Move most of geckolib into style::gecko

components/style/gecko/snapshot_helpers.rs

@@ -0,0 +1,53 @@
+/* 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/. */
+
+//! Element an snapshot common logic.
+
+use gecko_bindings::structs::nsIAtom;
+use std::{ptr, slice};
+use string_cache::Atom;
+
+pub type ClassOrClassList<T> = unsafe extern fn (T, *mut *mut nsIAtom, *mut *mut *mut nsIAtom) -> u32;
+
+pub fn has_class<T>(item: T,
+                    name: &Atom,
+                    getter: ClassOrClassList<T>) -> bool
+{
+    unsafe {
+        let mut class: *mut nsIAtom = ptr::null_mut();
+        let mut list: *mut *mut nsIAtom = ptr::null_mut();
+        let length = getter(item, &mut class, &mut list);
+        match length {
+            0 => false,
+            1 => name.as_ptr() == class,
+            n => {
+                let classes = slice::from_raw_parts(list, n as usize);
+                classes.iter().any(|ptr| name.as_ptr() == *ptr)
+            }
+        }
+    }
+}
+
+
+pub fn each_class<F, T>(item: T,
+                        mut callback: F,
+                        getter: ClassOrClassList<T>)
+    where F: FnMut(&Atom)
+{
+    unsafe {
+        let mut class: *mut nsIAtom = ptr::null_mut();
+        let mut list: *mut *mut nsIAtom = ptr::null_mut();
+        let length = getter(item, &mut class, &mut list);
+        match length {
+            0 => {}
+            1 => Atom::with(class, &mut callback),
+            n => {
+                let classes = slice::from_raw_parts(list, n as usize);
+                for c in classes {
+                    Atom::with(*c, &mut callback)
+                }
+            }
+        }
+    }
+}