如何优化正则表达式以兼容单尺寸与多尺寸匹配并实现指定分组提取

架构老林

2026-4-29

Hey there! Let's tackle this regex adjustment step by step.

First, let's break down why the original pattern fails for single-size cases: the original regex (?i)([a-z\d]+(?:[/-][a-z\d]+)?)[/-]([a-z\d]+(?:[/-][a-z\d]+)?) requires a mandatory separator (- or /) between two groups, so it can't match standalone values like 40 that have no separator at all. Also, it doesn't account for spaces around separators (like - or /) which you mentioned are valid.

Modified Regex Pattern

Here's an adjusted regex that handles both single-size and multi-size scenarios, captures the first size in group 1, supports all your separator variants, and ignores any leading content:

(?i).*?([a-z\d]+(?:[/-][a-z\d]+)?)(?:\s*[-/]\s*([a-z\d]+(?:[/-][a-z\d]+)?))?$

Breakdown of the Pattern

Let's break this down piece by piece to understand how it works:

(?i): Enables case-insensitive matching (kept from your original regex)
.*?: Non-greedy match for any leading content (like S1 - in your test cases) so we skip past irrelevant prefixes
([a-z\d]+(?:[/-][a-z\d]+)?): Group 1 – captures either a single size value (e.g., 40, XS) or a composite size with internal separators (e.g., XXS/XS, 40-42)
(?:\s*[-/]\s*([a-z\d]+(?:[/-][a-z\d]+)?))?: Optional non-capturing group for the second size part:
- \s*[-/]\s*: Matches valid separators (-, /, -, /) with optional whitespace before/after
- ([a-z\d]+(?:[/-][a-z\d]+)?): Group 2 – same logic as Group 1, captures the second size part (will be empty/null if there's only one size)
$: Ensures we match up to the end of the string, avoiding partial matches