initial import

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

flag.go

@@ -0,0 +1,81 @@
+package flag
+
+import (
+	"context"
+	"errors"
+	"flag"
+	"reflect"
+	"strconv"
+
+	"github.com/unistack-org/micro/v3/config"
+	rutil "github.com/unistack-org/micro/v3/util/reflect"
+)
+
+var (
+	DefaultStructTag = "flag"
+	ErrInvalidStruct = errors.New("invalid struct specified")
+)
+
+type flagConfig struct {
+	opts config.Options
+}
+
+func (c *flagConfig) Options() config.Options {
+	return c.opts
+}
+
+func (c *flagConfig) Init(opts ...config.Option) error {
+	for _, o := range opts {
+		o(&c.opts)
+	}
+
+	fields, err := rutil.StructFields(c.opts.Struct)
+	if err != nil {
+		return err
+	}
+
+	for _, sf := range fields {
+		tf, ok := sf.Field.Tag.Lookup(c.opts.StructTag)
+		if !ok {
+			continue
+		}
+		fn, fv, fd := getFlagOpts(tf)
+
+		switch sf.Value.Kind() {
+		case reflect.String:
+			v := sf.Value.Addr().Interface().(*string)
+			flag.StringVar(v, fn, fv, fd)
+		case reflect.Bool:
+			v := sf.Value.Addr().Interface().(*bool)
+			i, _ := strconv.ParseBool(fv)
+			flag.BoolVar(v, fn, i, fd)
+		}
+	}
+
+	return nil
+}
+
+func (c *flagConfig) Load(ctx context.Context) error {
+	flag.Parse()
+	return nil
+}
+
+func (c *flagConfig) Save(ctx context.Context) error {
+	return nil
+}
+
+func (c *flagConfig) String() string {
+	return "flag"
+}
+
+func (c *flagConfig) Name() string {
+	return c.opts.Name
+}
+
+func NewConfig(opts ...config.Option) config.Config {
+	options := config.NewOptions(opts...)
+	if len(options.StructTag) == 0 {
+		options.StructTag = DefaultStructTag
+	}
+	return &flagConfig{opts: options}
+}