Add HeapSizeOf support.

Part of Part of servo/heapsize#5.

Cargo.toml

@@ -17,6 +17,7 @@ doctest = false
 
 [features]
 unstable = ["html5ever_macros", "tendril/unstable", "string_cache/unstable", "string_cache_plugin", "rc/unstable"]
+heap_size = ["heapsize", "heapsize_plugin"]
 
 [dependencies]
 time = "0"
@@ -27,6 +28,8 @@ string_cache_plugin = { version = "0.1.5", optional = true }
 mac = "0"
 tendril = "0.1.3"
 rc = "0.1.1"
+heapsize = { version = "0.1.1", optional = true }
+heapsize_plugin = { version = "0.1.0", optional = true }
 
 [dev-dependencies]
 rustc-serialize = "0.3.15"

src/lib.rs

@@ -16,6 +16,11 @@
 
 #![cfg_attr(feature = "unstable", plugin(string_cache_plugin))]
 
+#![cfg_attr(feature = "heap_size", feature(plugin, custom_derive))]
+#![cfg_attr(feature = "heap_size", plugin(heapsize_plugin))]
+#[cfg(feature = "heap_size")]
+extern crate heapsize;
+
 extern crate rc;
 
 #[macro_use]

src/tree_builder/interface.rs

@@ -22,6 +22,7 @@ pub use self::NodeOrText::{AppendNode, AppendText};
 
 /// A document's quirks mode.
 #[derive(PartialEq, Eq, Copy, Clone, Hash, Debug)]
+#[cfg_attr(feature = "heap_size", derive(HeapSizeOf))]
 pub enum QuirksMode {
     Quirks,
     LimitedQuirks,