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 expected_type_and_name(&self) -> (Option<Type>, Option<NameOrNameRef>) {
 305         let mut node = match self.token.parent() {
 306             Some(it) => it,
 307             None => return (None, None),
 308         };
 309         loop {
 310             break match_ast! {
 311                 match node {
 312                     ast::LetStmt(it) => {
 313                         cov_mark::hit!(expected_type_let_with_leading_char);
 314                         cov_mark::hit!(expected_type_let_without_leading_char);
 315                         let ty = it.pat()
 316                             .and_then(|pat| self.sema.type_of_pat(&pat))
 317                             .or_else(|| it.initializer().and_then(|it| self.sema.type_of_expr(&it)));
 318                         let name = if let Some(ast::Pat::IdentPat(ident)) = it.pat() {
 319                             ident.name().map(NameOrNameRef::Name)
 320                         } else {
 321                             None
 322                         };
 323
 324                         (ty, name)
 325                     },
 326                     ast::ArgList(_it) => {
 327                         cov_mark::hit!(expected_type_fn_param_with_leading_char);
 328                         cov_mark::hit!(expected_type_fn_param_without_leading_char);
 329                         ActiveParameter::at_token(
 330                             &self.sema,
 331                             self.token.clone(),
 332                         ).map(|ap| {
 333                             let name = ap.ident().map(NameOrNameRef::Name);
 334                             (Some(ap.ty), name)
 335                         })
 336                         .unwrap_or((None, None))
 337                     },
 338                     ast::RecordExprFieldList(_it) => {
 339                         cov_mark::hit!(expected_type_struct_field_without_leading_char);
 340                         self.token.prev_sibling_or_token()
 341                             .and_then(|se| se.into_node())
 342                             .and_then(|node| ast::RecordExprField::cast(node))
 343                             .and_then(|rf| self.sema.resolve_record_field(&rf).zip(Some(rf)))
 344                             .map(|(f, rf)|(
 345                                 Some(f.0.ty(self.db)),
 346                                 rf.field_name().map(NameOrNameRef::NameRef),
 347                             ))
 348                             .unwrap_or((None, None))
 349                     },
 350                     ast::RecordExprField(it) => {
 351                         cov_mark::hit!(expected_type_struct_field_with_leading_char);
 352                         self.sema
 353                             .resolve_record_field(&it)
 354                             .map(|f|(
 355                                 Some(f.0.ty(self.db)),
 356                                 it.field_name().map(NameOrNameRef::NameRef),
 357                             ))
 358                             .unwrap_or((None, None))
 359                     },
 360                     ast::MatchExpr(it) => {
 361                         cov_mark::hit!(expected_type_match_arm_without_leading_char);
 362                         let ty = it.expr()
 363                             .and_then(|e| self.sema.type_of_expr(&e));
 364                         (ty, None)
 365                     },
 366                     ast::IfExpr(it) => {
 367                         cov_mark::hit!(expected_type_if_let_without_leading_char);
 368                         let ty = it.condition()
 369                             .and_then(|cond| cond.expr())
 370                             .and_then(|e| self.sema.type_of_expr(&e));
 371                         (ty, None)
 372                     },
 373                     ast::IdentPat(it) => {
 374                         cov_mark::hit!(expected_type_if_let_with_leading_char);
 375                         cov_mark::hit!(expected_type_match_arm_with_leading_char);
 376                         let ty = self.sema.type_of_pat(&ast::Pat::from(it));
 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 def = self.sema.to_def(&it);
 383                         (def.map(|def| def.ret_type(self.db)), None)
 384                     },
 385                     ast::Stmt(_it) => (None, None),
 386                     _ => {
 387                         match node.parent() {
 388                             Some(n) => {
 389                                 node = n;
 390                                 continue;
 391                             },
 392                             None => (None, None),
 393                         }
 394                     },
 395                 }
 396             };
 397         }
 398     }
 399
 400     fn fill(
 401         &mut self,
 402         original_file: &SyntaxNode,
 403         file_with_fake_ident: SyntaxNode,
 404         offset: TextSize,
 405     ) {
 406         let (expected_type, expected_name) = self.expected_type_and_name();
 407         self.expected_type = expected_type;
 408         self.expected_name = expected_name;
 409         self.attribute_under_caret = find_node_at_offset(&file_with_fake_ident, offset);
 410
 411         if let Some(lifetime) = find_node_at_offset::<ast::Lifetime>(&file_with_fake_ident, offset)
 412         {
 413             self.classify_lifetime(original_file, lifetime, offset);
 414         }
 415
 416         // First, let's try to complete a reference to some declaration.
 417         if let Some(name_ref) = find_node_at_offset::<ast::NameRef>(&file_with_fake_ident, offset) {
 418             // Special case, `trait T { fn foo(i_am_a_name_ref) {} }`.
 419             // See RFC#1685.
 420             if is_node::<ast::Param>(name_ref.syntax()) {
 421                 self.is_param = true;
 422                 return;
 423             }
 424             // FIXME: remove this (V) duplication and make the check more precise
 425             if name_ref.syntax().ancestors().find_map(ast::RecordPatFieldList::cast).is_some() {
 426                 self.record_pat_syntax =
 427                     self.sema.find_node_at_offset_with_macros(&original_file, offset);
 428             }
 429             self.classify_name_ref(original_file, name_ref, offset);
 430         }
 431
 432         // Otherwise, see if this is a declaration. We can use heuristics to
 433         // suggest declaration names, see `CompletionKind::Magic`.
 434         if let Some(name) = find_node_at_offset::<ast::Name>(&file_with_fake_ident, offset) {
 435             if let Some(bind_pat) = name.syntax().ancestors().find_map(ast::IdentPat::cast) {
 436                 self.is_pat_binding_or_const = true;
 437                 if bind_pat.at_token().is_some()
 438                     || bind_pat.ref_token().is_some()
 439                     || bind_pat.mut_token().is_some()
 440                 {
 441                     self.is_pat_binding_or_const = false;
 442                 }
 443                 if bind_pat.syntax().parent().and_then(ast::RecordPatFieldList::cast).is_some() {
 444                     self.is_pat_binding_or_const = false;
 445                 }
 446                 if let Some(Some(pat)) = bind_pat.syntax().ancestors().find_map(|node| {
 447                     match_ast! {
 448                         match node {
 449                             ast::LetStmt(it) => Some(it.pat()),
 450                             ast::Param(it) => Some(it.pat()),
 451                             _ => None,
 452                         }
 453                     }
 454                 }) {
 455                     if pat.syntax().text_range().contains_range(bind_pat.syntax().text_range()) {
 456                         self.is_pat_binding_or_const = false;
 457                         self.is_irrefutable_pat_binding = true;
 458                     }
 459                 }
 460
 461                 self.fill_impl_def();
 462             }
 463             if is_node::<ast::Param>(name.syntax()) {
 464                 self.is_param = true;
 465                 return;
 466             }
 467             // FIXME: remove this (^) duplication and make the check more precise
 468             if name.syntax().ancestors().find_map(ast::RecordPatFieldList::cast).is_some() {
 469                 self.record_pat_syntax =
 470                     self.sema.find_node_at_offset_with_macros(&original_file, offset);
 471             }
 472         }
 473     }
 474
 475     fn classify_lifetime(
 476         &mut self,
 477         original_file: &SyntaxNode,
 478         lifetime: ast::Lifetime,
 479         offset: TextSize,
 480     ) {
 481         self.lifetime_syntax =
 482             find_node_at_offset(original_file, lifetime.syntax().text_range().start());
 483         if let Some(parent) = lifetime.syntax().parent() {
 484             if parent.kind() == ERROR {
 485                 return;
 486             }
 487
 488             match_ast! {
 489                 match parent {
 490                     ast::LifetimeParam(_it) => {
 491                         self.lifetime_allowed = true;
 492                         self.lifetime_param_syntax =
 493                             self.sema.find_node_at_offset_with_macros(original_file, offset);
 494                     },
 495                     ast::BreakExpr(_it) => self.is_label_ref = true,
 496                     ast::ContinueExpr(_it) => self.is_label_ref = true,
 497                     ast::Label(_it) => (),
 498                     _ => self.lifetime_allowed = true,
 499                 }
 500             }
 501         }
 502     }
 503
 504     fn classify_name_ref(
 505         &mut self,
 506         original_file: &SyntaxNode,
 507         name_ref: ast::NameRef,
 508         offset: TextSize,
 509     ) {
 510         self.name_ref_syntax =
 511             find_node_at_offset(original_file, name_ref.syntax().text_range().start());
 512         let name_range = name_ref.syntax().text_range();
 513         if ast::RecordExprField::for_field_name(&name_ref).is_some() {
 514             self.record_lit_syntax =
 515                 self.sema.find_node_at_offset_with_macros(original_file, offset);
 516         }
 517
 518         self.fill_impl_def();
 519
 520         let top_node = name_ref
 521             .syntax()
 522             .ancestors()
 523             .take_while(|it| it.text_range() == name_range)
 524             .last()
 525             .unwrap();
 526
 527         match top_node.parent().map(|it| it.kind()) {
 528             Some(SOURCE_FILE) | Some(ITEM_LIST) => {
 529                 self.is_new_item = true;
 530                 return;
 531             }
 532             _ => (),
 533         }
 534
 535         self.use_item_syntax =
 536             self.sema.token_ancestors_with_macros(self.token.clone()).find_map(ast::Use::cast);
 537
 538         self.function_syntax = self
 539             .sema
 540             .token_ancestors_with_macros(self.token.clone())
 541             .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
 542             .find_map(ast::Fn::cast);
 543
 544         self.record_field_syntax = self
 545             .sema
 546             .token_ancestors_with_macros(self.token.clone())
 547             .take_while(|it| {
 548                 it.kind() != SOURCE_FILE && it.kind() != MODULE && it.kind() != CALL_EXPR
 549             })
 550             .find_map(ast::RecordExprField::cast);
 551
 552         let parent = match name_ref.syntax().parent() {
 553             Some(it) => it,
 554             None => return,
 555         };
 556
 557         if let Some(segment) = ast::PathSegment::cast(parent.clone()) {
 558             let path = segment.parent_path();
 559             self.is_call = path
 560                 .syntax()
 561                 .parent()
 562                 .and_then(ast::PathExpr::cast)
 563                 .and_then(|it| it.syntax().parent().and_then(ast::CallExpr::cast))
 564                 .is_some();
 565             self.is_macro_call = path.syntax().parent().and_then(ast::MacroCall::cast).is_some();
 566             self.is_pattern_call =
 567                 path.syntax().parent().and_then(ast::TupleStructPat::cast).is_some();
 568
 569             self.is_path_type = path.syntax().parent().and_then(ast::PathType::cast).is_some();
 570             self.has_type_args = segment.generic_arg_list().is_some();
 571
 572             if let Some(path) = path_or_use_tree_qualifier(&path) {
 573                 self.path_qual = path
 574                     .segment()
 575                     .and_then(|it| {
 576                         find_node_with_range::<ast::PathSegment>(
 577                             original_file,
 578                             it.syntax().text_range(),
 579                         )
 580                     })
 581                     .map(|it| it.parent_path());
 582                 return;
 583             }
 584
 585             if let Some(segment) = path.segment() {
 586                 if segment.coloncolon_token().is_some() {
 587                     return;
 588                 }
 589             }
 590
 591             self.is_trivial_path = true;
 592
 593             // Find either enclosing expr statement (thing with `;`) or a
 594             // block. If block, check that we are the last expr.
 595             self.can_be_stmt = name_ref
 596                 .syntax()
 597                 .ancestors()
 598                 .find_map(|node| {
 599                     if let Some(stmt) = ast::ExprStmt::cast(node.clone()) {
 600                         return Some(stmt.syntax().text_range() == name_ref.syntax().text_range());
 601                     }
 602                     if let Some(block) = ast::BlockExpr::cast(node) {
 603                         return Some(
 604                             block.tail_expr().map(|e| e.syntax().text_range())
 605                                 == Some(name_ref.syntax().text_range()),
 606                         );
 607                     }
 608                     None
 609                 })
 610                 .unwrap_or(false);
 611             self.is_expr = path.syntax().parent().and_then(ast::PathExpr::cast).is_some();
 612
 613             if let Some(off) = name_ref.syntax().text_range().start().checked_sub(2.into()) {
 614                 if let Some(if_expr) =
 615                     self.sema.find_node_at_offset_with_macros::<ast::IfExpr>(original_file, off)
 616                 {
 617                     if if_expr.syntax().text_range().end() < name_ref.syntax().text_range().start()
 618                     {
 619                         self.after_if = true;
 620                     }
 621                 }
 622             }
 623         }
 624         if let Some(field_expr) = ast::FieldExpr::cast(parent.clone()) {
 625             // The receiver comes before the point of insertion of the fake
 626             // ident, so it should have the same range in the non-modified file
 627             self.dot_receiver = field_expr
 628                 .expr()
 629                 .map(|e| e.syntax().text_range())
 630                 .and_then(|r| find_node_with_range(original_file, r));
 631             self.dot_receiver_is_ambiguous_float_literal =
 632                 if let Some(ast::Expr::Literal(l)) = &self.dot_receiver {
 633                     match l.kind() {
 634                         ast::LiteralKind::FloatNumber { .. } => l.token().text().ends_with('.'),
 635                         _ => false,
 636                     }
 637                 } else {
 638                     false
 639                 };
 640         }
 641         if let Some(method_call_expr) = ast::MethodCallExpr::cast(parent) {
 642             // As above
 643             self.dot_receiver = method_call_expr
 644                 .receiver()
 645                 .map(|e| e.syntax().text_range())
 646                 .and_then(|r| find_node_with_range(original_file, r));
 647             self.is_call = true;
 648         }
 649     }
 650 }
 651
 652 fn find_node_with_range<N: AstNode>(syntax: &SyntaxNode, range: TextRange) -> Option<N> {
 653     syntax.covering_element(range).ancestors().find_map(N::cast)
 654 }
 655
 656 fn is_node<N: AstNode>(node: &SyntaxNode) -> bool {
 657     match node.ancestors().find_map(N::cast) {
 658         None => false,
 659         Some(n) => n.syntax().text_range() == node.text_range(),
 660     }
 661 }
 662
 663 fn path_or_use_tree_qualifier(path: &ast::Path) -> Option<ast::Path> {
 664     if let Some(qual) = path.qualifier() {
 665         return Some(qual);
 666     }
 667     let use_tree_list = path.syntax().ancestors().find_map(ast::UseTreeList::cast)?;
 668     let use_tree = use_tree_list.syntax().parent().and_then(ast::UseTree::cast)?;
 669     use_tree.path()
 670 }
 671
 672 #[cfg(test)]
 673 mod tests {
 674     use expect_test::{expect, Expect};
 675     use hir::HirDisplay;
 676
 677     use crate::test_utils::{position, TEST_CONFIG};
 678
 679     use super::CompletionContext;
 680
 681     fn check_expected_type_and_name(ra_fixture: &str, expect: Expect) {
 682         let (db, pos) = position(ra_fixture);
 683         let completion_context = CompletionContext::new(&db, pos, &TEST_CONFIG).unwrap();
 684
 685         let ty = completion_context
 686             .expected_type
 687             .map(|t| t.display_test(&db).to_string())
 688             .unwrap_or("?".to_owned());
 689
 690         let name = completion_context
 691             .expected_name
 692             .map_or_else(|| "?".to_owned(), |name| name.to_string());
 693
 694         expect.assert_eq(&format!("ty: {}, name: {}", ty, name));
 695     }
 696
 697     #[test]
 698     fn expected_type_let_without_leading_char() {
 699         cov_mark::check!(expected_type_let_without_leading_char);
 700         check_expected_type_and_name(
 701             r#"
 702 fn foo() {
 703     let x: u32 = $0;
 704 }
 705 "#,
 706             expect![[r#"ty: u32, name: x"#]],
 707         );
 708     }
 709
 710     #[test]
 711     fn expected_type_let_with_leading_char() {
 712         cov_mark::check!(expected_type_let_with_leading_char);
 713         check_expected_type_and_name(
 714             r#"
 715 fn foo() {
 716     let x: u32 = c$0;
 717 }
 718 "#,
 719             expect![[r#"ty: u32, name: x"#]],
 720         );
 721     }
 722
 723     #[test]
 724     fn expected_type_let_pat() {
 725         check_expected_type_and_name(
 726             r#"
 727 fn foo() {
 728     let x$0 = 0u32;
 729 }
 730 "#,
 731             expect![[r#"ty: u32, name: ?"#]],
 732         );
 733         check_expected_type_and_name(
 734             r#"
 735 fn foo() {
 736     let $0 = 0u32;
 737 }
 738 "#,
 739             expect![[r#"ty: u32, name: ?"#]],
 740         );
 741     }
 742
 743     #[test]
 744     fn expected_type_fn_param_without_leading_char() {
 745         cov_mark::check!(expected_type_fn_param_without_leading_char);
 746         check_expected_type_and_name(
 747             r#"
 748 fn foo() {
 749     bar($0);
 750 }
 751
 752 fn bar(x: u32) {}
 753 "#,
 754             expect![[r#"ty: u32, name: x"#]],
 755         );
 756     }
 757
 758     #[test]
 759     fn expected_type_fn_param_with_leading_char() {
 760         cov_mark::check!(expected_type_fn_param_with_leading_char);
 761         check_expected_type_and_name(
 762             r#"
 763 fn foo() {
 764     bar(c$0);
 765 }
 766
 767 fn bar(x: u32) {}
 768 "#,
 769             expect![[r#"ty: u32, name: x"#]],
 770         );
 771     }
 772
 773     #[test]
 774     fn expected_type_struct_field_without_leading_char() {
 775         cov_mark::check!(expected_type_struct_field_without_leading_char);
 776         check_expected_type_and_name(
 777             r#"
 778 struct Foo { a: u32 }
 779 fn foo() {
 780     Foo { a: $0 };
 781 }
 782 "#,
 783             expect![[r#"ty: u32, name: a"#]],
 784         )
 785     }
 786
 787     #[test]
 788     fn expected_type_struct_field_with_leading_char() {
 789         cov_mark::check!(expected_type_struct_field_with_leading_char);
 790         check_expected_type_and_name(
 791             r#"
 792 struct Foo { a: u32 }
 793 fn foo() {
 794     Foo { a: c$0 };
 795 }
 796 "#,
 797             expect![[r#"ty: u32, name: a"#]],
 798         );
 799     }
 800
 801     #[test]
 802     fn expected_type_match_arm_without_leading_char() {
 803         cov_mark::check!(expected_type_match_arm_without_leading_char);
 804         check_expected_type_and_name(
 805             r#"
 806 enum E { X }
 807 fn foo() {
 808    match E::X { $0 }
 809 }
 810 "#,
 811             expect![[r#"ty: E, name: ?"#]],
 812         );
 813     }
 814
 815     #[test]
 816     fn expected_type_match_arm_with_leading_char() {
 817         cov_mark::check!(expected_type_match_arm_with_leading_char);
 818         check_expected_type_and_name(
 819             r#"
 820 enum E { X }
 821 fn foo() {
 822    match E::X { c$0 }
 823 }
 824 "#,
 825             expect![[r#"ty: E, name: ?"#]],
 826         );
 827     }
 828
 829     #[test]
 830     fn expected_type_if_let_without_leading_char() {
 831         cov_mark::check!(expected_type_if_let_without_leading_char);
 832         check_expected_type_and_name(
 833             r#"
 834 enum Foo { Bar, Baz, Quux }
 835
 836 fn foo() {
 837     let f = Foo::Quux;
 838     if let $0 = f { }
 839 }
 840 "#,
 841             expect![[r#"ty: Foo, name: ?"#]],
 842         )
 843     }
 844
 845     #[test]
 846     fn expected_type_if_let_with_leading_char() {
 847         cov_mark::check!(expected_type_if_let_with_leading_char);
 848         check_expected_type_and_name(
 849             r#"
 850 enum Foo { Bar, Baz, Quux }
 851
 852 fn foo() {
 853     let f = Foo::Quux;
 854     if let c$0 = f { }
 855 }
 856 "#,
 857             expect![[r#"ty: Foo, name: ?"#]],
 858         )
 859     }
 860
 861     #[test]
 862     fn expected_type_fn_ret_without_leading_char() {
 863         cov_mark::check!(expected_type_fn_ret_without_leading_char);
 864         check_expected_type_and_name(
 865             r#"
 866 fn foo() -> u32 {
 867     $0
 868 }
 869 "#,
 870             expect![[r#"ty: u32, name: ?"#]],
 871         )
 872     }
 873
 874     #[test]
 875     fn expected_type_fn_ret_with_leading_char() {
 876         cov_mark::check!(expected_type_fn_ret_with_leading_char);
 877         check_expected_type_and_name(
 878             r#"
 879 fn foo() -> u32 {
 880     c$0
 881 }
 882 "#,
 883             expect![[r#"ty: u32, name: ?"#]],
 884         )
 885     }
 886
 887     #[test]
 888     fn expected_type_fn_ret_fn_ref_fully_typed() {
 889         check_expected_type_and_name(
 890             r#"
 891 fn foo() -> u32 {
 892     foo$0
 893 }
 894 "#,
 895             expect![[r#"ty: u32, name: ?"#]],
 896         )
 897     }
 898 }