正则表达式优化需求：仅匹配括号内的A-D、+、'及括号，寻求修正

Got it, let's sort out this regex issue. Your original pattern ^[A-D\(\)\'+]+$ works for matching your allowed characters, but it doesn't enforce that every single character must live inside properly paired parentheses—which is why it's letting invalid stuff like A+B or (A slip through.

Here's the corrected regex that fits your exact requirements:

^(\([A-D'+]+\))+$

Let's break down what each part does, step by step:

• ^ and $: These anchor the entire string, so we're checking from the very first character to the very last—no partial matches allowed.
• (\([A-D'+]+\))+: This is the core rule, broken down further:
  • \(: Matches an opening parenthesis (escaped because parentheses are special regex characters that define groups).
  • [A-D'+]+: Matches one or more of your allowed inner characters: A-D, +, or '. The + here ensures the parentheses aren't empty (if you do need to allow empty parentheses later, swap this to *).
  • \): Matches a closing parenthesis to complete the group.
  • The outer + lets you chain multiple valid parenthetical groups, just like your example (A+B+C+D)(A+B)(A').

Valid Test Cases (Will Match): #

• ✅ (A+B+C+D)(A+B)(A') (your sample input)
• ✅ (A')
• ✅ (B+C)

Invalid Test Cases (Will Be Rejected): #

• ❌ A+B (no parentheses at all)
• ❌ (A+B (unclosed opening parenthesis)
• ❌ A+B) (unopened closing parenthesis)
• ❌ (A+B)C (character outside parentheses)
• ❌ () (empty parentheses, blocked by the inner +—remove if you need to allow this)

If you ever need to support nested parentheses (like ((A+B)C)), we'd need to adjust the regex to handle recursion, but based on your example, it looks like you're working with flat, non-nested groups, so this should solve your problem perfectly.

内容的提问来源于stack exchange，提问作者waterbottle