[rustc.git] / src / tools / rust-analyzer / crates / hir-def / src / path / lower.rs

//! Transforms syntax into `Path` objects, ideally with accounting for hygiene

use std::iter;

use crate::type_ref::ConstRefOrPath;

use either::Either;
use hir_expand::name::{name, AsName};
use intern::Interned;
use syntax::ast::{self, AstNode, HasTypeBounds};

use super::AssociatedTypeBinding;
use crate::{
    body::LowerCtx,
    path::{GenericArg, GenericArgs, ModPath, Path, PathKind},
    type_ref::{LifetimeRef, TypeBound, TypeRef},
};

/// Converts an `ast::Path` to `Path`. Works with use trees.
/// It correctly handles `$crate` based path from macro call.
pub(super) fn lower_path(mut path: ast::Path, ctx: &LowerCtx<'_>) -> Option<Path> {
    let mut kind = PathKind::Plain;
    let mut type_anchor = None;
    let mut segments = Vec::new();
    let mut generic_args = Vec::new();
    let hygiene = ctx.hygiene();
    loop {
        let segment = path.segment()?;

        if segment.coloncolon_token().is_some() {
            kind = PathKind::Abs;
        }

        match segment.kind()? {
            ast::PathSegmentKind::Name(name_ref) => {
                // FIXME: this should just return name
                match hygiene.name_ref_to_name(ctx.db.upcast(), name_ref) {
                    Either::Left(name) => {
                        let args = segment
                            .generic_arg_list()
                            .and_then(|it| lower_generic_args(ctx, it))
                            .or_else(|| {
                                lower_generic_args_from_fn_path(
                                    ctx,
                                    segment.param_list(),
                                    segment.ret_type(),
                                )
                            })
                            .map(Interned::new);
                        if let Some(_) = args {
                            generic_args.resize(segments.len(), None);
                            generic_args.push(args);
                        }
                        segments.push(name);
                    }
                    Either::Right(crate_id) => {
                        kind = PathKind::DollarCrate(crate_id);
                        break;
                    }
                }
            }
            ast::PathSegmentKind::SelfTypeKw => {
                segments.push(name![Self]);
            }
            ast::PathSegmentKind::Type { type_ref, trait_ref } => {
                assert!(path.qualifier().is_none()); // this can only occur at the first segment

                let self_type = TypeRef::from_ast(ctx, type_ref?);

                match trait_ref {
                    // <T>::foo
                    None => {
                        type_anchor = Some(Interned::new(self_type));
                        kind = PathKind::Plain;
                    }
                    // <T as Trait<A>>::Foo desugars to Trait<Self=T, A>::Foo
                    Some(trait_ref) => {
                        let Path { mod_path, generic_args: path_generic_args, .. } =
                            Path::from_src(trait_ref.path()?, ctx)?;
                        let num_segments = mod_path.segments().len();
                        kind = mod_path.kind;

                        segments.extend(mod_path.segments().iter().cloned().rev());
                        if let Some(path_generic_args) = path_generic_args {
                            generic_args.resize(segments.len() - num_segments, None);
                            generic_args.extend(Vec::from(path_generic_args).into_iter().rev());
                        } else {
                            generic_args.resize(segments.len(), None);
                        }

                        let self_type = GenericArg::Type(self_type);

                        // Insert the type reference (T in the above example) as Self parameter for the trait
                        let last_segment = generic_args.get_mut(segments.len() - num_segments)?;
                        *last_segment = Some(Interned::new(match last_segment.take() {
                            Some(it) => GenericArgs {
                                args: iter::once(self_type)
                                    .chain(it.args.iter().cloned())
                                    .collect(),

                                has_self_type: true,
                                bindings: it.bindings.clone(),
                                desugared_from_fn: it.desugared_from_fn,
                            },
                            None => GenericArgs {
                                args: Box::new([self_type]),
                                has_self_type: true,
                                ..GenericArgs::empty()
                            },
                        }));
                    }
                }
            }
            ast::PathSegmentKind::CrateKw => {
                kind = PathKind::Crate;
                break;
            }
            ast::PathSegmentKind::SelfKw => {
                // don't break out if `self` is the last segment of a path, this mean we got a
                // use tree like `foo::{self}` which we want to resolve as `foo`
                if !segments.is_empty() {
                    kind = PathKind::Super(0);
                    break;
                }
            }
            ast::PathSegmentKind::SuperKw => {
                let nested_super_count = if let PathKind::Super(n) = kind { n } else { 0 };
                kind = PathKind::Super(nested_super_count + 1);
            }
        }
        path = match qualifier(&path) {
            Some(it) => it,
            None => break,
        };
    }
    segments.reverse();
    if !generic_args.is_empty() {
        generic_args.resize(segments.len(), None);
        generic_args.reverse();
    }

    if segments.is_empty() && kind == PathKind::Plain && type_anchor.is_none() {
        // plain empty paths don't exist, this means we got a single `self` segment as our path
        kind = PathKind::Super(0);
    }

    // handle local_inner_macros :
    // Basically, even in rustc it is quite hacky:
    // https://github.com/rust-lang/rust/blob/614f273e9388ddd7804d5cbc80b8865068a3744e/src/librustc_resolve/macros.rs#L456
    // We follow what it did anyway :)
    if segments.len() == 1 && kind == PathKind::Plain {
        if let Some(_macro_call) = path.syntax().parent().and_then(ast::MacroCall::cast) {
            if let Some(crate_id) = hygiene.local_inner_macros(ctx.db.upcast(), path) {
                kind = PathKind::DollarCrate(crate_id);
            }
        }
    }

    let mod_path = Interned::new(ModPath::from_segments(kind, segments));
    return Some(Path {
        type_anchor,
        mod_path,
        generic_args: if generic_args.is_empty() { None } else { Some(generic_args.into()) },
    });

    fn qualifier(path: &ast::Path) -> Option<ast::Path> {
        if let Some(q) = path.qualifier() {
            return Some(q);
        }
        // FIXME: this bottom up traversal is not too precise.
        // Should we handle do a top-down analysis, recording results?
        let use_tree_list = path.syntax().ancestors().find_map(ast::UseTreeList::cast)?;
        let use_tree = use_tree_list.parent_use_tree();
        use_tree.path()
    }
}

pub(super) fn lower_generic_args(
    lower_ctx: &LowerCtx<'_>,
    node: ast::GenericArgList,
) -> Option<GenericArgs> {
    let mut args = Vec::new();
    let mut bindings = Vec::new();
    for generic_arg in node.generic_args() {
        match generic_arg {
            ast::GenericArg::TypeArg(type_arg) => {
                let type_ref = TypeRef::from_ast_opt(lower_ctx, type_arg.ty());
                args.push(GenericArg::Type(type_ref));
            }
            ast::GenericArg::AssocTypeArg(assoc_type_arg) => {
                if let Some(name_ref) = assoc_type_arg.name_ref() {
                    let name = name_ref.as_name();
                    let args = assoc_type_arg
                        .generic_arg_list()
                        .and_then(|args| lower_generic_args(lower_ctx, args))
                        .map(Interned::new);
                    let type_ref = assoc_type_arg.ty().map(|it| TypeRef::from_ast(lower_ctx, it));
                    let bounds = if let Some(l) = assoc_type_arg.type_bound_list() {
                        l.bounds()
                            .map(|it| Interned::new(TypeBound::from_ast(lower_ctx, it)))
                            .collect()
                    } else {
                        Box::default()
                    };
                    bindings.push(AssociatedTypeBinding { name, args, type_ref, bounds });
                }
            }
            ast::GenericArg::LifetimeArg(lifetime_arg) => {
                if let Some(lifetime) = lifetime_arg.lifetime() {
                    let lifetime_ref = LifetimeRef::new(&lifetime);
                    args.push(GenericArg::Lifetime(lifetime_ref))
                }
            }
            ast::GenericArg::ConstArg(arg) => {
                let arg = ConstRefOrPath::from_expr_opt(arg.expr());
                args.push(GenericArg::Const(arg))
            }
        }
    }

    if args.is_empty() && bindings.is_empty() {
        return None;
    }
    Some(GenericArgs {
        args: args.into_boxed_slice(),
        has_self_type: false,
        bindings: bindings.into_boxed_slice(),
        desugared_from_fn: false,
    })
}

/// Collect `GenericArgs` from the parts of a fn-like path, i.e. `Fn(X, Y)
/// -> Z` (which desugars to `Fn<(X, Y), Output=Z>`).
fn lower_generic_args_from_fn_path(
    ctx: &LowerCtx<'_>,
    params: Option<ast::ParamList>,
    ret_type: Option<ast::RetType>,
) -> Option<GenericArgs> {
    let params = params?;
    let mut param_types = Vec::new();
    for param in params.params() {
        let type_ref = TypeRef::from_ast_opt(ctx, param.ty());
        param_types.push(type_ref);
    }
    let args = Box::new([GenericArg::Type(TypeRef::Tuple(param_types))]);
    let bindings = if let Some(ret_type) = ret_type {
        let type_ref = TypeRef::from_ast_opt(ctx, ret_type.ty());
        Box::new([AssociatedTypeBinding {
            name: name![Output],
            args: None,
            type_ref: Some(type_ref),
            bounds: Box::default(),
        }])
    } else {
        // -> ()
        let type_ref = TypeRef::Tuple(Vec::new());
        Box::new([AssociatedTypeBinding {
            name: name![Output],
            args: None,
            type_ref: Some(type_ref),
            bounds: Box::default(),
        }])
    };
    Some(GenericArgs { args, has_self_type: false, bindings, desugared_from_fn: true })
}
Commit	Line	Data
064997fb FG	1	//! Transforms syntax into `Path` objects, ideally with accounting for hygiene
064997fb FG	2
9ffffee4 FG	3	use std::iter;
9ffffee4 FG	4
353b0b11	5	use crate::type_ref::ConstRefOrPath;
064997fb FG	6
	7	use either::Either;
	8	use hir_expand::name::{name, AsName};
9ffffee4	9	use intern::Interned;
064997fb FG	10	use syntax::ast::{self, AstNode, HasTypeBounds};
	11
	12	use super::AssociatedTypeBinding;
	13	use crate::{
	14	body::LowerCtx,
	15	path::{GenericArg, GenericArgs, ModPath, Path, PathKind},
	16	type_ref::{LifetimeRef, TypeBound, TypeRef},
	17	};
	18
	19	/// Converts an `ast::Path` to `Path`. Works with use trees.
	20	/// It correctly handles `$crate` based path from macro call.
	21	pub(super) fn lower_path(mut path: ast::Path, ctx: &LowerCtx<'_>) -> Option<Path> {
	22	let mut kind = PathKind::Plain;
	23	let mut type_anchor = None;
	24	let mut segments = Vec::new();
	25	let mut generic_args = Vec::new();
	26	let hygiene = ctx.hygiene();
	27	loop {
	28	let segment = path.segment()?;
	29
	30	if segment.coloncolon_token().is_some() {
	31	kind = PathKind::Abs;
	32	}
	33
	34	match segment.kind()? {
	35	ast::PathSegmentKind::Name(name_ref) => {
	36	// FIXME: this should just return name
	37	match hygiene.name_ref_to_name(ctx.db.upcast(), name_ref) {
	38	Either::Left(name) => {
	39	let args = segment
	40	.generic_arg_list()
	41	.and_then(\|it\| lower_generic_args(ctx, it))
	42	.or_else(\|\| {
	43	lower_generic_args_from_fn_path(
	44	ctx,
	45	segment.param_list(),
	46	segment.ret_type(),
	47	)
	48	})
	49	.map(Interned::new);
9ffffee4 FG	50	if let Some(_) = args {
	51	generic_args.resize(segments.len(), None);
	52	generic_args.push(args);
	53	}
064997fb	54	segments.push(name);
064997fb FG	55	}
	56	Either::Right(crate_id) => {
	57	kind = PathKind::DollarCrate(crate_id);
	58	break;
	59	}
	60	}
	61	}
	62	ast::PathSegmentKind::SelfTypeKw => {
	63	segments.push(name![Self]);
064997fb FG	64	}
	65	ast::PathSegmentKind::Type { type_ref, trait_ref } => {
	66	assert!(path.qualifier().is_none()); // this can only occur at the first segment
	67
	68	let self_type = TypeRef::from_ast(ctx, type_ref?);
	69
	70	match trait_ref {
	71	// <T>::foo
	72	None => {
	73	type_anchor = Some(Interned::new(self_type));
	74	kind = PathKind::Plain;
	75	}
	76	// <T as Trait<A>>::Foo desugars to Trait<Self=T, A>::Foo
	77	Some(trait_ref) => {
	78	let Path { mod_path, generic_args: path_generic_args, .. } =
	79	Path::from_src(trait_ref.path()?, ctx)?;
	80	let num_segments = mod_path.segments().len();
	81	kind = mod_path.kind;
	82
	83	segments.extend(mod_path.segments().iter().cloned().rev());
9ffffee4 FG	84	if let Some(path_generic_args) = path_generic_args {
	85	generic_args.resize(segments.len() - num_segments, None);
	86	generic_args.extend(Vec::from(path_generic_args).into_iter().rev());
	87	} else {
	88	generic_args.resize(segments.len(), None);
	89	}
	90
	91	let self_type = GenericArg::Type(self_type);
064997fb FG	92
064997fb FG	93	// Insert the type reference (T in the above example) as Self parameter for the trait
9ffffee4 FG	94	let last_segment = generic_args.get_mut(segments.len() - num_segments)?;
	95	*last_segment = Some(Interned::new(match last_segment.take() {
	96	Some(it) => GenericArgs {
	97	args: iter::once(self_type)
	98	.chain(it.args.iter().cloned())
	99	.collect(),
	100
	101	has_self_type: true,
	102	bindings: it.bindings.clone(),
	103	desugared_from_fn: it.desugared_from_fn,
	104	},
	105	None => GenericArgs {
	106	args: Box::new([self_type]),
	107	has_self_type: true,
	108	..GenericArgs::empty()
	109	},
	110	}));
064997fb FG	111	}
	112	}
	113	}
	114	ast::PathSegmentKind::CrateKw => {
	115	kind = PathKind::Crate;
	116	break;
	117	}
	118	ast::PathSegmentKind::SelfKw => {
	119	// don't break out if `self` is the last segment of a path, this mean we got a
	120	// use tree like `foo::{self}` which we want to resolve as `foo`
	121	if !segments.is_empty() {
	122	kind = PathKind::Super(0);
	123	break;
	124	}
	125	}
	126	ast::PathSegmentKind::SuperKw => {
	127	let nested_super_count = if let PathKind::Super(n) = kind { n } else { 0 };
	128	kind = PathKind::Super(nested_super_count + 1);
	129	}
	130	}
	131	path = match qualifier(&path) {
	132	Some(it) => it,
	133	None => break,
	134	};
	135	}
	136	segments.reverse();
9ffffee4 FG	137	if !generic_args.is_empty() {
	138	generic_args.resize(segments.len(), None);
	139	generic_args.reverse();
	140	}
064997fb FG	141
	142	if segments.is_empty() && kind == PathKind::Plain && type_anchor.is_none() {
	143	// plain empty paths don't exist, this means we got a single `self` segment as our path
	144	kind = PathKind::Super(0);
	145	}
	146
	147	// handle local_inner_macros :
	148	// Basically, even in rustc it is quite hacky:
	149	// https://github.com/rust-lang/rust/blob/614f273e9388ddd7804d5cbc80b8865068a3744e/src/librustc_resolve/macros.rs#L456
	150	// We follow what it did anyway :)
	151	if segments.len() == 1 && kind == PathKind::Plain {
	152	if let Some(_macro_call) = path.syntax().parent().and_then(ast::MacroCall::cast) {
	153	if let Some(crate_id) = hygiene.local_inner_macros(ctx.db.upcast(), path) {
	154	kind = PathKind::DollarCrate(crate_id);
	155	}
	156	}
	157	}
	158
	159	let mod_path = Interned::new(ModPath::from_segments(kind, segments));
9ffffee4 FG	160	return Some(Path {
	161	type_anchor,
	162	mod_path,
	163	generic_args: if generic_args.is_empty() { None } else { Some(generic_args.into()) },
	164	});
064997fb FG	165
	166	fn qualifier(path: &ast::Path) -> Option<ast::Path> {
	167	if let Some(q) = path.qualifier() {
	168	return Some(q);
	169	}
	170	// FIXME: this bottom up traversal is not too precise.
	171	// Should we handle do a top-down analysis, recording results?
	172	let use_tree_list = path.syntax().ancestors().find_map(ast::UseTreeList::cast)?;
	173	let use_tree = use_tree_list.parent_use_tree();
	174	use_tree.path()
	175	}
	176	}
	177
	178	pub(super) fn lower_generic_args(
	179	lower_ctx: &LowerCtx<'_>,
	180	node: ast::GenericArgList,
	181	) -> Option<GenericArgs> {
	182	let mut args = Vec::new();
	183	let mut bindings = Vec::new();
	184	for generic_arg in node.generic_args() {
	185	match generic_arg {
	186	ast::GenericArg::TypeArg(type_arg) => {
	187	let type_ref = TypeRef::from_ast_opt(lower_ctx, type_arg.ty());
	188	args.push(GenericArg::Type(type_ref));
	189	}
	190	ast::GenericArg::AssocTypeArg(assoc_type_arg) => {
	191	if let Some(name_ref) = assoc_type_arg.name_ref() {
	192	let name = name_ref.as_name();
487cf647 FG	193	let args = assoc_type_arg
	194	.generic_arg_list()
	195	.and_then(\|args\| lower_generic_args(lower_ctx, args))
	196	.map(Interned::new);
064997fb FG	197	let type_ref = assoc_type_arg.ty().map(\|it\| TypeRef::from_ast(lower_ctx, it));
	198	let bounds = if let Some(l) = assoc_type_arg.type_bound_list() {
	199	l.bounds()
	200	.map(\|it\| Interned::new(TypeBound::from_ast(lower_ctx, it)))
	201	.collect()
	202	} else {
9ffffee4	203	Box::default()
064997fb	204	};
487cf647	205	bindings.push(AssociatedTypeBinding { name, args, type_ref, bounds });
064997fb FG	206	}
	207	}
	208	ast::GenericArg::LifetimeArg(lifetime_arg) => {
	209	if let Some(lifetime) = lifetime_arg.lifetime() {
	210	let lifetime_ref = LifetimeRef::new(&lifetime);
	211	args.push(GenericArg::Lifetime(lifetime_ref))
	212	}
	213	}
	214	ast::GenericArg::ConstArg(arg) => {
353b0b11	215	let arg = ConstRefOrPath::from_expr_opt(arg.expr());
064997fb FG	216	args.push(GenericArg::Const(arg))
	217	}
	218	}
	219	}
	220
	221	if args.is_empty() && bindings.is_empty() {
	222	return None;
	223	}
9ffffee4 FG	224	Some(GenericArgs {
	225	args: args.into_boxed_slice(),
	226	has_self_type: false,
	227	bindings: bindings.into_boxed_slice(),
	228	desugared_from_fn: false,
	229	})
064997fb FG	230	}
	231
	232	/// Collect `GenericArgs` from the parts of a fn-like path, i.e. `Fn(X, Y)
	233	/// -> Z` (which desugars to `Fn<(X, Y), Output=Z>`).
	234	fn lower_generic_args_from_fn_path(
	235	ctx: &LowerCtx<'_>,
	236	params: Option<ast::ParamList>,
	237	ret_type: Option<ast::RetType>,
	238	) -> Option<GenericArgs> {
064997fb FG	239	let params = params?;
	240	let mut param_types = Vec::new();
	241	for param in params.params() {
	242	let type_ref = TypeRef::from_ast_opt(ctx, param.ty());
	243	param_types.push(type_ref);
	244	}
9ffffee4 FG	245	let args = Box::new([GenericArg::Type(TypeRef::Tuple(param_types))]);
9ffffee4 FG	246	let bindings = if let Some(ret_type) = ret_type {
064997fb	247	let type_ref = TypeRef::from_ast_opt(ctx, ret_type.ty());
9ffffee4	248	Box::new([AssociatedTypeBinding {
064997fb	249	name: name![Output],
487cf647	250	args: None,
064997fb	251	type_ref: Some(type_ref),
9ffffee4 FG	252	bounds: Box::default(),
9ffffee4 FG	253	}])
064997fb FG	254	} else {
	255	// -> ()
	256	let type_ref = TypeRef::Tuple(Vec::new());
9ffffee4	257	Box::new([AssociatedTypeBinding {
064997fb	258	name: name![Output],
487cf647	259	args: None,
064997fb	260	type_ref: Some(type_ref),
9ffffee4 FG	261	bounds: Box::default(),
	262	}])
	263	};
064997fb FG	264	Some(GenericArgs { args, has_self_type: false, bindings, desugared_from_fn: true })
064997fb FG	265	}