style: Better debugging for stylesheets and URLs.

Bug: 1470145
Reviewed-by: xidorn
MozReview-Commit-ID: FIcz2K1ZYX0

components/style/stylesheets/mod.rs

@@ -61,22 +61,52 @@ pub type UrlExtraData = ::servo_url::ServoUrl;
 
 /// Extra data that the backend may need to resolve url values.
 #[cfg(feature = "gecko")]
-pub type UrlExtraData =
-    ::gecko_bindings::sugar::refptr::RefPtr<::gecko_bindings::structs::URLExtraData>;
+#[derive(Clone, PartialEq)]
+pub struct UrlExtraData(
+    pub ::gecko_bindings::sugar::refptr::RefPtr<::gecko_bindings::structs::URLExtraData>
+);
 
 #[cfg(feature = "gecko")]
 impl UrlExtraData {
-    /// Returns a string for the url.
-    ///
-    /// Unimplemented currently.
-    pub fn as_str(&self) -> &str {
-        // TODO
-        "(stylo: not supported)"
+    /// True if this URL scheme is chrome.
+    #[inline]
+    pub fn is_chrome(&self) -> bool {
+        self.0.mIsChrome
     }
 
-    /// True if this URL scheme is chrome.
-    pub fn is_chrome(&self) -> bool {
-        self.mIsChrome
+    /// Create a reference to this `UrlExtraData` from a reference to pointer.
+    ///
+    /// The pointer must be valid and non null.
+    ///
+    /// This method doesn't touch refcount.
+    #[inline]
+    pub unsafe fn from_ptr_ref(ptr: &*mut ::gecko_bindings::structs::URLExtraData) -> &Self {
+        ::std::mem::transmute(ptr)
+    }
+}
+
+#[cfg(feature = "gecko")]
+impl fmt::Debug for UrlExtraData {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        use gecko_bindings::{structs, bindings};
+
+        struct DebugURI(*mut structs::nsIURI);
+        impl fmt::Debug for DebugURI {
+            fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+                use nsstring::nsCString;
+                let mut spec = nsCString::new();
+                unsafe {
+                    bindings::Gecko_nsIURI_Debug(self.0, &mut spec);
+                }
+                spec.fmt(formatter)
+            }
+        }
+
+        formatter.debug_struct("URLExtraData")
+            .field("is_chrome", &self.is_chrome())
+            .field("base", &DebugURI(self.0.mBaseURI.raw::<structs::nsIURI>()))
+            .field("referrer", &DebugURI(self.0.mReferrer.raw::<structs::nsIURI>()))
+            .finish()
     }
 }
 

components/style/stylesheets/stylesheet.rs

@@ -176,7 +176,7 @@ macro_rules! rule_filter {
 }
 
 /// A trait to represent a given stylesheet in a document.
-pub trait StylesheetInDocument {
+pub trait StylesheetInDocument : ::std::fmt::Debug {
     /// Get the stylesheet origin.
     fn origin(&self, guard: &SharedRwLockReadGuard) -> Origin;
 
@@ -263,7 +263,7 @@ impl StylesheetInDocument for Stylesheet {
 
 /// A simple wrapper over an `Arc<Stylesheet>`, with pointer comparison, and
 /// suitable for its use in a `StylesheetSet`.
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 #[cfg_attr(feature = "servo", derive(MallocSizeOf))]
 pub struct DocumentStyleSheet(
     #[cfg_attr(feature = "servo", ignore_malloc_size_of = "Arc")] pub Arc<Stylesheet>,