), 'g', -1, 64)
+ case reflect.Float32:
+ return strconv.FormatFloat(rv.Float(), 'g', -1, 32)
+ case reflect.Bool:
+ return strconv.FormatBool(rv.Bool())
+ }
+ return fmt.Sprintf("%v", src)
+}
+
+func asBytes(buf []byte, rv reflect.Value) (b []byte, ok bool) {
+ switch rv.Kind() {
+ case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+ return strconv.AppendInt(buf, rv.Int(), 10), true
+ case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+ return strconv.AppendUint(buf, rv.Uint(), 10), true
+ case reflect.Float32:
+ return strconv.AppendFloat(buf, rv.Float(), 'g', -1, 32), true
+ case reflect.Float64:
+ return strconv.AppendFloat(buf, rv.Float(), 'g', -1, 64), true
+ case reflect.Bool:
+ return strconv.AppendBool(buf, rv.Bool()), true
+ case reflect.String:
+ s := rv.String()
+ return append(buf, s...), true
+ }
+ return
+}
+
+type decimalDecompose interface {
+ // Decompose returns the internal decimal state in parts.
+ // If the provided buf has sufficient capacity, buf may be returned as the coefficient with
+ // the value set and length set as appropriate.
+ Decompose(buf []byte) (form byte, negative bool, coefficient []byte, exponent int32)
+}
+
+type decimalCompose interface {
+ // Compose sets the internal decimal value from parts. If the value cannot be
+ // represented then an error should be returned.
+ Compose(form byte, negative bool, coefficient []byte, exponent int32) error
+}