1 files changed, 66 insertions, 6 deletions
diff --git a/src/components/style/parsing_utils.rs b/src/components/style/parsing_utils.rs
index df355629971..3afd7ba0353 100644
--- a/src/components/style/parsing_utils.rs
+++ b/src/components/style/parsing_utils.rs
@@ -4,18 +4,78 @@
 
 
 use std::ascii::StrAsciiExt;
-use cssparser::ast::{ComponentValue, Ident, SkipWhitespaceIterable};
+use cssparser::ast::{ComponentValue, Ident, Comma, SkipWhitespaceIterable, SkipWhitespaceIterator};
 
 
-pub fn one_component_value<'a>(input: &'a [ComponentValue]) -> Option<&'a ComponentValue> {
+pub fn one_component_value<'a>(input: &'a [ComponentValue]) -> Result<&'a ComponentValue, ()> {
     let mut iter = input.skip_whitespace();
-    iter.next().filtered(|_| iter.next().is_none())
+    match iter.next() {
+        Some(value) => if iter.next().is_none() { Ok(value) } else { Err(()) },
+        None => Err(())
+    }
 }
 
 
-pub fn get_ident_lower(component_value: &ComponentValue) -> Option<String> {
+pub fn get_ident_lower(component_value: &ComponentValue) -> Result<String, ()> {
     match component_value {
-        &Ident(ref value) => Some(value.as_slice().to_ascii_lower()),
-        _ => None,
+        &Ident(ref value) => Ok(value.as_slice().to_ascii_lower()),
+        _ => Err(()),
+    }
+}
+
+
+pub struct BufferedIter<E, I> {
+    iter: I,
+    buffer: Option<E>,
+}
+
+impl<E, I: Iterator<E>> BufferedIter<E, I> {
+    pub fn new(iter: I) -> BufferedIter<E, I> {
+        BufferedIter {
+            iter: iter,
+            buffer: None,
+        }
+    }
+
+    #[inline]
+    pub fn push_back(&mut self, value: E) {
+        assert!(self.buffer.is_none());
+        self.buffer = Some(value);
+    }
+}
+
+impl<E, I: Iterator<E>> Iterator<E> for BufferedIter<E, I> {
+    #[inline]
+    fn next(&mut self) -> Option<E> {
+        if self.buffer.is_some() {
+            self.buffer.take()
+        }
+        else {
+            self.iter.next()
+        }
+    }
+}
+
+pub type ParserIter<'a, 'b> = &'a mut BufferedIter<&'b ComponentValue, SkipWhitespaceIterator<'b>>;
+
+
+#[inline]
+pub fn parse_slice_comma_separated<T>(input: &[ComponentValue],
+                                      parse_one: |ParserIter| -> Result<T, ()>)
+                                      -> Result<Vec<T>, ()> {
+    parse_comma_separated(&mut BufferedIter::new(input.skip_whitespace()), parse_one)
+}
+
+#[inline]
+pub fn parse_comma_separated<T>(iter: ParserIter,
+                                parse_one: |ParserIter| -> Result<T, ()>)
+                                -> Result<Vec<T>, ()> {
+    let mut values = vec![try!(parse_one(iter))];
+    for component_value in iter {
+        match component_value {
+            &Comma => values.push(try!(parse_one(iter))),
+            _ => return Err(())
+        }
     }
+    Ok(values)
 }