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