1 files changed, 60 insertions, 0 deletions
diff --git a/servo/components/style/properties_and_values/syntax/ascii.rs b/servo/components/style/properties_and_values/syntax/ascii.rs
new file mode 100644
index 0000000000..e1a1b08535
--- /dev/null
+++ b/servo/components/style/properties_and_values/syntax/ascii.rs
@@ -0,0 +1,60 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+/// Trims ASCII whitespace characters from a slice, and returns the trimmed input.
+pub fn trim_ascii_whitespace(input: &str) -> &str {
+    if input.is_empty() {
+        return input;
+    }
+
+    let mut start = 0;
+    {
+        let mut iter = input.as_bytes().iter();
+        loop {
+            let byte = match iter.next() {
+                Some(b) => b,
+                None => return "",
+            };
+
+            if !byte.is_ascii_whitespace() {
+                break;
+            }
+            start += 1;
+        }
+    }
+
+    let mut end = input.len();
+    assert!(start < end);
+    {
+        let mut iter = input.as_bytes()[start..].iter().rev();
+        loop {
+            let byte = match iter.next() {
+                Some(b) => b,
+                None => {
+                    debug_assert!(false, "We should have caught this in the loop above!");
+                    return "";
+                },
+            };
+
+            if !byte.is_ascii_whitespace() {
+                break;
+            }
+            end -= 1;
+        }
+    }
+
+    &input[start..end]
+}
+
+#[test]
+fn trim_ascii_whitespace_test() {
+    fn test(i: &str, o: &str) {
+        assert_eq!(trim_ascii_whitespace(i), o)
+    }
+
+    test("", "");
+    test(" ", "");
+    test(" a b c ", "a b c");
+    test(" \t \t \ta b c \t \t \t \t", "a b c");
+}