convert to a library crate, with a runnable example

examples/bell_state.rs

@@ -0,0 +1,16 @@
+use libquil_sys::{compile_program, get_chip, parse_program, print_program};
+
+const PROGRAM: &str = r#"
+DECLARE ro BIT[2]
+DECLARE theta REAL
+RX(theta) 0
+X 0
+CNOT 0 1
+"#;
+
+fn main() {
+    let parsed_program = parse_program(PROGRAM.to_string());
+    let chip = get_chip();
+    let compiled_program = compile_program(&parsed_program, &chip);
+    print_program(&compiled_program)
+}

src/main.rs → src/lib.rs

@@ -2,13 +2,33 @@
 #![allow(non_camel_case_types)]
 #![allow(non_snake_case)]
 
+use std::sync::Once;
+
 include!(concat!(env!("OUT_DIR"), "/bindings.rs"));
 
-struct Chip(chip_specification);
+#[derive(Debug)]
+pub struct Chip(chip_specification);
+
+#[derive(Debug)]
+pub struct Program(quil_program);
+
+static START: Once = Once::new();
 
-struct Program(quil_program);
+/// Initializes libquilc using it's core image. No-op after the first call.
+fn init_libquilc() {
+    START.call_once(|| {
+        let bytes = b"libquilc.core\0".to_vec();
+        let mut c_chars: Vec<i8> = bytes.iter().map(|c| *c as i8).collect();
+        let ptr = c_chars.as_mut_ptr();
+        unsafe {
+            init(ptr);
+        }
+    })
+}
 
-fn parse_program(program: String) -> Program {
+/// Parses a String into a Program object for use with other libquil calls.
+pub fn parse_program(program: String) -> Program {
+    init_libquilc();
     let mut c_chars: Vec<i8> = program
         .as_bytes()
         .to_vec()
@@ -25,7 +45,9 @@ fn parse_program(program: String) -> Program {
     Program(parsed_program)
 }
 
-fn compile_program(program: &Program, chip: &Chip) -> Program {
+/// Compiles the program, optimized for the given Chip.
+pub fn compile_program(program: &Program, chip: &Chip) -> Program {
+    init_libquilc();
     let mut compiled_program: quil_program = std::ptr::null_mut();
 
     unsafe {
@@ -35,7 +57,9 @@ fn compile_program(program: &Program, chip: &Chip) -> Program {
     Program(compiled_program)
 }
 
-fn get_chip() -> Chip {
+/// Get an arbritrary Chip.
+pub fn get_chip() -> Chip {
+    init_libquilc();
     let mut chip: chip_specification = std::ptr::null_mut();
 
     unsafe {
@@ -45,27 +69,10 @@ fn get_chip() -> Chip {
     Chip(chip)
 }
 
-fn print_program(program: &Program) {
+/// Prints the given Program to stdout
+pub fn print_program(program: &Program) {
+    init_libquilc();
     unsafe {
         quilc_print_program.unwrap()(program.0);
     }
 }
-
-fn init_libquilc() {
-    let bytes = b"libquilc.core\0".to_vec();
-    let mut c_chars: Vec<i8> = bytes.iter().map(|c| *c as i8).collect();
-    let ptr = c_chars.as_mut_ptr();
-    unsafe {
-        init(ptr);
-    }
-}
-
-fn main() {
-    init_libquilc();
-
-    let program = parse_program("H 0".to_string());
-    print_program(&program);
-    let chip = get_chip();
-    let program = compile_program(&program, &chip);
-    print_program(&program);
-}