Add a nonzero crate

components/nonzero/Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+name = "nonzero"
+version = "0.0.1"
+authors = ["The Servo Project Developers"]
+license = "MPL-2.0"
+publish = false
+
+[lib]
+path = "lib.rs"
+
+[features]
+unstable = ["serde/unstable"]
+
+[dependencies]
+serde = "1.0.14"

components/nonzero/lib.rs

@@ -0,0 +1,42 @@
+/* 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/. */
+
+//! `NonZero*` types that are either `core::nonzero::NonZero<_>`
+//! or some stable types with an equivalent API (but no memory layout optimization).
+
+#![cfg_attr(feature = "unstable", feature(nonzero))]
+
+#[cfg(not(feature = "unstable"))]
+#[macro_use]
+extern crate serde;
+
+pub use imp::*;
+
+#[cfg(feature = "unstable")]
+mod imp {
+    extern crate core;
+    use self::core::nonzero::NonZero;
+
+    pub type NonZeroU32 = NonZero<u32>;
+}
+
+#[cfg(not(feature = "unstable"))]
+mod imp {
+    #[derive(Clone, Copy, Debug, Deserialize, Eq, Hash, Ord, PartialEq, PartialOrd, Serialize)]
+    pub struct NonZeroU32(u32);
+
+    impl NonZeroU32 {
+        pub fn new(x: u32) -> Option<Self> {
+            if x != 0 {
+                Some(NonZeroU32(x))
+            } else {
+                None
+            }
+        }
+
+        pub fn get(self) -> u32 {
+            self.0
+        }
+    }
+}