stylo: Implement support for the contents property.

components/style/properties/gecko.mako.rs

@@ -1355,6 +1355,93 @@ fn static_assert() {
     ${impl_coord_copy('column_width', 'mColumnWidth')}
 </%self:impl_trait>
 
+<%self:impl_trait style_struct_name="Counters"
+                  skip_longhands="content">
+    pub fn set_content(&mut self, v: longhands::content::computed_value::T) {
+        use properties::longhands::content::computed_value::T;
+        use properties::longhands::content::computed_value::ContentItem;
+        use gecko_bindings::structs::nsStyleContentData;
+        use gecko_bindings::structs::nsStyleContentType::*;
+        use gecko_bindings::bindings::Gecko_ClearStyleContents;
+
+        // Converts a string as utf16, and returns an owned, zero-terminated raw buffer.
+        fn as_utf16_and_forget(s: &str) -> *mut u16 {
+            use std::mem;
+            let mut vec = s.encode_utf16().collect::<Vec<_>>();
+            vec.push(0u16);
+            let ptr = vec.as_mut_ptr();
+            mem::forget(vec);
+            ptr
+        }
+
+        #[inline(always)]
+        #[cfg(debug_assertions)]
+        fn set_image_tracked(contents: &mut nsStyleContentData, val: bool) {
+            contents.mImageTracked = val;
+        }
+
+        #[inline(always)]
+        #[cfg(not(debug_assertions))]
+        fn set_image_tracked(_contents: &mut nsStyleContentData, _val: bool) {}
+
+        // Ensure destructors run, otherwise we could leak.
+        if !self.gecko.mContents.is_empty() {
+            unsafe {
+                Gecko_ClearStyleContents(&mut self.gecko);
+            }
+        }
+
+        match v {
+            T::none |
+            T::normal => {}, // Do nothing, already cleared.
+            T::Content(items) => {
+                // NB: set_len also reserves the appropriate space.
+                unsafe { self.gecko.mContents.set_len(items.len() as u32) }
+                for (i, item) in items.into_iter().enumerate() {
+                    // TODO: Servo lacks support for attr(), and URIs,
+                    // We don't support images, but need to remember to
+                    // explicitly initialize mImageTracked in debug builds.
+                    set_image_tracked(&mut self.gecko.mContents[i], false);
+                    // NB: Gecko compares the mString value if type is not image
+                    // or URI independently of whatever gets there. In the quote
+                    // cases, they set it to null, so do the same here.
+                    unsafe {
+                        *self.gecko.mContents[i].mContent.mString.as_mut() = ptr::null_mut();
+                    }
+                    match item {
+                        ContentItem::String(value) => {
+                            self.gecko.mContents[i].mType = eStyleContentType_String;
+                            unsafe {
+                                // NB: we share allocators, so doing this is fine.
+                                *self.gecko.mContents[i].mContent.mString.as_mut() =
+                                    as_utf16_and_forget(&value);
+                            }
+                        }
+                        ContentItem::OpenQuote
+                            => self.gecko.mContents[i].mType = eStyleContentType_OpenQuote,
+                        ContentItem::CloseQuote
+                            => self.gecko.mContents[i].mType = eStyleContentType_CloseQuote,
+                        ContentItem::NoOpenQuote
+                            => self.gecko.mContents[i].mType = eStyleContentType_NoOpenQuote,
+                        ContentItem::NoCloseQuote
+                            => self.gecko.mContents[i].mType = eStyleContentType_NoCloseQuote,
+                        ContentItem::Counter(..) |
+                        ContentItem::Counters(..)
+                            => self.gecko.mContents[i].mType = eStyleContentType_Uninitialized,
+                    }
+                }
+            }
+        }
+    }
+
+    pub fn copy_content_from(&mut self, other: &Self) {
+        use gecko_bindings::bindings::Gecko_CopyStyleContentsFrom;
+        unsafe {
+            Gecko_CopyStyleContentsFrom(&mut self.gecko, &other.gecko)
+        }
+    }
+</%self:impl_trait>
+
 <%def name="define_ffi_struct_accessor(style_struct)">
 #[no_mangle]
 #[allow(non_snake_case, unused_variables)]

ports/geckolib/gecko_bindings/bindings.rs

@@ -314,6 +314,9 @@ extern "C" {
                                       capacity: usize, elem_size: usize);
     pub fn Gecko_ClearPODTArray(array: *mut ::std::os::raw::c_void,
                                 elem_size: usize, elem_align: usize);
+    pub fn Gecko_ClearStyleContents(content: *mut nsStyleContent);
+    pub fn Gecko_CopyStyleContentsFrom(content: *mut nsStyleContent,
+                                       other: *const nsStyleContent);
     pub fn Gecko_EnsureImageLayersLength(layers: *mut nsStyleImageLayers,
                                          len: usize);
     pub fn Gecko_InitializeImageLayer(layer: *mut Layer,

ports/geckolib/gecko_bindings/sugar/ns_t_array.rs

@@ -2,7 +2,7 @@
  * 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 bindings::Gecko_EnsureTArrayCapacity;
+use bindings;
 use std::mem;
 use std::ops::{Deref, DerefMut};
 use std::os::raw::c_void;
@@ -38,6 +38,7 @@ impl<T> nsTArray<T> {
     // unsafe, since header may be in shared static or something
     unsafe fn header_mut<'a>(&'a mut self) -> &'a mut nsTArrayHeader {
         debug_assert!(!self.mBuffer.is_null());
+
         mem::transmute(self.mBuffer)
     }
 
@@ -47,12 +48,37 @@ impl<T> nsTArray<T> {
         (self.mBuffer as *const nsTArrayHeader).offset(1) as *mut _
     }
 
-    fn ensure_capacity(&mut self, cap: usize) {
-        unsafe {
-            Gecko_EnsureTArrayCapacity(self as *mut nsTArray<T> as *mut c_void, cap, mem::size_of::<T>())
+    /// Ensures the array has enough capacity at least to hold `cap` elements.
+    ///
+    /// NOTE: This doesn't call the constructor on the values!
+    pub fn ensure_capacity(&mut self, cap: usize) {
+        if cap >= self.len() {
+            unsafe {
+                bindings::Gecko_EnsureTArrayCapacity(self as *mut nsTArray<T> as *mut _,
+                                                     cap, mem::size_of::<T>())
+            }
+        }
+    }
+
+    /// Clears the array storage without calling the destructor on the values.
+    #[inline]
+    pub unsafe fn clear(&mut self) {
+        if self.len() != 0 {
+            bindings::Gecko_ClearPODTArray(self as *mut nsTArray<T> as *mut _,
+                                           mem::size_of::<T>(),
+                                           mem::align_of::<T>());
         }
     }
 
+
+    /// Clears a POD array. This is safe since copy types are memcopyable.
+    #[inline]
+    pub fn clear_pod(&mut self)
+        where T: Copy
+    {
+        unsafe { self.clear() }
+    }
+
     // unsafe because the array may contain uninits
     // This will not call constructors, either manually
     // add bindings or run the typed ensurecapacity call