Add a token position and detailed info to a lexical error message

3 files changed, 21 insertions, 7 deletions

diff --git a/spec/lexer.go b/spec/lexer.go
index 1f50a27..30757c6 100644
--- a/spec/lexer.go
+++ b/spec/lexer.go
@@ -88,10 +88,11 @@ func newEOFToken() *token {
 	}
 }
 
-func newInvalidToken(text string) *token {
+func newInvalidToken(text string, pos Position) *token {
 	return &token{
 		kind: tokenKindInvalid,
 		text: text,
+		pos:  pos,
 	}
 }
 
@@ -157,7 +158,7 @@ func (l *lexer) lexAndSkipWSs() (*token, error) {
 			return nil, err
 		}
 		if tok.Invalid {
-			newInvalidToken(tok.Text())
+			return newInvalidToken(tok.Text(), newPosition(l.row)), nil
 		}
 		if tok.EOF {
 			return newEOFToken(), nil
@@ -182,8 +183,9 @@ func (l *lexer) lexAndSkipWSs() (*token, error) {
 	case "identifier":
 		if strings.HasPrefix(tok.Text(), "_") {
 			return nil, &verr.SpecError{
-				Cause: synErrAutoGenID,
-				Row:   l.row,
+				Cause:  synErrAutoGenID,
+				Detail: tok.Text(),
+				Row:    l.row,
 			}
 		}
 		return newIDToken(tok.Text(), newPosition(l.row)), nil
@@ -257,6 +259,6 @@ func (l *lexer) lexAndSkipWSs() (*token, error) {
 	case "expansion":
 		return newSymbolToken(tokenKindExpantion, newPosition(l.row)), nil
 	default:
-		return newInvalidToken(tok.Text()), nil
+		return newInvalidToken(tok.Text(), newPosition(l.row)), nil
 	}
 }
diff --git a/spec/lexer_test.go b/spec/lexer_test.go
index 569f278..e016def 100644
--- a/spec/lexer_test.go
+++ b/spec/lexer_test.go
@@ -24,6 +24,10 @@ func TestLexer_Run(t *testing.T) {
 		return newPositionToken(num, newPosition(1))
 	}
 
+	invalidTok := func(text string) *token {
+		return newInvalidToken(text, newPosition(1))
+	}
+
 	tests := []struct {
 		caption string
 		src     string
@@ -131,7 +135,7 @@ bar // This is the fourth comment.
 			src:     `abc!!!def`,
 			tokens: []*token{
 				idTok("abc"),
-				newInvalidToken("!!!"),
+				invalidTok("!!!"),
 				idTok("def"),
 				newEOFToken(),
 			},
diff --git a/spec/parser.go b/spec/parser.go
index 4773da6..29248f4 100644
--- a/spec/parser.go
+++ b/spec/parser.go
@@ -76,6 +76,14 @@ func raiseSyntaxError(row int, synErr *SyntaxError) {
 	})
 }
 
+func raiseSyntaxErrorWithDetail(row int, synErr *SyntaxError, detail string) {
+	panic(&verr.SpecError{
+		Cause:  synErr,
+		Detail: detail,
+		Row:    row,
+	})
+}
+
 func Parse(src io.Reader) (*RootNode, error) {
 	p, err := newParser(src)
 	if err != nil {
@@ -426,7 +434,7 @@ func (p *parser) consume(expected tokenKind) bool {
 	}
 	p.pos = tok.pos
 	if tok.kind == tokenKindInvalid {
-		raiseSyntaxError(p.pos.Row, synErrInvalidToken)
+		raiseSyntaxErrorWithDetail(p.pos.Row, synErrInvalidToken, tok.text)
 	}
 	if tok.kind == expected {
 		p.lastTok = tok