making the loader function customizable

Signed-off-by: Jakub Doka <jakub.doka2@gmail.com>

lang/README.md

@@ -571,7 +571,7 @@ Vec := fn($Elem: type): type return struct {
 	len: uint,
 	cap: uint,
 
-	new := fn(): Self return .{data: @bitcast(0), len: 0, cap: 0}
+	new := fn(): Self return .{data: @bitcast(@alignof(Elem)), len: 0, cap: 0}
 
 	deinit := fn(vec: ^Self): void {
 		free(@bitcast(vec.data), vec.cap * @sizeof(Elem), @alignof(Elem));

lang/src/fs.rs

@@ -37,15 +37,16 @@ impl log::Log for Logger {
 }
 
 #[derive(Default)]
-pub struct Options {
+pub struct Options<'a> {
     pub fmt: bool,
     pub fmt_stdout: bool,
     pub dump_asm: bool,
     pub in_house_regalloc: bool,
     pub extra_threads: usize,
+    pub resolver: Option<PathResolver<'a>>,
 }
 
-impl Options {
+impl Options<'static> {
     pub fn from_args(args: &[&str], out: &mut Vec<u8>) -> std::io::Result<Self> {
         if args.contains(&"--help") || args.contains(&"-h") {
             writeln!(out, "Usage: hbc [OPTIONS...] <FILE>")?;
@@ -71,6 +72,7 @@ impl Options {
                 .transpose()?
                 .map_or(1, NonZeroUsize::get)
                 - 1,
+            ..Default::default()
         })
     }
 }
@@ -81,7 +83,11 @@ pub fn run_compiler(
     out: &mut Vec<u8>,
     warnings: &mut String,
 ) -> std::io::Result<()> {
-    let parsed = parse_from_fs(options.extra_threads, root_file)?;
+    let parsed = parse_from_fs(
+        options.extra_threads,
+        root_file,
+        options.resolver.unwrap_or(&default_resolve),
+    )?;
 
     if (options.fmt || options.fmt_stdout) && !parsed.errors.is_empty() {
         *out = parsed.errors.into_bytes();
@@ -220,8 +226,7 @@ pub struct Loaded {
     errors: String,
 }
 
-pub fn parse_from_fs(extra_threads: usize, root: &str) -> io::Result<Loaded> {
+fn default_resolve(path: &str, from: &str, tmp: &mut PathBuf) -> Result<PathBuf, CantLoadFile> {
-    fn resolve(path: &str, from: &str, tmp: &mut PathBuf) -> Result<PathBuf, CantLoadFile> {
     tmp.clear();
     match Path::new(from).parent() {
         Some(parent) => tmp.extend([parent, Path::new(path)]),
@@ -229,14 +234,23 @@ pub fn parse_from_fs(extra_threads: usize, root: &str) -> io::Result<Loaded> {
     };
 
     tmp.canonicalize().map_err(|source| CantLoadFile { path: std::mem::take(tmp), source })
-    }
+}
 
-    #[derive(Debug)]
+/// fn(path, from, tmp)
-    struct CantLoadFile {
+pub type PathResolver<'a> =
+    &'a (dyn Fn(&str, &str, &mut PathBuf) -> Result<PathBuf, CantLoadFile> + Send + Sync);
+
+#[derive(Debug)]
+pub struct CantLoadFile {
     path: PathBuf,
     source: io::Error,
-    }
+}
 
+pub fn parse_from_fs(
+    extra_threads: usize,
+    root: &str,
+    resolve: PathResolver,
+) -> io::Result<Loaded> {
     impl core::fmt::Display for CantLoadFile {
         fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
             write!(f, "can't load file: {}", display_rel_path(&self.path),)