1 files changed, 60 insertions, 0 deletions
diff --git a/src/util/str.rs b/src/util/str.rs
new file mode 100644
index 0000000..b2eb41a
--- /dev/null
+++ b/src/util/str.rs
@@ -0,0 +1,60 @@
+// Copyright 2014-2017 The html5ever Project Developers. See the
+// COPYRIGHT file at the top-level directory of this distribution.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use mac::{_tt_as_expr_hack, matches};
+use std::fmt;
+
+pub fn to_escaped_string<T: fmt::Debug>(x: &T) -> String {
+    // FIXME: don't allocate twice
+    let string = format!("{:?}", x);
+    string.chars().flat_map(|c| c.escape_default()).collect()
+}
+
+/// If `c` is an ASCII letter, return the corresponding lowercase
+/// letter, otherwise None.
+pub fn lower_ascii_letter(c: char) -> Option<char> {
+    match c {
+        'a'..='z' => Some(c),
+        'A'..='Z' => Some((c as u8 - b'A' + b'a') as char),
+        _ => None,
+    }
+}
+
+/// Is the character an ASCII alphanumeric character?
+pub fn is_ascii_alnum(c: char) -> bool {
+    matches!(c, '0'..='9' | 'a'..='z' | 'A'..='Z')
+}
+
+/// ASCII whitespace characters, as defined by
+/// tree construction modes that treat them specially.
+pub fn is_ascii_whitespace(c: char) -> bool {
+    matches!(c, '\t' | '\r' | '\n' | '\x0C' | ' ')
+}
+
+#[cfg(test)]
+#[allow(non_snake_case)]
+mod test {
+    use super::{is_ascii_alnum, lower_ascii_letter};
+    use mac::test_eq;
+
+    test_eq!(lower_letter_a_is_a, lower_ascii_letter('a'), Some('a'));
+    test_eq!(lower_letter_A_is_a, lower_ascii_letter('A'), Some('a'));
+    test_eq!(lower_letter_symbol_is_None, lower_ascii_letter('!'), None);
+    test_eq!(
+        lower_letter_nonascii_is_None,
+        lower_ascii_letter('\u{a66e}'),
+        None
+    );
+
+    test_eq!(is_alnum_a, is_ascii_alnum('a'), true);
+    test_eq!(is_alnum_A, is_ascii_alnum('A'), true);
+    test_eq!(is_alnum_1, is_ascii_alnum('1'), true);
+    test_eq!(is_not_alnum_symbol, is_ascii_alnum('!'), false);
+    test_eq!(is_not_alnum_nonascii, is_ascii_alnum('\u{a66e}'), false);
+}