proper parsing reserved ranges

formatter.go

@@ -130,7 +130,12 @@ func (f *Formatter) VisitReserved(r *Reserved) {
 	f.begin("reserved")
 	io.WriteString(f.w, "reserved ")
 	if len(r.Ranges) > 0 {
-		io.WriteString(f.w, r.Ranges)
+		for i, each := range r.Ranges {
+			if i > 0 {
+				io.WriteString(f.w, ",")
+			}
+			fmt.Fprintf(f.w, "%s", each.String())
+		}
 	} else {
 		for i, each := range r.FieldNames {
 			if i > 0 {

reserved.go

@@ -3,12 +3,11 @@ package proto
 import (
 	"fmt"
 	"strconv"
-	"strings"
 )
 
 // Reserved statements declare a range of field numbers or field names that cannot be used in a message.
 type Reserved struct {
-	Ranges     string
+	Ranges     []Range
 	FieldNames []string
 	Comment    *Comment
 }
@@ -37,16 +36,52 @@ func (r *Reserved) Accept(v Visitor) {
 }
 
 func (r *Reserved) parse(p *Parser) error {
-	// TODO proper parsing ranges
-	content := strings.TrimSpace(p.s.scanUntil(';'))
-	if strings.Contains(content, "\"") {
-		quoted := strings.Split(content, ",")
-		for _, each := range quoted {
-			r.FieldNames = append(r.FieldNames, strings.Trim(strings.TrimSpace(each), "\""))
+	seenRangeTo := false
+	for {
+		tok, lit := p.scanIgnoreWhitespace()
+		if len(lit) == 0 {
+			return p.unexpected(lit, "reserved string or integer", r)
+		}
+		// first char that determined tok
+		ch := []rune(lit)[0]
+		if isDigit(ch) {
+			// use unread here because scanInteger does not look at buf
+			p.s.unread(ch)
+			i, err := p.s.scanInteger()
+			if err != nil {
+				return p.unexpected(lit, "reserved integer", r)
+			}
+			if seenRangeTo {
+				// replace last two ranges with one
+				if len(r.Ranges) < 1 {
+					p.unexpected(lit, "reserved integer", r)
+				}
+				from := r.Ranges[len(r.Ranges)-1]
+				r.Ranges = append(r.Ranges[0:len(r.Ranges)-1], Range{From: from.From, To: i})
+				seenRangeTo = false
+			} else {
+				r.Ranges = append(r.Ranges, Range{From: i, To: i})
+			}
+			continue
+		}
+		if tIDENT == tok && "to" == lit {
+			seenRangeTo = true
+			continue
+		}
+		if tQUOTE == tok || tSINGLEQUOTE == tok {
+			// use unread here because scanLiteral does not look at buf
+			p.s.unread(ch)
+			field, isString := p.s.scanLiteral()
+			if !isString {
+				return p.unexpected(lit, "reserved string", r)
+			}
+			r.FieldNames = append(r.FieldNames, field)
+			continue
+		}
+		if tSEMICOLON == tok {
+			p.unscan()
+			break
 		}
-	} else {
-		r.Ranges = content
 	}
-	p.s.unread(';') // put it back for reading inline comments TODO
 	return nil
 }

reserved_test.go

@@ -13,7 +13,10 @@ func TestReservedRanges(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	if got, want := r.Ranges, "2, 15, 9 to 11"; got != want {
+	if got, want := r.Ranges[0].String(), "2"; got != want {
+		t.Errorf("got [%v] want [%v]", got, want)
+	}
+	if got, want := r.Ranges[2].String(), "9 to 11"; got != want {
 		t.Errorf("got [%v] want [%v]", got, want)
 	}
 }
@@ -27,7 +30,7 @@ func TestReservedFieldNames(t *testing.T) {
 		t.Fatal(err)
 	}
 	if got, want := len(r.FieldNames), 2; got != want {
-		t.Errorf("got [%v] want [%v]", got, want)
+		t.Fatalf("got [%v] want [%v]", got, want)
 	}
 	if got, want := r.FieldNames[0], "foo"; got != want {
 		t.Errorf("got [%v] want [%v]", got, want)