From 515ebb2db14356833d3e7b70b034170978e50666 Mon Sep 17 00:00:00 2001
From: Alex Crichton <alex@alexcrichton.com>
Date: Sun, 19 Apr 2015 10:38:48 -0700
Subject: [PATCH] Add Ruby to Rust example

---
 ruby-to-rust/Cargo.toml  |  8 ++++++++
 ruby-to-rust/Makefile    |  9 +++++++++
 ruby-to-rust/src/lib.rs  |  4 ++++
 ruby-to-rust/src/main.rb | 11 +++++++++++
 4 files changed, 32 insertions(+)
 create mode 100644 ruby-to-rust/Cargo.toml
 create mode 100644 ruby-to-rust/Makefile
 create mode 100644 ruby-to-rust/src/lib.rs
 create mode 100644 ruby-to-rust/src/main.rb

diff --git a/ruby-to-rust/Cargo.toml b/ruby-to-rust/Cargo.toml
new file mode 100644
index 0000000..72caf09
--- /dev/null
+++ b/ruby-to-rust/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "ruby-to-rust"
+version = "0.1.0"
+authors = ["Alex Crichton <alex@alexcrichton.com>"]
+
+[lib]
+name = "double_input"
+crate-type = ["dylib"]
diff --git a/ruby-to-rust/Makefile b/ruby-to-rust/Makefile
new file mode 100644
index 0000000..582f0ca
--- /dev/null
+++ b/ruby-to-rust/Makefile
@@ -0,0 +1,9 @@
+all: target/libdouble_input.so
+	ruby src/main.rb
+
+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
diff --git a/ruby-to-rust/src/lib.rs b/ruby-to-rust/src/lib.rs
new file mode 100644
index 0000000..bf573d1
--- /dev/null
+++ b/ruby-to-rust/src/lib.rs
@@ -0,0 +1,4 @@
+#[no_mangle]
+pub extern fn double_input(input: i32) -> i32 {
+    input * 2
+}
diff --git a/ruby-to-rust/src/main.rb b/ruby-to-rust/src/main.rb
new file mode 100644
index 0000000..e106332
--- /dev/null
+++ b/ruby-to-rust/src/main.rb
@@ -0,0 +1,11 @@
+require 'ffi'
+
+module Hello
+  extend FFI::Library
+  ffi_lib 'target/libdouble_input.so'
+  attach_function :double_input, [ :int ], :int
+end
+
+input = 4
+output = Hello.double_input(input)
+puts "#{input} * 2 = #{output}"