src/ty.rs

use super::*;

use common::word;
use generics::{lifetime, lifetime_def, ty_param_bound, bound_lifetimes};
use nom::{digit, multispace as space};

use std::str;

#[derive(Debug, Clone, Eq, PartialEq)]
pub enum Ty {
    /// A variable-length array (`[T]`)
    Vec(Box<Ty>),
    /// A fixed length array (`[T; n]`)
    FixedLengthVec(Box<Ty>, usize),
    /// A raw pointer (`*const T` or `*mut T`)
    Ptr(Box<MutTy>),
    /// A reference (`&'a T` or `&'a mut T`)
    Rptr(Option<Lifetime>, Box<MutTy>),
    /// A bare function (e.g. `fn(usize) -> bool`)
    BareFn(Box<BareFnTy>),
    /// The never type (`!`)
    Never,
    /// A tuple (`(A, B, C, D, ...)`)
    Tup(Vec<Ty>),
    /// A path (`module::module::...::Type`), optionally
    /// "qualified", e.g. `<Vec<T> as SomeTrait>::SomeType`.
    ///
    /// Type parameters are stored in the Path itself
    Path(Option<QSelf>, Path),
    /// Something like `A+B`. Note that `B` must always be a path.
    ObjectSum(Box<Ty>, Vec<TyParamBound>),
    /// A type like `for<'a> Foo<&'a Bar>`
    PolyTraitRef(Vec<TyParamBound>),
    /// An `impl TraitA+TraitB` type.
    ImplTrait(Vec<TyParamBound>),
    /// No-op; kept solely so that we can pretty-print faithfully
    Paren(Box<Ty>),
    /// TyKind::Infer means the type should be inferred instead of it having been
    /// specified. This can appear anywhere in a type.
    Infer,
}

#[derive(Debug, Clone, Eq, PartialEq)]
pub struct MutTy {
    pub ty: Ty,
    pub mutability: Mutability,
}

#[derive(Debug, Clone, Eq, PartialEq)]
pub enum Mutability {
    Mutable,
    Immutable,
}

#[derive(Debug, Clone, Eq, PartialEq)]
pub struct Path {
    pub global: bool,
    pub segments: Vec<PathSegment>,
}

/// A segment of a path: an identifier, an optional lifetime, and a set of types.
///
/// E.g. `std`, `String` or `Box<T>`
#[derive(Debug, Clone, Eq, PartialEq)]
pub struct PathSegment {
    pub ident: Ident,
    pub parameters: PathParameters,
}

impl PathSegment {
    pub fn ident(ident: Ident) -> Self {
        PathSegment {
            ident: ident,
            parameters: PathParameters::none(),
        }
    }
}

/// Parameters of a path segment.
///
/// E.g. `<A, B>` as in `Foo<A, B>` or `(A, B)` as in `Foo(A, B)`
#[derive(Debug, Clone, Eq, PartialEq)]
pub enum PathParameters {
    /// The `<'a, A, B, C>` in `foo::bar::baz::<'a, A, B, C>`
    AngleBracketed(AngleBracketedParameterData),
    /// The `(A, B)` and `C` in `Foo(A, B) -> C`
    Parenthesized(ParenthesizedParameterData),
}

impl PathParameters {
    pub fn none() -> Self {
        PathParameters::AngleBracketed(AngleBracketedParameterData::default())
    }
}

/// A path like `Foo<'a, T>`
#[derive(Debug, Clone, Eq, PartialEq, Default)]
pub struct AngleBracketedParameterData {
    /// The lifetime parameters for this path segment.
    pub lifetimes: Vec<Lifetime>,
    /// The type parameters for this path segment, if present.
    pub types: Vec<Ty>,
    /// Bindings (equality constraints) on associated types, if present.
    ///
    /// E.g., `Foo<A=Bar>`.
    pub bindings: Vec<TypeBinding>,
}

/// Bind a type to an associated type: `A=Foo`.
#[derive(Debug, Clone, Eq, PartialEq)]
pub struct TypeBinding {
    pub ident: Ident,
    pub ty: Ty,
}

/// A path like `Foo(A,B) -> C`
#[derive(Debug, Clone, Eq, PartialEq)]
pub struct ParenthesizedParameterData {
    /// `(A, B)`
    pub inputs: Vec<Ty>,
    /// `C`
    pub output: Option<Ty>,
}

#[derive(Debug, Clone, Eq, PartialEq)]
pub struct PolyTraitRef {
    /// The `'a` in `<'a> Foo<&'a T>`
    pub bound_lifetimes: Vec<LifetimeDef>,
    /// The `Foo<&'a T>` in `<'a> Foo<&'a T>`
    pub trait_ref: Path,
}

/// The explicit Self type in a "qualified path". The actual
/// path, including the trait and the associated item, is stored
/// separately. `position` represents the index of the associated
/// item qualified with this Self type.
///
/// ```rust,ignore
/// <Vec<T> as a::b::Trait>::AssociatedItem
///  ^~~~~     ~~~~~~~~~~~~~~^
///  ty        position = 3
///
/// <Vec<T>>::AssociatedItem
///  ^~~~~    ^
///  ty       position = 0
/// ```
#[derive(Debug, Clone, Eq, PartialEq)]
pub struct QSelf {
    pub ty: Box<Ty>,
    pub position: usize
}

#[derive(Debug, Clone, Eq, PartialEq)]
pub struct BareFnTy {
    pub lifetimes: Vec<LifetimeDef>,
    pub decl: FnDecl
}

/// Header (not the body) of a function declaration.
///
/// E.g. `fn foo(bar: baz)`
#[derive(Debug, Clone, Eq, PartialEq)]
pub struct FnDecl {
    pub inputs: Vec<Arg>,
    pub output: FunctionRetTy,
}

/// An argument in a function header.
///
/// E.g. `bar: usize` as in `fn foo(bar: usize)`
#[derive(Debug, Clone, Eq, PartialEq)]
pub struct Arg {
    pub pat: Option<Ident>,
    pub ty: Ty,
}

#[derive(Debug, Clone, Eq, PartialEq)]
pub enum FunctionRetTy {
    /// Return type is not specified.
    ///
    /// Functions default to `()` and
    /// closures default to inference. Span points to where return
    /// type would be inserted.
    Default,
    /// Everything else
    Ty(Ty),
}

named!(pub ty<&str, Ty>, alt!(
    delimited!(
        punct!("["),
        ty,
        punct!("]")
    ) => { |elem| Ty::Vec(Box::new(elem)) }
    |
    chain!(
        punct!("[") ~
        elem: ty ~
        punct!(";") ~
        space? ~
        size: map_res!(digit, str::parse),
        move || Ty::FixedLengthVec(Box::new(elem), size)
    )
    |
    chain!(
        punct!("*") ~
        mutability: alt!(
            punct!("const") => { |_| Mutability::Immutable }
            |
            punct!("mut") => { |_| Mutability::Mutable }
        ) ~
        target: ty,
        move || Ty::Ptr(Box::new(MutTy {
            ty: target,
            mutability: mutability,
        }))
    )
    |
    chain!(
        punct!("&") ~
        life: lifetime? ~
        mutability: mutability ~
        target: ty,
        move || Ty::Rptr(life, Box::new(MutTy {
            ty: target,
            mutability: mutability,
        }))
    )
    |
    chain!(
        punct!("fn") ~
        space ~
        lifetimes: opt_vec!(delimited!(
            punct!("<"),
            separated_list!(punct!(","), lifetime_def),
            punct!(">")
        )) ~
        punct!("(") ~
        inputs: separated_list!(punct!(","), fn_arg) ~
        punct!(")") ~
        output: opt!(preceded!(
            punct!("->"),
            ty
        )),
        move || Ty::BareFn(Box::new(BareFnTy {
            lifetimes: lifetimes,
            decl: FnDecl {
                inputs: inputs,
                output: match output {
                    Some(ty) => FunctionRetTy::Ty(ty),
                    None => FunctionRetTy::Default,
                },
            },
        }))
    )
    |
    punct!("!") => { |_| Ty::Never }
    |
    delimited!(
        punct!("("),
        separated_list!(punct!(","), ty),
        punct!(")")
    ) => { Ty::Tup }
    |
    path => { |p| Ty::Path(None, p) }
    |
    chain!(
        punct!("<") ~
        this: map!(ty, Box::new) ~
        path: opt!(preceded!(
            tuple!(punct!("as"), space),
            path
        )) ~
        punct!(">") ~
        punct!("::") ~
        rest: separated_nonempty_list!(punct!("::"), path_segment),
        move || {
            match path {
                Some(mut path) => {
                    let pos = path.segments.len();
                    path.segments.extend(rest);
                    Ty::Path(Some(QSelf { ty: this, position: pos }), path)
                }
                None => {
                    Ty::Path(Some(QSelf { ty: this, position: 0 }), Path {
                        global: false,
                        segments: rest,
                    })
                }
            }
        }
    )
    |
    preceded!(
        tuple!(punct!("impl"), space),
        separated_nonempty_list!(punct!("+"), ty_param_bound)
    ) => { Ty::ImplTrait }
    |
    delimited!(
        punct!("("),
        ty,
        punct!(")")
    ) => { |inner| Ty::Paren(Box::new(inner)) }
));

named!(mutability<&str, Mutability>, preceded!(
    opt!(space),
    alt!(
        terminated!(tag_s!("mut"), space) => { |_| Mutability::Mutable }
        |
        epsilon!() => { |_| Mutability::Immutable }
    )
));

named!(path<&str, Path>, chain!(
    global: punct!("::")? ~
    segments: separated_nonempty_list!(punct!("::"), path_segment),
    move || Path {
        global: global.is_some(),
        segments: segments,
    }
));

named!(path_segment<&str, PathSegment>, alt!(
    chain!(
        ident: word ~
        punct!("<") ~
        lifetimes: separated_list!(punct!(","), lifetime) ~
        types: opt_vec!(preceded!(
            cond!(!lifetimes.is_empty(), punct!(",")),
            separated_nonempty_list!(
                punct!(","),
                terminated!(ty, not!(peek!(punct!("="))))
            )
        )) ~
        bindings: opt_vec!(preceded!(
            cond!(!lifetimes.is_empty() || !types.is_empty(), punct!(",")),
            separated_nonempty_list!(punct!(","), type_binding)
        )) ~
        punct!(">"),
        move || PathSegment {
            ident: ident,
            parameters: PathParameters::AngleBracketed(
                AngleBracketedParameterData {
                    lifetimes: lifetimes,
                    types: types,
                    bindings: bindings,
                }
            ),
        }
    )
    |
    map!(word, PathSegment::ident)
));

named!(type_binding<&str, TypeBinding>, chain!(
    ident: word ~
    punct!("=") ~
    ty: ty,
    move || TypeBinding {
        ident: ident,
        ty: ty,
    }
));

named!(pub poly_trait_ref<&str, PolyTraitRef>, chain!(
    bound_lifetimes: bound_lifetimes ~
    trait_ref: path,
    move || PolyTraitRef {
        bound_lifetimes: bound_lifetimes,
        trait_ref: trait_ref,
    }
));

named!(fn_arg<&str, Arg>, chain!(
    pat: opt!(terminated!(word, punct!(":"))) ~
    ty: ty,
    move || Arg {
        pat: pat,
        ty: ty,
    }
));