Merge pull request #248 from wader/parse-unexpected-multibyte-token-o…

…ffset

set correct offset for multibyte tokens

compiler_test.go

@@ -2,6 +2,7 @@ package gojq_test
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"log"
 	"os"
@@ -275,6 +276,36 @@ func TestCodeCompile_OptimizeJumps(t *testing.T) {
 	}
 }
 
+func TestParseErrorTokenOffset(t *testing.T) {
+	testCases := []struct {
+		src    string
+		offset int
+	}{
+		{src: "^", offset: 1},
+		{src: " ^", offset: 2},
+		{src: " ^ ", offset: 2},
+		{src: "👍", offset: 4},
+		{src: " 👍", offset: 5},
+		{src: " 👍 ", offset: 5},
+		{src: "test👍", offset: 8},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.src, func(t *testing.T) {
+			_, err := gojq.Parse(tc.src)
+			if err == nil {
+				t.Fatal("expected: error")
+			}
+			var pe *gojq.ParseError
+			if !errors.As(err, &pe) {
+				t.Fatalf("expected: *gojq.ParseError, got %v", err)
+			}
+			if pe.Offset != tc.offset {
+				t.Fatalf("expected: %v, got %v", tc.offset, pe.Offset)
+			}
+		})
+	}
+}
+
 func TestCodeRun_Race(t *testing.T) {
 	query, err := gojq.Parse("range(10)")
 	if err != nil {

lexer.go

@@ -235,7 +235,8 @@ func (l *lexer) Lex(lval *yySymType) (tokenType int) {
 	default:
 		if ch >= utf8.RuneSelf {
 			r, size := utf8.DecodeRuneInString(l.source[l.offset-1:])
-			l.offset += size
+			// -1 to adjust for first byte consumed by next()
+			l.offset += size - 1
 			l.token = string(r)
 		}
 	}