Add node to Rust example

.gitignore

@@ -1,2 +1,3 @@
 Cargo.lock
 target
+node_modules

node-to-rust/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "node-to-rust"
+version = "0.1.0"
+authors = ["Alex Crichton <alex@alexcrichton.com>"]
+
+[lib]
+name = "double_input"
+crate-type = ["dylib"]

node-to-rust/Makefile

@@ -0,0 +1,9 @@
+all: target/libdouble_input.so
+	node src/main.js
+
+target/libdouble_input.so: src/lib.rs Cargo.toml
+	cargo build
+	(cd target && ln -nsf debug/libdouble_input-* libdouble_input.so)
+
+clean:
+	rm -rf target

node-to-rust/src/lib.rs

@@ -0,0 +1,4 @@
+#[no_mangle]
+pub extern fn double_input(input: i32) -> i32 {
+    input * 2
+}

node-to-rust/src/main.js

@@ -0,0 +1,9 @@
+var ffi = require('ffi');
+
+var lib = ffi.Library('target/libdouble_input.so', {
+  'double_input': [ 'int', [ 'int' ] ]
+});
+
+var input = 4;
+var output = lib.double_input(input);
+console.log(input + " * 2 = " + output);