Initial import of regex-automata-0.1.9.
Bug: 155309706
Change-Id: I20031167cbe49d12754936285a0781eb7a3b8bfd
diff --git a/tests/unescape.rs b/tests/unescape.rs
new file mode 100644
index 0000000..43fe04e
--- /dev/null
+++ b/tests/unescape.rs
@@ -0,0 +1,84 @@
+#[derive(Clone, Copy, Eq, PartialEq)]
+enum State {
+ /// The state after seeing a `\`.
+ Escape,
+ /// The state after seeing a `\x`.
+ HexFirst,
+ /// The state after seeing a `\x[0-9A-Fa-f]`.
+ HexSecond(char),
+ /// Default state.
+ Literal,
+}
+
+pub fn unescape(s: &str) -> Vec<u8> {
+ use self::State::*;
+
+ let mut bytes = vec![];
+ let mut state = Literal;
+ for c in s.chars() {
+ match state {
+ Escape => match c {
+ '\\' => {
+ bytes.push(b'\\');
+ state = Literal;
+ }
+ 'n' => {
+ bytes.push(b'\n');
+ state = Literal;
+ }
+ 'r' => {
+ bytes.push(b'\r');
+ state = Literal;
+ }
+ 't' => {
+ bytes.push(b'\t');
+ state = Literal;
+ }
+ 'x' => {
+ state = HexFirst;
+ }
+ c => {
+ bytes.extend(format!(r"\{}", c).into_bytes());
+ state = Literal;
+ }
+ },
+ HexFirst => match c {
+ '0'..='9' | 'A'..='F' | 'a'..='f' => {
+ state = HexSecond(c);
+ }
+ c => {
+ bytes.extend(format!(r"\x{}", c).into_bytes());
+ state = Literal;
+ }
+ },
+ HexSecond(first) => match c {
+ '0'..='9' | 'A'..='F' | 'a'..='f' => {
+ let ordinal = format!("{}{}", first, c);
+ let byte = u8::from_str_radix(&ordinal, 16).unwrap();
+ bytes.push(byte);
+ state = Literal;
+ }
+ c => {
+ let original = format!(r"\x{}{}", first, c);
+ bytes.extend(original.into_bytes());
+ state = Literal;
+ }
+ },
+ Literal => match c {
+ '\\' => {
+ state = Escape;
+ }
+ c => {
+ bytes.extend(c.to_string().as_bytes());
+ }
+ },
+ }
+ }
+ match state {
+ Escape => bytes.push(b'\\'),
+ HexFirst => bytes.extend(b"\\x"),
+ HexSecond(c) => bytes.extend(format!("\\x{}", c).into_bytes()),
+ Literal => {}
+ }
+ bytes
+}