i need fsm

cmd/cli/main.go

@@ -40,6 +40,12 @@ func Main() {
 	}
 	cmd := positional[0]
 
+	q, err := BuildQuery(positional)
+	if err != nil {
+		panic(err)
+	}
+	panic(q)
+
 	likePattern := ""
 	notLikePattern := ""
 	i := 1

cmd/cli/query.go

@@ -0,0 +1,76 @@
+package cli
+
+import (
+	"fmt"
+	"io"
+
+	"gogs.inhome.blapointe.com/ana-ledger/src/ledger"
+)
+
+type Query struct{}
+
+func BuildQuery(args args) (ledger.Like, error) {
+	likes := make(ledger.Likes, 0)
+
+	for _, ok := args.peek(); ok; _, ok = args.peek() {
+		like, err := buildOneQuery(args)
+		if err != nil {
+			return nil, err
+		}
+		likes = append(likes, like)
+	}
+
+	return likes.Any, nil
+}
+
+func buildOneQuery(args args) (ledger.Like, error) {
+	word, ok := args.peek()
+	if !ok {
+		return nil, io.EOF
+	}
+
+	likes := make(ledger.Likes, 0)
+
+	for _, ok := args.peek(); ok; _, ok = args.peek() {
+		switch word {
+		case "and":
+			if len(likes) == 0 {
+				return nil, fmt.Errorf("and without predicate")
+			}
+			args.pop()
+			like, err := buildOneQuery(args)
+			if err != nil {
+				return nil, err
+			}
+			likes = append(likes, like)
+		case "not":
+			args.pop()
+			like, err := buildOneQuery(args)
+			if err != nil {
+				return nil, err
+			}
+			likes = append(likes, like)
+		default:
+			return nil, io.EOF
+			if next, _ := args.peek(); next != "and" {
+				return likes.All, nil
+			}
+		}
+	}
+	return nil, io.EOF
+}
+
+type args []string
+
+func (args *args) pop() string {
+	first := (*args)[0]
+	*args = (*args)[1:]
+	return first
+}
+
+func (args *args) peek() (string, bool) {
+	if len(*args) == 0 {
+		return "", false
+	}
+	return (*args)[0], true
+}