1 files changed, 73 insertions, 0 deletions
diff --git a/autochomp/build.rs b/autochomp/build.rs
new file mode 100644
index 0000000..952d49c
--- /dev/null
+++ b/autochomp/build.rs
@@ -0,0 +1,73 @@
+use std::{
+    env,
+    error::Error,
+    fmt::Display,
+    fs,
+    io::{Read, Write},
+    path::Path,
+    process::exit,
+};
+
+use chomp::{
+    chomp::{
+        check::{InlineCall, TypeCheck},
+        context::Context,
+        visit::Visitable,
+    },
+    lower::{rust::RustBackend, Backend, GenerateCode},
+    nibble::cst::File,
+};
+
+const PATH: &str = "src/nibble.nb";
+
+#[derive(Debug)]
+struct UndecVar;
+
+impl Display for UndecVar {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "Undeclared variable somewhere.")
+    }
+}
+impl Error for UndecVar {}
+
+fn main() {
+    println!("cargo:rerun-if-changed={}", PATH);
+
+    let out_dir = env::var("OUT_DIR").unwrap();
+
+    let mut input = String::new();
+    let res = fs::File::open(PATH)
+        .map_err(|e| Box::new(e) as Box<dyn Error>)
+        .and_then(|mut file| file.read_to_string(&mut input).map_err(|e| Box::new(e) as Box<dyn Error>))
+        .and_then(|_| syn::parse_str(&input).map_err(|e| Box::new(e) as Box<dyn Error>))
+        .and_then(|nibble: File| nibble.convert().ok_or(Box::new(UndecVar) as Box<dyn Error>))
+        .and_then(|(funs, goal)| {
+            funs.into_iter()
+                .try_rfold(goal, |goal, function| {
+                    goal.fold(&mut InlineCall::new(function))
+                })
+                .map_err(|e| Box::new(e) as Box<dyn Error>)
+        })
+        .and_then(|term| {
+            let mut context = Context::default();
+            term.fold(&mut TypeCheck {
+                context: &mut context,
+            })
+            .map_err(|e| Box::new(e) as Box<dyn Error>)
+        })
+        .map(|typed| {
+            let mut backend = RustBackend::default();
+            let id = typed.gen(&mut backend);
+            backend.emit_code(id)
+        })
+        .and_then(|code| {
+            fs::File::create(Path::new(&out_dir).join("nibble.rs"))
+                .and_then(|mut f| write!(f, "{}", code))
+                .map_err(|e| Box::new(e) as Box<dyn Error>)
+        });
+
+    if let Err(e) = res {
+        eprintln!("{}", e);
+        exit(1)
+    }
+}