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authorAleksey Kladov <[email protected]>2021-05-22 14:23:07 +0100
committerAleksey Kladov <[email protected]>2021-05-22 14:23:07 +0100
commite6776c3e1b66c8946873d20e1e3bc1d743c952fe (patch)
treed966d440b955cf3aa0258484170048790283b309 /crates/ide_assists/src/ast_transform.rs
parent47d7434dde215460fc95916f2703c6925f58dcce (diff)
use more precise name
Diffstat (limited to 'crates/ide_assists/src/ast_transform.rs')
-rw-r--r--crates/ide_assists/src/ast_transform.rs164
1 files changed, 0 insertions, 164 deletions
diff --git a/crates/ide_assists/src/ast_transform.rs b/crates/ide_assists/src/ast_transform.rs
deleted file mode 100644
index 5d9cc5551..000000000
--- a/crates/ide_assists/src/ast_transform.rs
+++ /dev/null
@@ -1,164 +0,0 @@
1//! `AstTransformer`s are functions that replace nodes in an AST and can be easily combined.
2use hir::{HirDisplay, SemanticsScope};
3use ide_db::helpers::mod_path_to_ast;
4use rustc_hash::FxHashMap;
5use syntax::{
6 ast::{self, AstNode},
7 ted,
8};
9
10/// `AstTransform` helps with applying bulk transformations to syntax nodes.
11///
12/// This is mostly useful for IDE code generation. If you paste some existing
13/// code into a new context (for example, to add method overrides to an `impl`
14/// block), you generally want to appropriately qualify the names, and sometimes
15/// you might want to substitute generic parameters as well:
16///
17/// ```
18/// mod x {
19/// pub struct A<V>;
20/// pub trait T<U> { fn foo(&self, _: U) -> A<U>; }
21/// }
22///
23/// mod y {
24/// use x::T;
25///
26/// impl T<()> for () {
27/// // If we invoke **Add Missing Members** here, we want to copy-paste `foo`.
28/// // But we want a slightly-modified version of it:
29/// fn foo(&self, _: ()) -> x::A<()> {}
30/// }
31/// }
32/// ```
33///
34/// So, a single `AstTransform` describes such function from `SyntaxNode` to
35/// `SyntaxNode`. Note that the API here is a bit too high-order and high-brow.
36/// We'd want to somehow express this concept simpler, but so far nobody got to
37/// simplifying this!
38pub(crate) struct AstTransform<'a> {
39 pub(crate) subst: (hir::Trait, ast::Impl),
40 pub(crate) target_scope: &'a SemanticsScope<'a>,
41 pub(crate) source_scope: &'a SemanticsScope<'a>,
42}
43
44impl<'a> AstTransform<'a> {
45 pub(crate) fn apply(&self, item: ast::AssocItem) {
46 if let Some(ctx) = self.build_ctx() {
47 ctx.apply(item)
48 }
49 }
50 fn build_ctx(&self) -> Option<Ctx<'a>> {
51 let db = self.source_scope.db;
52 let target_module = self.target_scope.module()?;
53 let source_module = self.source_scope.module()?;
54
55 let substs = get_syntactic_substs(self.subst.1.clone()).unwrap_or_default();
56 let generic_def: hir::GenericDef = self.subst.0.into();
57 let substs_by_param: FxHashMap<_, _> = generic_def
58 .type_params(db)
59 .into_iter()
60 // this is a trait impl, so we need to skip the first type parameter -- this is a bit hacky
61 .skip(1)
62 // The actual list of trait type parameters may be longer than the one
63 // used in the `impl` block due to trailing default type parameters.
64 // For that case we extend the `substs` with an empty iterator so we
65 // can still hit those trailing values and check if they actually have
66 // a default type. If they do, go for that type from `hir` to `ast` so
67 // the resulting change can be applied correctly.
68 .zip(substs.into_iter().map(Some).chain(std::iter::repeat(None)))
69 .filter_map(|(k, v)| match v {
70 Some(v) => Some((k, v)),
71 None => {
72 let default = k.default(db)?;
73 Some((
74 k,
75 ast::make::ty(&default.display_source_code(db, source_module.into()).ok()?),
76 ))
77 }
78 })
79 .collect();
80
81 let res = Ctx { substs: substs_by_param, target_module, source_scope: self.source_scope };
82 Some(res)
83 }
84}
85
86struct Ctx<'a> {
87 substs: FxHashMap<hir::TypeParam, ast::Type>,
88 target_module: hir::Module,
89 source_scope: &'a SemanticsScope<'a>,
90}
91
92impl<'a> Ctx<'a> {
93 fn apply(&self, item: ast::AssocItem) {
94 for event in item.syntax().preorder() {
95 let node = match event {
96 syntax::WalkEvent::Enter(_) => continue,
97 syntax::WalkEvent::Leave(it) => it,
98 };
99 if let Some(path) = ast::Path::cast(node.clone()) {
100 self.transform_path(path);
101 }
102 }
103 }
104 fn transform_path(&self, path: ast::Path) -> Option<()> {
105 if path.qualifier().is_some() {
106 return None;
107 }
108 if path.segment().and_then(|s| s.param_list()).is_some() {
109 // don't try to qualify `Fn(Foo) -> Bar` paths, they are in prelude anyway
110 return None;
111 }
112
113 let resolution = self.source_scope.speculative_resolve(&path)?;
114
115 match resolution {
116 hir::PathResolution::TypeParam(tp) => {
117 if let Some(subst) = self.substs.get(&tp) {
118 ted::replace(path.syntax(), subst.clone_subtree().clone_for_update().syntax())
119 }
120 }
121 hir::PathResolution::Def(def) => {
122 let found_path =
123 self.target_module.find_use_path(self.source_scope.db.upcast(), def)?;
124 let res = mod_path_to_ast(&found_path).clone_for_update();
125 if let Some(args) = path.segment().and_then(|it| it.generic_arg_list()) {
126 if let Some(segment) = res.segment() {
127 let old = segment.get_or_create_generic_arg_list();
128 ted::replace(old.syntax(), args.clone_subtree().syntax().clone_for_update())
129 }
130 }
131 ted::replace(path.syntax(), res.syntax())
132 }
133 hir::PathResolution::Local(_)
134 | hir::PathResolution::ConstParam(_)
135 | hir::PathResolution::SelfType(_)
136 | hir::PathResolution::Macro(_)
137 | hir::PathResolution::AssocItem(_) => (),
138 }
139 Some(())
140 }
141}
142
143// FIXME: It would probably be nicer if we could get this via HIR (i.e. get the
144// trait ref, and then go from the types in the substs back to the syntax).
145fn get_syntactic_substs(impl_def: ast::Impl) -> Option<Vec<ast::Type>> {
146 let target_trait = impl_def.trait_()?;
147 let path_type = match target_trait {
148 ast::Type::PathType(path) => path,
149 _ => return None,
150 };
151 let generic_arg_list = path_type.path()?.segment()?.generic_arg_list()?;
152
153 let mut result = Vec::new();
154 for generic_arg in generic_arg_list.generic_args() {
155 match generic_arg {
156 ast::GenericArg::TypeArg(type_arg) => result.push(type_arg.ty()?),
157 ast::GenericArg::AssocTypeArg(_)
158 | ast::GenericArg::LifetimeArg(_)
159 | ast::GenericArg::ConstArg(_) => (),
160 }
161 }
162
163 Some(result)
164}