src/generics.rs

use super::*;

#[derive(Debug, Clone, Eq, PartialEq, Default)]
pub struct Generics {
    pub lifetimes: Vec<LifetimeDef>,
    pub ty_params: Vec<TyParam>,
    pub where_clause: Vec<WherePredicate>,
}

#[derive(Debug, Clone, Eq, PartialEq)]
pub struct Lifetime {
    pub ident: Ident,
}

#[derive(Debug, Clone, Eq, PartialEq)]
pub struct LifetimeDef {
    pub lifetime: Lifetime,
    pub bounds: Vec<Lifetime>,
}

#[derive(Debug, Clone, Eq, PartialEq)]
pub struct TyParam {
    pub ident: Ident,
    pub bounds: Vec<TyParamBound>,
    pub default: Option<Ty>,
}

#[derive(Debug, Clone, Eq, PartialEq)]
pub enum TyParamBound {
    MaybeSized,
    Region(Lifetime),
    Trait(PolyTraitRef),
}

/// A single predicate in a `where` clause
#[derive(Debug, Clone, Eq, PartialEq)]
pub enum WherePredicate {
    /// A type binding, e.g. `for<'c> Foo: Send+Clone+'c`
    BoundPredicate(WhereBoundPredicate),
    /// A lifetime predicate, e.g. `'a: 'b+'c`
    RegionPredicate(WhereRegionPredicate),
}

/// A type bound.
///
/// E.g. `for<'c> Foo: Send+Clone+'c`
#[derive(Debug, Clone, Eq, PartialEq)]
pub struct WhereBoundPredicate {
    /// Any lifetimes from a `for` binding
    pub bound_lifetimes: Vec<LifetimeDef>,
    /// The type being bounded
    pub bounded_ty: Ty,
    /// Trait and lifetime bounds (`Clone+Send+'static`)
    pub bounds: Vec<TyParamBound>,
}

/// A lifetime predicate.
///
/// E.g. `'a: 'b+'c`
#[derive(Debug, Clone, Eq, PartialEq)]
pub struct WhereRegionPredicate {
    pub lifetime: Lifetime,
    pub bounds: Vec<Lifetime>,
}

#[cfg(feature = "parsing")]
pub mod parsing {
    use super::*;
    use common::parsing::word;
    use ty::parsing::{ty, poly_trait_ref};
    use nom::multispace;

    named!(pub generics<&str, Generics>, do_parse!(
        bracketed: alt!(
            do_parse!(
                punct!("<") >>
                lifetimes: separated_list!(punct!(","), lifetime_def) >>
                ty_params: opt_vec!(preceded!(
                    cond!(!lifetimes.is_empty(), punct!(",")),
                    separated_nonempty_list!(punct!(","), ty_param)
                )) >>
                punct!(">") >>
                (lifetimes, ty_params)
            )
            |
            epsilon!() => { |_| (Vec::new(), Vec::new()) }
        ) >>
        where_clause: opt_vec!(do_parse!(
            punct!("where") >>
            multispace >>
            predicates: separated_nonempty_list!(punct!(","), where_predicate) >>
            opt!(punct!(",")) >>
            (predicates)
        )) >>
        (Generics {
            lifetimes: bracketed.0,
            ty_params: bracketed.1,
            where_clause: where_clause,
        })
    ));

    named!(pub lifetime<&str, Lifetime>, preceded!(
        punct!("'"),
        map!(word, |ident| Lifetime {
            ident: format!("'{}", ident).into(),
        })
    ));

    named!(pub lifetime_def<&str, LifetimeDef>, do_parse!(
        life: lifetime >>
        bounds: opt_vec!(preceded!(
            punct!(":"),
            separated_nonempty_list!(punct!(","), lifetime)
        )) >>
        (LifetimeDef {
            lifetime: life,
            bounds: bounds,
        })
    ));

    named!(pub bound_lifetimes<&str, Vec<LifetimeDef> >, opt_vec!(do_parse!(
        punct!("for") >>
        punct!("<") >>
        lifetimes: separated_list!(punct!(","), lifetime_def) >>
        punct!(">") >>
        (lifetimes)
    )));

    named!(ty_param<&str, TyParam>, do_parse!(
        ident: word >>
        bounds: opt_vec!(preceded!(
            punct!(":"),
            separated_nonempty_list!(punct!("+"), ty_param_bound)
        )) >>
        default: opt!(preceded!(
            punct!("="),
            ty
        )) >>
        (TyParam {
            ident: ident,
            bounds: bounds,
            default: default,
        })
    ));

    named!(pub ty_param_bound<&str, TyParamBound>, alt!(
        tuple!(punct!("?"), punct!("Sized")) => { |_| TyParamBound::MaybeSized }
        |
        lifetime => { TyParamBound::Region }
        |
        poly_trait_ref => { TyParamBound::Trait }
    ));

    named!(where_predicate<&str, WherePredicate>, alt!(
        do_parse!(
            ident: lifetime >>
            punct!(":") >>
            bounds: separated_nonempty_list!(punct!("+"), lifetime) >>
            (WherePredicate::RegionPredicate(WhereRegionPredicate {
                lifetime: ident,
                bounds: bounds,
            }))
        )
        |
        do_parse!(
            bound_lifetimes: bound_lifetimes >>
            bounded_ty: ty >>
            punct!(":") >>
            bounds: separated_nonempty_list!(punct!("+"), ty_param_bound) >>
            (WherePredicate::BoundPredicate(WhereBoundPredicate {
                bound_lifetimes: bound_lifetimes,
                bounded_ty: bounded_ty,
                bounds: bounds,
            }))
        )
    ));
}

#[cfg(feature = "printing")]
mod printing {
    use super::*;
    use quote::{Tokens, ToTokens};

    impl ToTokens for Lifetime {
        fn to_tokens(&self, tokens: &mut Tokens) {
            self.ident.to_tokens(tokens);
        }
    }

    impl ToTokens for LifetimeDef {
        fn to_tokens(&self, tokens: &mut Tokens) {
            self.lifetime.to_tokens(tokens);
            if !self.bounds.is_empty() {
                tokens.append(":");
                tokens.append_separated(&self.bounds, "+");
            }
        }
    }

    impl ToTokens for TyParamBound {
        fn to_tokens(&self, tokens: &mut Tokens) {
            match *self {
                TyParamBound::MaybeSized => tokens.append("?Sized"),
                TyParamBound::Region(ref lifetime) => lifetime.to_tokens(tokens),
                TyParamBound::Trait(ref trait_ref) => trait_ref.to_tokens(tokens),
            }
        }
    }
}