Bunch of improvements

src/parse/import.rs

@@ -0,0 +1,58 @@
+use chumsky::{Parser, prelude::*, text::Character};
+use super::name;
+
+enum Import {
+    Name(Vec<String>, String),
+    All(Vec<String>)
+}
+
+fn prefix(pre: Vec<String>, im: Import) -> Import {
+    match im {
+        Import::Name(ns, name) => Import::Name(
+            pre.into_iter().chain(ns.into_iter()).collect(),
+            name
+        ),
+        Import::All(ns) => Import::All(
+            pre.into_iter().chain(ns.into_iter()).collect()
+        )
+    }
+}
+
+
+type BoxedStrIter = Box<dyn Iterator<Item = String>>;
+type BoxedStrIterIter = Box<dyn Iterator<Item = BoxedStrIter>>;
+
+fn init_table(name: String) -> BoxedStrIterIter {
+    Box::new(vec![Box::new(vec![name].into_iter()) as BoxedStrIter].into_iter())
+}
+
+pub fn import_parser() -> impl Parser<char, Vec<Import>, Error = Simple<char>> {
+    recursive(|expr: Recursive<char, BoxedStrIterIter, Simple<char>>| {
+        name::modname_parser()
+            .padded()
+            .then_ignore(just("::"))
+            .repeated()
+            .then(
+                choice((
+                    expr.clone()
+                        .separated_by(just(','))
+                        .delimited_by(just('('), just(')'))
+                        .map(|v| Box::new(v.into_iter().flatten()) as BoxedStrIterIter),
+                    just("*").map(|s| init_table(s.to_string())),
+                    name::modname_parser().map(init_table)
+                )).padded()
+            ).map(|(pre, post)| {
+                Box::new(post.map(move |el| {
+                    Box::new(pre.clone().into_iter().chain(el)) as BoxedStrIter
+                })) as BoxedStrIterIter
+            })
+    }).padded().map(|paths| {
+        paths.filter_map(|namespaces| {
+            let mut path: Vec<String> = namespaces.collect();
+            match path.pop()?.as_str() {
+                "*" => Some(Import::All(path)),
+                name => Some(Import::Name(path, name.to_owned()))
+            }
+        }).collect()
+    })
+}