mox!

vendor/github.com/mjl-/bstore/default.go

@@ -0,0 +1,80 @@
+package bstore
+
+import (
+	"fmt"
+	"reflect"
+	"time"
+)
+
+var zerotime = time.Time{}
+
+// applyDefault replaces zero values for fields that have a Default value configured.
+func (tv *typeVersion) applyDefault(rv reflect.Value) error {
+	for _, f := range tv.Fields[1:] {
+		fv := rv.FieldByIndex(f.structField.Index)
+		if err := f.applyDefault(fv); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (f field) applyDefault(rv reflect.Value) error {
+	switch f.Type.Kind {
+	case kindBytes, kindBinaryMarshal, kindMap:
+		return nil
+
+	case kindSlice, kindStruct:
+		return f.Type.applyDefault(rv)
+
+	case kindBool, kindInt, kindInt8, kindInt16, kindInt32, kindInt64, kindUint, kindUint8, kindUint16, kindUint32, kindUint64, kindFloat32, kindFloat64, kindString, kindTime:
+		if !f.defaultValue.IsValid() || !rv.IsZero() {
+			return nil
+		}
+		fv := f.defaultValue
+		// Time is special. "now" is encoded as the zero value of time.Time.
+		if f.Type.Kind == kindTime && fv.Interface() == zerotime {
+			now := time.Now().Round(0)
+			if f.Type.Ptr {
+				fv = reflect.ValueOf(&now)
+			} else {
+				fv = reflect.ValueOf(now)
+			}
+		} else if f.Type.Ptr {
+			fv = reflect.New(f.structField.Type.Elem())
+			fv.Elem().Set(f.defaultValue)
+		}
+		rv.Set(fv)
+		return nil
+
+	default:
+		return fmt.Errorf("internal error: missing case for %v", f.Type.Kind)
+	}
+}
+
+// only for recursing. we do not support recursing into maps because it would
+// involve more work making values settable. and how sensible it it anyway?
+func (ft fieldType) applyDefault(rv reflect.Value) error {
+	if ft.Ptr && (rv.IsZero() || rv.IsNil()) {
+		return nil
+	} else if ft.Ptr {
+		rv = rv.Elem()
+	}
+	switch ft.Kind {
+	case kindSlice:
+		n := rv.Len()
+		for i := 0; i < n; i++ {
+			if err := ft.List.applyDefault(rv.Index(i)); err != nil {
+				return err
+			}
+		}
+	case kindStruct:
+		for _, nf := range ft.Fields {
+			nfv := rv.FieldByIndex(nf.structField.Index)
+			if err := nf.applyDefault(nfv); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}