Add unicode feature to switch between regex and regex-lite dep

Author: yujincheng08

Cargo.toml

@@ -13,4 +13,9 @@ edition = "2018"
 [dependencies]
 encoding_rs = "0.8.32"
 lazy_static = "1.4.0"
-regex = "1.5.5"
+regex = { version = "1.5.5", optional = true }
+regex-lite = { version = "0.1" }
+
+[features]
+default = ["unicode"]
+unicode = ["dep:regex"]

src/lib.rs

@@ -71,7 +71,10 @@ use encoding_rs::EncoderResult;
 use encoding_rs::Encoding;
 use encoding_rs::WINDOWS_1252;
 use lazy_static::lazy_static;
+#[cfg(feature = "unicode")]
 use regex::Regex;
+#[cfg(not(feature = "unicode"))]
+use regex_lite::Regex;
 use std::collections::HashMap;
 use std::collections::VecDeque;
 use std::convert::From;