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: event.rs
    path of file: ./repos/rust-analyzer/crates/parser/src
    
    the code of the file until where you have to start completion: //! This module provides a way to construct a `File`.
//! It is intended to be completely decoupled from the
//! parser, so as to allow to evolve the tree representation
//! and the parser algorithm independently.
use std::mem;

use crate::{
    output::Output,
    SyntaxKind::{self, *},
};

/// `Parser` produces a flat list of `Event`s.
/// They are converted to a tree-structure in
/// a separate pass, via `TreeBuilder`.
#[derive(Debug)]
pub(crate) enum Event {
    /// This event signifies the start of the node.
    /// It should be either abandoned (in which case the
    /// `kind` is `TOMBSTONE`, and the event is ignored),
    /// or completed via a `Finish` event.
    ///
    /// All tokens between a `Start` and a `Finish` would
    /// become the children of the respective node.
    ///
    /// For left-recursive syntactic constructs, the parser produces
    /// a child node before it sees a parent. `forward_parent`
    /// saves the position of current event's parent.
    ///
    /// Co
    
pub(super) fn process(mut events: Vec<Event>) -> Output {
    let mut res = Output::default();
    let mut forward_parents = Vec::new();

    for i in 0..events.len() {
        match mem::replace(&mut events[i], Event::tombstone()) {
            Event::Start { kind, forward_parent } => {
                // For events[A, B, C], B is A's forward_parent, C is B's forward_parent,
                // in the normal control flow, the parent-child relation: `A -> B -> C`,
                // while with the magic forward_parent, it writes: `C <- B <- A`.

                // append `A` into parents.
                forward_parents.push(kind);
                let mut idx = i;
                let mut fp = forward_parent;
                while let Some(fwd) = fp {
                    idx += fwd as usize;
                    // append `A`'s forward_parent `B`
                    fp = match mem::replace(&mut events[idx], Event::tombstone()) {
                        Event::Start { kind, forward_parent } => {
                            forward_parents.push(kind);
                            forward_parent
                        }
                        _ => unreachable!(),
                    };
                    // append `B`'s forward_parent `C` in the next stage.
                }

                for kind in forward_parents.drain(..).rev() {
                    if kind != TOMBSTONE {
                        res.enter_node(kind);
                    }
                }
            }
            Event::Finish => res.leave_node(),
            Event::Token { kind, n_raw_tokens } => {
                res.token(kind, n_raw_tokens);
            }
            Event::FloatSplitHack { ends_in_dot } => {
                res.float_split_hack(ends_in_dot);
                let ev = mem::replace(&mut events[i + 1], Event::tombstone());
                assert!(matches!(ev, Event::Finish), "{ev:?}");
            }
            Event::Error { msg } => res.error(msg),
        }
    }

    res
}