From f7458e606cd7f92787b67f69c26f9e92e63ec0d0 Mon Sep 17 00:00:00 2001
From: Henry Lin <henry.ys.lin@gmail.com>
Date: Sun, 20 Aug 2023 11:14:13 +0800
Subject: [PATCH] Fix dash escape at the end of the entire char class

---
 src/helper.ts                           | 38 +++++++++++++++++++++++++
 src/modifiers/CharacterClassModifier.ts | 35 ++++++-----------------
 2 files changed, 46 insertions(+), 27 deletions(-)

diff --git a/src/helper.ts b/src/helper.ts
index e996600..c84aad3 100644
--- a/src/helper.ts
+++ b/src/helper.ts
@@ -176,3 +176,41 @@ export function wrapIfNeeded(regExp: string): string {
   }
   return `(?:${regExp})`;
 }
+
+export function escapeForCharClass(option: string): string {
+  if (option.startsWith('-')) {
+    option = '\\-' + option.substring(1);
+  }
+  let charEscaped = false;
+  for (let i = 0; i < option.length; i++) {
+    const char = option[i];
+    if (charEscaped) {
+      charEscaped = false;
+    } else if (char === '\\' || char === '-') {
+      if (i === option.length - 1) {
+        // escape characters at the end of the string
+        option = option.slice(0, -1) + '\\' + char;
+        break;
+      } else {
+        charEscaped = true;
+      }
+    } else if (char === ']' || char === '^') {
+      // escape this character
+      option = option.substring(0, i) + '\\' + option.substring(i);
+      charEscaped = true;
+    }
+  }
+  return option;
+}
+
+export function countTail(str: string, char: string): number {
+  let count = 0;
+  for (let i = str.length - 1; i >= 0; i--) {
+    if (str[i] === char) {
+      count++;
+    } else {
+      break;
+    }
+  }
+  return count;
+}
diff --git a/src/modifiers/CharacterClassModifier.ts b/src/modifiers/CharacterClassModifier.ts
index 5eb8a8e..5a83dbb 100644
--- a/src/modifiers/CharacterClassModifier.ts
+++ b/src/modifiers/CharacterClassModifier.ts
@@ -1,30 +1,5 @@
 import { RegExpModifier } from '../types';
-
-function escapeForCharClass(option: string): string {
-  if (option.startsWith('-')) {
-    option = '\\-' + option.substring(1);
-  }
-  let charEscaped = false;
-  for (let i = 0; i < option.length; i++) {
-    const char = option[i];
-    if (charEscaped) {
-      charEscaped = false;
-    } else if (char === '\\' || char === '-') {
-      if (i === option.length - 1) {
-        // escape backslash at the end of the string
-        option = option.substring(0, option.length - 1) + '\\' + char;
-        break;
-      } else {
-        charEscaped = true;
-      }
-    } else if (char === ']' || char === '^') {
-      // escape this character
-      option = option.substring(0, i) + '\\' + option.substring(i);
-      charEscaped = true;
-    }
-  }
-  return option;
-}
+import { countTail, escapeForCharClass } from '../helper';
 
 export default class CharacterClassModifier implements RegExpModifier {
   private readonly options: string[] = [];
@@ -47,7 +22,13 @@ export default class CharacterClassModifier implements RegExpModifier {
       combined = '-' + combined.substring(2);
     }
     if (combined.endsWith('\\-')) {
-      combined = combined.substring(0, combined.length - 2) + '-';
+      const before = countTail(combined.slice(0, -2), '\\');
+      if (before % 2 === 0) {
+        combined = combined.slice(0, -2) + '-';
+      }
+    }
+    if (countTail(combined, '\\') % 2 === 1) {
+      combined += '\\';
     }
     return [`[${this.negative ? '^' : ''}${combined}]`, regExp];
   }