Vendor things

third-party/vendor/regex-automata-0.1.10/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
+}