separating the cli parsing

hblang/src/fs.rs

@@ -4,7 +4,7 @@ use {
         parser::{self, Ast},
     },
     alloc::{string::String, vec::Vec},
-    core::fmt::Write,
+    core::{fmt::Write, num::NonZeroUsize},
     hashbrown::hash_map,
     std::{
         collections::VecDeque,
@@ -39,6 +39,33 @@ pub struct Options {
     pub extra_threads: usize,
 }
 
+impl Options {
+    pub fn from_args(args: &[&str]) -> std::io::Result<Self> {
+        if args.contains(&"--help") || args.contains(&"-h") {
+            log::error!("Usage: hbc [OPTIONS...] <FILE>");
+            log::error!(include_str!("../command-help.txt"));
+            return Err(std::io::ErrorKind::Other.into());
+        }
+
+        Ok(Options {
+            fmt: args.contains(&"--fmt"),
+            fmt_stdout: args.contains(&"--fmt-stdout"),
+            dump_asm: args.contains(&"--dump-asm"),
+            extra_threads: args
+                .iter()
+                .position(|&a| a == "--threads")
+                .map(|i| {
+                    args[i + 1].parse::<NonZeroUsize>().map_err(|e| {
+                        std::io::Error::other(format!("--threads expects non zero integer: {e}"))
+                    })
+                })
+                .transpose()?
+                .map_or(1, NonZeroUsize::get)
+                - 1,
+        })
+    }
+}
+
 pub fn format_to(ast: &parser::Ast, source: &str, out: &mut String) -> core::fmt::Result {
     for (i, expr) in ast.exprs().iter().enumerate() {
         parser::Formatter::new(&ast.file).fmt(expr, out)?;

hblang/src/main.rs

@@ -1,33 +1,15 @@
 #[cfg(feature = "std")]
 fn main() -> std::io::Result<()> {
-    use std::{io::Write, num::NonZeroUsize};
+    use std::io::Write;
 
     log::set_logger(&hblang::Logger).unwrap();
 
     let args = std::env::args().collect::<Vec<_>>();
     let args = args.iter().map(String::as_str).collect::<Vec<_>>();
-
-    if args.contains(&"--help") || args.contains(&"-h") {
-        println!("Usage: hbc [OPTIONS...] <FILE>");
-        println!(include_str!("../command-help.txt"));
-        return Err(std::io::ErrorKind::Other.into());
-    }
+    let opts = hblang::Options::from_args(&args)?;
+    let file = args.iter().filter(|a| !a.starts_with('-')).nth(1).copied().unwrap_or("main.hb");
 
     let mut out = Vec::new();
-    hblang::run_compiler(
-        args.iter().filter(|a| !a.starts_with('-')).nth(1).copied().unwrap_or("main.hb"),
-        hblang::Options {
-            fmt: args.contains(&"--fmt"),
-            fmt_stdout: args.contains(&"--fmt-stdout"),
-            dump_asm: args.contains(&"--dump-asm"),
-            extra_threads: args
-                .iter()
-                .position(|&a| a == "--threads")
-                .map(|i| args[i + 1].parse::<NonZeroUsize>().expect("--threads expects integer"))
-                .map_or(1, NonZeroUsize::get)
-                - 1,
-        },
-        &mut out,
-    )?;
+    hblang::run_compiler(file, opts, &mut out)?;
     std::io::stdout().write_all(&out)
 }