From e5fb2fe4f4dfc7dff550b934933b88e9392a6e11 Mon Sep 17 00:00:00 2001
From: Ryo Nihei <nihei.dev@gmail.com>
Date: Wed, 24 Feb 2021 01:30:08 +0900
Subject: Add range expression

[a-z] matches any one character from a to z. The order of the characters depends on Unicode code points.
---
 compiler/lexer.go | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

(limited to 'compiler/lexer.go')

diff --git a/compiler/lexer.go b/compiler/lexer.go
index 91cd209..acc9658 100644
--- a/compiler/lexer.go
+++ b/compiler/lexer.go
@@ -19,6 +19,7 @@ const (
 	tokenKindGroupClose      = tokenKind(")")
 	tokenKindBExpOpen        = tokenKind("[")
 	tokenKindBExpClose       = tokenKind("]")
+	tokenKindCharRange       = tokenKind("-")
 	tokenKindEOF             = tokenKind("eof")
 )
 
@@ -124,6 +125,8 @@ func (l *lexer) nextInDefault(c rune) (*token, error) {
 
 func (l *lexer) nextInBExp(c rune) (*token, error) {
 	switch c {
+	case '-':
+		return newToken(tokenKindCharRange, nullChar), nil
 	case ']':
 		l.mode = lexerModeDefault
 		return newToken(tokenKindBExpClose, nullChar), nil
@@ -138,7 +141,7 @@ func (l *lexer) nextInBExp(c rune) (*token, error) {
 			}
 		}
 		switch {
-		case c == '\\' || c == ']':
+		case c == '\\' || c == '-' || c == ']':
 			return newToken(tokenKindChar, c), nil
 		default:
 			return nil, &SyntaxError{
-- 
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