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[rust.git] / 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 {
259             TextRange::empty(self.position.offset)
260         }
261     }
262
263     fn fill_keyword_patterns(&mut self, file_with_fake_ident: &SyntaxNode, offset: TextSize) {
264         let fake_ident_token = file_with_fake_ident.token_at_offset(offset).right_biased().unwrap();
265         let syntax_element = NodeOrToken::Token(fake_ident_token);
266         self.block_expr_parent = has_block_expr_parent(syntax_element.clone());
267         self.unsafe_is_prev = unsafe_is_prev(syntax_element.clone());
268         self.if_is_prev = if_is_prev(syntax_element.clone());
269         self.bind_pat_parent = has_bind_pat_parent(syntax_element.clone());
270         self.ref_pat_parent = has_ref_parent(syntax_element.clone());
271         self.in_loop_body = is_in_loop_body(syntax_element.clone());
272         self.has_trait_parent = has_trait_parent(syntax_element.clone());
273         self.has_impl_parent = has_impl_parent(syntax_element.clone());
274         self.inside_impl_trait_block = inside_impl_trait_block(syntax_element.clone());
275         self.has_field_list_parent = has_field_list_parent(syntax_element.clone());
276         self.impl_as_prev_sibling = has_impl_as_prev_sibling(syntax_element.clone());
277         self.trait_as_prev_sibling = has_trait_as_prev_sibling(syntax_element.clone());
278         self.is_match_arm = is_match_arm(syntax_element.clone());
279         self.has_item_list_or_source_file_parent =
280             has_item_list_or_source_file_parent(syntax_element.clone());
281         self.mod_declaration_under_caret =
282             find_node_at_offset::<ast::Module>(&file_with_fake_ident, offset)
283                 .filter(|module| module.item_list().is_none());
284         self.for_is_prev2 = for_is_prev2(syntax_element.clone());
285         self.fn_is_prev = fn_is_prev(syntax_element.clone());
286         self.incomplete_let =
287             syntax_element.ancestors().take(6).find_map(ast::LetStmt::cast).map_or(false, |it| {
288                 it.syntax().text_range().end() == syntax_element.text_range().end()
289             });
290     }
291
292     fn fill_impl_def(&mut self) {
293         self.impl_def = self
294             .sema
295             .token_ancestors_with_macros(self.token.clone())
296             .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
297             .find_map(ast::Impl::cast);
298     }
299
300     fn fill(
301         &mut self,
302         original_file: &SyntaxNode,
303         file_with_fake_ident: SyntaxNode,
304         offset: TextSize,
305     ) {
306         let (expected_type, expected_name) = {
307             let mut node = match self.token.parent() {
308                 Some(it) => it,
309                 None => return,
310             };
311             loop {
312                 break match_ast! {
313                     match node {
314                         ast::LetStmt(it) => {
315                             cov_mark::hit!(expected_type_let_with_leading_char);
316                             cov_mark::hit!(expected_type_let_without_leading_char);
317                             let ty = it.pat()
318                                 .and_then(|pat| self.sema.type_of_pat(&pat));
319                             let name = if let Some(ast::Pat::IdentPat(ident)) = it.pat() {
320                                 ident.name().map(NameOrNameRef::Name)
321                             } else {
322                                 None
323                             };
324
325                             (ty, name)
326                         },
327                         ast::ArgList(_it) => {
328                             cov_mark::hit!(expected_type_fn_param_with_leading_char);
329                             cov_mark::hit!(expected_type_fn_param_without_leading_char);
330                             ActiveParameter::at_token(
331                                 &self.sema,
332                                 self.token.clone(),
333                             ).map(|ap| {
334                                 let name = ap.ident().map(NameOrNameRef::Name);
335                                 (Some(ap.ty), name)
336                             })
337                             .unwrap_or((None, None))
338                         },
339                         ast::RecordExprFieldList(_it) => {
340                             cov_mark::hit!(expected_type_struct_field_without_leading_char);
341                             self.token.prev_sibling_or_token()
342                                 .and_then(|se| se.into_node())
343                                 .and_then(|node| ast::RecordExprField::cast(node))
344                                 .and_then(|rf| self.sema.resolve_record_field(&rf).zip(Some(rf)))
345                                 .map(|(f, rf)|(
346                                     Some(f.0.signature_ty(self.db)),
347                                     rf.field_name().map(NameOrNameRef::NameRef),
348                                 ))
349                                 .unwrap_or((None, None))
350                         },
351                         ast::RecordExprField(it) => {
352                             cov_mark::hit!(expected_type_struct_field_with_leading_char);
353                             self.sema
354                                 .resolve_record_field(&it)
355                                 .map(|f|(
356                                     Some(f.0.signature_ty(self.db)),
357                                     it.field_name().map(NameOrNameRef::NameRef),
358                                 ))
359                                 .unwrap_or((None, None))
360                         },
361                         ast::MatchExpr(it) => {
362                             cov_mark::hit!(expected_type_match_arm_without_leading_char);
363                             let ty = it.expr()
364                                 .and_then(|e| self.sema.type_of_expr(&e));
365
366                             (ty, None)
367                         },
368                         ast::IdentPat(it) => {
369                             cov_mark::hit!(expected_type_if_let_with_leading_char);
370                             cov_mark::hit!(expected_type_match_arm_with_leading_char);
371                             let ty = self.sema.type_of_pat(&ast::Pat::from(it));
372
373                             (ty, None)
374                         },
375                         ast::Fn(_it) => {
376                             cov_mark::hit!(expected_type_fn_ret_with_leading_char);
377                             cov_mark::hit!(expected_type_fn_ret_without_leading_char);
378                             let ty = self.token.ancestors()
379                                 .find_map(|ancestor| ast::Expr::cast(ancestor))
380                                 .and_then(|expr| self.sema.type_of_expr(&expr));
381
382                             (ty, None)
383                         },
384                         _ => {
385                             match node.parent() {
386                                 Some(n) => {
387                                     node = n;
388                                     continue;
389                                 },
390                                 None => (None, None),
391                             }
392                         },
393                     }
394                 };
395             }
396         };
397         self.expected_type = expected_type;
398         self.expected_name = expected_name;
399         self.attribute_under_caret = find_node_at_offset(&file_with_fake_ident, offset);
400
401         if let Some(lifetime) = find_node_at_offset::<ast::Lifetime>(&file_with_fake_ident, offset)
402         {
403             self.classify_lifetime(original_file, lifetime, offset);
404         }
405
406         // First, let's try to complete a reference to some declaration.
407         if let Some(name_ref) = find_node_at_offset::<ast::NameRef>(&file_with_fake_ident, offset) {
408             // Special case, `trait T { fn foo(i_am_a_name_ref) {} }`.
409             // See RFC#1685.
410             if is_node::<ast::Param>(name_ref.syntax()) {
411                 self.is_param = true;
412                 return;
413             }
414             // FIXME: remove this (V) duplication and make the check more precise
415             if name_ref.syntax().ancestors().find_map(ast::RecordPatFieldList::cast).is_some() {
416                 self.record_pat_syntax =
417                     self.sema.find_node_at_offset_with_macros(&original_file, offset);
418             }
419             self.classify_name_ref(original_file, name_ref, offset);
420         }
421
422         // Otherwise, see if this is a declaration. We can use heuristics to
423         // suggest declaration names, see `CompletionKind::Magic`.
424         if let Some(name) = find_node_at_offset::<ast::Name>(&file_with_fake_ident, offset) {
425             if let Some(bind_pat) = name.syntax().ancestors().find_map(ast::IdentPat::cast) {
426                 self.is_pat_binding_or_const = true;
427                 if bind_pat.at_token().is_some()
428                     || bind_pat.ref_token().is_some()
429                     || bind_pat.mut_token().is_some()
430                 {
431                     self.is_pat_binding_or_const = false;
432                 }
433                 if bind_pat.syntax().parent().and_then(ast::RecordPatFieldList::cast).is_some() {
434                     self.is_pat_binding_or_const = false;
435                 }
436                 if let Some(Some(pat)) = bind_pat.syntax().ancestors().find_map(|node| {
437                     match_ast! {
438                         match node {
439                             ast::LetStmt(it) => Some(it.pat()),
440                             ast::Param(it) => Some(it.pat()),
441                             _ => None,
442                         }
443                     }
444                 }) {
445                     if pat.syntax().text_range().contains_range(bind_pat.syntax().text_range()) {
446                         self.is_pat_binding_or_const = false;
447                         self.is_irrefutable_pat_binding = true;
448                     }
449                 }
450
451                 self.fill_impl_def();
452             }
453             if is_node::<ast::Param>(name.syntax()) {
454                 self.is_param = true;
455                 return;
456             }
457             // FIXME: remove this (^) duplication and make the check more precise
458             if name.syntax().ancestors().find_map(ast::RecordPatFieldList::cast).is_some() {
459                 self.record_pat_syntax =
460                     self.sema.find_node_at_offset_with_macros(&original_file, offset);
461             }
462         }
463     }
464
465     fn classify_lifetime(
466         &mut self,
467         original_file: &SyntaxNode,
468         lifetime: ast::Lifetime,
469         offset: TextSize,
470     ) {
471         self.lifetime_syntax =
472             find_node_at_offset(original_file, lifetime.syntax().text_range().start());
473         if let Some(parent) = lifetime.syntax().parent() {
474             if parent.kind() == syntax::SyntaxKind::ERROR {
475                 return;
476             }
477
478             match_ast! {
479                 match parent {
480                     ast::LifetimeParam(_it) => {
481                         self.lifetime_allowed = true;
482                         self.lifetime_param_syntax =
483                             self.sema.find_node_at_offset_with_macros(original_file, offset);
484                     },
485                     ast::BreakExpr(_it) => self.is_label_ref = true,
486                     ast::ContinueExpr(_it) => self.is_label_ref = true,
487                     ast::Label(_it) => (),
488                     _ => self.lifetime_allowed = true,
489                 }
490             }
491         }
492     }
493
494     fn classify_name_ref(
495         &mut self,
496         original_file: &SyntaxNode,
497         name_ref: ast::NameRef,
498         offset: TextSize,
499     ) {
500         self.name_ref_syntax =
501             find_node_at_offset(original_file, name_ref.syntax().text_range().start());
502         let name_range = name_ref.syntax().text_range();
503         if ast::RecordExprField::for_field_name(&name_ref).is_some() {
504             self.record_lit_syntax =
505                 self.sema.find_node_at_offset_with_macros(original_file, offset);
506         }
507
508         self.fill_impl_def();
509
510         let top_node = name_ref
511             .syntax()
512             .ancestors()
513             .take_while(|it| it.text_range() == name_range)
514             .last()
515             .unwrap();
516
517         match top_node.parent().map(|it| it.kind()) {
518             Some(SOURCE_FILE) | Some(ITEM_LIST) => {
519                 self.is_new_item = true;
520                 return;
521             }
522             _ => (),
523         }
524
525         self.use_item_syntax =
526             self.sema.token_ancestors_with_macros(self.token.clone()).find_map(ast::Use::cast);
527
528         self.function_syntax = self
529             .sema
530             .token_ancestors_with_macros(self.token.clone())
531             .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
532             .find_map(ast::Fn::cast);
533
534         self.record_field_syntax = self
535             .sema
536             .token_ancestors_with_macros(self.token.clone())
537             .take_while(|it| {
538                 it.kind() != SOURCE_FILE && it.kind() != MODULE && it.kind() != CALL_EXPR
539             })
540             .find_map(ast::RecordExprField::cast);
541
542         let parent = match name_ref.syntax().parent() {
543             Some(it) => it,
544             None => return,
545         };
546
547         if let Some(segment) = ast::PathSegment::cast(parent.clone()) {
548             let path = segment.parent_path();
549             self.is_call = path
550                 .syntax()
551                 .parent()
552                 .and_then(ast::PathExpr::cast)
553                 .and_then(|it| it.syntax().parent().and_then(ast::CallExpr::cast))
554                 .is_some();
555             self.is_macro_call = path.syntax().parent().and_then(ast::MacroCall::cast).is_some();
556             self.is_pattern_call =
557                 path.syntax().parent().and_then(ast::TupleStructPat::cast).is_some();
558
559             self.is_path_type = path.syntax().parent().and_then(ast::PathType::cast).is_some();
560             self.has_type_args = segment.generic_arg_list().is_some();
561
562             if let Some(path) = path_or_use_tree_qualifier(&path) {
563                 self.path_qual = path
564                     .segment()
565                     .and_then(|it| {
566                         find_node_with_range::<ast::PathSegment>(
567                             original_file,
568                             it.syntax().text_range(),
569                         )
570                     })
571                     .map(|it| it.parent_path());
572                 return;
573             }
574
575             if let Some(segment) = path.segment() {
576                 if segment.coloncolon_token().is_some() {
577                     return;
578                 }
579             }
580
581             self.is_trivial_path = true;
582
583             // Find either enclosing expr statement (thing with `;`) or a
584             // block. If block, check that we are the last expr.
585             self.can_be_stmt = name_ref
586                 .syntax()
587                 .ancestors()
588                 .find_map(|node| {
589                     if let Some(stmt) = ast::ExprStmt::cast(node.clone()) {
590                         return Some(stmt.syntax().text_range() == name_ref.syntax().text_range());
591                     }
592                     if let Some(block) = ast::BlockExpr::cast(node) {
593                         return Some(
594                             block.tail_expr().map(|e| e.syntax().text_range())
595                                 == Some(name_ref.syntax().text_range()),
596                         );
597                     }
598                     None
599                 })
600                 .unwrap_or(false);
601             self.is_expr = path.syntax().parent().and_then(ast::PathExpr::cast).is_some();
602
603             if let Some(off) = name_ref.syntax().text_range().start().checked_sub(2.into()) {
604                 if let Some(if_expr) =
605                     self.sema.find_node_at_offset_with_macros::<ast::IfExpr>(original_file, off)
606                 {
607                     if if_expr.syntax().text_range().end() < name_ref.syntax().text_range().start()
608                     {
609                         self.after_if = true;
610                     }
611                 }
612             }
613         }
614         if let Some(field_expr) = ast::FieldExpr::cast(parent.clone()) {
615             // The receiver comes before the point of insertion of the fake
616             // ident, so it should have the same range in the non-modified file
617             self.dot_receiver = field_expr
618                 .expr()
619                 .map(|e| e.syntax().text_range())
620                 .and_then(|r| find_node_with_range(original_file, r));
621             self.dot_receiver_is_ambiguous_float_literal =
622                 if let Some(ast::Expr::Literal(l)) = &self.dot_receiver {
623                     match l.kind() {
624                         ast::LiteralKind::FloatNumber { .. } => l.token().text().ends_with('.'),
625                         _ => false,
626                     }
627                 } else {
628                     false
629                 };
630         }
631         if let Some(method_call_expr) = ast::MethodCallExpr::cast(parent) {
632             // As above
633             self.dot_receiver = method_call_expr
634                 .receiver()
635                 .map(|e| e.syntax().text_range())
636                 .and_then(|r| find_node_with_range(original_file, r));
637             self.is_call = true;
638         }
639     }
640 }
641
642 fn find_node_with_range<N: AstNode>(syntax: &SyntaxNode, range: TextRange) -> Option<N> {
643     syntax.covering_element(range).ancestors().find_map(N::cast)
644 }
645
646 fn is_node<N: AstNode>(node: &SyntaxNode) -> bool {
647     match node.ancestors().find_map(N::cast) {
648         None => false,
649         Some(n) => n.syntax().text_range() == node.text_range(),
650     }
651 }
652
653 fn path_or_use_tree_qualifier(path: &ast::Path) -> Option<ast::Path> {
654     if let Some(qual) = path.qualifier() {
655         return Some(qual);
656     }
657     let use_tree_list = path.syntax().ancestors().find_map(ast::UseTreeList::cast)?;
658     let use_tree = use_tree_list.syntax().parent().and_then(ast::UseTree::cast)?;
659     use_tree.path()
660 }
661
662 #[cfg(test)]
663 mod tests {
664     use expect_test::{expect, Expect};
665     use hir::HirDisplay;
666
667     use crate::test_utils::{position, TEST_CONFIG};
668
669     use super::CompletionContext;
670
671     fn check_expected_type_and_name(ra_fixture: &str, expect: Expect) {
672         let (db, pos) = position(ra_fixture);
673         let completion_context = CompletionContext::new(&db, pos, &TEST_CONFIG).unwrap();
674
675         let ty = completion_context
676             .expected_type
677             .map(|t| t.display_test(&db).to_string())
678             .unwrap_or("?".to_owned());
679
680         let name = completion_context
681             .expected_name
682             .map_or_else(|| "?".to_owned(), |name| name.to_string());
683
684         expect.assert_eq(&format!("ty: {}, name: {}", ty, name));
685     }
686
687     #[test]
688     fn expected_type_let_without_leading_char() {
689         cov_mark::check!(expected_type_let_without_leading_char);
690         check_expected_type_and_name(
691             r#"
692 fn foo() {
693     let x: u32 = $0;
694 }
695 "#,
696             expect![[r#"ty: u32, name: x"#]],
697         );
698     }
699
700     #[test]
701     fn expected_type_let_with_leading_char() {
702         cov_mark::check!(expected_type_let_with_leading_char);
703         check_expected_type_and_name(
704             r#"
705 fn foo() {
706     let x: u32 = c$0;
707 }
708 "#,
709             expect![[r#"ty: u32, name: x"#]],
710         );
711     }
712
713     #[test]
714     fn expected_type_fn_param_without_leading_char() {
715         cov_mark::check!(expected_type_fn_param_without_leading_char);
716         check_expected_type_and_name(
717             r#"
718 fn foo() {
719     bar($0);
720 }
721
722 fn bar(x: u32) {}
723 "#,
724             expect![[r#"ty: u32, name: x"#]],
725         );
726     }
727
728     #[test]
729     fn expected_type_fn_param_with_leading_char() {
730         cov_mark::check!(expected_type_fn_param_with_leading_char);
731         check_expected_type_and_name(
732             r#"
733 fn foo() {
734     bar(c$0);
735 }
736
737 fn bar(x: u32) {}
738 "#,
739             expect![[r#"ty: u32, name: x"#]],
740         );
741     }
742
743     #[test]
744     fn expected_type_struct_field_without_leading_char() {
745         cov_mark::check!(expected_type_struct_field_without_leading_char);
746         check_expected_type_and_name(
747             r#"
748 struct Foo { a: u32 }
749 fn foo() {
750     Foo { a: $0 };
751 }
752 "#,
753             expect![[r#"ty: u32, name: a"#]],
754         )
755     }
756
757     #[test]
758     fn expected_type_struct_field_with_leading_char() {
759         cov_mark::check!(expected_type_struct_field_with_leading_char);
760         check_expected_type_and_name(
761             r#"
762 struct Foo { a: u32 }
763 fn foo() {
764     Foo { a: c$0 };
765 }
766 "#,
767             expect![[r#"ty: u32, name: a"#]],
768         );
769     }
770
771     #[test]
772     fn expected_type_match_arm_without_leading_char() {
773         cov_mark::check!(expected_type_match_arm_without_leading_char);
774         check_expected_type_and_name(
775             r#"
776 enum E { X }
777 fn foo() {
778    match E::X { $0 }
779 }
780 "#,
781             expect![[r#"ty: E, name: ?"#]],
782         );
783     }
784
785     #[test]
786     fn expected_type_match_arm_with_leading_char() {
787         cov_mark::check!(expected_type_match_arm_with_leading_char);
788         check_expected_type_and_name(
789             r#"
790 enum E { X }
791 fn foo() {
792    match E::X { c$0 }
793 }
794 "#,
795             expect![[r#"ty: E, name: ?"#]],
796         );
797     }
798
799     #[test]
800     fn expected_type_if_let_without_leading_char() {
801         check_expected_type_and_name(
802             r#"
803 enum Foo { Bar, Baz, Quux }
804
805 fn foo() {
806     let f = Foo::Quux;
807     if let $0 = f { }
808 }
809 "#,
810             expect![[r#"ty: (), name: ?"#]],
811         ) // FIXME should be `ty: u32, name: ?`
812     }
813
814     #[test]
815     fn expected_type_if_let_with_leading_char() {
816         cov_mark::check!(expected_type_if_let_with_leading_char);
817         check_expected_type_and_name(
818             r#"
819 enum Foo { Bar, Baz, Quux }
820
821 fn foo() {
822     let f = Foo::Quux;
823     if let c$0 = f { }
824 }
825 "#,
826             expect![[r#"ty: Foo, name: ?"#]],
827         )
828     }
829
830     #[test]
831     fn expected_type_fn_ret_without_leading_char() {
832         cov_mark::check!(expected_type_fn_ret_without_leading_char);
833         check_expected_type_and_name(
834             r#"
835 fn foo() -> u32 {
836     $0
837 }
838 "#,
839             expect![[r#"ty: (), name: ?"#]],
840         ) // FIXME this should be `ty: u32, name: ?`
841     }
842
843     #[test]
844     fn expected_type_fn_ret_with_leading_char() {
845         cov_mark::check!(expected_type_fn_ret_with_leading_char);
846         check_expected_type_and_name(
847             r#"
848 fn foo() -> u32 {
849     c$0
850 }
851 "#,
852             expect![[r#"ty: u32, name: ?"#]],
853         )
854     }
855 }