1 files changed, 32 insertions, 0 deletions
diff --git a/components/style/errors.rs b/components/style/errors.rs
new file mode 100644
index 00000000000..f04f4969293
--- /dev/null
+++ b/components/style/errors.rs
@@ -0,0 +1,32 @@
+/* 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 http://mozilla.org/MPL/2.0/. */
+
+
+use cssparser::ast::{SyntaxError, SourceLocation};
+
+
+pub struct ErrorLoggerIterator<I>(pub I);
+
+impl<T, I: Iterator<Result<T, SyntaxError>>> Iterator<T> for ErrorLoggerIterator<I> {
+    fn next(&mut self) -> Option<T> {
+        let ErrorLoggerIterator(ref mut this) = *self;
+        loop {
+            match this.next() {
+                Some(Ok(v)) => return Some(v),
+                Some(Err(error)) => log_css_error(error.location,
+                                                  format!("{:?}", error.reason).as_slice()),
+                None => return None,
+            }
+        }
+   }
+}
+
+
+/// Defaults to a no-op.
+/// Set a `RUST_LOG=style::errors` environment variable
+/// to log CSS parse errors to stderr.
+pub fn log_css_error(location: SourceLocation, message: &str) {
+    // TODO eventually this will got into a "web console" or something.
+    info!("{:u}:{:u} {:s}", location.line, location.column, message)
+}