add config

config/source/flag/flag.go

@@ -0,0 +1,97 @@
+package flag
+
+import (
+	"errors"
+	"flag"
+	"github.com/imdario/mergo"
+	"github.com/micro/go-micro/config/source"
+	"strings"
+	"time"
+)
+
+type flagsrc struct {
+	opts source.Options
+}
+
+func (fs *flagsrc) Read() (*source.ChangeSet, error) {
+	if !flag.Parsed() {
+		return nil, errors.New("flags not parsed")
+	}
+
+	var changes map[string]interface{}
+
+	visitFn := func(f *flag.Flag) {
+		n := strings.ToLower(f.Name)
+		keys := strings.FieldsFunc(n, split)
+		reverse(keys)
+
+		tmp := make(map[string]interface{})
+		for i, k := range keys {
+			if i == 0 {
+				tmp[k] = f.Value
+				continue
+			}
+
+			tmp = map[string]interface{}{k: tmp}
+		}
+
+		mergo.Map(&changes, tmp) // need to sort error handling
+		return
+	}
+
+	unset, ok := fs.opts.Context.Value(includeUnsetKey{}).(bool)
+	if ok && unset {
+		flag.VisitAll(visitFn)
+	} else {
+		flag.Visit(visitFn)
+	}
+
+	b, err := fs.opts.Encoder.Encode(changes)
+	if err != nil {
+		return nil, err
+	}
+
+	cs := &source.ChangeSet{
+		Format:    fs.opts.Encoder.String(),
+		Data:      b,
+		Timestamp: time.Now(),
+		Source:    fs.String(),
+	}
+	cs.Checksum = cs.Sum()
+
+	return cs, nil
+}
+
+func split(r rune) bool {
+	return r == '-' || r == '_'
+}
+
+func reverse(ss []string) {
+	for i := len(ss)/2 - 1; i >= 0; i-- {
+		opp := len(ss) - 1 - i
+		ss[i], ss[opp] = ss[opp], ss[i]
+	}
+}
+
+func (fs *flagsrc) Watch() (source.Watcher, error) {
+	return source.NewNoopWatcher()
+}
+
+func (fs *flagsrc) String() string {
+	return "flag"
+}
+
+// NewSource returns a config source for integrating parsed flags.
+// Hyphens are delimiters for nesting, and all keys are lowercased.
+//
+// Example:
+//      dbhost := flag.String("database-host", "localhost", "the db host name")
+//
+//      {
+//          "database": {
+//              "host": "localhost"
+//          }
+//      }
+func NewSource(opts ...source.Option) source.Source {
+	return &flagsrc{opts: source.NewOptions(opts...)}
+}