bug fixes and performance improvements

src/pipeline/import_abs_path.rs

@@ -0,0 +1,32 @@
+use std::rc::Rc;
+
+use crate::representations::tree::Module;
+use crate::representations::sourcefile::absolute_path;
+use crate::utils::{Substack};
+use crate::interner::{Token, Interner};
+
+use super::error::{ProjectError, TooManySupers};
+
+pub fn import_abs_path(
+  src_path: &[Token<String>],
+  mod_stack: Substack<Token<String>>,
+  module: &Module<impl Clone, impl Clone>,
+  import_path: &[Token<String>],
+  i: &Interner,
+) -> Result<Vec<Token<String>>, Rc<dyn ProjectError>> {
+  // path of module within file
+  let mod_pathv = mod_stack.iter().rev_vec_clone();
+  // path of module within compilation
+  let abs_pathv = src_path.iter().copied()
+    .chain(mod_pathv.iter().copied())
+    .collect::<Vec<_>>();
+  // preload-target path relative to module
+  // preload-target path within compilation
+  absolute_path(&abs_pathv, import_path, i, &|n| {
+    module.items.contains_key(&n)
+  }).map_err(|_| TooManySupers{
+      path: import_path.iter().map(|t| i.r(*t)).cloned().collect(),
+      offender_file: src_path.iter().map(|t| i.r(*t)).cloned().collect(),
+      offender_mod: mod_pathv.iter().map(|t| i.r(*t)).cloned().collect(),
+  }.rc())
+}