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                         let name = if let Some(ast::Pat::IdentPat(ident)) = it.pat() {
 318                             ident.name().map(NameOrNameRef::Name)
 319                         } else {
 320                             None
 321                         };
 322
 323                         (ty, name)
 324                     },
 325                     ast::ArgList(_it) => {
 326                         cov_mark::hit!(expected_type_fn_param_with_leading_char);
 327                         cov_mark::hit!(expected_type_fn_param_without_leading_char);
 328                         ActiveParameter::at_token(
 329                             &self.sema,
 330                             self.token.clone(),
 331                         ).map(|ap| {
 332                             let name = ap.ident().map(NameOrNameRef::Name);
 333                             (Some(ap.ty), name)
 334                         })
 335                         .unwrap_or((None, None))
 336                     },
 337                     ast::RecordExprFieldList(_it) => {
 338                         cov_mark::hit!(expected_type_struct_field_without_leading_char);
 339                         self.token.prev_sibling_or_token()
 340                             .and_then(|se| se.into_node())
 341                             .and_then(|node| ast::RecordExprField::cast(node))
 342                             .and_then(|rf| self.sema.resolve_record_field(&rf).zip(Some(rf)))
 343                             .map(|(f, rf)|(
 344                                 Some(f.0.ty(self.db)),
 345                                 rf.field_name().map(NameOrNameRef::NameRef),
 346                             ))
 347                             .unwrap_or((None, None))
 348                     },
 349                     ast::RecordExprField(it) => {
 350                         cov_mark::hit!(expected_type_struct_field_with_leading_char);
 351                         self.sema
 352                             .resolve_record_field(&it)
 353                             .map(|f|(
 354                                 Some(f.0.ty(self.db)),
 355                                 it.field_name().map(NameOrNameRef::NameRef),
 356                             ))
 357                             .unwrap_or((None, None))
 358                     },
 359                     ast::MatchExpr(it) => {
 360                         cov_mark::hit!(expected_type_match_arm_without_leading_char);
 361                         let ty = it.expr()
 362                             .and_then(|e| self.sema.type_of_expr(&e));
 363                         (ty, None)
 364                     },
 365                     ast::IfExpr(it) => {
 366                         cov_mark::hit!(expected_type_if_let_without_leading_char);
 367                         let ty = it.condition()
 368                             .and_then(|cond| cond.expr())
 369                             .and_then(|e| self.sema.type_of_expr(&e));
 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                         (ty, None)
 377                     },
 378                     ast::Fn(it) => {
 379                         cov_mark::hit!(expected_type_fn_ret_with_leading_char);
 380                         cov_mark::hit!(expected_type_fn_ret_without_leading_char);
 381                         let def = self.sema.to_def(&it);
 382                         (def.map(|def| def.ret_type(self.db)), None)
 383                     },
 384                     ast::Stmt(it) => (None, None),
 385                     _ => {
 386                         match node.parent() {
 387                             Some(n) => {
 388                                 node = n;
 389                                 continue;
 390                             },
 391                             None => (None, None),
 392                         }
 393                     },
 394                 }
 395             };
 396         }
 397     }
 398
 399     fn fill(
 400         &mut self,
 401         original_file: &SyntaxNode,
 402         file_with_fake_ident: SyntaxNode,
 403         offset: TextSize,
 404     ) {
 405         let (expected_type, expected_name) = self.expected_type_and_name();
 406         self.expected_type = expected_type;
 407         self.expected_name = expected_name;
 408         self.attribute_under_caret = find_node_at_offset(&file_with_fake_ident, offset);
 409
 410         if let Some(lifetime) = find_node_at_offset::<ast::Lifetime>(&file_with_fake_ident, offset)
 411         {
 412             self.classify_lifetime(original_file, lifetime, offset);
 413         }
 414
 415         // First, let's try to complete a reference to some declaration.
 416         if let Some(name_ref) = find_node_at_offset::<ast::NameRef>(&file_with_fake_ident, offset) {
 417             // Special case, `trait T { fn foo(i_am_a_name_ref) {} }`.
 418             // See RFC#1685.
 419             if is_node::<ast::Param>(name_ref.syntax()) {
 420                 self.is_param = true;
 421                 return;
 422             }
 423             // FIXME: remove this (V) duplication and make the check more precise
 424             if name_ref.syntax().ancestors().find_map(ast::RecordPatFieldList::cast).is_some() {
 425                 self.record_pat_syntax =
 426                     self.sema.find_node_at_offset_with_macros(&original_file, offset);
 427             }
 428             self.classify_name_ref(original_file, name_ref, offset);
 429         }
 430
 431         // Otherwise, see if this is a declaration. We can use heuristics to
 432         // suggest declaration names, see `CompletionKind::Magic`.
 433         if let Some(name) = find_node_at_offset::<ast::Name>(&file_with_fake_ident, offset) {
 434             if let Some(bind_pat) = name.syntax().ancestors().find_map(ast::IdentPat::cast) {
 435                 self.is_pat_binding_or_const = true;
 436                 if bind_pat.at_token().is_some()
 437                     || bind_pat.ref_token().is_some()
 438                     || bind_pat.mut_token().is_some()
 439                 {
 440                     self.is_pat_binding_or_const = false;
 441                 }
 442                 if bind_pat.syntax().parent().and_then(ast::RecordPatFieldList::cast).is_some() {
 443                     self.is_pat_binding_or_const = false;
 444                 }
 445                 if let Some(Some(pat)) = bind_pat.syntax().ancestors().find_map(|node| {
 446                     match_ast! {
 447                         match node {
 448                             ast::LetStmt(it) => Some(it.pat()),
 449                             ast::Param(it) => Some(it.pat()),
 450                             _ => None,
 451                         }
 452                     }
 453                 }) {
 454                     if pat.syntax().text_range().contains_range(bind_pat.syntax().text_range()) {
 455                         self.is_pat_binding_or_const = false;
 456                         self.is_irrefutable_pat_binding = true;
 457                     }
 458                 }
 459
 460                 self.fill_impl_def();
 461             }
 462             if is_node::<ast::Param>(name.syntax()) {
 463                 self.is_param = true;
 464                 return;
 465             }
 466             // FIXME: remove this (^) duplication and make the check more precise
 467             if name.syntax().ancestors().find_map(ast::RecordPatFieldList::cast).is_some() {
 468                 self.record_pat_syntax =
 469                     self.sema.find_node_at_offset_with_macros(&original_file, offset);
 470             }
 471         }
 472     }
 473
 474     fn classify_lifetime(
 475         &mut self,
 476         original_file: &SyntaxNode,
 477         lifetime: ast::Lifetime,
 478         offset: TextSize,
 479     ) {
 480         self.lifetime_syntax =
 481             find_node_at_offset(original_file, lifetime.syntax().text_range().start());
 482         if let Some(parent) = lifetime.syntax().parent() {
 483             if parent.kind() == ERROR {
 484                 return;
 485             }
 486
 487             match_ast! {
 488                 match parent {
 489                     ast::LifetimeParam(_it) => {
 490                         self.lifetime_allowed = true;
 491                         self.lifetime_param_syntax =
 492                             self.sema.find_node_at_offset_with_macros(original_file, offset);
 493                     },
 494                     ast::BreakExpr(_it) => self.is_label_ref = true,
 495                     ast::ContinueExpr(_it) => self.is_label_ref = true,
 496                     ast::Label(_it) => (),
 497                     _ => self.lifetime_allowed = true,
 498                 }
 499             }
 500         }
 501     }
 502
 503     fn classify_name_ref(
 504         &mut self,
 505         original_file: &SyntaxNode,
 506         name_ref: ast::NameRef,
 507         offset: TextSize,
 508     ) {
 509         self.name_ref_syntax =
 510             find_node_at_offset(original_file, name_ref.syntax().text_range().start());
 511         let name_range = name_ref.syntax().text_range();
 512         if ast::RecordExprField::for_field_name(&name_ref).is_some() {
 513             self.record_lit_syntax =
 514                 self.sema.find_node_at_offset_with_macros(original_file, offset);
 515         }
 516
 517         self.fill_impl_def();
 518
 519         let top_node = name_ref
 520             .syntax()
 521             .ancestors()
 522             .take_while(|it| it.text_range() == name_range)
 523             .last()
 524             .unwrap();
 525
 526         match top_node.parent().map(|it| it.kind()) {
 527             Some(SOURCE_FILE) | Some(ITEM_LIST) => {
 528                 self.is_new_item = true;
 529                 return;
 530             }
 531             _ => (),
 532         }
 533
 534         self.use_item_syntax =
 535             self.sema.token_ancestors_with_macros(self.token.clone()).find_map(ast::Use::cast);
 536
 537         self.function_syntax = self
 538             .sema
 539             .token_ancestors_with_macros(self.token.clone())
 540             .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
 541             .find_map(ast::Fn::cast);
 542
 543         self.record_field_syntax = self
 544             .sema
 545             .token_ancestors_with_macros(self.token.clone())
 546             .take_while(|it| {
 547                 it.kind() != SOURCE_FILE && it.kind() != MODULE && it.kind() != CALL_EXPR
 548             })
 549             .find_map(ast::RecordExprField::cast);
 550
 551         let parent = match name_ref.syntax().parent() {
 552             Some(it) => it,
 553             None => return,
 554         };
 555
 556         if let Some(segment) = ast::PathSegment::cast(parent.clone()) {
 557             let path = segment.parent_path();
 558             self.is_call = path
 559                 .syntax()
 560                 .parent()
 561                 .and_then(ast::PathExpr::cast)
 562                 .and_then(|it| it.syntax().parent().and_then(ast::CallExpr::cast))
 563                 .is_some();
 564             self.is_macro_call = path.syntax().parent().and_then(ast::MacroCall::cast).is_some();
 565             self.is_pattern_call =
 566                 path.syntax().parent().and_then(ast::TupleStructPat::cast).is_some();
 567
 568             self.is_path_type = path.syntax().parent().and_then(ast::PathType::cast).is_some();
 569             self.has_type_args = segment.generic_arg_list().is_some();
 570
 571             if let Some(path) = path_or_use_tree_qualifier(&path) {
 572                 self.path_qual = path
 573                     .segment()
 574                     .and_then(|it| {
 575                         find_node_with_range::<ast::PathSegment>(
 576                             original_file,
 577                             it.syntax().text_range(),
 578                         )
 579                     })
 580                     .map(|it| it.parent_path());
 581                 return;
 582             }
 583
 584             if let Some(segment) = path.segment() {
 585                 if segment.coloncolon_token().is_some() {
 586                     return;
 587                 }
 588             }
 589
 590             self.is_trivial_path = true;
 591
 592             // Find either enclosing expr statement (thing with `;`) or a
 593             // block. If block, check that we are the last expr.
 594             self.can_be_stmt = name_ref
 595                 .syntax()
 596                 .ancestors()
 597                 .find_map(|node| {
 598                     if let Some(stmt) = ast::ExprStmt::cast(node.clone()) {
 599                         return Some(stmt.syntax().text_range() == name_ref.syntax().text_range());
 600                     }
 601                     if let Some(block) = ast::BlockExpr::cast(node) {
 602                         return Some(
 603                             block.tail_expr().map(|e| e.syntax().text_range())
 604                                 == Some(name_ref.syntax().text_range()),
 605                         );
 606                     }
 607                     None
 608                 })
 609                 .unwrap_or(false);
 610             self.is_expr = path.syntax().parent().and_then(ast::PathExpr::cast).is_some();
 611
 612             if let Some(off) = name_ref.syntax().text_range().start().checked_sub(2.into()) {
 613                 if let Some(if_expr) =
 614                     self.sema.find_node_at_offset_with_macros::<ast::IfExpr>(original_file, off)
 615                 {
 616                     if if_expr.syntax().text_range().end() < name_ref.syntax().text_range().start()
 617                     {
 618                         self.after_if = true;
 619                     }
 620                 }
 621             }
 622         }
 623         if let Some(field_expr) = ast::FieldExpr::cast(parent.clone()) {
 624             // The receiver comes before the point of insertion of the fake
 625             // ident, so it should have the same range in the non-modified file
 626             self.dot_receiver = field_expr
 627                 .expr()
 628                 .map(|e| e.syntax().text_range())
 629                 .and_then(|r| find_node_with_range(original_file, r));
 630             self.dot_receiver_is_ambiguous_float_literal =
 631                 if let Some(ast::Expr::Literal(l)) = &self.dot_receiver {
 632                     match l.kind() {
 633                         ast::LiteralKind::FloatNumber { .. } => l.token().text().ends_with('.'),
 634                         _ => false,
 635                     }
 636                 } else {
 637                     false
 638                 };
 639         }
 640         if let Some(method_call_expr) = ast::MethodCallExpr::cast(parent) {
 641             // As above
 642             self.dot_receiver = method_call_expr
 643                 .receiver()
 644                 .map(|e| e.syntax().text_range())
 645                 .and_then(|r| find_node_with_range(original_file, r));
 646             self.is_call = true;
 647         }
 648     }
 649 }
 650
 651 fn find_node_with_range<N: AstNode>(syntax: &SyntaxNode, range: TextRange) -> Option<N> {
 652     syntax.covering_element(range).ancestors().find_map(N::cast)
 653 }
 654
 655 fn is_node<N: AstNode>(node: &SyntaxNode) -> bool {
 656     match node.ancestors().find_map(N::cast) {
 657         None => false,
 658         Some(n) => n.syntax().text_range() == node.text_range(),
 659     }
 660 }
 661
 662 fn path_or_use_tree_qualifier(path: &ast::Path) -> Option<ast::Path> {
 663     if let Some(qual) = path.qualifier() {
 664         return Some(qual);
 665     }
 666     let use_tree_list = path.syntax().ancestors().find_map(ast::UseTreeList::cast)?;
 667     let use_tree = use_tree_list.syntax().parent().and_then(ast::UseTree::cast)?;
 668     use_tree.path()
 669 }
 670
 671 #[cfg(test)]
 672 mod tests {
 673     use expect_test::{expect, Expect};
 674     use hir::HirDisplay;
 675
 676     use crate::test_utils::{position, TEST_CONFIG};
 677
 678     use super::CompletionContext;
 679
 680     fn check_expected_type_and_name(ra_fixture: &str, expect: Expect) {
 681         let (db, pos) = position(ra_fixture);
 682         let completion_context = CompletionContext::new(&db, pos, &TEST_CONFIG).unwrap();
 683
 684         let ty = completion_context
 685             .expected_type
 686             .map(|t| t.display_test(&db).to_string())
 687             .unwrap_or("?".to_owned());
 688
 689         let name = completion_context
 690             .expected_name
 691             .map_or_else(|| "?".to_owned(), |name| name.to_string());
 692
 693         expect.assert_eq(&format!("ty: {}, name: {}", ty, name));
 694     }
 695
 696     #[test]
 697     fn expected_type_let_without_leading_char() {
 698         cov_mark::check!(expected_type_let_without_leading_char);
 699         check_expected_type_and_name(
 700             r#"
 701 fn foo() {
 702     let x: u32 = $0;
 703 }
 704 "#,
 705             expect![[r#"ty: u32, name: x"#]],
 706         );
 707     }
 708
 709     #[test]
 710     fn expected_type_let_with_leading_char() {
 711         cov_mark::check!(expected_type_let_with_leading_char);
 712         check_expected_type_and_name(
 713             r#"
 714 fn foo() {
 715     let x: u32 = c$0;
 716 }
 717 "#,
 718             expect![[r#"ty: u32, name: x"#]],
 719         );
 720     }
 721
 722     #[test]
 723     fn expected_type_fn_param_without_leading_char() {
 724         cov_mark::check!(expected_type_fn_param_without_leading_char);
 725         check_expected_type_and_name(
 726             r#"
 727 fn foo() {
 728     bar($0);
 729 }
 730
 731 fn bar(x: u32) {}
 732 "#,
 733             expect![[r#"ty: u32, name: x"#]],
 734         );
 735     }
 736
 737     #[test]
 738     fn expected_type_fn_param_with_leading_char() {
 739         cov_mark::check!(expected_type_fn_param_with_leading_char);
 740         check_expected_type_and_name(
 741             r#"
 742 fn foo() {
 743     bar(c$0);
 744 }
 745
 746 fn bar(x: u32) {}
 747 "#,
 748             expect![[r#"ty: u32, name: x"#]],
 749         );
 750     }
 751
 752     #[test]
 753     fn expected_type_struct_field_without_leading_char() {
 754         cov_mark::check!(expected_type_struct_field_without_leading_char);
 755         check_expected_type_and_name(
 756             r#"
 757 struct Foo { a: u32 }
 758 fn foo() {
 759     Foo { a: $0 };
 760 }
 761 "#,
 762             expect![[r#"ty: u32, name: a"#]],
 763         )
 764     }
 765
 766     #[test]
 767     fn expected_type_struct_field_with_leading_char() {
 768         cov_mark::check!(expected_type_struct_field_with_leading_char);
 769         check_expected_type_and_name(
 770             r#"
 771 struct Foo { a: u32 }
 772 fn foo() {
 773     Foo { a: c$0 };
 774 }
 775 "#,
 776             expect![[r#"ty: u32, name: a"#]],
 777         );
 778     }
 779
 780     #[test]
 781     fn expected_type_match_arm_without_leading_char() {
 782         cov_mark::check!(expected_type_match_arm_without_leading_char);
 783         check_expected_type_and_name(
 784             r#"
 785 enum E { X }
 786 fn foo() {
 787    match E::X { $0 }
 788 }
 789 "#,
 790             expect![[r#"ty: E, name: ?"#]],
 791         );
 792     }
 793
 794     #[test]
 795     fn expected_type_match_arm_with_leading_char() {
 796         cov_mark::check!(expected_type_match_arm_with_leading_char);
 797         check_expected_type_and_name(
 798             r#"
 799 enum E { X }
 800 fn foo() {
 801    match E::X { c$0 }
 802 }
 803 "#,
 804             expect![[r#"ty: E, name: ?"#]],
 805         );
 806     }
 807
 808     #[test]
 809     fn expected_type_if_let_without_leading_char() {
 810         cov_mark::check!(expected_type_if_let_without_leading_char);
 811         check_expected_type_and_name(
 812             r#"
 813 enum Foo { Bar, Baz, Quux }
 814
 815 fn foo() {
 816     let f = Foo::Quux;
 817     if let $0 = f { }
 818 }
 819 "#,
 820             expect![[r#"ty: Foo, name: ?"#]],
 821         )
 822     }
 823
 824     #[test]
 825     fn expected_type_if_let_with_leading_char() {
 826         cov_mark::check!(expected_type_if_let_with_leading_char);
 827         check_expected_type_and_name(
 828             r#"
 829 enum Foo { Bar, Baz, Quux }
 830
 831 fn foo() {
 832     let f = Foo::Quux;
 833     if let c$0 = f { }
 834 }
 835 "#,
 836             expect![[r#"ty: Foo, name: ?"#]],
 837         )
 838     }
 839
 840     #[test]
 841     fn expected_type_fn_ret_without_leading_char() {
 842         cov_mark::check!(expected_type_fn_ret_without_leading_char);
 843         check_expected_type_and_name(
 844             r#"
 845 fn foo() -> u32 {
 846     $0
 847 }
 848 "#,
 849             expect![[r#"ty: u32, name: ?"#]],
 850         )
 851     }
 852
 853     #[test]
 854     fn expected_type_fn_ret_with_leading_char() {
 855         cov_mark::check!(expected_type_fn_ret_with_leading_char);
 856         check_expected_type_and_name(
 857             r#"
 858 fn foo() -> u32 {
 859     c$0
 860 }
 861 "#,
 862             expect![[r#"ty: u32, name: ?"#]],
 863         )
 864     }
 865
 866     #[test]
 867     fn expected_type_fn_ret_fn_ref_fully_typed() {
 868         check_expected_type_and_name(
 869             r#"
 870 fn foo() -> u32 {
 871     foo$0
 872 }
 873 "#,
 874             expect![[r#"ty: u32, name: ?"#]],
 875         )
 876     }
 877 }