src/tools/rust-analyzer/crates/ide-completion/src/completions/expr.rs

   1 //! Completion of names from the current scope in expression position.
   2
   3 use hir::ScopeDef;
   4 use syntax::ast;
   5
   6 use crate::{
   7     completions::record::add_default_update,
   8     context::{ExprCtx, PathCompletionCtx, Qualified},
   9     CompletionContext, Completions,
  10 };
  11
  12 pub(crate) fn complete_expr_path(
  13     acc: &mut Completions,
  14     ctx: &CompletionContext<'_>,
  15     path_ctx @ PathCompletionCtx { qualified, .. }: &PathCompletionCtx,
  16     expr_ctx: &ExprCtx,
  17 ) {
  18     let _p = profile::span("complete_expr_path");
  19     if !ctx.qualifier_ctx.none() {
  20         return;
  21     }
  22
  23     let &ExprCtx {
  24         in_block_expr,
  25         in_loop_body,
  26         after_if_expr,
  27         in_condition,
  28         incomplete_let,
  29         ref ref_expr_parent,
  30         ref is_func_update,
  31         ref innermost_ret_ty,
  32         ref impl_,
  33         in_match_guard,
  34         ..
  35     } = expr_ctx;
  36
  37     let wants_mut_token =
  38         ref_expr_parent.as_ref().map(|it| it.mut_token().is_none()).unwrap_or(false);
  39
  40     let scope_def_applicable = |def| match def {
  41         ScopeDef::GenericParam(hir::GenericParam::LifetimeParam(_)) | ScopeDef::Label(_) => false,
  42         ScopeDef::ModuleDef(hir::ModuleDef::Macro(mac)) => mac.is_fn_like(ctx.db),
  43         _ => true,
  44     };
  45
  46     let add_assoc_item = |acc: &mut Completions, item| match item {
  47         hir::AssocItem::Function(func) => acc.add_function(ctx, path_ctx, func, None),
  48         hir::AssocItem::Const(ct) => acc.add_const(ctx, ct),
  49         hir::AssocItem::TypeAlias(ty) => acc.add_type_alias(ctx, ty),
  50     };
  51
  52     match qualified {
  53         Qualified::TypeAnchor { ty: None, trait_: None } => ctx
  54             .traits_in_scope()
  55             .iter()
  56             .flat_map(|&it| hir::Trait::from(it).items(ctx.sema.db))
  57             .for_each(|item| add_assoc_item(acc, item)),
  58         Qualified::TypeAnchor { trait_: Some(trait_), .. } => {
  59             trait_.items(ctx.sema.db).into_iter().for_each(|item| add_assoc_item(acc, item))
  60         }
  61         Qualified::TypeAnchor { ty: Some(ty), trait_: None } => {
  62             if let Some(hir::Adt::Enum(e)) = ty.as_adt() {
  63                 cov_mark::hit!(completes_variant_through_alias);
  64                 acc.add_enum_variants(ctx, path_ctx, e);
  65             }
  66
  67             ctx.iterate_path_candidates(&ty, |item| {
  68                 add_assoc_item(acc, item);
  69             });
  70
  71             // Iterate assoc types separately
  72             ty.iterate_assoc_items(ctx.db, ctx.krate, |item| {
  73                 if let hir::AssocItem::TypeAlias(ty) = item {
  74                     acc.add_type_alias(ctx, ty)
  75                 }
  76                 None::<()>
  77             });
  78         }
  79         Qualified::With { resolution: None, .. } => {}
  80         Qualified::With { resolution: Some(resolution), .. } => {
  81             // Add associated types on type parameters and `Self`.
  82             ctx.scope.assoc_type_shorthand_candidates(resolution, |_, alias| {
  83                 acc.add_type_alias(ctx, alias);
  84                 None::<()>
  85             });
  86             match resolution {
  87                 hir::PathResolution::Def(hir::ModuleDef::Module(module)) => {
  88                     let module_scope = module.scope(ctx.db, Some(ctx.module));
  89                     for (name, def) in module_scope {
  90                         if scope_def_applicable(def) {
  91                             acc.add_path_resolution(ctx, path_ctx, name, def);
  92                         }
  93                     }
  94                 }
  95                 hir::PathResolution::Def(
  96                     def @ (hir::ModuleDef::Adt(_)
  97                     | hir::ModuleDef::TypeAlias(_)
  98                     | hir::ModuleDef::BuiltinType(_)),
  99                 ) => {
 100                     let ty = match def {
 101                         hir::ModuleDef::Adt(adt) => adt.ty(ctx.db),
 102                         hir::ModuleDef::TypeAlias(a) => a.ty(ctx.db),
 103                         hir::ModuleDef::BuiltinType(builtin) => {
 104                             cov_mark::hit!(completes_primitive_assoc_const);
 105                             builtin.ty(ctx.db)
 106                         }
 107                         _ => return,
 108                     };
 109
 110                     if let Some(hir::Adt::Enum(e)) = ty.as_adt() {
 111                         cov_mark::hit!(completes_variant_through_alias);
 112                         acc.add_enum_variants(ctx, path_ctx, e);
 113                     }
 114
 115                     // XXX: For parity with Rust bug #22519, this does not complete Ty::AssocType.
 116                     // (where AssocType is defined on a trait, not an inherent impl)
 117
 118                     ctx.iterate_path_candidates(&ty, |item| {
 119                         add_assoc_item(acc, item);
 120                     });
 121
 122                     // Iterate assoc types separately
 123                     ty.iterate_assoc_items(ctx.db, ctx.krate, |item| {
 124                         if let hir::AssocItem::TypeAlias(ty) = item {
 125                             acc.add_type_alias(ctx, ty)
 126                         }
 127                         None::<()>
 128                     });
 129                 }
 130                 hir::PathResolution::Def(hir::ModuleDef::Trait(t)) => {
 131                     // Handles `Trait::assoc` as well as `<Ty as Trait>::assoc`.
 132                     for item in t.items(ctx.db) {
 133                         add_assoc_item(acc, item);
 134                     }
 135                 }
 136                 hir::PathResolution::TypeParam(_) | hir::PathResolution::SelfType(_) => {
 137                     let ty = match resolution {
 138                         hir::PathResolution::TypeParam(param) => param.ty(ctx.db),
 139                         hir::PathResolution::SelfType(impl_def) => impl_def.self_ty(ctx.db),
 140                         _ => return,
 141                     };
 142
 143                     if let Some(hir::Adt::Enum(e)) = ty.as_adt() {
 144                         cov_mark::hit!(completes_variant_through_self);
 145                         acc.add_enum_variants(ctx, path_ctx, e);
 146                     }
 147
 148                     ctx.iterate_path_candidates(&ty, |item| {
 149                         add_assoc_item(acc, item);
 150                     });
 151                 }
 152                 _ => (),
 153             }
 154         }
 155         Qualified::Absolute => acc.add_crate_roots(ctx, path_ctx),
 156         Qualified::No => {
 157             acc.add_nameref_keywords_with_colon(ctx);
 158             if let Some(adt) =
 159                 ctx.expected_type.as_ref().and_then(|ty| ty.strip_references().as_adt())
 160             {
 161                 let self_ty = (|| ctx.sema.to_def(impl_.as_ref()?)?.self_ty(ctx.db).as_adt())();
 162                 let complete_self = self_ty == Some(adt);
 163
 164                 match adt {
 165                     hir::Adt::Struct(strukt) => {
 166                         let path = ctx
 167                             .module
 168                             .find_use_path(
 169                                 ctx.db,
 170                                 hir::ModuleDef::from(strukt),
 171                                 ctx.config.prefer_no_std,
 172                             )
 173                             .filter(|it| it.len() > 1);
 174
 175                         acc.add_struct_literal(ctx, path_ctx, strukt, path, None);
 176
 177                         if complete_self {
 178                             acc.add_struct_literal(
 179                                 ctx,
 180                                 path_ctx,
 181                                 strukt,
 182                                 None,
 183                                 Some(hir::known::SELF_TYPE),
 184                             );
 185                         }
 186                     }
 187                     hir::Adt::Union(un) => {
 188                         let path = ctx
 189                             .module
 190                             .find_use_path(
 191                                 ctx.db,
 192                                 hir::ModuleDef::from(un),
 193                                 ctx.config.prefer_no_std,
 194                             )
 195                             .filter(|it| it.len() > 1);
 196
 197                         acc.add_union_literal(ctx, un, path, None);
 198                         if complete_self {
 199                             acc.add_union_literal(ctx, un, None, Some(hir::known::SELF_TYPE));
 200                         }
 201                     }
 202                     hir::Adt::Enum(e) => {
 203                         super::enum_variants_with_paths(
 204                             acc,
 205                             ctx,
 206                             e,
 207                             impl_,
 208                             |acc, ctx, variant, path| {
 209                                 acc.add_qualified_enum_variant(ctx, path_ctx, variant, path)
 210                             },
 211                         );
 212                     }
 213                 }
 214             }
 215             ctx.process_all_names(&mut |name, def| match def {
 216                 ScopeDef::ModuleDef(hir::ModuleDef::Trait(t)) => {
 217                     let assocs = t.items_with_supertraits(ctx.db);
 218                     match &*assocs {
 219                         // traits with no assoc items are unusable as expressions since
 220                         // there is no associated item path that can be constructed with them
 221                         [] => (),
 222                         // FIXME: Render the assoc item with the trait qualified
 223                         &[_item] => acc.add_path_resolution(ctx, path_ctx, name, def),
 224                         // FIXME: Append `::` to the thing here, since a trait on its own won't work
 225                         [..] => acc.add_path_resolution(ctx, path_ctx, name, def),
 226                     }
 227                 }
 228                 _ if scope_def_applicable(def) => acc.add_path_resolution(ctx, path_ctx, name, def),
 229                 _ => (),
 230             });
 231
 232             match is_func_update {
 233                 Some(record_expr) => {
 234                     let ty = ctx.sema.type_of_expr(&ast::Expr::RecordExpr(record_expr.clone()));
 235
 236                     match ty.as_ref().and_then(|t| t.original.as_adt()) {
 237                         Some(hir::Adt::Union(_)) => (),
 238                         _ => {
 239                             cov_mark::hit!(functional_update);
 240                             let missing_fields =
 241                                 ctx.sema.record_literal_missing_fields(record_expr);
 242                             if !missing_fields.is_empty() {
 243                                 add_default_update(acc, ctx, ty);
 244                             }
 245                         }
 246                     };
 247                 }
 248                 None => {
 249                     let mut add_keyword = |kw, snippet| {
 250                         acc.add_keyword_snippet_expr(ctx, incomplete_let, kw, snippet)
 251                     };
 252
 253                     if !in_block_expr {
 254                         add_keyword("unsafe", "unsafe {\n    $0\n}");
 255                     }
 256                     add_keyword("match", "match $1 {\n    $0\n}");
 257                     add_keyword("while", "while $1 {\n    $0\n}");
 258                     add_keyword("while let", "while let $1 = $2 {\n    $0\n}");
 259                     add_keyword("loop", "loop {\n    $0\n}");
 260                     if in_match_guard {
 261                         add_keyword("if", "if $0");
 262                     } else {
 263                         add_keyword("if", "if $1 {\n    $0\n}");
 264                     }
 265                     add_keyword("if let", "if let $1 = $2 {\n    $0\n}");
 266                     add_keyword("for", "for $1 in $2 {\n    $0\n}");
 267                     add_keyword("true", "true");
 268                     add_keyword("false", "false");
 269
 270                     if in_condition || in_block_expr {
 271                         add_keyword("let", "let");
 272                     }
 273
 274                     if after_if_expr {
 275                         add_keyword("else", "else {\n    $0\n}");
 276                         add_keyword("else if", "else if $1 {\n    $0\n}");
 277                     }
 278
 279                     if wants_mut_token {
 280                         add_keyword("mut", "mut ");
 281                     }
 282
 283                     if in_loop_body {
 284                         if in_block_expr {
 285                             add_keyword("continue", "continue;");
 286                             add_keyword("break", "break;");
 287                         } else {
 288                             add_keyword("continue", "continue");
 289                             add_keyword("break", "break");
 290                         }
 291                     }
 292
 293                     if let Some(ret_ty) = innermost_ret_ty {
 294                         add_keyword(
 295                             "return",
 296                             match (ret_ty.is_unit(), in_block_expr) {
 297                                 (true, true) => {
 298                                     cov_mark::hit!(return_unit_block);
 299                                     "return;"
 300                                 }
 301                                 (true, false) => {
 302                                     cov_mark::hit!(return_unit_no_block);
 303                                     "return"
 304                                 }
 305                                 (false, true) => {
 306                                     cov_mark::hit!(return_value_block);
 307                                     "return $0;"
 308                                 }
 309                                 (false, false) => {
 310                                     cov_mark::hit!(return_value_no_block);
 311                                     "return $0"
 312                                 }
 313                             },
 314                         );
 315                     }
 316                 }
 317             }
 318         }
 319     }
 320 }