add regex

regex/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "regex"
+version = "0.1.0"
+authors = ["Hatter Jiang <jht5945@gmail.com>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+regex = "1.3.1"
+
+
+

regex/src/main.rs

@@ -0,0 +1,27 @@
+use regex::Regex;
+
+const TO_SEARCH: &str = "
+On 2010-03-14, foo happened. On 2014-10-14, bar happened.
+";
+
+fn main() {
+    let re = Regex::new(r"(\d{4})-(\d{2})-(\d{2})").unwrap();
+    
+    for caps in re.captures_iter(TO_SEARCH) {
+        println!("year: {}, month: {}, day: {}",
+             caps.get(1).unwrap().as_str(),
+             caps.get(2).unwrap().as_str(),
+             caps.get(3).unwrap().as_str());
+    }
+
+    let re2 = Regex::new(r"(\d+)").unwrap();
+    println!("{}", re2.replace_all("Hello 100, 200", | caps: &regex::Captures | {
+        "(".to_owned() + &caps[1] + ")"
+    }));
+    println!("{}", re2.replace_all("Hello 100, 200", | caps: &regex::Captures<'_> | {
+        "[".to_owned() + &caps[1] + "]"
+    }));
+
+    let re3 = Regex::new(r"(?P<x>\d+)").unwrap();
+    println!("{}", re3.replace_all("Hello 100, 200", "<$x>"));
+}