crates/ide_completion/src/context.rs

   1 //! See `CompletionContext` structure.
   2
   3 use hir::{Local, ScopeDef, Semantics, SemanticsScope, Type};
   4 use ide_db::{
   5     base_db::{FilePosition, SourceDatabase},
   6     call_info::ActiveParameter,
   7     RootDatabase,
   8 };
   9 use syntax::{
  10     algo::find_node_at_offset,
  11     ast::{self, NameOrNameRef, NameOwner},
  12     match_ast, AstNode, NodeOrToken,
  13     SyntaxKind::{self, *},
  14     SyntaxNode, SyntaxToken, TextRange, TextSize, T,
  15 };
  16 use text_edit::Indel;
  17
  18 use crate::{
  19     patterns::{
  20         for_is_prev2, has_bind_pat_parent, has_block_expr_parent, has_field_list_parent,
  21         has_impl_as_prev_sibling, has_impl_parent, has_item_list_or_source_file_parent,
  22         has_ref_parent, has_trait_as_prev_sibling, has_trait_parent, inside_impl_trait_block,
  23         is_in_loop_body, is_match_arm, previous_token,
  24     },
  25     CompletionConfig,
  26 };
  27
  28 /// `CompletionContext` is created early during completion to figure out, where
  29 /// exactly is the cursor, syntax-wise.
  30 #[derive(Debug)]
  31 pub(crate) struct CompletionContext<'a> {
  32     pub(super) sema: Semantics<'a, RootDatabase>,
  33     pub(super) scope: SemanticsScope<'a>,
  34     pub(super) db: &'a RootDatabase,
  35     pub(super) config: &'a CompletionConfig,
  36     pub(super) position: FilePosition,
  37     /// The token before the cursor, in the original file.
  38     pub(super) original_token: SyntaxToken,
  39     /// The token before the cursor, in the macro-expanded file.
  40     pub(super) token: SyntaxToken,
  41     pub(super) krate: Option<hir::Crate>,
  42     pub(super) expected_name: Option<NameOrNameRef>,
  43     pub(super) expected_type: Option<Type>,
  44     pub(super) name_ref_syntax: Option<ast::NameRef>,
  45     pub(super) lifetime_syntax: Option<ast::Lifetime>,
  46     pub(super) lifetime_param_syntax: Option<ast::LifetimeParam>,
  47     pub(super) function_syntax: Option<ast::Fn>,
  48     pub(super) use_item_syntax: Option<ast::Use>,
  49     pub(super) record_lit_syntax: Option<ast::RecordExpr>,
  50     pub(super) record_pat_syntax: Option<ast::RecordPat>,
  51     pub(super) record_field_syntax: Option<ast::RecordExprField>,
  52     pub(super) impl_def: Option<ast::Impl>,
  53     pub(super) lifetime_allowed: bool,
  54     /// FIXME: `ActiveParameter` is string-based, which is very very wrong
  55     pub(super) active_parameter: Option<ActiveParameter>,
  56     pub(super) is_param: bool,
  57     pub(super) is_label_ref: bool,
  58     /// If a name-binding or reference to a const in a pattern.
  59     /// Irrefutable patterns (like let) are excluded.
  60     pub(super) is_pat_binding_or_const: bool,
  61     pub(super) is_irrefutable_pat_binding: bool,
  62     /// A single-indent path, like `foo`. `::foo` should not be considered a trivial path.
  63     pub(super) is_trivial_path: bool,
  64     /// If not a trivial path, the prefix (qualifier).
  65     pub(super) path_qual: Option<ast::Path>,
  66     pub(super) after_if: bool,
  67     /// `true` if we are a statement or a last expr in the block.
  68     pub(super) can_be_stmt: bool,
  69     /// `true` if we expect an expression at the cursor position.
  70     pub(super) is_expr: bool,
  71     /// Something is typed at the "top" level, in module or impl/trait.
  72     pub(super) is_new_item: bool,
  73     /// The receiver if this is a field or method access, i.e. writing something.$0
  74     pub(super) dot_receiver: Option<ast::Expr>,
  75     pub(super) dot_receiver_is_ambiguous_float_literal: bool,
  76     /// If this is a call (method or function) in particular, i.e. the () are already there.
  77     pub(super) is_call: bool,
  78     /// Like `is_call`, but for tuple patterns.
  79     pub(super) is_pattern_call: bool,
  80     /// If this is a macro call, i.e. the () are already there.
  81     pub(super) is_macro_call: bool,
  82     pub(super) is_path_type: bool,
  83     pub(super) has_type_args: bool,
  84     pub(super) attribute_under_caret: Option<ast::Attr>,
  85     pub(super) locals: Vec<(String, Local)>,
  86
  87     pub(super) mod_declaration_under_caret: Option<ast::Module>,
  88     pub(super) has_trait_parent: bool,
  89     pub(super) has_impl_parent: bool,
  90
  91     // keyword patterns
  92     pub(super) previous_token: Option<SyntaxToken>,
  93     pub(super) block_expr_parent: bool,
  94     pub(super) bind_pat_parent: bool,
  95     pub(super) ref_pat_parent: bool,
  96     pub(super) in_loop_body: bool,
  97     pub(super) has_field_list_parent: bool,
  98     pub(super) trait_as_prev_sibling: bool,
  99     pub(super) impl_as_prev_sibling: bool,
 100     pub(super) is_match_arm: bool,
 101     pub(super) has_item_list_or_source_file_parent: bool,
 102     pub(super) incomplete_let: bool,
 103
 104     no_completion_required: bool,
 105 }
 106
 107 impl<'a> CompletionContext<'a> {
 108     pub(super) fn new(
 109         db: &'a RootDatabase,
 110         position: FilePosition,
 111         config: &'a CompletionConfig,
 112     ) -> Option<CompletionContext<'a>> {
 113         let sema = Semantics::new(db);
 114
 115         let original_file = sema.parse(position.file_id);
 116
 117         // Insert a fake ident to get a valid parse tree. We will use this file
 118         // to determine context, though the original_file will be used for
 119         // actual completion.
 120         let file_with_fake_ident = {
 121             let parse = db.parse(position.file_id);
 122             let edit = Indel::insert(position.offset, "intellijRulezz".to_string());
 123             parse.reparse(&edit).tree()
 124         };
 125         let fake_ident_token =
 126             file_with_fake_ident.syntax().token_at_offset(position.offset).right_biased().unwrap();
 127
 128         let krate = sema.to_module_def(position.file_id).map(|m| m.krate());
 129         let original_token =
 130             original_file.syntax().token_at_offset(position.offset).left_biased()?;
 131         let token = sema.descend_into_macros(original_token.clone());
 132         let scope = sema.scope_at_offset(&token, position.offset);
 133         let mut locals = vec![];
 134         scope.process_all_names(&mut |name, scope| {
 135             if let ScopeDef::Local(local) = scope {
 136                 locals.push((name.to_string(), local));
 137             }
 138         });
 139         let mut ctx = CompletionContext {
 140             sema,
 141             scope,
 142             db,
 143             config,
 144             position,
 145             original_token,
 146             token,
 147             krate,
 148             lifetime_allowed: false,
 149             expected_name: None,
 150             expected_type: None,
 151             name_ref_syntax: None,
 152             lifetime_syntax: None,
 153             lifetime_param_syntax: None,
 154             function_syntax: None,
 155             use_item_syntax: None,
 156             record_lit_syntax: None,
 157             record_pat_syntax: None,
 158             record_field_syntax: None,
 159             impl_def: None,
 160             active_parameter: ActiveParameter::at(db, position),
 161             is_label_ref: false,
 162             is_param: false,
 163             is_pat_binding_or_const: false,
 164             is_irrefutable_pat_binding: false,
 165             is_trivial_path: false,
 166             path_qual: None,
 167             after_if: false,
 168             can_be_stmt: false,
 169             is_expr: false,
 170             is_new_item: false,
 171             dot_receiver: None,
 172             dot_receiver_is_ambiguous_float_literal: false,
 173             is_call: false,
 174             is_pattern_call: false,
 175             is_macro_call: false,
 176             is_path_type: false,
 177             has_type_args: false,
 178             attribute_under_caret: None,
 179             mod_declaration_under_caret: None,
 180             previous_token: None,
 181             block_expr_parent: false,
 182             bind_pat_parent: false,
 183             ref_pat_parent: false,
 184             in_loop_body: false,
 185             has_trait_parent: false,
 186             has_impl_parent: 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             no_completion_required: false,
 193             incomplete_let: false,
 194             locals,
 195         };
 196
 197         let mut original_file = original_file.syntax().clone();
 198         let mut speculative_file = file_with_fake_ident.syntax().clone();
 199         let mut offset = position.offset;
 200         let mut fake_ident_token = fake_ident_token;
 201
 202         // Are we inside a macro call?
 203         while let (Some(actual_macro_call), Some(macro_call_with_fake_ident)) = (
 204             find_node_at_offset::<ast::MacroCall>(&original_file, offset),
 205             find_node_at_offset::<ast::MacroCall>(&speculative_file, offset),
 206         ) {
 207             if actual_macro_call.path().as_ref().map(|s| s.syntax().text())
 208                 != macro_call_with_fake_ident.path().as_ref().map(|s| s.syntax().text())
 209             {
 210                 break;
 211             }
 212             let speculative_args = match macro_call_with_fake_ident.token_tree() {
 213                 Some(tt) => tt,
 214                 None => break,
 215             };
 216             if let (Some(actual_expansion), Some(speculative_expansion)) = (
 217                 ctx.sema.expand(&actual_macro_call),
 218                 ctx.sema.speculative_expand(
 219                     &actual_macro_call,
 220                     &speculative_args,
 221                     fake_ident_token,
 222                 ),
 223             ) {
 224                 let new_offset = speculative_expansion.1.text_range().start();
 225                 if new_offset > actual_expansion.text_range().end() {
 226                     break;
 227                 }
 228                 original_file = actual_expansion;
 229                 speculative_file = speculative_expansion.0;
 230                 fake_ident_token = speculative_expansion.1;
 231                 offset = new_offset;
 232             } else {
 233                 break;
 234             }
 235         }
 236         ctx.fill_keyword_patterns(&speculative_file, offset);
 237         ctx.fill(&original_file, speculative_file, offset);
 238         Some(ctx)
 239     }
 240
 241     /// Checks whether completions in that particular case don't make much sense.
 242     /// Examples:
 243     /// - `fn $0` -- we expect function name, it's unlikely that "hint" will be helpful.
 244     ///   Exception for this case is `impl Trait for Foo`, where we would like to hint trait method names.
 245     /// - `for _ i$0` -- obviously, it'll be "in" keyword.
 246     pub(crate) fn no_completion_required(&self) -> bool {
 247         self.no_completion_required
 248     }
 249
 250     /// The range of the identifier that is being completed.
 251     pub(crate) fn source_range(&self) -> TextRange {
 252         // check kind of macro-expanded token, but use range of original token
 253         let kind = self.token.kind();
 254         if kind == IDENT || kind == LIFETIME_IDENT || kind == UNDERSCORE || kind.is_keyword() {
 255             cov_mark::hit!(completes_if_prefix_is_keyword);
 256             self.original_token.text_range()
 257         } else if kind == CHAR {
 258             // assume we are completing a lifetime but the user has only typed the '
 259             cov_mark::hit!(completes_if_lifetime_without_idents);
 260             TextRange::at(self.original_token.text_range().start(), TextSize::from(1))
 261         } else {
 262             TextRange::empty(self.position.offset)
 263         }
 264     }
 265
 266     pub(crate) fn previous_token_is(&self, kind: SyntaxKind) -> bool {
 267         self.previous_token.as_ref().map_or(false, |tok| tok.kind() == kind)
 268     }
 269
 270     fn fill_keyword_patterns(&mut self, file_with_fake_ident: &SyntaxNode, offset: TextSize) {
 271         let fake_ident_token = file_with_fake_ident.token_at_offset(offset).right_biased().unwrap();
 272         let syntax_element = NodeOrToken::Token(fake_ident_token);
 273         self.previous_token = previous_token(syntax_element.clone());
 274         self.block_expr_parent = has_block_expr_parent(syntax_element.clone());
 275         self.bind_pat_parent = has_bind_pat_parent(syntax_element.clone());
 276         self.ref_pat_parent = has_ref_parent(syntax_element.clone());
 277         self.in_loop_body = is_in_loop_body(syntax_element.clone());
 278         self.has_trait_parent = has_trait_parent(syntax_element.clone());
 279         self.has_impl_parent = has_impl_parent(syntax_element.clone());
 280         self.has_field_list_parent = has_field_list_parent(syntax_element.clone());
 281         self.impl_as_prev_sibling = has_impl_as_prev_sibling(syntax_element.clone());
 282         self.trait_as_prev_sibling = has_trait_as_prev_sibling(syntax_element.clone());
 283         self.is_match_arm = is_match_arm(syntax_element.clone());
 284
 285         self.has_item_list_or_source_file_parent =
 286             has_item_list_or_source_file_parent(syntax_element.clone());
 287         self.mod_declaration_under_caret =
 288             find_node_at_offset::<ast::Module>(&file_with_fake_ident, offset)
 289                 .filter(|module| module.item_list().is_none());
 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         let inside_impl_trait_block = inside_impl_trait_block(syntax_element.clone());
 296         let fn_is_prev = self.previous_token_is(T![fn]);
 297         let for_is_prev2 = for_is_prev2(syntax_element.clone());
 298         self.no_completion_required = (fn_is_prev && !inside_impl_trait_block) || for_is_prev2;
 299     }
 300
 301     fn fill_impl_def(&mut self) {
 302         self.impl_def = self
 303             .sema
 304             .token_ancestors_with_macros(self.token.clone())
 305             .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
 306             .find_map(ast::Impl::cast);
 307     }
 308
 309     fn expected_type_and_name(&self) -> (Option<Type>, Option<NameOrNameRef>) {
 310         let mut node = match self.token.parent() {
 311             Some(it) => it,
 312             None => return (None, None),
 313         };
 314         loop {
 315             break match_ast! {
 316                 match node {
 317                     ast::LetStmt(it) => {
 318                         cov_mark::hit!(expected_type_let_with_leading_char);
 319                         cov_mark::hit!(expected_type_let_without_leading_char);
 320                         let ty = it.pat()
 321                             .and_then(|pat| self.sema.type_of_pat(&pat))
 322                             .or_else(|| it.initializer().and_then(|it| self.sema.type_of_expr(&it)));
 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                         // wouldn't try {} be nice...
 346                         (|| {
 347                             let expr_field = self.token.prev_sibling_or_token()?
 348                                       .into_node()
 349                                       .and_then(|node| ast::RecordExprField::cast(node))?;
 350                             let (_, _, ty) = self.sema.resolve_record_field(&expr_field)?;
 351                             Some((
 352                                 Some(ty),
 353                                 expr_field.field_name().map(NameOrNameRef::NameRef),
 354                             ))
 355                         })().unwrap_or((None, None))
 356                     },
 357                     ast::RecordExprField(it) => {
 358                         cov_mark::hit!(expected_type_struct_field_with_leading_char);
 359                         (
 360                             it.expr().as_ref().and_then(|e| self.sema.type_of_expr(e)),
 361                             it.field_name().map(NameOrNameRef::NameRef),
 362                         )
 363                     },
 364                     ast::MatchExpr(it) => {
 365                         cov_mark::hit!(expected_type_match_arm_without_leading_char);
 366                         let ty = it.expr()
 367                             .and_then(|e| self.sema.type_of_expr(&e));
 368                         (ty, None)
 369                     },
 370                     ast::IfExpr(it) => {
 371                         cov_mark::hit!(expected_type_if_let_without_leading_char);
 372                         let ty = it.condition()
 373                             .and_then(|cond| cond.expr())
 374                             .and_then(|e| self.sema.type_of_expr(&e));
 375                         (ty, None)
 376                     },
 377                     ast::IdentPat(it) => {
 378                         cov_mark::hit!(expected_type_if_let_with_leading_char);
 379                         cov_mark::hit!(expected_type_match_arm_with_leading_char);
 380                         let ty = self.sema.type_of_pat(&ast::Pat::from(it));
 381                         (ty, None)
 382                     },
 383                     ast::Fn(it) => {
 384                         cov_mark::hit!(expected_type_fn_ret_with_leading_char);
 385                         cov_mark::hit!(expected_type_fn_ret_without_leading_char);
 386                         let def = self.sema.to_def(&it);
 387                         (def.map(|def| def.ret_type(self.db)), None)
 388                     },
 389                     ast::ClosureExpr(it) => {
 390                         let ty = self.sema.type_of_expr(&it.into());
 391                         ty.and_then(|ty| ty.as_callable(self.db))
 392                             .map(|c| (Some(c.return_type()), None))
 393                             .unwrap_or((None, None))
 394                     },
 395                     ast::Stmt(_it) => (None, None),
 396                     _ => {
 397                         match node.parent() {
 398                             Some(n) => {
 399                                 node = n;
 400                                 continue;
 401                             },
 402                             None => (None, None),
 403                         }
 404                     },
 405                 }
 406             };
 407         }
 408     }
 409
 410     fn fill(
 411         &mut self,
 412         original_file: &SyntaxNode,
 413         file_with_fake_ident: SyntaxNode,
 414         offset: TextSize,
 415     ) {
 416         let (expected_type, expected_name) = self.expected_type_and_name();
 417         self.expected_type = expected_type;
 418         self.expected_name = expected_name;
 419         self.attribute_under_caret = find_node_at_offset(&file_with_fake_ident, offset);
 420
 421         if let Some(lifetime) = find_node_at_offset::<ast::Lifetime>(&file_with_fake_ident, offset)
 422         {
 423             self.classify_lifetime(original_file, lifetime, offset);
 424         }
 425
 426         // First, let's try to complete a reference to some declaration.
 427         if let Some(name_ref) = find_node_at_offset::<ast::NameRef>(&file_with_fake_ident, offset) {
 428             // Special case, `trait T { fn foo(i_am_a_name_ref) {} }`.
 429             // See RFC#1685.
 430             if is_node::<ast::Param>(name_ref.syntax()) {
 431                 self.is_param = true;
 432                 return;
 433             }
 434             // FIXME: remove this (V) duplication and make the check more precise
 435             if name_ref.syntax().ancestors().find_map(ast::RecordPatFieldList::cast).is_some() {
 436                 self.record_pat_syntax =
 437                     self.sema.find_node_at_offset_with_macros(&original_file, offset);
 438             }
 439             self.classify_name_ref(original_file, name_ref, offset);
 440         }
 441
 442         // Otherwise, see if this is a declaration. We can use heuristics to
 443         // suggest declaration names, see `CompletionKind::Magic`.
 444         if let Some(name) = find_node_at_offset::<ast::Name>(&file_with_fake_ident, offset) {
 445             if let Some(bind_pat) = name.syntax().ancestors().find_map(ast::IdentPat::cast) {
 446                 self.is_pat_binding_or_const = true;
 447                 if bind_pat.at_token().is_some()
 448                     || bind_pat.ref_token().is_some()
 449                     || bind_pat.mut_token().is_some()
 450                 {
 451                     self.is_pat_binding_or_const = false;
 452                 }
 453                 if bind_pat.syntax().parent().and_then(ast::RecordPatFieldList::cast).is_some() {
 454                     self.is_pat_binding_or_const = false;
 455                 }
 456                 if let Some(Some(pat)) = bind_pat.syntax().ancestors().find_map(|node| {
 457                     match_ast! {
 458                         match node {
 459                             ast::LetStmt(it) => Some(it.pat()),
 460                             ast::Param(it) => Some(it.pat()),
 461                             _ => None,
 462                         }
 463                     }
 464                 }) {
 465                     if pat.syntax().text_range().contains_range(bind_pat.syntax().text_range()) {
 466                         self.is_pat_binding_or_const = false;
 467                         self.is_irrefutable_pat_binding = true;
 468                     }
 469                 }
 470
 471                 self.fill_impl_def();
 472             }
 473             if is_node::<ast::Param>(name.syntax()) {
 474                 self.is_param = true;
 475                 return;
 476             }
 477             // FIXME: remove this (^) duplication and make the check more precise
 478             if name.syntax().ancestors().find_map(ast::RecordPatFieldList::cast).is_some() {
 479                 self.record_pat_syntax =
 480                     self.sema.find_node_at_offset_with_macros(&original_file, offset);
 481             }
 482         }
 483     }
 484
 485     fn classify_lifetime(
 486         &mut self,
 487         original_file: &SyntaxNode,
 488         lifetime: ast::Lifetime,
 489         offset: TextSize,
 490     ) {
 491         self.lifetime_syntax =
 492             find_node_at_offset(original_file, lifetime.syntax().text_range().start());
 493         if let Some(parent) = lifetime.syntax().parent() {
 494             if parent.kind() == ERROR {
 495                 return;
 496             }
 497
 498             match_ast! {
 499                 match parent {
 500                     ast::LifetimeParam(_it) => {
 501                         self.lifetime_allowed = true;
 502                         self.lifetime_param_syntax =
 503                             self.sema.find_node_at_offset_with_macros(original_file, offset);
 504                     },
 505                     ast::BreakExpr(_it) => self.is_label_ref = true,
 506                     ast::ContinueExpr(_it) => self.is_label_ref = true,
 507                     ast::Label(_it) => (),
 508                     _ => self.lifetime_allowed = true,
 509                 }
 510             }
 511         }
 512     }
 513
 514     fn classify_name_ref(
 515         &mut self,
 516         original_file: &SyntaxNode,
 517         name_ref: ast::NameRef,
 518         offset: TextSize,
 519     ) {
 520         self.name_ref_syntax =
 521             find_node_at_offset(original_file, name_ref.syntax().text_range().start());
 522         let name_range = name_ref.syntax().text_range();
 523         if ast::RecordExprField::for_field_name(&name_ref).is_some() {
 524             self.record_lit_syntax =
 525                 self.sema.find_node_at_offset_with_macros(original_file, offset);
 526         }
 527
 528         self.fill_impl_def();
 529
 530         let top_node = name_ref
 531             .syntax()
 532             .ancestors()
 533             .take_while(|it| it.text_range() == name_range)
 534             .last()
 535             .unwrap();
 536
 537         match top_node.parent().map(|it| it.kind()) {
 538             Some(SOURCE_FILE) | Some(ITEM_LIST) => {
 539                 self.is_new_item = true;
 540                 return;
 541             }
 542             _ => (),
 543         }
 544
 545         self.use_item_syntax =
 546             self.sema.token_ancestors_with_macros(self.token.clone()).find_map(ast::Use::cast);
 547
 548         self.function_syntax = self
 549             .sema
 550             .token_ancestors_with_macros(self.token.clone())
 551             .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
 552             .find_map(ast::Fn::cast);
 553
 554         self.record_field_syntax = self
 555             .sema
 556             .token_ancestors_with_macros(self.token.clone())
 557             .take_while(|it| {
 558                 it.kind() != SOURCE_FILE && it.kind() != MODULE && it.kind() != CALL_EXPR
 559             })
 560             .find_map(ast::RecordExprField::cast);
 561
 562         let parent = match name_ref.syntax().parent() {
 563             Some(it) => it,
 564             None => return,
 565         };
 566
 567         if let Some(segment) = ast::PathSegment::cast(parent.clone()) {
 568             let path = segment.parent_path();
 569             self.is_call = path
 570                 .syntax()
 571                 .parent()
 572                 .and_then(ast::PathExpr::cast)
 573                 .and_then(|it| it.syntax().parent().and_then(ast::CallExpr::cast))
 574                 .is_some();
 575             self.is_macro_call = path.syntax().parent().and_then(ast::MacroCall::cast).is_some();
 576             self.is_pattern_call =
 577                 path.syntax().parent().and_then(ast::TupleStructPat::cast).is_some();
 578
 579             self.is_path_type = path.syntax().parent().and_then(ast::PathType::cast).is_some();
 580             self.has_type_args = segment.generic_arg_list().is_some();
 581
 582             if let Some(path) = path_or_use_tree_qualifier(&path) {
 583                 self.path_qual = path
 584                     .segment()
 585                     .and_then(|it| {
 586                         find_node_with_range::<ast::PathSegment>(
 587                             original_file,
 588                             it.syntax().text_range(),
 589                         )
 590                     })
 591                     .map(|it| it.parent_path());
 592                 return;
 593             }
 594
 595             if let Some(segment) = path.segment() {
 596                 if segment.coloncolon_token().is_some() {
 597                     return;
 598                 }
 599             }
 600
 601             self.is_trivial_path = true;
 602
 603             // Find either enclosing expr statement (thing with `;`) or a
 604             // block. If block, check that we are the last expr.
 605             self.can_be_stmt = name_ref
 606                 .syntax()
 607                 .ancestors()
 608                 .find_map(|node| {
 609                     if let Some(stmt) = ast::ExprStmt::cast(node.clone()) {
 610                         return Some(stmt.syntax().text_range() == name_ref.syntax().text_range());
 611                     }
 612                     if let Some(block) = ast::BlockExpr::cast(node) {
 613                         return Some(
 614                             block.tail_expr().map(|e| e.syntax().text_range())
 615                                 == Some(name_ref.syntax().text_range()),
 616                         );
 617                     }
 618                     None
 619                 })
 620                 .unwrap_or(false);
 621             self.is_expr = path.syntax().parent().and_then(ast::PathExpr::cast).is_some();
 622
 623             if let Some(off) = name_ref.syntax().text_range().start().checked_sub(2.into()) {
 624                 if let Some(if_expr) =
 625                     self.sema.find_node_at_offset_with_macros::<ast::IfExpr>(original_file, off)
 626                 {
 627                     if if_expr.syntax().text_range().end() < name_ref.syntax().text_range().start()
 628                     {
 629                         self.after_if = true;
 630                     }
 631                 }
 632             }
 633         }
 634         if let Some(field_expr) = ast::FieldExpr::cast(parent.clone()) {
 635             // The receiver comes before the point of insertion of the fake
 636             // ident, so it should have the same range in the non-modified file
 637             self.dot_receiver = field_expr
 638                 .expr()
 639                 .map(|e| e.syntax().text_range())
 640                 .and_then(|r| find_node_with_range(original_file, r));
 641             self.dot_receiver_is_ambiguous_float_literal =
 642                 if let Some(ast::Expr::Literal(l)) = &self.dot_receiver {
 643                     match l.kind() {
 644                         ast::LiteralKind::FloatNumber { .. } => l.token().text().ends_with('.'),
 645                         _ => false,
 646                     }
 647                 } else {
 648                     false
 649                 };
 650         }
 651         if let Some(method_call_expr) = ast::MethodCallExpr::cast(parent) {
 652             // As above
 653             self.dot_receiver = method_call_expr
 654                 .receiver()
 655                 .map(|e| e.syntax().text_range())
 656                 .and_then(|r| find_node_with_range(original_file, r));
 657             self.is_call = true;
 658         }
 659     }
 660 }
 661
 662 fn find_node_with_range<N: AstNode>(syntax: &SyntaxNode, range: TextRange) -> Option<N> {
 663     syntax.covering_element(range).ancestors().find_map(N::cast)
 664 }
 665
 666 fn is_node<N: AstNode>(node: &SyntaxNode) -> bool {
 667     match node.ancestors().find_map(N::cast) {
 668         None => false,
 669         Some(n) => n.syntax().text_range() == node.text_range(),
 670     }
 671 }
 672
 673 fn path_or_use_tree_qualifier(path: &ast::Path) -> Option<ast::Path> {
 674     if let Some(qual) = path.qualifier() {
 675         return Some(qual);
 676     }
 677     let use_tree_list = path.syntax().ancestors().find_map(ast::UseTreeList::cast)?;
 678     let use_tree = use_tree_list.syntax().parent().and_then(ast::UseTree::cast)?;
 679     use_tree.path()
 680 }
 681
 682 #[cfg(test)]
 683 mod tests {
 684     use expect_test::{expect, Expect};
 685     use hir::HirDisplay;
 686
 687     use crate::test_utils::{position, TEST_CONFIG};
 688
 689     use super::CompletionContext;
 690
 691     fn check_expected_type_and_name(ra_fixture: &str, expect: Expect) {
 692         let (db, pos) = position(ra_fixture);
 693         let completion_context = CompletionContext::new(&db, pos, &TEST_CONFIG).unwrap();
 694
 695         let ty = completion_context
 696             .expected_type
 697             .map(|t| t.display_test(&db).to_string())
 698             .unwrap_or("?".to_owned());
 699
 700         let name = completion_context
 701             .expected_name
 702             .map_or_else(|| "?".to_owned(), |name| name.to_string());
 703
 704         expect.assert_eq(&format!("ty: {}, name: {}", ty, name));
 705     }
 706
 707     #[test]
 708     fn expected_type_let_without_leading_char() {
 709         cov_mark::check!(expected_type_let_without_leading_char);
 710         check_expected_type_and_name(
 711             r#"
 712 fn foo() {
 713     let x: u32 = $0;
 714 }
 715 "#,
 716             expect![[r#"ty: u32, name: x"#]],
 717         );
 718     }
 719
 720     #[test]
 721     fn expected_type_let_with_leading_char() {
 722         cov_mark::check!(expected_type_let_with_leading_char);
 723         check_expected_type_and_name(
 724             r#"
 725 fn foo() {
 726     let x: u32 = c$0;
 727 }
 728 "#,
 729             expect![[r#"ty: u32, name: x"#]],
 730         );
 731     }
 732
 733     #[test]
 734     fn expected_type_let_pat() {
 735         check_expected_type_and_name(
 736             r#"
 737 fn foo() {
 738     let x$0 = 0u32;
 739 }
 740 "#,
 741             expect![[r#"ty: u32, name: ?"#]],
 742         );
 743         check_expected_type_and_name(
 744             r#"
 745 fn foo() {
 746     let $0 = 0u32;
 747 }
 748 "#,
 749             expect![[r#"ty: u32, name: ?"#]],
 750         );
 751     }
 752
 753     #[test]
 754     fn expected_type_fn_param_without_leading_char() {
 755         cov_mark::check!(expected_type_fn_param_without_leading_char);
 756         check_expected_type_and_name(
 757             r#"
 758 fn foo() {
 759     bar($0);
 760 }
 761
 762 fn bar(x: u32) {}
 763 "#,
 764             expect![[r#"ty: u32, name: x"#]],
 765         );
 766     }
 767
 768     #[test]
 769     fn expected_type_fn_param_with_leading_char() {
 770         cov_mark::check!(expected_type_fn_param_with_leading_char);
 771         check_expected_type_and_name(
 772             r#"
 773 fn foo() {
 774     bar(c$0);
 775 }
 776
 777 fn bar(x: u32) {}
 778 "#,
 779             expect![[r#"ty: u32, name: x"#]],
 780         );
 781     }
 782
 783     #[test]
 784     fn expected_type_struct_field_without_leading_char() {
 785         cov_mark::check!(expected_type_struct_field_without_leading_char);
 786         check_expected_type_and_name(
 787             r#"
 788 struct Foo { a: u32 }
 789 fn foo() {
 790     Foo { a: $0 };
 791 }
 792 "#,
 793             expect![[r#"ty: u32, name: a"#]],
 794         )
 795     }
 796
 797     #[test]
 798     fn expected_type_generic_struct_field() {
 799         check_expected_type_and_name(
 800             r#"
 801 struct Foo<T> { a: T }
 802 fn foo() -> Foo<u32> {
 803     Foo { a: $0 }
 804 }
 805 "#,
 806             expect![[r#"ty: u32, name: a"#]],
 807         )
 808     }
 809
 810     #[test]
 811     fn expected_type_struct_field_with_leading_char() {
 812         cov_mark::check!(expected_type_struct_field_with_leading_char);
 813         check_expected_type_and_name(
 814             r#"
 815 struct Foo { a: u32 }
 816 fn foo() {
 817     Foo { a: c$0 };
 818 }
 819 "#,
 820             expect![[r#"ty: u32, name: a"#]],
 821         );
 822     }
 823
 824     #[test]
 825     fn expected_type_match_arm_without_leading_char() {
 826         cov_mark::check!(expected_type_match_arm_without_leading_char);
 827         check_expected_type_and_name(
 828             r#"
 829 enum E { X }
 830 fn foo() {
 831    match E::X { $0 }
 832 }
 833 "#,
 834             expect![[r#"ty: E, name: ?"#]],
 835         );
 836     }
 837
 838     #[test]
 839     fn expected_type_match_arm_with_leading_char() {
 840         cov_mark::check!(expected_type_match_arm_with_leading_char);
 841         check_expected_type_and_name(
 842             r#"
 843 enum E { X }
 844 fn foo() {
 845    match E::X { c$0 }
 846 }
 847 "#,
 848             expect![[r#"ty: E, name: ?"#]],
 849         );
 850     }
 851
 852     #[test]
 853     fn expected_type_if_let_without_leading_char() {
 854         cov_mark::check!(expected_type_if_let_without_leading_char);
 855         check_expected_type_and_name(
 856             r#"
 857 enum Foo { Bar, Baz, Quux }
 858
 859 fn foo() {
 860     let f = Foo::Quux;
 861     if let $0 = f { }
 862 }
 863 "#,
 864             expect![[r#"ty: Foo, name: ?"#]],
 865         )
 866     }
 867
 868     #[test]
 869     fn expected_type_if_let_with_leading_char() {
 870         cov_mark::check!(expected_type_if_let_with_leading_char);
 871         check_expected_type_and_name(
 872             r#"
 873 enum Foo { Bar, Baz, Quux }
 874
 875 fn foo() {
 876     let f = Foo::Quux;
 877     if let c$0 = f { }
 878 }
 879 "#,
 880             expect![[r#"ty: Foo, name: ?"#]],
 881         )
 882     }
 883
 884     #[test]
 885     fn expected_type_fn_ret_without_leading_char() {
 886         cov_mark::check!(expected_type_fn_ret_without_leading_char);
 887         check_expected_type_and_name(
 888             r#"
 889 fn foo() -> u32 {
 890     $0
 891 }
 892 "#,
 893             expect![[r#"ty: u32, name: ?"#]],
 894         )
 895     }
 896
 897     #[test]
 898     fn expected_type_fn_ret_with_leading_char() {
 899         cov_mark::check!(expected_type_fn_ret_with_leading_char);
 900         check_expected_type_and_name(
 901             r#"
 902 fn foo() -> u32 {
 903     c$0
 904 }
 905 "#,
 906             expect![[r#"ty: u32, name: ?"#]],
 907         )
 908     }
 909
 910     #[test]
 911     fn expected_type_fn_ret_fn_ref_fully_typed() {
 912         check_expected_type_and_name(
 913             r#"
 914 fn foo() -> u32 {
 915     foo$0
 916 }
 917 "#,
 918             expect![[r#"ty: u32, name: ?"#]],
 919         )
 920     }
 921
 922     #[test]
 923     fn expected_type_closure_param_return() {
 924         // FIXME: make this work with `|| $0`
 925         check_expected_type_and_name(
 926             r#"
 927 fn foo() {
 928     bar(|| a$0);
 929 }
 930
 931 fn bar(f: impl FnOnce() -> u32) {}
 932 #[lang = "fn_once"]
 933 trait FnOnce { type Output; }
 934 "#,
 935             expect![[r#"ty: u32, name: ?"#]],
 936         );
 937     }
 938
 939     #[test]
 940     fn expected_type_generic_function() {
 941         check_expected_type_and_name(
 942             r#"
 943 fn foo() {
 944     bar::<u32>($0);
 945 }
 946
 947 fn bar<T>(t: T) {}
 948 "#,
 949             expect![[r#"ty: u32, name: t"#]],
 950         );
 951     }
 952
 953     #[test]
 954     fn expected_type_generic_method() {
 955         check_expected_type_and_name(
 956             r#"
 957 fn foo() {
 958     S(1u32).bar($0);
 959 }
 960
 961 struct S<T>(T);
 962 impl<T> S<T> {
 963     fn bar(self, t: T) {}
 964 }
 965 "#,
 966             expect![[r#"ty: u32, name: t"#]],
 967         );
 968     }
 969 }