Command line processsing, debug options

rust/src/main.rs

@@ -1,36 +1,55 @@
 mod parser;
 mod evaluator;
 
+use clap::Parser;
+
 use std::io;
 use std::io::prelude::*;
-use std::env;
 use std::fs::File;
+use std::path::PathBuf;
 
-fn repl() {
+#[derive(Parser, Debug)]
+#[clap(author, version, about = "Interpreter for Deelang")]
+struct Cli {
+    #[clap(help="Specify a file to run")]
+    file: Option<PathBuf>,
+    #[clap(short, long, help="Only parse, do not evaluate")]
+    parse_only: bool,
+}
+
+fn repl(cli: &Cli) {
     loop {
         let mut line = String::new();
         io::stdin().read_line(&mut line).unwrap();
         let tree = parser::parse_stmt(&line);
-        match &tree {
-            parser::Stmt::ReplPrint(expr) => println!("{}", evaluator::eval(expr)),
-            _ => (),
-        };
+        if cli.parse_only {
+            println!("{:#?}", tree);
+        } else {
+            match &tree {
+                parser::Stmt::ReplPrint(expr) =>
+                    println!("{}", evaluator::eval(expr)),
+                _ => todo!(),
+            }
+        }
     }
 }
 
-fn script(filename: &str) {
-    let mut file = File::open(filename).expect("Could not read file");
+fn script(cli: &Cli) {
+    let mut file = File::open(cli.file.as_ref().unwrap()).expect("Could not read file");
     let mut prgm = String::new();
     file.read_to_string(&mut prgm).unwrap();
     let tree = parser::parse(&prgm);
-    println!("{:#?}", tree);
+    if cli.parse_only {
+        println!("{:#?}", tree);
+    } else {
+        todo!();
+    }
 }
 
 fn main() {
-    let args: Vec<String> = env::args().collect();
-    if args.len() == 1 {
-        repl();
-    } else {
-        script(&args[1]);
+    let cli = Cli::parse();
+    match cli.file {
+        None => repl(&cli),
+        Some(_) => script(&cli),
     }
 }

rust/src/parser.rs

@@ -160,7 +160,6 @@ fn preprocess(input: &str) -> String {
         output.push_str(line.trim());
         output.push('\n');
     }
-    println!("{}", output);
     output
 }