crates/ide_completion/src/context.rs

   1 //! See `CompletionContext` structure.
   2
   3 use hir::{Local, ScopeDef, Semantics, SemanticsScope, Type};
   4 use ide_db::base_db::{FilePosition, SourceDatabase};
   5 use ide_db::{call_info::ActiveParameter, RootDatabase};
   6 use syntax::{
   7     algo::find_node_at_offset,
   8     ast::{self, NameOrNameRef, NameOwner},
   9     match_ast, AstNode, NodeOrToken,
  10     SyntaxKind::*,
  11     SyntaxNode, SyntaxToken, TextRange, TextSize,
  12 };
  13
  14 use text_edit::Indel;
  15
  16 use crate::{
  17     patterns::{
  18         fn_is_prev, for_is_prev2, has_bind_pat_parent, has_block_expr_parent,
  19         has_field_list_parent, has_impl_as_prev_sibling, has_impl_parent,
  20         has_item_list_or_source_file_parent, has_ref_parent, has_trait_as_prev_sibling,
  21         has_trait_parent, if_is_prev, inside_impl_trait_block, is_in_loop_body, is_match_arm,
  22         unsafe_is_prev,
  23     },
  24     CompletionConfig,
  25 };
  26
  27 /// `CompletionContext` is created early during completion to figure out, where
  28 /// exactly is the cursor, syntax-wise.
  29 #[derive(Debug)]
  30 pub(crate) struct CompletionContext<'a> {
  31     pub(super) sema: Semantics<'a, RootDatabase>,
  32     pub(super) scope: SemanticsScope<'a>,
  33     pub(super) db: &'a RootDatabase,
  34     pub(super) config: &'a CompletionConfig,
  35     pub(super) position: FilePosition,
  36     /// The token before the cursor, in the original file.
  37     pub(super) original_token: SyntaxToken,
  38     /// The token before the cursor, in the macro-expanded file.
  39     pub(super) token: SyntaxToken,
  40     pub(super) krate: Option<hir::Crate>,
  41     pub(super) expected_name: Option<NameOrNameRef>,
  42     pub(super) expected_type: Option<Type>,
  43     pub(super) name_ref_syntax: Option<ast::NameRef>,
  44     pub(super) lifetime_syntax: Option<ast::Lifetime>,
  45     pub(super) lifetime_param_syntax: Option<ast::LifetimeParam>,
  46     pub(super) function_syntax: Option<ast::Fn>,
  47     pub(super) use_item_syntax: Option<ast::Use>,
  48     pub(super) record_lit_syntax: Option<ast::RecordExpr>,
  49     pub(super) record_pat_syntax: Option<ast::RecordPat>,
  50     pub(super) record_field_syntax: Option<ast::RecordExprField>,
  51     pub(super) impl_def: Option<ast::Impl>,
  52     pub(super) lifetime_allowed: bool,
  53     /// FIXME: `ActiveParameter` is string-based, which is very very wrong
  54     pub(super) active_parameter: Option<ActiveParameter>,
  55     pub(super) is_param: bool,
  56     pub(super) is_label_ref: bool,
  57     /// If a name-binding or reference to a const in a pattern.
  58     /// Irrefutable patterns (like let) are excluded.
  59     pub(super) is_pat_binding_or_const: bool,
  60     pub(super) is_irrefutable_pat_binding: bool,
  61     /// A single-indent path, like `foo`. `::foo` should not be considered a trivial path.
  62     pub(super) is_trivial_path: bool,
  63     /// If not a trivial path, the prefix (qualifier).
  64     pub(super) path_qual: Option<ast::Path>,
  65     pub(super) after_if: bool,
  66     /// `true` if we are a statement or a last expr in the block.
  67     pub(super) can_be_stmt: bool,
  68     /// `true` if we expect an expression at the cursor position.
  69     pub(super) is_expr: bool,
  70     /// Something is typed at the "top" level, in module or impl/trait.
  71     pub(super) is_new_item: bool,
  72     /// The receiver if this is a field or method access, i.e. writing something.$0
  73     pub(super) dot_receiver: Option<ast::Expr>,
  74     pub(super) dot_receiver_is_ambiguous_float_literal: bool,
  75     /// If this is a call (method or function) in particular, i.e. the () are already there.
  76     pub(super) is_call: bool,
  77     /// Like `is_call`, but for tuple patterns.
  78     pub(super) is_pattern_call: bool,
  79     /// If this is a macro call, i.e. the () are already there.
  80     pub(super) is_macro_call: bool,
  81     pub(super) is_path_type: bool,
  82     pub(super) has_type_args: bool,
  83     pub(super) attribute_under_caret: Option<ast::Attr>,
  84     pub(super) mod_declaration_under_caret: Option<ast::Module>,
  85     pub(super) unsafe_is_prev: bool,
  86     pub(super) if_is_prev: bool,
  87     pub(super) block_expr_parent: bool,
  88     pub(super) bind_pat_parent: bool,
  89     pub(super) ref_pat_parent: bool,
  90     pub(super) in_loop_body: bool,
  91     pub(super) has_trait_parent: bool,
  92     pub(super) has_impl_parent: bool,
  93     pub(super) inside_impl_trait_block: bool,
  94     pub(super) has_field_list_parent: bool,
  95     pub(super) trait_as_prev_sibling: bool,
  96     pub(super) impl_as_prev_sibling: bool,
  97     pub(super) is_match_arm: bool,
  98     pub(super) has_item_list_or_source_file_parent: bool,
  99     pub(super) for_is_prev2: bool,
 100     pub(super) fn_is_prev: bool,
 101     pub(super) incomplete_let: bool,
 102     pub(super) locals: Vec<(String, Local)>,
 103 }
 104
 105 impl<'a> CompletionContext<'a> {
 106     pub(super) fn new(
 107         db: &'a RootDatabase,
 108         position: FilePosition,
 109         config: &'a CompletionConfig,
 110     ) -> Option<CompletionContext<'a>> {
 111         let sema = Semantics::new(db);
 112
 113         let original_file = sema.parse(position.file_id);
 114
 115         // Insert a fake ident to get a valid parse tree. We will use this file
 116         // to determine context, though the original_file will be used for
 117         // actual completion.
 118         let file_with_fake_ident = {
 119             let parse = db.parse(position.file_id);
 120             let edit = Indel::insert(position.offset, "intellijRulezz".to_string());
 121             parse.reparse(&edit).tree()
 122         };
 123         let fake_ident_token =
 124             file_with_fake_ident.syntax().token_at_offset(position.offset).right_biased().unwrap();
 125
 126         let krate = sema.to_module_def(position.file_id).map(|m| m.krate());
 127         let original_token =
 128             original_file.syntax().token_at_offset(position.offset).left_biased()?;
 129         let token = sema.descend_into_macros(original_token.clone());
 130         let scope = sema.scope_at_offset(&token, position.offset);
 131         let mut locals = vec![];
 132         scope.process_all_names(&mut |name, scope| {
 133             if let ScopeDef::Local(local) = scope {
 134                 locals.push((name.to_string(), local));
 135             }
 136         });
 137         let mut ctx = CompletionContext {
 138             sema,
 139             scope,
 140             db,
 141             config,
 142             position,
 143             original_token,
 144             token,
 145             krate,
 146             lifetime_allowed: false,
 147             expected_name: None,
 148             expected_type: None,
 149             name_ref_syntax: None,
 150             lifetime_syntax: None,
 151             lifetime_param_syntax: None,
 152             function_syntax: None,
 153             use_item_syntax: None,
 154             record_lit_syntax: None,
 155             record_pat_syntax: None,
 156             record_field_syntax: None,
 157             impl_def: None,
 158             active_parameter: ActiveParameter::at(db, position),
 159             is_label_ref: false,
 160             is_param: false,
 161             is_pat_binding_or_const: false,
 162             is_irrefutable_pat_binding: false,
 163             is_trivial_path: false,
 164             path_qual: None,
 165             after_if: false,
 166             can_be_stmt: false,
 167             is_expr: false,
 168             is_new_item: false,
 169             dot_receiver: None,
 170             dot_receiver_is_ambiguous_float_literal: false,
 171             is_call: false,
 172             is_pattern_call: false,
 173             is_macro_call: false,
 174             is_path_type: false,
 175             has_type_args: false,
 176             attribute_under_caret: None,
 177             mod_declaration_under_caret: None,
 178             unsafe_is_prev: false,
 179             if_is_prev: false,
 180             block_expr_parent: false,
 181             bind_pat_parent: false,
 182             ref_pat_parent: false,
 183             in_loop_body: false,
 184             has_trait_parent: false,
 185             has_impl_parent: false,
 186             inside_impl_trait_block: false,
 187             has_field_list_parent: false,
 188             trait_as_prev_sibling: false,
 189             impl_as_prev_sibling: false,
 190             is_match_arm: false,
 191             has_item_list_or_source_file_parent: false,
 192             for_is_prev2: false,
 193             fn_is_prev: false,
 194             incomplete_let: false,
 195             locals,
 196         };
 197
 198         let mut original_file = original_file.syntax().clone();
 199         let mut hypothetical_file = file_with_fake_ident.syntax().clone();
 200         let mut offset = position.offset;
 201         let mut fake_ident_token = fake_ident_token;
 202
 203         // Are we inside a macro call?
 204         while let (Some(actual_macro_call), Some(macro_call_with_fake_ident)) = (
 205             find_node_at_offset::<ast::MacroCall>(&original_file, offset),
 206             find_node_at_offset::<ast::MacroCall>(&hypothetical_file, offset),
 207         ) {
 208             if actual_macro_call.path().as_ref().map(|s| s.syntax().text())
 209                 != macro_call_with_fake_ident.path().as_ref().map(|s| s.syntax().text())
 210             {
 211                 break;
 212             }
 213             let hypothetical_args = match macro_call_with_fake_ident.token_tree() {
 214                 Some(tt) => tt,
 215                 None => break,
 216             };
 217             if let (Some(actual_expansion), Some(hypothetical_expansion)) = (
 218                 ctx.sema.expand(&actual_macro_call),
 219                 ctx.sema.speculative_expand(
 220                     &actual_macro_call,
 221                     &hypothetical_args,
 222                     fake_ident_token,
 223                 ),
 224             ) {
 225                 let new_offset = hypothetical_expansion.1.text_range().start();
 226                 if new_offset > actual_expansion.text_range().end() {
 227                     break;
 228                 }
 229                 original_file = actual_expansion;
 230                 hypothetical_file = hypothetical_expansion.0;
 231                 fake_ident_token = hypothetical_expansion.1;
 232                 offset = new_offset;
 233             } else {
 234                 break;
 235             }
 236         }
 237         ctx.fill_keyword_patterns(&hypothetical_file, offset);
 238         ctx.fill(&original_file, hypothetical_file, offset);
 239         Some(ctx)
 240     }
 241
 242     /// Checks whether completions in that particular case don't make much sense.
 243     /// Examples:
 244     /// - `fn $0` -- we expect function name, it's unlikely that "hint" will be helpful.
 245     ///   Exception for this case is `impl Trait for Foo`, where we would like to hint trait method names.
 246     /// - `for _ i$0` -- obviously, it'll be "in" keyword.
 247     pub(crate) fn no_completion_required(&self) -> bool {
 248         (self.fn_is_prev && !self.inside_impl_trait_block) || self.for_is_prev2
 249     }
 250
 251     /// The range of the identifier that is being completed.
 252     pub(crate) fn source_range(&self) -> TextRange {
 253         // check kind of macro-expanded token, but use range of original token
 254         let kind = self.token.kind();
 255         if kind == IDENT || kind == LIFETIME_IDENT || kind == UNDERSCORE || kind.is_keyword() {
 256             cov_mark::hit!(completes_if_prefix_is_keyword);
 257             self.original_token.text_range()
 258         } else if kind == CHAR {
 259             // assume we are completing a lifetime but the user has only typed the '
 260             cov_mark::hit!(completes_if_lifetime_without_idents);
 261             TextRange::at(self.original_token.text_range().start(), TextSize::from(1))
 262         } else {
 263             TextRange::empty(self.position.offset)
 264         }
 265     }
 266
 267     fn fill_keyword_patterns(&mut self, file_with_fake_ident: &SyntaxNode, offset: TextSize) {
 268         let fake_ident_token = file_with_fake_ident.token_at_offset(offset).right_biased().unwrap();
 269         let syntax_element = NodeOrToken::Token(fake_ident_token);
 270         self.block_expr_parent = has_block_expr_parent(syntax_element.clone());
 271         self.unsafe_is_prev = unsafe_is_prev(syntax_element.clone());
 272         self.if_is_prev = if_is_prev(syntax_element.clone());
 273         self.bind_pat_parent = has_bind_pat_parent(syntax_element.clone());
 274         self.ref_pat_parent = has_ref_parent(syntax_element.clone());
 275         self.in_loop_body = is_in_loop_body(syntax_element.clone());
 276         self.has_trait_parent = has_trait_parent(syntax_element.clone());
 277         self.has_impl_parent = has_impl_parent(syntax_element.clone());
 278         self.inside_impl_trait_block = inside_impl_trait_block(syntax_element.clone());
 279         self.has_field_list_parent = has_field_list_parent(syntax_element.clone());
 280         self.impl_as_prev_sibling = has_impl_as_prev_sibling(syntax_element.clone());
 281         self.trait_as_prev_sibling = has_trait_as_prev_sibling(syntax_element.clone());
 282         self.is_match_arm = is_match_arm(syntax_element.clone());
 283         self.has_item_list_or_source_file_parent =
 284             has_item_list_or_source_file_parent(syntax_element.clone());
 285         self.mod_declaration_under_caret =
 286             find_node_at_offset::<ast::Module>(&file_with_fake_ident, offset)
 287                 .filter(|module| module.item_list().is_none());
 288         self.for_is_prev2 = for_is_prev2(syntax_element.clone());
 289         self.fn_is_prev = fn_is_prev(syntax_element.clone());
 290         self.incomplete_let =
 291             syntax_element.ancestors().take(6).find_map(ast::LetStmt::cast).map_or(false, |it| {
 292                 it.syntax().text_range().end() == syntax_element.text_range().end()
 293             });
 294     }
 295
 296     fn fill_impl_def(&mut self) {
 297         self.impl_def = self
 298             .sema
 299             .token_ancestors_with_macros(self.token.clone())
 300             .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
 301             .find_map(ast::Impl::cast);
 302     }
 303
 304     fn fill(
 305         &mut self,
 306         original_file: &SyntaxNode,
 307         file_with_fake_ident: SyntaxNode,
 308         offset: TextSize,
 309     ) {
 310         let (expected_type, expected_name) = {
 311             let mut node = match self.token.parent() {
 312                 Some(it) => it,
 313                 None => return,
 314             };
 315             loop {
 316                 break match_ast! {
 317                     match node {
 318                         ast::LetStmt(it) => {
 319                             cov_mark::hit!(expected_type_let_with_leading_char);
 320                             cov_mark::hit!(expected_type_let_without_leading_char);
 321                             let ty = it.pat()
 322                                 .and_then(|pat| self.sema.type_of_pat(&pat));
 323                             let name = if let Some(ast::Pat::IdentPat(ident)) = it.pat() {
 324                                 ident.name().map(NameOrNameRef::Name)
 325                             } else {
 326                                 None
 327                             };
 328
 329                             (ty, name)
 330                         },
 331                         ast::ArgList(_it) => {
 332                             cov_mark::hit!(expected_type_fn_param_with_leading_char);
 333                             cov_mark::hit!(expected_type_fn_param_without_leading_char);
 334                             ActiveParameter::at_token(
 335                                 &self.sema,
 336                                 self.token.clone(),
 337                             ).map(|ap| {
 338                                 let name = ap.ident().map(NameOrNameRef::Name);
 339                                 (Some(ap.ty), name)
 340                             })
 341                             .unwrap_or((None, None))
 342                         },
 343                         ast::RecordExprFieldList(_it) => {
 344                             cov_mark::hit!(expected_type_struct_field_without_leading_char);
 345                             self.token.prev_sibling_or_token()
 346                                 .and_then(|se| se.into_node())
 347                                 .and_then(|node| ast::RecordExprField::cast(node))
 348                                 .and_then(|rf| self.sema.resolve_record_field(&rf).zip(Some(rf)))
 349                                 .map(|(f, rf)|(
 350                                     Some(f.0.ty(self.db)),
 351                                     rf.field_name().map(NameOrNameRef::NameRef),
 352                                 ))
 353                                 .unwrap_or((None, None))
 354                         },
 355                         ast::RecordExprField(it) => {
 356                             cov_mark::hit!(expected_type_struct_field_with_leading_char);
 357                             self.sema
 358                                 .resolve_record_field(&it)
 359                                 .map(|f|(
 360                                     Some(f.0.ty(self.db)),
 361                                     it.field_name().map(NameOrNameRef::NameRef),
 362                                 ))
 363                                 .unwrap_or((None, None))
 364                         },
 365                         ast::MatchExpr(it) => {
 366                             cov_mark::hit!(expected_type_match_arm_without_leading_char);
 367                             let ty = it.expr()
 368                                 .and_then(|e| self.sema.type_of_expr(&e));
 369
 370                             (ty, None)
 371                         },
 372                         ast::IdentPat(it) => {
 373                             cov_mark::hit!(expected_type_if_let_with_leading_char);
 374                             cov_mark::hit!(expected_type_match_arm_with_leading_char);
 375                             let ty = self.sema.type_of_pat(&ast::Pat::from(it));
 376
 377                             (ty, None)
 378                         },
 379                         ast::Fn(_it) => {
 380                             cov_mark::hit!(expected_type_fn_ret_with_leading_char);
 381                             cov_mark::hit!(expected_type_fn_ret_without_leading_char);
 382                             let ty = self.token.ancestors()
 383                                 .find_map(|ancestor| ast::Expr::cast(ancestor))
 384                                 .and_then(|expr| self.sema.type_of_expr(&expr));
 385
 386                             (ty, None)
 387                         },
 388                         _ => {
 389                             match node.parent() {
 390                                 Some(n) => {
 391                                     node = n;
 392                                     continue;
 393                                 },
 394                                 None => (None, None),
 395                             }
 396                         },
 397                     }
 398                 };
 399             }
 400         };
 401         self.expected_type = expected_type;
 402         self.expected_name = expected_name;
 403         self.attribute_under_caret = find_node_at_offset(&file_with_fake_ident, offset);
 404
 405         if let Some(lifetime) = find_node_at_offset::<ast::Lifetime>(&file_with_fake_ident, offset)
 406         {
 407             self.classify_lifetime(original_file, lifetime, offset);
 408         }
 409
 410         // First, let's try to complete a reference to some declaration.
 411         if let Some(name_ref) = find_node_at_offset::<ast::NameRef>(&file_with_fake_ident, offset) {
 412             // Special case, `trait T { fn foo(i_am_a_name_ref) {} }`.
 413             // See RFC#1685.
 414             if is_node::<ast::Param>(name_ref.syntax()) {
 415                 self.is_param = true;
 416                 return;
 417             }
 418             // FIXME: remove this (V) duplication and make the check more precise
 419             if name_ref.syntax().ancestors().find_map(ast::RecordPatFieldList::cast).is_some() {
 420                 self.record_pat_syntax =
 421                     self.sema.find_node_at_offset_with_macros(&original_file, offset);
 422             }
 423             self.classify_name_ref(original_file, name_ref, offset);
 424         }
 425
 426         // Otherwise, see if this is a declaration. We can use heuristics to
 427         // suggest declaration names, see `CompletionKind::Magic`.
 428         if let Some(name) = find_node_at_offset::<ast::Name>(&file_with_fake_ident, offset) {
 429             if let Some(bind_pat) = name.syntax().ancestors().find_map(ast::IdentPat::cast) {
 430                 self.is_pat_binding_or_const = true;
 431                 if bind_pat.at_token().is_some()
 432                     || bind_pat.ref_token().is_some()
 433                     || bind_pat.mut_token().is_some()
 434                 {
 435                     self.is_pat_binding_or_const = false;
 436                 }
 437                 if bind_pat.syntax().parent().and_then(ast::RecordPatFieldList::cast).is_some() {
 438                     self.is_pat_binding_or_const = false;
 439                 }
 440                 if let Some(Some(pat)) = bind_pat.syntax().ancestors().find_map(|node| {
 441                     match_ast! {
 442                         match node {
 443                             ast::LetStmt(it) => Some(it.pat()),
 444                             ast::Param(it) => Some(it.pat()),
 445                             _ => None,
 446                         }
 447                     }
 448                 }) {
 449                     if pat.syntax().text_range().contains_range(bind_pat.syntax().text_range()) {
 450                         self.is_pat_binding_or_const = false;
 451                         self.is_irrefutable_pat_binding = true;
 452                     }
 453                 }
 454
 455                 self.fill_impl_def();
 456             }
 457             if is_node::<ast::Param>(name.syntax()) {
 458                 self.is_param = true;
 459                 return;
 460             }
 461             // FIXME: remove this (^) duplication and make the check more precise
 462             if name.syntax().ancestors().find_map(ast::RecordPatFieldList::cast).is_some() {
 463                 self.record_pat_syntax =
 464                     self.sema.find_node_at_offset_with_macros(&original_file, offset);
 465             }
 466         }
 467     }
 468
 469     fn classify_lifetime(
 470         &mut self,
 471         original_file: &SyntaxNode,
 472         lifetime: ast::Lifetime,
 473         offset: TextSize,
 474     ) {
 475         self.lifetime_syntax =
 476             find_node_at_offset(original_file, lifetime.syntax().text_range().start());
 477         if let Some(parent) = lifetime.syntax().parent() {
 478             if parent.kind() == ERROR {
 479                 return;
 480             }
 481
 482             match_ast! {
 483                 match parent {
 484                     ast::LifetimeParam(_it) => {
 485                         self.lifetime_allowed = true;
 486                         self.lifetime_param_syntax =
 487                             self.sema.find_node_at_offset_with_macros(original_file, offset);
 488                     },
 489                     ast::BreakExpr(_it) => self.is_label_ref = true,
 490                     ast::ContinueExpr(_it) => self.is_label_ref = true,
 491                     ast::Label(_it) => (),
 492                     _ => self.lifetime_allowed = true,
 493                 }
 494             }
 495         }
 496     }
 497
 498     fn classify_name_ref(
 499         &mut self,
 500         original_file: &SyntaxNode,
 501         name_ref: ast::NameRef,
 502         offset: TextSize,
 503     ) {
 504         self.name_ref_syntax =
 505             find_node_at_offset(original_file, name_ref.syntax().text_range().start());
 506         let name_range = name_ref.syntax().text_range();
 507         if ast::RecordExprField::for_field_name(&name_ref).is_some() {
 508             self.record_lit_syntax =
 509                 self.sema.find_node_at_offset_with_macros(original_file, offset);
 510         }
 511
 512         self.fill_impl_def();
 513
 514         let top_node = name_ref
 515             .syntax()
 516             .ancestors()
 517             .take_while(|it| it.text_range() == name_range)
 518             .last()
 519             .unwrap();
 520
 521         match top_node.parent().map(|it| it.kind()) {
 522             Some(SOURCE_FILE) | Some(ITEM_LIST) => {
 523                 self.is_new_item = true;
 524                 return;
 525             }
 526             _ => (),
 527         }
 528
 529         self.use_item_syntax =
 530             self.sema.token_ancestors_with_macros(self.token.clone()).find_map(ast::Use::cast);
 531
 532         self.function_syntax = self
 533             .sema
 534             .token_ancestors_with_macros(self.token.clone())
 535             .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
 536             .find_map(ast::Fn::cast);
 537
 538         self.record_field_syntax = self
 539             .sema
 540             .token_ancestors_with_macros(self.token.clone())
 541             .take_while(|it| {
 542                 it.kind() != SOURCE_FILE && it.kind() != MODULE && it.kind() != CALL_EXPR
 543             })
 544             .find_map(ast::RecordExprField::cast);
 545
 546         let parent = match name_ref.syntax().parent() {
 547             Some(it) => it,
 548             None => return,
 549         };
 550
 551         if let Some(segment) = ast::PathSegment::cast(parent.clone()) {
 552             let path = segment.parent_path();
 553             self.is_call = path
 554                 .syntax()
 555                 .parent()
 556                 .and_then(ast::PathExpr::cast)
 557                 .and_then(|it| it.syntax().parent().and_then(ast::CallExpr::cast))
 558                 .is_some();
 559             self.is_macro_call = path.syntax().parent().and_then(ast::MacroCall::cast).is_some();
 560             self.is_pattern_call =
 561                 path.syntax().parent().and_then(ast::TupleStructPat::cast).is_some();
 562
 563             self.is_path_type = path.syntax().parent().and_then(ast::PathType::cast).is_some();
 564             self.has_type_args = segment.generic_arg_list().is_some();
 565
 566             if let Some(path) = path_or_use_tree_qualifier(&path) {
 567                 self.path_qual = path
 568                     .segment()
 569                     .and_then(|it| {
 570                         find_node_with_range::<ast::PathSegment>(
 571                             original_file,
 572                             it.syntax().text_range(),
 573                         )
 574                     })
 575                     .map(|it| it.parent_path());
 576                 return;
 577             }
 578
 579             if let Some(segment) = path.segment() {
 580                 if segment.coloncolon_token().is_some() {
 581                     return;
 582                 }
 583             }
 584
 585             self.is_trivial_path = true;
 586
 587             // Find either enclosing expr statement (thing with `;`) or a
 588             // block. If block, check that we are the last expr.
 589             self.can_be_stmt = name_ref
 590                 .syntax()
 591                 .ancestors()
 592                 .find_map(|node| {
 593                     if let Some(stmt) = ast::ExprStmt::cast(node.clone()) {
 594                         return Some(stmt.syntax().text_range() == name_ref.syntax().text_range());
 595                     }
 596                     if let Some(block) = ast::BlockExpr::cast(node) {
 597                         return Some(
 598                             block.tail_expr().map(|e| e.syntax().text_range())
 599                                 == Some(name_ref.syntax().text_range()),
 600                         );
 601                     }
 602                     None
 603                 })
 604                 .unwrap_or(false);
 605             self.is_expr = path.syntax().parent().and_then(ast::PathExpr::cast).is_some();
 606
 607             if let Some(off) = name_ref.syntax().text_range().start().checked_sub(2.into()) {
 608                 if let Some(if_expr) =
 609                     self.sema.find_node_at_offset_with_macros::<ast::IfExpr>(original_file, off)
 610                 {
 611                     if if_expr.syntax().text_range().end() < name_ref.syntax().text_range().start()
 612                     {
 613                         self.after_if = true;
 614                     }
 615                 }
 616             }
 617         }
 618         if let Some(field_expr) = ast::FieldExpr::cast(parent.clone()) {
 619             // The receiver comes before the point of insertion of the fake
 620             // ident, so it should have the same range in the non-modified file
 621             self.dot_receiver = field_expr
 622                 .expr()
 623                 .map(|e| e.syntax().text_range())
 624                 .and_then(|r| find_node_with_range(original_file, r));
 625             self.dot_receiver_is_ambiguous_float_literal =
 626                 if let Some(ast::Expr::Literal(l)) = &self.dot_receiver {
 627                     match l.kind() {
 628                         ast::LiteralKind::FloatNumber { .. } => l.token().text().ends_with('.'),
 629                         _ => false,
 630                     }
 631                 } else {
 632                     false
 633                 };
 634         }
 635         if let Some(method_call_expr) = ast::MethodCallExpr::cast(parent) {
 636             // As above
 637             self.dot_receiver = method_call_expr
 638                 .receiver()
 639                 .map(|e| e.syntax().text_range())
 640                 .and_then(|r| find_node_with_range(original_file, r));
 641             self.is_call = true;
 642         }
 643     }
 644 }
 645
 646 fn find_node_with_range<N: AstNode>(syntax: &SyntaxNode, range: TextRange) -> Option<N> {
 647     syntax.covering_element(range).ancestors().find_map(N::cast)
 648 }
 649
 650 fn is_node<N: AstNode>(node: &SyntaxNode) -> bool {
 651     match node.ancestors().find_map(N::cast) {
 652         None => false,
 653         Some(n) => n.syntax().text_range() == node.text_range(),
 654     }
 655 }
 656
 657 fn path_or_use_tree_qualifier(path: &ast::Path) -> Option<ast::Path> {
 658     if let Some(qual) = path.qualifier() {
 659         return Some(qual);
 660     }
 661     let use_tree_list = path.syntax().ancestors().find_map(ast::UseTreeList::cast)?;
 662     let use_tree = use_tree_list.syntax().parent().and_then(ast::UseTree::cast)?;
 663     use_tree.path()
 664 }
 665
 666 #[cfg(test)]
 667 mod tests {
 668     use expect_test::{expect, Expect};
 669     use hir::HirDisplay;
 670
 671     use crate::test_utils::{position, TEST_CONFIG};
 672
 673     use super::CompletionContext;
 674
 675     fn check_expected_type_and_name(ra_fixture: &str, expect: Expect) {
 676         let (db, pos) = position(ra_fixture);
 677         let completion_context = CompletionContext::new(&db, pos, &TEST_CONFIG).unwrap();
 678
 679         let ty = completion_context
 680             .expected_type
 681             .map(|t| t.display_test(&db).to_string())
 682             .unwrap_or("?".to_owned());
 683
 684         let name = completion_context
 685             .expected_name
 686             .map_or_else(|| "?".to_owned(), |name| name.to_string());
 687
 688         expect.assert_eq(&format!("ty: {}, name: {}", ty, name));
 689     }
 690
 691     #[test]
 692     fn expected_type_let_without_leading_char() {
 693         cov_mark::check!(expected_type_let_without_leading_char);
 694         check_expected_type_and_name(
 695             r#"
 696 fn foo() {
 697     let x: u32 = $0;
 698 }
 699 "#,
 700             expect![[r#"ty: u32, name: x"#]],
 701         );
 702     }
 703
 704     #[test]
 705     fn expected_type_let_with_leading_char() {
 706         cov_mark::check!(expected_type_let_with_leading_char);
 707         check_expected_type_and_name(
 708             r#"
 709 fn foo() {
 710     let x: u32 = c$0;
 711 }
 712 "#,
 713             expect![[r#"ty: u32, name: x"#]],
 714         );
 715     }
 716
 717     #[test]
 718     fn expected_type_fn_param_without_leading_char() {
 719         cov_mark::check!(expected_type_fn_param_without_leading_char);
 720         check_expected_type_and_name(
 721             r#"
 722 fn foo() {
 723     bar($0);
 724 }
 725
 726 fn bar(x: u32) {}
 727 "#,
 728             expect![[r#"ty: u32, name: x"#]],
 729         );
 730     }
 731
 732     #[test]
 733     fn expected_type_fn_param_with_leading_char() {
 734         cov_mark::check!(expected_type_fn_param_with_leading_char);
 735         check_expected_type_and_name(
 736             r#"
 737 fn foo() {
 738     bar(c$0);
 739 }
 740
 741 fn bar(x: u32) {}
 742 "#,
 743             expect![[r#"ty: u32, name: x"#]],
 744         );
 745     }
 746
 747     #[test]
 748     fn expected_type_struct_field_without_leading_char() {
 749         cov_mark::check!(expected_type_struct_field_without_leading_char);
 750         check_expected_type_and_name(
 751             r#"
 752 struct Foo { a: u32 }
 753 fn foo() {
 754     Foo { a: $0 };
 755 }
 756 "#,
 757             expect![[r#"ty: u32, name: a"#]],
 758         )
 759     }
 760
 761     #[test]
 762     fn expected_type_struct_field_with_leading_char() {
 763         cov_mark::check!(expected_type_struct_field_with_leading_char);
 764         check_expected_type_and_name(
 765             r#"
 766 struct Foo { a: u32 }
 767 fn foo() {
 768     Foo { a: c$0 };
 769 }
 770 "#,
 771             expect![[r#"ty: u32, name: a"#]],
 772         );
 773     }
 774
 775     #[test]
 776     fn expected_type_match_arm_without_leading_char() {
 777         cov_mark::check!(expected_type_match_arm_without_leading_char);
 778         check_expected_type_and_name(
 779             r#"
 780 enum E { X }
 781 fn foo() {
 782    match E::X { $0 }
 783 }
 784 "#,
 785             expect![[r#"ty: E, name: ?"#]],
 786         );
 787     }
 788
 789     #[test]
 790     fn expected_type_match_arm_with_leading_char() {
 791         cov_mark::check!(expected_type_match_arm_with_leading_char);
 792         check_expected_type_and_name(
 793             r#"
 794 enum E { X }
 795 fn foo() {
 796    match E::X { c$0 }
 797 }
 798 "#,
 799             expect![[r#"ty: E, name: ?"#]],
 800         );
 801     }
 802
 803     #[test]
 804     fn expected_type_if_let_without_leading_char() {
 805         check_expected_type_and_name(
 806             r#"
 807 enum Foo { Bar, Baz, Quux }
 808
 809 fn foo() {
 810     let f = Foo::Quux;
 811     if let $0 = f { }
 812 }
 813 "#,
 814             expect![[r#"ty: (), name: ?"#]],
 815         ) // FIXME should be `ty: u32, name: ?`
 816     }
 817
 818     #[test]
 819     fn expected_type_if_let_with_leading_char() {
 820         cov_mark::check!(expected_type_if_let_with_leading_char);
 821         check_expected_type_and_name(
 822             r#"
 823 enum Foo { Bar, Baz, Quux }
 824
 825 fn foo() {
 826     let f = Foo::Quux;
 827     if let c$0 = f { }
 828 }
 829 "#,
 830             expect![[r#"ty: Foo, name: ?"#]],
 831         )
 832     }
 833
 834     #[test]
 835     fn expected_type_fn_ret_without_leading_char() {
 836         cov_mark::check!(expected_type_fn_ret_without_leading_char);
 837         check_expected_type_and_name(
 838             r#"
 839 fn foo() -> u32 {
 840     $0
 841 }
 842 "#,
 843             expect![[r#"ty: (), name: ?"#]],
 844         ) // FIXME this should be `ty: u32, name: ?`
 845     }
 846
 847     #[test]
 848     fn expected_type_fn_ret_with_leading_char() {
 849         cov_mark::check!(expected_type_fn_ret_with_leading_char);
 850         check_expected_type_and_name(
 851             r#"
 852 fn foo() -> u32 {
 853     c$0
 854 }
 855 "#,
 856             expect![[r#"ty: u32, name: ?"#]],
 857         )
 858     }
 859 }