1 files changed, 75 insertions, 0 deletions
diff --git a/src/text_format.rs b/src/text_format.rs
new file mode 100644
index 0000000..f49f4c2
--- /dev/null
+++ b/src/text_format.rs
@@ -0,0 +1,75 @@
+pub fn escape_bytes_to(bytes: &[u8], buf: &mut String) {
+    for &c in bytes {
+        match c {
+            b'\n' => buf.push_str(r"\n"),
+            b'\r' => buf.push_str(r"\r"),
+            b'\t' => buf.push_str(r"\t"),
+            b'\'' => buf.push_str("\\\'"),
+            b'"' => buf.push_str("\\\""),
+            b'\\' => buf.push_str(r"\\"),
+            b'\x20'..=b'\x7e' => buf.push(c as char),
+            _ => {
+                buf.push('\\');
+                buf.push((b'0' + (c >> 6)) as char);
+                buf.push((b'0' + ((c >> 3) & 7)) as char);
+                buf.push((b'0' + (c & 7)) as char);
+            }
+        }
+    }
+}
+
+pub fn quote_bytes_to(bytes: &[u8], buf: &mut String) {
+    buf.push('"');
+    escape_bytes_to(bytes, buf);
+    buf.push('"');
+}
+
+#[cfg(test)]
+mod test {
+    use crate::lexer::str_lit::StrLit;
+    use crate::text_format::escape_bytes_to;
+
+    fn escape(data: &[u8]) -> String {
+        let mut s = String::with_capacity(data.len() * 4);
+        escape_bytes_to(data, &mut s);
+        s
+    }
+
+    fn unescape_string(escaped: &str) -> Vec<u8> {
+        StrLit {
+            escaped: escaped.to_owned(),
+        }
+        .decode_bytes()
+        .expect("decode_bytes")
+    }
+
+    fn test_escape_unescape(text: &str, escaped: &str) {
+        assert_eq!(text.as_bytes(), &unescape_string(escaped)[..]);
+        assert_eq!(escaped, &escape(text.as_bytes())[..]);
+    }
+
+    #[test]
+    fn test_print_to_bytes() {
+        assert_eq!("ab", escape(b"ab"));
+        assert_eq!("a\\\\023", escape(b"a\\023"));
+        assert_eq!("a\\r\\n\\t \\'\\\"\\\\", escape(b"a\r\n\t '\"\\"));
+        assert_eq!("\\344\\275\\240\\345\\245\\275", escape("你好".as_bytes()));
+    }
+
+    #[test]
+    fn test_unescape_string() {
+        test_escape_unescape("", "");
+        test_escape_unescape("aa", "aa");
+        test_escape_unescape("\n", "\\n");
+        test_escape_unescape("\r", "\\r");
+        test_escape_unescape("\t", "\\t");
+        test_escape_unescape("你好", "\\344\\275\\240\\345\\245\\275");
+        // hex
+        assert_eq!(b"aaa\x01bbb", &unescape_string("aaa\\x01bbb")[..]);
+        assert_eq!(b"aaa\xcdbbb", &unescape_string("aaa\\xCDbbb")[..]);
+        assert_eq!(b"aaa\xcdbbb", &unescape_string("aaa\\xCDbbb")[..]);
+        // quotes
+        assert_eq!(b"aaa\"bbb", &unescape_string("aaa\\\"bbb")[..]);
+        assert_eq!(b"aaa\'bbb", &unescape_string("aaa\\\'bbb")[..]);
+    }
+}