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: repr.rs
    path of file: ./repos/lalrpop/lalrpop/src/grammar
    
    the code of the file until where you have to start completion: //! Compiled representation of a grammar. Simplified, normalized
//! version of `parse_tree`. The normalization passes produce this
//! representation incrementally.

use crate::collections::{map, Map};
use crate::grammar::free_variables::FreeVariables;
use crate::grammar::pattern::Pattern;
use crate::message::Content;
use crate::util::Sep;
use std::fmt::{Debug, Display, Error, Formatter};
use string_cache::DefaultAtom as Atom;

// These concepts we re-use wholesale
pub use crate::grammar::parse_tree::{
    Annotation, InternToken, Lifetime, Name, NonterminalString, Path, Span, TerminalLiteral,
    TerminalString, TypeBound, TypeParameter, Visibility,
};

#[derive(Clone, Debug)]
pub struct Grammar {
    // a unique prefix that can be appended to identifiers to ensure
    // that they do not conflict with any action strings
    pub prefix: String,

    // algorithm user requested for this parser
    pub algorithm: Algorithm,

    // true if the grammar mentions the `!` terminal anywhere
    pub uses_error_recovery: bool,

    // these are the nonterminals that were declared to be public; the
    // key is the user's name for the symbol, the value is the
    // artificial symbol we introduce, which will always have a single
    // production like `Foo' = Foo`.
    pub start_nonterminals: Map<NonterminalString, NonterminalString>,

    // the "use foo;" statements that the user declared
    pub uses: Vec<String>,

    // type parameters declared on the grammar, like `grammar<T>;`
    pub type_parameters: Vec<TypeParameter>,

    // actual parameters declared on the grammar, like the `x: u32` in `grammar(x: u32);`
    pub parameters: Vec<Parameter>,

    // where clauses declared on the grammar, like `grammar<T> where T: Sized`
    pub where_clauses: Vec<WhereClause>,

 
    
    fn fmt(&self, fmt: &mut Formatter) -> Result<(), Error> {
        match *self {
            TypeRepr::Tuple(ref types) => write!(fmt, "({})", Sep(", ", types)),
            TypeRepr::Slice(ref ty) => write!(fmt, "[{}]", ty),
            TypeRepr::Nominal(ref data) => write!(fmt, "{}", data),
            TypeRepr::Associated {
                ref type_parameter,
                ref id,
            } => write!(fmt, "{}::{}", type_parameter, id),
            TypeRepr::Lifetime(ref id) => write!(fmt, "{}", id),
            TypeRepr::Ref {
                lifetime: None,
                mutable: false,
                ref referent,
            } => write!(fmt, "&{}", referent),
            TypeRepr::Ref {
                lifetime: Some(ref l),
                mutable: false,
                ref referent,
            } => write!(fmt, "&{} {}", l, referent),
            TypeRepr::Ref {
                lifetime: None,
                mutable: true,
                ref referent,
            } => write!(fmt, "&mut {}", referent),
            TypeRepr::Ref {
                lifetime: Some(ref l),
                mutable: true,
                ref referent,
            } => write!(fmt, "&{} mut {}", l, referent),
            TypeRepr::TraitObject(ref data) => write!(fmt, "dyn {}", data),
            TypeRepr::Fn {
                ref forall,
                ref path,
                ref parameters,
                ref ret,
            } => {
                write!(fmt, "dyn ")?;
                if !forall.is_empty() {
                    write!(fmt, "for<{}> ", Sep(", ", forall),)?;
                }
                write!(fmt, "{}({})", path, Sep(", ", parameters))?;
                if let Some(ret) = ret {
                    write!(fmt, " -> {}", ret)?;
                }
                Ok(())
            }
        }
    }