From 8e08b86304f8cf91e06f64855c8de306ad7efaa4 Mon Sep 17 00:00:00 2001 From: rdambrosio Date: Thu, 17 Jun 2021 19:54:28 -0400 Subject: Feat: inline generics in const and func trait completions --- crates/ide_db/src/lib.rs | 1 + crates/ide_db/src/path_transform.rs | 160 ++++++++++++++++++++++++++++++++++++ 2 files changed, 161 insertions(+) create mode 100644 crates/ide_db/src/path_transform.rs (limited to 'crates/ide_db/src') diff --git a/crates/ide_db/src/lib.rs b/crates/ide_db/src/lib.rs index 7bbd08d6f..bde8767dd 100644 --- a/crates/ide_db/src/lib.rs +++ b/crates/ide_db/src/lib.rs @@ -14,6 +14,7 @@ pub mod ty_filter; pub mod traits; pub mod call_info; pub mod helpers; +pub mod path_transform; pub mod search; pub mod rename; diff --git a/crates/ide_db/src/path_transform.rs b/crates/ide_db/src/path_transform.rs new file mode 100644 index 000000000..f3d7aa920 --- /dev/null +++ b/crates/ide_db/src/path_transform.rs @@ -0,0 +1,160 @@ +//! See [`PathTransform`]. + +use crate::helpers::mod_path_to_ast; +use hir::{HirDisplay, SemanticsScope}; +use rustc_hash::FxHashMap; +use syntax::{ + ast::{self, AstNode}, + ted, +}; + +/// `PathTransform` substitutes path in SyntaxNodes in bulk. +/// +/// This is mostly useful for IDE code generation. If you paste some existing +/// code into a new context (for example, to add method overrides to an `impl` +/// block), you generally want to appropriately qualify the names, and sometimes +/// you might want to substitute generic parameters as well: +/// +/// ``` +/// mod x { +/// pub struct A; +/// pub trait T { fn foo(&self, _: U) -> A; } +/// } +/// +/// mod y { +/// use x::T; +/// +/// impl T<()> for () { +/// // If we invoke **Add Missing Members** here, we want to copy-paste `foo`. +/// // But we want a slightly-modified version of it: +/// fn foo(&self, _: ()) -> x::A<()> {} +/// } +/// } +/// ``` +pub struct PathTransform<'a> { + pub subst: (hir::Trait, ast::Impl), + pub target_scope: &'a SemanticsScope<'a>, + pub source_scope: &'a SemanticsScope<'a>, +} + +impl<'a> PathTransform<'a> { + pub fn apply(&self, item: ast::AssocItem) { + if let Some(ctx) = self.build_ctx() { + ctx.apply(item) + } + } + fn build_ctx(&self) -> Option> { + let db = self.source_scope.db; + let target_module = self.target_scope.module()?; + let source_module = self.source_scope.module()?; + + let substs = get_syntactic_substs(self.subst.1.clone()).unwrap_or_default(); + let generic_def: hir::GenericDef = self.subst.0.into(); + let substs_by_param: FxHashMap<_, _> = generic_def + .type_params(db) + .into_iter() + // this is a trait impl, so we need to skip the first type parameter -- this is a bit hacky + .skip(1) + // The actual list of trait type parameters may be longer than the one + // used in the `impl` block due to trailing default type parameters. + // For that case we extend the `substs` with an empty iterator so we + // can still hit those trailing values and check if they actually have + // a default type. If they do, go for that type from `hir` to `ast` so + // the resulting change can be applied correctly. + .zip(substs.into_iter().map(Some).chain(std::iter::repeat(None))) + .filter_map(|(k, v)| match v { + Some(v) => Some((k, v)), + None => { + let default = k.default(db)?; + Some(( + k, + ast::make::ty(&default.display_source_code(db, source_module.into()).ok()?), + )) + } + }) + .collect(); + + let res = Ctx { substs: substs_by_param, target_module, source_scope: self.source_scope }; + Some(res) + } +} + +struct Ctx<'a> { + substs: FxHashMap, + target_module: hir::Module, + source_scope: &'a SemanticsScope<'a>, +} + +impl<'a> Ctx<'a> { + fn apply(&self, item: ast::AssocItem) { + for event in item.syntax().preorder() { + let node = match event { + syntax::WalkEvent::Enter(_) => continue, + syntax::WalkEvent::Leave(it) => it, + }; + if let Some(path) = ast::Path::cast(node.clone()) { + self.transform_path(path); + } + } + } + fn transform_path(&self, path: ast::Path) -> Option<()> { + if path.qualifier().is_some() { + return None; + } + if path.segment().and_then(|s| s.param_list()).is_some() { + // don't try to qualify `Fn(Foo) -> Bar` paths, they are in prelude anyway + return None; + } + + let resolution = self.source_scope.speculative_resolve(&path)?; + + match resolution { + hir::PathResolution::TypeParam(tp) => { + if let Some(subst) = self.substs.get(&tp) { + ted::replace(path.syntax(), subst.clone_subtree().clone_for_update().syntax()) + } + } + hir::PathResolution::Def(def) => { + let found_path = + self.target_module.find_use_path(self.source_scope.db.upcast(), def)?; + let res = mod_path_to_ast(&found_path).clone_for_update(); + if let Some(args) = path.segment().and_then(|it| it.generic_arg_list()) { + if let Some(segment) = res.segment() { + let old = segment.get_or_create_generic_arg_list(); + ted::replace(old.syntax(), args.clone_subtree().syntax().clone_for_update()) + } + } + ted::replace(path.syntax(), res.syntax()) + } + hir::PathResolution::Local(_) + | hir::PathResolution::ConstParam(_) + | hir::PathResolution::SelfType(_) + | hir::PathResolution::Macro(_) + | hir::PathResolution::AssocItem(_) => (), + } + Some(()) + } +} + +// FIXME: It would probably be nicer if we could get this via HIR (i.e. get the +// trait ref, and then go from the types in the substs back to the syntax). +fn get_syntactic_substs(impl_def: ast::Impl) -> Option> { + let target_trait = impl_def.trait_()?; + let path_type = match target_trait { + ast::Type::PathType(path) => path, + _ => return None, + }; + let generic_arg_list = path_type.path()?.segment()?.generic_arg_list()?; + + let mut result = Vec::new(); + for generic_arg in generic_arg_list.generic_args() { + match generic_arg { + ast::GenericArg::TypeArg(type_arg) => result.push(type_arg.ty()?), + ast::GenericArg::AssocTypeArg(_) + | ast::GenericArg::LifetimeArg(_) + | ast::GenericArg::ConstArg(_) => (), + } + } + + Some(result) +} -- cgit v1.2.3