How to Use regex for Pattern Matching in Rust

Use the regex crate with lazy_static! to compile patterns once and replace_all to transform text.

use lazy_static::lazy_static;
use regex::Regex;

lazy_static! {
    static ref EXTRA_SPACE: Regex = Regex::new("(?m)^ >").unwrap();
}

fn cleanup(input: String) -> String {
    EXTRA_SPACE.replace_all(&input, ">").to_string()
}

This pattern matches a space after > at the start of a line and removes it, as seen in cleanup_blockquotes.rs.

Regular expressions are like search templates that find specific text patterns in your data. You define the pattern once, and the computer uses it to find or fix matching text automatically. It's like using a "Find and Replace" tool that understands complex rules instead of just exact words.