You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: mod_path.rs
    path of file: ./repos/rust-analyzer/crates/hir-expand/src
    
    the code of the file until where you have to start completion: //! A lowering for `use`-paths (more generally, paths without angle-bracketed segments).

use std::{
    fmt::{self, Display as _},
    iter,
};

use crate::{
    db::ExpandDatabase,
    hygiene::{marks_rev, SyntaxContextExt, Transparency},
    name::{known, AsName, Name},
    tt,
};
use base_db::CrateId;
use smallvec::SmallVec;
use span::SyntaxContextId;
use syntax::{ast, AstNode};

#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct ModPath {
    pub kind: PathKind,
    segments: SmallVec<[Name; 1]>,
}

#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct UnescapedModPath<'a>(&'a ModPath);

impl<'a> UnescapedModPath<'a> {
    pub fn display(&'a self, db: &'a dyn crate::db::ExpandDatabase) -> impl fmt::Display + 'a {
        UnescapedDisplay { db, path: self }
    }
}

#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub enum PathKind {
    Plain,
    /// `self::` is `Super(0)`
    Super(u8),
    Crate,
    /// Absolute path (::foo)
    Abs,
    // FIXME: Can we remove this somehow?
    /// `$crate` from macro expansion
    DollarCrate(CrateId),
}

impl ModPath {
    pub fn from_src(
        db: &dyn ExpandDatabase,
        path: ast::Path,
   
    
fn convert_path_tt(db: &dyn ExpandDatabase, tt: &[tt::TokenTree]) -> Option<ModPath> {
    let mut leaves = tt.iter().filter_map(|tt| match tt {
        tt::TokenTree::Leaf(leaf) => Some(leaf),
        tt::TokenTree::Subtree(_) => None,
    });
    let mut segments = smallvec::smallvec![];
    let kind = match leaves.next()? {
        tt::Leaf::Punct(tt::Punct { char: ':', .. }) => match leaves.next()? {
            tt::Leaf::Punct(tt::Punct { char: ':', .. }) => PathKind::Abs,
            _ => return None,
        },
        tt::Leaf::Ident(tt::Ident { text, span }) if text == "$crate" => {
            resolve_crate_root(db, span.ctx).map(PathKind::DollarCrate).unwrap_or(PathKind::Crate)
        }
        tt::Leaf::Ident(tt::Ident { text, .. }) if text == "self" => PathKind::Super(0),
        tt::Leaf::Ident(tt::Ident { text, .. }) if text == "super" => {
            let mut deg = 1;
            while let Some(tt::Leaf::Ident(tt::Ident { text, .. })) = leaves.next() {
                if text != "super" {
                    segments.push(Name::new_text_dont_use(text.clone()));
                    break;
                }
                deg += 1;
            }
            PathKind::Super(deg)
        }
        tt::Leaf::Ident(tt::Ident { text, .. }) if text == "crate" => PathKind::Crate,
        tt::Leaf::Ident(ident) => {
            segments.push(Name::new_text_dont_use(ident.text.clone()));
            PathKind::Plain
        }
        _ => return None,
    };
    segments.extend(leaves.filter_map(|leaf| match leaf {
        ::tt::Leaf::Ident(ident) => Some(Name::new_text_dont_use(ident.text.clone())),
        _ => None,
    }));
    Some(ModPath { kind, segments })
}