src/tools/rust-analyzer/crates/hir-def/src/path.rs - toolchain/rustc - Git at Google

 //! A desugared representation of paths like `crate::foo` or `<Type as Trait>::bar`.
 mod lower;

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

 use crate::{
     lang_item::LangItemTarget,
     lower::LowerCtx,
     type_ref::{ConstRef, LifetimeRef, TypeBound, TypeRef},
 };
 use hir_expand::name::Name;
 use intern::Interned;
 use syntax::ast;

 pub use hir_expand::mod_path::{path, ModPath, PathKind};

 #[derive(Debug, Clone, PartialEq, Eq)]
 pub enum ImportAlias {
     /// Unnamed alias, as in `use Foo as _;`
     Underscore,
     /// Named alias
     Alias(Name),
 }

 impl Display for ImportAlias {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
             ImportAlias::Underscore => f.write_str("_"),
             ImportAlias::Alias(name) => f.write_str(&name.to_smol_str()),
         }
     }
 }

 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub enum Path {
     /// A normal path
     Normal {
         /// Type based path like `<T>::foo`.
         /// Note that paths like `<Type as Trait>::foo` are desugared to `Trait::<Self=Type>::foo`.
         type_anchor: Option<Interned<TypeRef>>,
         mod_path: Interned<ModPath>,
         /// Invariant: the same len as `self.mod_path.segments` or `None` if all segments are `None`.
         generic_args: Option<Box<[Option<Interned<GenericArgs>>]>>,
     },
     /// A link to a lang item. It is used in desugaring of things like `it?`. We can show these
     /// links via a normal path since they might be private and not accessible in the usage place.
     LangItem(LangItemTarget, Option<Name>),
 }

 /// Generic arguments to a path segment (e.g. the `i32` in `Option<i32>`). This
 /// also includes bindings of associated types, like in `Iterator<Item = Foo>`.
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct GenericArgs {
     pub args: Box<[GenericArg]>,
     /// This specifies whether the args contain a Self type as the first
     /// element. This is the case for path segments like `<T as Trait>`, where
     /// `T` is actually a type parameter for the path `Trait` specifying the
     /// Self type. Otherwise, when we have a path `Trait<X, Y>`, the Self type
     /// is left out.
     pub has_self_type: bool,
     /// Associated type bindings like in `Iterator<Item = T>`.
     pub bindings: Box<[AssociatedTypeBinding]>,
     /// Whether these generic args were desugared from `Trait(Arg) -> Output`
     /// parenthesis notation typically used for the `Fn` traits.
     pub desugared_from_fn: bool,
 }

 /// An associated type binding like in `Iterator<Item = T>`.
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct AssociatedTypeBinding {
     /// The name of the associated type.
     pub name: Name,
     /// The generic arguments to the associated type. e.g. For `Trait<Assoc<'a, T> = &'a T>`, this
     /// would be `['a, T]`.
     pub args: Option<Interned<GenericArgs>>,
     /// The type bound to this associated type (in `Item = T`, this would be the
     /// `T`). This can be `None` if there are bounds instead.
     pub type_ref: Option<TypeRef>,
     /// Bounds for the associated type, like in `Iterator<Item:
     /// SomeOtherTrait>`. (This is the unstable `associated_type_bounds`
     /// feature.)
     pub bounds: Box<[Interned<TypeBound>]>,
 }

 /// A single generic argument.
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub enum GenericArg {
     Type(TypeRef),
     Lifetime(LifetimeRef),
     Const(ConstRef),
 }

 impl Path {
     /// Converts an `ast::Path` to `Path`. Works with use trees.
     /// It correctly handles `$crate` based path from macro call.
     pub fn from_src(ctx: &LowerCtx<'_>, path: ast::Path) -> Option<Path> {
         lower::lower_path(ctx, path)
     }

     /// Converts a known mod path to `Path`.
     pub fn from_known_path(
         path: ModPath,
         generic_args: impl Into<Box<[Option<Interned<GenericArgs>>]>>,
     ) -> Path {
         let generic_args = generic_args.into();
         assert_eq!(path.len(), generic_args.len());
         Path::Normal {
             type_anchor: None,
             mod_path: Interned::new(path),
             generic_args: Some(generic_args),
         }
     }

     /// Converts a known mod path to `Path`.
     pub fn from_known_path_with_no_generic(path: ModPath) -> Path {
         Path::Normal { type_anchor: None, mod_path: Interned::new(path), generic_args: None }
     }

     pub fn kind(&self) -> &PathKind {
         match self {
             Path::Normal { mod_path, .. } => &mod_path.kind,
             Path::LangItem(..) => &PathKind::Abs,
         }
     }

     pub fn type_anchor(&self) -> Option<&TypeRef> {
         match self {
             Path::Normal { type_anchor, .. } => type_anchor.as_deref(),
             Path::LangItem(..) => None,
         }
     }

     pub fn segments(&self) -> PathSegments<'_> {
         match self {
             Path::Normal { mod_path, generic_args, .. } => {
                 let s = PathSegments {
                     segments: mod_path.segments(),
                     generic_args: generic_args.as_deref(),
                 };
                 if let Some(generic_args) = s.generic_args {
                     assert_eq!(s.segments.len(), generic_args.len());
                 }
                 s
             }
             Path::LangItem(_, seg) => PathSegments {
                 segments: seg.as_ref().map_or(&[], |seg| std::slice::from_ref(seg)),
                 generic_args: None,
             },
         }
     }

     pub fn mod_path(&self) -> Option<&ModPath> {
         match self {
             Path::Normal { mod_path, .. } => Some(mod_path),
             Path::LangItem(..) => None,
         }
     }

     pub fn qualifier(&self) -> Option<Path> {
         let Path::Normal { mod_path, generic_args, type_anchor } = self else {
             return None;
         };
         if mod_path.is_ident() {
             return None;
         }
         let res = Path::Normal {
             type_anchor: type_anchor.clone(),
             mod_path: Interned::new(ModPath::from_segments(
                 mod_path.kind,
                 mod_path.segments()[..mod_path.segments().len() - 1].iter().cloned(),
             )),
             generic_args: generic_args.as_ref().map(|it| it[..it.len() - 1].to_vec().into()),
         };
         Some(res)
     }

     pub fn is_self_type(&self) -> bool {
         let Path::Normal { mod_path, generic_args, type_anchor } = self else {
             return false;
         };
         type_anchor.is_none() && generic_args.as_deref().is_none() && mod_path.is_Self()
     }
 }

 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct PathSegment<'a> {
     pub name: &'a Name,
     pub args_and_bindings: Option<&'a GenericArgs>,
 }

 pub struct PathSegments<'a> {
     segments: &'a [Name],
     generic_args: Option<&'a [Option<Interned<GenericArgs>>]>,
 }

 impl<'a> PathSegments<'a> {
     pub const EMPTY: PathSegments<'static> = PathSegments { segments: &[], generic_args: None };
     pub fn is_empty(&self) -> bool {
         self.len() == 0
     }
     pub fn len(&self) -> usize {
         self.segments.len()
     }
     pub fn first(&self) -> Option<PathSegment<'a>> {
         self.get(0)
     }
     pub fn last(&self) -> Option<PathSegment<'a>> {
         self.get(self.len().checked_sub(1)?)
     }
     pub fn get(&self, idx: usize) -> Option<PathSegment<'a>> {
         let res = PathSegment {
             name: self.segments.get(idx)?,
             args_and_bindings: self.generic_args.and_then(|it| it.get(idx)?.as_deref()),
         };
         Some(res)
     }
     pub fn skip(&self, len: usize) -> PathSegments<'a> {
         PathSegments {
             segments: self.segments.get(len..).unwrap_or(&[]),
             generic_args: self.generic_args.and_then(|it| it.get(len..)),
         }
     }
     pub fn take(&self, len: usize) -> PathSegments<'a> {
         PathSegments {
             segments: self.segments.get(..len).unwrap_or(self.segments),
             generic_args: self.generic_args.map(|it| it.get(..len).unwrap_or(it)),
         }
     }
     pub fn iter(&self) -> impl Iterator<Item = PathSegment<'a>> {
         self.segments
             .iter()
             .zip(self.generic_args.into_iter().flatten().chain(iter::repeat(&None)))
             .map(|(name, args)| PathSegment { name, args_and_bindings: args.as_deref() })
     }
 }

 impl GenericArgs {
     pub(crate) fn from_ast(
         lower_ctx: &LowerCtx<'_>,
         node: ast::GenericArgList,
     ) -> Option<GenericArgs> {
         lower::lower_generic_args(lower_ctx, node)
     }

     pub(crate) fn empty() -> GenericArgs {
         GenericArgs {
             args: Box::default(),
             has_self_type: false,
             bindings: Box::default(),
             desugared_from_fn: false,
         }
     }
 }

 impl From<Name> for Path {
     fn from(name: Name) -> Path {
         Path::Normal {
             type_anchor: None,
             mod_path: Interned::new(ModPath::from_segments(PathKind::Plain, iter::once(name))),
             generic_args: None,
         }
     }
 }

 impl From<Name> for Box<Path> {
     fn from(name: Name) -> Box<Path> {
         Box::new(Path::from(name))
     }
 }
	//! A desugared representation of paths like `crate::foo` or `<Type as Trait>::bar`.
	mod lower;

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

	use crate::{
	lang_item::LangItemTarget,
	lower::LowerCtx,
	type_ref::{ConstRef, LifetimeRef, TypeBound, TypeRef},
	};
	use hir_expand::name::Name;
	use intern::Interned;
	use syntax::ast;

	pub use hir_expand::mod_path::{path, ModPath, PathKind};

	#[derive(Debug, Clone, PartialEq, Eq)]
	pub enum ImportAlias {
	/// Unnamed alias, as in `use Foo as _;`
	Underscore,
	/// Named alias
	Alias(Name),
	}

	impl Display for ImportAlias {
	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
	match self {
	ImportAlias::Underscore => f.write_str("_"),
	ImportAlias::Alias(name) => f.write_str(&name.to_smol_str()),
	}
	}
	}

	#[derive(Debug, Clone, PartialEq, Eq, Hash)]
	pub enum Path {
	/// A normal path
	Normal {
	/// Type based path like `<T>::foo`.
	/// Note that paths like `<Type as Trait>::foo` are desugared to `Trait::<Self=Type>::foo`.
	type_anchor: Option<Interned<TypeRef>>,
	mod_path: Interned<ModPath>,
	/// Invariant: the same len as `self.mod_path.segments` or `None` if all segments are `None`.
	generic_args: Option<Box<[Option<Interned<GenericArgs>>]>>,
	},
	/// A link to a lang item. It is used in desugaring of things like `it?`. We can show these
	/// links via a normal path since they might be private and not accessible in the usage place.
	LangItem(LangItemTarget, Option<Name>),
	}

	/// Generic arguments to a path segment (e.g. the `i32` in `Option<i32>`). This
	/// also includes bindings of associated types, like in `Iterator<Item = Foo>`.
	#[derive(Debug, Clone, PartialEq, Eq, Hash)]
	pub struct GenericArgs {
	pub args: Box<[GenericArg]>,
	/// This specifies whether the args contain a Self type as the first
	/// element. This is the case for path segments like `<T as Trait>`, where
	/// `T` is actually a type parameter for the path `Trait` specifying the
	/// Self type. Otherwise, when we have a path `Trait<X, Y>`, the Self type
	/// is left out.
	pub has_self_type: bool,
	/// Associated type bindings like in `Iterator<Item = T>`.
	pub bindings: Box<[AssociatedTypeBinding]>,
	/// Whether these generic args were desugared from `Trait(Arg) -> Output`
	/// parenthesis notation typically used for the `Fn` traits.
	pub desugared_from_fn: bool,
	}

	/// An associated type binding like in `Iterator<Item = T>`.
	#[derive(Debug, Clone, PartialEq, Eq, Hash)]
	pub struct AssociatedTypeBinding {
	/// The name of the associated type.
	pub name: Name,
	/// The generic arguments to the associated type. e.g. For `Trait<Assoc<'a, T> = &'a T>`, this
	/// would be `['a, T]`.
	pub args: Option<Interned<GenericArgs>>,
	/// The type bound to this associated type (in `Item = T`, this would be the
	/// `T`). This can be `None` if there are bounds instead.
	pub type_ref: Option<TypeRef>,
	/// Bounds for the associated type, like in `Iterator<Item:
	/// SomeOtherTrait>`. (This is the unstable `associated_type_bounds`
	/// feature.)
	pub bounds: Box<[Interned<TypeBound>]>,
	}

	/// A single generic argument.
	#[derive(Debug, Clone, PartialEq, Eq, Hash)]
	pub enum GenericArg {
	Type(TypeRef),
	Lifetime(LifetimeRef),
	Const(ConstRef),
	}

	impl Path {
	/// Converts an `ast::Path` to `Path`. Works with use trees.
	/// It correctly handles `$crate` based path from macro call.
	pub fn from_src(ctx: &LowerCtx<'_>, path: ast::Path) -> Option<Path> {
	lower::lower_path(ctx, path)
	}

	/// Converts a known mod path to `Path`.
	pub fn from_known_path(
	path: ModPath,
	generic_args: impl Into<Box<[Option<Interned<GenericArgs>>]>>,
	) -> Path {
	let generic_args = generic_args.into();
	assert_eq!(path.len(), generic_args.len());
	Path::Normal {
	type_anchor: None,
	mod_path: Interned::new(path),
	generic_args: Some(generic_args),
	}
	}

	/// Converts a known mod path to `Path`.
	pub fn from_known_path_with_no_generic(path: ModPath) -> Path {
	Path::Normal { type_anchor: None, mod_path: Interned::new(path), generic_args: None }
	}

	pub fn kind(&self) -> &PathKind {
	match self {
	Path::Normal { mod_path, .. } => &mod_path.kind,
	Path::LangItem(..) => &PathKind::Abs,
	}
	}

	pub fn type_anchor(&self) -> Option<&TypeRef> {
	match self {
	Path::Normal { type_anchor, .. } => type_anchor.as_deref(),
	Path::LangItem(..) => None,
	}
	}

	pub fn segments(&self) -> PathSegments<'_> {
	match self {
	Path::Normal { mod_path, generic_args, .. } => {
	let s = PathSegments {
	segments: mod_path.segments(),
	generic_args: generic_args.as_deref(),
	};
	if let Some(generic_args) = s.generic_args {
	assert_eq!(s.segments.len(), generic_args.len());
	}
	s
	}
	Path::LangItem(_, seg) => PathSegments {
	segments: seg.as_ref().map_or(&[], \|seg\| std::slice::from_ref(seg)),
	generic_args: None,
	},
	}
	}

	pub fn mod_path(&self) -> Option<&ModPath> {
	match self {
	Path::Normal { mod_path, .. } => Some(mod_path),
	Path::LangItem(..) => None,
	}
	}

	pub fn qualifier(&self) -> Option<Path> {
	let Path::Normal { mod_path, generic_args, type_anchor } = self else {
	return None;
	};
	if mod_path.is_ident() {
	return None;
	}
	let res = Path::Normal {
	type_anchor: type_anchor.clone(),
	mod_path: Interned::new(ModPath::from_segments(
	mod_path.kind,
	mod_path.segments()[..mod_path.segments().len() - 1].iter().cloned(),
	)),
	generic_args: generic_args.as_ref().map(\|it\| it[..it.len() - 1].to_vec().into()),
	};
	Some(res)
	}

	pub fn is_self_type(&self) -> bool {
	let Path::Normal { mod_path, generic_args, type_anchor } = self else {
	return false;
	};
	type_anchor.is_none() && generic_args.as_deref().is_none() && mod_path.is_Self()
	}
	}

	#[derive(Debug, Clone, PartialEq, Eq, Hash)]
	pub struct PathSegment<'a> {
	pub name: &'a Name,
	pub args_and_bindings: Option<&'a GenericArgs>,
	}

	pub struct PathSegments<'a> {
	segments: &'a [Name],
	generic_args: Option<&'a [Option<Interned<GenericArgs>>]>,
	}

	impl<'a> PathSegments<'a> {
	pub const EMPTY: PathSegments<'static> = PathSegments { segments: &[], generic_args: None };
	pub fn is_empty(&self) -> bool {
	self.len() == 0
	}
	pub fn len(&self) -> usize {
	self.segments.len()
	}
	pub fn first(&self) -> Option<PathSegment<'a>> {
	self.get(0)
	}
	pub fn last(&self) -> Option<PathSegment<'a>> {
	self.get(self.len().checked_sub(1)?)
	}
	pub fn get(&self, idx: usize) -> Option<PathSegment<'a>> {
	let res = PathSegment {
	name: self.segments.get(idx)?,
	args_and_bindings: self.generic_args.and_then(\|it\| it.get(idx)?.as_deref()),
	};
	Some(res)
	}
	pub fn skip(&self, len: usize) -> PathSegments<'a> {
	PathSegments {
	segments: self.segments.get(len..).unwrap_or(&[]),
	generic_args: self.generic_args.and_then(\|it\| it.get(len..)),
	}
	}
	pub fn take(&self, len: usize) -> PathSegments<'a> {
	PathSegments {
	segments: self.segments.get(..len).unwrap_or(self.segments),
	generic_args: self.generic_args.map(\|it\| it.get(..len).unwrap_or(it)),
	}
	}
	pub fn iter(&self) -> impl Iterator<Item = PathSegment<'a>> {
	self.segments
	.iter()
	.zip(self.generic_args.into_iter().flatten().chain(iter::repeat(&None)))
	.map(\|(name, args)\| PathSegment { name, args_and_bindings: args.as_deref() })
	}
	}

	impl GenericArgs {
	pub(crate) fn from_ast(
	lower_ctx: &LowerCtx<'_>,
	node: ast::GenericArgList,
	) -> Option<GenericArgs> {
	lower::lower_generic_args(lower_ctx, node)
	}

	pub(crate) fn empty() -> GenericArgs {
	GenericArgs {
	args: Box::default(),
	has_self_type: false,
	bindings: Box::default(),
	desugared_from_fn: false,
	}
	}
	}

	impl From<Name> for Path {
	fn from(name: Name) -> Path {
	Path::Normal {
	type_anchor: None,
	mod_path: Interned::new(ModPath::from_segments(PathKind::Plain, iter::once(name))),
	generic_args: None,
	}
	}
	}

	impl From<Name> for Box<Path> {
	fn from(name: Name) -> Box<Path> {
	Box::new(Path::from(name))
	}
	}