Add variable resolution; the error behavior is pretty bad here.

src/bin.rs

@@ -3,10 +3,8 @@ use codespan_reporting::diagnostic::Diagnostic;
 use codespan_reporting::files::SimpleFiles;
 use codespan_reporting::term;
 use codespan_reporting::term::termcolor::{ColorChoice, StandardStream};
-use ngr::error::Error;
-use ngr::syntax::Program;
-use pretty::{Arena, Pretty};
-use std::fs;
+use ngr::passes::run_front_end;
+use pretty::Arena;
 
 #[derive(Parser, Debug)]
 #[clap(author, version, about, long_about = None)]
@@ -19,36 +17,27 @@ struct CommandLineArguments {
     file: String,
 }
 
-fn compile_file(
-    file_database: &mut SimpleFiles<String, String>,
-    initial_file_name: &str,
-) -> Result<Program, Error> {
-    let initial_file_contents = fs::read_to_string(initial_file_name)?;
-    let initial_file = file_database.add(initial_file_name.to_string(), initial_file_contents);
-    let db_version = file_database.get(initial_file)?;
-    let db_version_source = db_version.source();
-    Ok(Program::parse(initial_file, db_version_source)?)
-}
-
 fn main() {
     let args = CommandLineArguments::parse();
     let mut file_database = SimpleFiles::new();
     let initial_file_name = &args.file;
+    let mut hil_conversion_result = run_front_end(&mut file_database, initial_file_name);
 
-    match compile_file(&mut file_database, initial_file_name) {
-        Ok(p) => {
-            let arena = Arena::new();
-            p.pretty(&arena)
-                .into_doc()
-                .render_colored(72, StandardStream::stdout(ColorChoice::Auto))
-                .unwrap()
-        }
-        Err(e) => {
-            let diagnostic = Diagnostic::from(e);
-            let writer = StandardStream::stderr(ColorChoice::Auto);
-            let config = codespan_reporting::term::Config::default();
+    let writer = StandardStream::stderr(ColorChoice::Auto);
+    let config = codespan_reporting::term::Config::default();
 
-            term::emit(&mut writer.lock(), &config, &file_database, &diagnostic).unwrap();
-        }
+    for error in hil_conversion_result.errors.drain(..) {
+        term::emit(&mut writer.lock(), &config, &file_database, &Diagnostic::from(error)).unwrap();
+    }
+    for warning in hil_conversion_result.warnings.drain(..) {
+        term::emit(&mut writer.lock(), &config, &file_database, &Diagnostic::from(warning)).unwrap();
+    }
+
+    if let Some((tree, variable_map)) = hil_conversion_result.result {
+        let arena = Arena::new();
+        tree.pretty(&variable_map, &arena)
+            .into_doc()
+            .render_colored(72, StandardStream::stdout(ColorChoice::Auto))
+            .unwrap()
     }
 }