fix CharLit parser bug

parser/parser.go

@@ -285,13 +285,7 @@ func (p *Parser) parseOperand() ast.Expr {
 		return x
 
 	case token.Char:
-		x := &ast.CharLit{
+		return p.parseCharLit()
-			Value:    rune(p.tokenLit[1]),
-			ValuePos: p.pos,
-			Literal:  p.tokenLit,
-		}
-		p.next()
-		return x
 
 	case token.String:
 		v, _ := strconv.Unquote(p.tokenLit)
@@ -355,6 +349,28 @@ func (p *Parser) parseOperand() ast.Expr {
 	return &ast.BadExpr{From: pos, To: p.pos}
 }
 
+func (p *Parser) parseCharLit() ast.Expr {
+	if n := len(p.tokenLit); n >= 3 {
+		if code, _, _, err := strconv.UnquoteChar(p.tokenLit[1:n-1], '\''); err == nil {
+			x := &ast.CharLit{
+				Value:    rune(code),
+				ValuePos: p.pos,
+				Literal:  p.tokenLit,
+			}
+			p.next()
+			return x
+		}
+	}
+
+	pos := p.pos
+	p.error(pos, "illegal char literal")
+	p.next()
+	return &ast.BadExpr{
+		From: pos,
+		To:   p.pos,
+	}
+}
+
 func (p *Parser) parseFuncLit() ast.Expr {
 	if p.trace {
 		defer un(trace(p, "FuncLit"))

parser/parser_char_test.go

@@ -0,0 +1,24 @@
+package parser_test
+
+import (
+	"testing"
+
+	"github.com/d5/tengo/ast"
+)
+
+func TestChar(t *testing.T) {
+	expect(t, `'A'`, func(p pfn) []ast.Stmt {
+		return stmts(
+			exprStmt(
+				charLit('A', 1)))
+	})
+	expect(t, `'九'`, func(p pfn) []ast.Stmt {
+		return stmts(
+			exprStmt(
+				charLit('九', 1)))
+	})
+
+	expectError(t, `''`)
+	expectError(t, `'AB'`)
+	expectError(t, `'A九'`)
+}

parser/parser_test.go

@@ -207,6 +207,10 @@ func stringLit(value string, pos scanner.Pos) *ast.StringLit {
 	return &ast.StringLit{Value: value, ValuePos: pos}
 }
 
+func charLit(value rune, pos scanner.Pos) *ast.CharLit {
+	return &ast.CharLit{Value: value, ValuePos: pos, Literal: fmt.Sprintf("'%c'", value)}
+}
+
 func boolLit(value bool, pos scanner.Pos) *ast.BoolLit {
 	return &ast.BoolLit{Value: value, ValuePos: pos}
 }

vm/vm_char_test.go

@@ -0,0 +1,9 @@
+package vm_test
+
+import "testing"
+
+func TestChar(t *testing.T) {
+	expect(t, `out = 'a'`, 'a')
+	expect(t, `out = '九'`, rune(20061))
+	expect(t, `out = 'Æ'`, rune(198))
+}