Handle block scalar header with both indicators

The lexer did not recognize block scalar header with both
indentation indicator and chomping indicator.

Closes #399

decode_test.go

@@ -2890,3 +2890,56 @@ func TestSameNameInineStruct(t *testing.T) {
  t.Fatalf("failed to decode")
  }
 }
+
+func TestIssue399(t *testing.T) {
+ tests := map[string]struct {
+ in string
+ out string
+ }{
+ "indent indicator": {
+ in: `|2-
+
+ text
+`,
+ out: `|2-
+
+ text
+`,
+ },
+ "indent indicator with comment": {
+ in: `|2- # some comment
+
+ text
+`,
+ out: `|2- # some comment
+
+ text
+`,
+ },
+ "indent indicator with comment more spaces": {
+ in: `|2- # some comment
+
+ text
+`,
+ out: `|2- # some comment
+
+ text
+`,
+ },
+ }
+
+ for name, test := range tests {
+ t.Run(name, func(t *testing.T) {
+ f, err := parser.ParseBytes([]byte(test.in), parser.ParseComments)
+ if err != nil {
+ t.Fatalf("parse: %v", err)
+ }
+ got := f.String()
+ if test.out != got {
+ t.Logf("%q", test.out)
+ t.Logf("%q", got)
+ t.Fatalf("failed to round-trip.\nexpected:\n%s\nbut got:\n%s\n", test.out, got)
+ }
+ })
+ }
+}

scanner/scanner.go

@@ -501,10 +501,10 @@ func trimCommentFromLiteralOpt(text string) (string, error) {
  if idx < 0 {
  return text, nil
  }
- if idx == 0 {
+ if idx == 0 || text[idx-1] != ' ' {
  return "", xerrors.New("invalid literal header")
  }
- return text[:idx-1], nil
+ return strings.TrimRight(text[:idx], " \t"), nil
 }
 
 func (s *Scanner) scanLiteral(ctx *Context, c rune) {
@@ -554,9 +554,8 @@ func (s *Scanner) scanLiteralHeader(ctx *Context) (pos int, err error) {
  if err != nil {
  return
  }
- switch opt {
- case "", "+", "-",
- "0", "1", "2", "3", "4", "5", "6", "7", "8", "9":
+
+ if isBlockScalarHeader(opt) {
  hasComment := len(opt) < orgOptLen
  if header == '|' {
  if hasComment {
@@ -593,14 +592,48 @@ func (s *Scanner) scanLiteralHeader(ctx *Context) (pos int, err error) {
  ctx.resetBuffer()
  ctx.literalOpt = opt
  return
+ } else {
+ err = xerrors.New("invalid literal header")
+ return
  }
- break
  }
  }
  err = xerrors.New("invalid literal header")
  return
 }
 
+func isBlockScalarHeader(s string) bool {
+ // https://yaml.org/spec/1.2.2/#811-block-scalar-headers
+ switch len(s) {
+ case 0:
+ // no indicator
+ return true
+ case 1:
+ return isIndentationIndicator(s) || isChompingIndicator(s)
+ case 2:
+ return (isIndentationIndicator(s[0:1]) && isChompingIndicator(s[1:2])) ||
+ (isChompingIndicator(s[0:1]) && isIndentationIndicator(s[1:2]))
+ default:
+ return false
+ }
+}
+
+func isIndentationIndicator(s string) bool {
+ switch s {
+ case "0", "1", "2", "3", "4", "5", "6", "7", "8", "9":
+ return true
+ }
+ return false
+}
+
+func isChompingIndicator(s string) bool {
+ switch s {
+ case "+", "-":
+ return true
+ }
+ return false
+}
+
 func (s *Scanner) scanNewLine(ctx *Context, c rune) {
  if len(ctx.buf) > 0 && s.savedPos == nil {
  s.savedPos = s.pos()