aboutsummaryrefslogtreecommitdiff
path: root/crates/ra_ide/src/completion/completion_context.rs
blob: dd87bd119e1973317e53ff2d57046767a544c2a1 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
//! FIXME: write short doc here

use hir::{Semantics, SemanticsScope, Type};
use ra_db::SourceDatabase;
use ra_ide_db::RootDatabase;
use ra_syntax::{
    algo::{find_covering_element, find_node_at_offset},
    ast, match_ast, AstNode,
    SyntaxKind::*,
    SyntaxNode, SyntaxToken, TextRange, TextSize,
};
use ra_text_edit::AtomTextEdit;

use crate::{call_info::ActiveParameter, completion::CompletionConfig, FilePosition};

/// `CompletionContext` is created early during completion to figure out, where
/// exactly is the cursor, syntax-wise.
#[derive(Debug)]
pub(crate) struct CompletionContext<'a> {
    pub(super) sema: Semantics<'a, RootDatabase>,
    pub(super) db: &'a RootDatabase,
    pub(super) config: &'a CompletionConfig,
    pub(super) offset: TextSize,
    /// The token before the cursor, in the original file.
    pub(super) original_token: SyntaxToken,
    /// The token before the cursor, in the macro-expanded file.
    pub(super) token: SyntaxToken,
    pub(super) krate: Option<hir::Crate>,
    pub(super) expected_type: Option<Type>,
    pub(super) name_ref_syntax: Option<ast::NameRef>,
    pub(super) function_syntax: Option<ast::FnDef>,
    pub(super) use_item_syntax: Option<ast::UseItem>,
    pub(super) record_lit_syntax: Option<ast::RecordLit>,
    pub(super) record_pat_syntax: Option<ast::RecordPat>,
    pub(super) record_field_syntax: Option<ast::RecordField>,
    pub(super) impl_def: Option<ast::ImplDef>,
    /// FIXME: `ActiveParameter` is string-based, which is very wrong
    pub(super) active_parameter: Option<ActiveParameter>,
    pub(super) is_param: bool,
    /// If a name-binding or reference to a const in a pattern.
    /// Irrefutable patterns (like let) are excluded.
    pub(super) is_pat_binding_or_const: bool,
    /// A single-indent path, like `foo`. `::foo` should not be considered a trivial path.
    pub(super) is_trivial_path: bool,
    /// If not a trivial path, the prefix (qualifier).
    pub(super) path_prefix: Option<hir::Path>,
    pub(super) after_if: bool,
    /// `true` if we are a statement or a last expr in the block.
    pub(super) can_be_stmt: bool,
    /// Something is typed at the "top" level, in module or impl/trait.
    pub(super) is_new_item: bool,
    /// The receiver if this is a field or method access, i.e. writing something.<|>
    pub(super) dot_receiver: Option<ast::Expr>,
    pub(super) dot_receiver_is_ambiguous_float_literal: bool,
    /// If this is a call (method or function) in particular, i.e. the () are already there.
    pub(super) is_call: bool,
    /// If this is a macro call, i.e. the () are already there.
    pub(super) is_macro_call: bool,
    pub(super) is_path_type: bool,
    pub(super) has_type_args: bool,
    pub(super) attribute_under_caret: Option<ast::Attr>,
}

impl<'a> CompletionContext<'a> {
    pub(super) fn new(
        db: &'a RootDatabase,
        position: FilePosition,
        config: &'a CompletionConfig,
    ) -> Option<CompletionContext<'a>> {
        let sema = Semantics::new(db);

        let original_file = sema.parse(position.file_id);

        // Insert a fake ident to get a valid parse tree. We will use this file
        // to determine context, though the original_file will be used for
        // actual completion.
        let file_with_fake_ident = {
            let parse = db.parse(position.file_id);
            let edit = AtomTextEdit::insert(position.offset, "intellijRulezz".to_string());
            parse.reparse(&edit).tree()
        };
        let fake_ident_token =
            file_with_fake_ident.syntax().token_at_offset(position.offset).right_biased().unwrap();

        let krate = sema.to_module_def(position.file_id).map(|m| m.krate());
        let original_token =
            original_file.syntax().token_at_offset(position.offset).left_biased()?;
        let token = sema.descend_into_macros(original_token.clone());
        let mut ctx = CompletionContext {
            sema,
            db,
            config,
            original_token,
            token,
            offset: position.offset,
            krate,
            expected_type: None,
            name_ref_syntax: None,
            function_syntax: None,
            use_item_syntax: None,
            record_lit_syntax: None,
            record_pat_syntax: None,
            record_field_syntax: None,
            impl_def: None,
            active_parameter: ActiveParameter::at(db, position),
            is_param: false,
            is_pat_binding_or_const: false,
            is_trivial_path: false,
            path_prefix: None,
            after_if: false,
            can_be_stmt: false,
            is_new_item: false,
            dot_receiver: None,
            is_call: false,
            is_macro_call: false,
            is_path_type: false,
            has_type_args: false,
            dot_receiver_is_ambiguous_float_literal: false,
            attribute_under_caret: None,
        };

        let mut original_file = original_file.syntax().clone();
        let mut hypothetical_file = file_with_fake_ident.syntax().clone();
        let mut offset = position.offset;
        let mut fake_ident_token = fake_ident_token;

        // Are we inside a macro call?
        while let (Some(actual_macro_call), Some(macro_call_with_fake_ident)) = (
            find_node_at_offset::<ast::MacroCall>(&original_file, offset),
            find_node_at_offset::<ast::MacroCall>(&hypothetical_file, offset),
        ) {
            if actual_macro_call.path().as_ref().map(|s| s.syntax().text())
                != macro_call_with_fake_ident.path().as_ref().map(|s| s.syntax().text())
            {
                break;
            }
            let hypothetical_args = match macro_call_with_fake_ident.token_tree() {
                Some(tt) => tt,
                None => break,
            };
            if let (Some(actual_expansion), Some(hypothetical_expansion)) = (
                ctx.sema.expand(&actual_macro_call),
                ctx.sema.expand_hypothetical(
                    &actual_macro_call,
                    &hypothetical_args,
                    fake_ident_token,
                ),
            ) {
                let new_offset = hypothetical_expansion.1.text_range().start();
                if new_offset > actual_expansion.text_range().end() {
                    break;
                }
                original_file = actual_expansion;
                hypothetical_file = hypothetical_expansion.0;
                fake_ident_token = hypothetical_expansion.1;
                offset = new_offset;
            } else {
                break;
            }
        }

        ctx.fill(&original_file, hypothetical_file, offset);
        Some(ctx)
    }

    // The range of the identifier that is being completed.
    pub(crate) fn source_range(&self) -> TextRange {
        // check kind of macro-expanded token, but use range of original token
        match self.token.kind() {
            // workaroud when completion is triggered by trigger characters.
            IDENT => self.original_token.text_range(),
            _ => TextRange::empty(self.offset),
        }
    }

    pub(crate) fn scope(&self) -> SemanticsScope<'_, RootDatabase> {
        self.sema.scope_at_offset(&self.token.parent(), self.offset)
    }

    fn fill(
        &mut self,
        original_file: &SyntaxNode,
        file_with_fake_ident: SyntaxNode,
        offset: TextSize,
    ) {
        // FIXME: this is wrong in at least two cases:
        //  * when there's no token `foo(<|>)`
        //  * when there is a token, but it happens to have type of it's own
        self.expected_type = self
            .token
            .ancestors()
            .find_map(|node| {
                let ty = match_ast! {
                    match node {
                        ast::Pat(it) => self.sema.type_of_pat(&it),
                        ast::Expr(it) => self.sema.type_of_expr(&it),
                        _ => return None,
                    }
                };
                Some(ty)
            })
            .flatten();
        self.attribute_under_caret = find_node_at_offset(&file_with_fake_ident, offset);

        // First, let's try to complete a reference to some declaration.
        if let Some(name_ref) = find_node_at_offset::<ast::NameRef>(&file_with_fake_ident, offset) {
            // Special case, `trait T { fn foo(i_am_a_name_ref) {} }`.
            // See RFC#1685.
            if is_node::<ast::Param>(name_ref.syntax()) {
                self.is_param = true;
                return;
            }
            // FIXME: remove this (V) duplication and make the check more precise
            if name_ref.syntax().ancestors().find_map(ast::RecordFieldPatList::cast).is_some() {
                self.record_pat_syntax =
                    self.sema.find_node_at_offset_with_macros(&original_file, offset);
            }
            self.classify_name_ref(original_file, name_ref, offset);
        }

        // Otherwise, see if this is a declaration. We can use heuristics to
        // suggest declaration names, see `CompletionKind::Magic`.
        if let Some(name) = find_node_at_offset::<ast::Name>(&file_with_fake_ident, offset) {
            if let Some(bind_pat) = name.syntax().ancestors().find_map(ast::BindPat::cast) {
                self.is_pat_binding_or_const = true;
                if bind_pat.at_token().is_some()
                    || bind_pat.ref_token().is_some()
                    || bind_pat.mut_token().is_some()
                {
                    self.is_pat_binding_or_const = false;
                }
                if bind_pat.syntax().parent().and_then(ast::RecordFieldPatList::cast).is_some() {
                    self.is_pat_binding_or_const = false;
                }
                if let Some(let_stmt) = bind_pat.syntax().ancestors().find_map(ast::LetStmt::cast) {
                    if let Some(pat) = let_stmt.pat() {
                        if pat.syntax().text_range().contains_range(bind_pat.syntax().text_range())
                        {
                            self.is_pat_binding_or_const = false;
                        }
                    }
                }
            }
            if is_node::<ast::Param>(name.syntax()) {
                self.is_param = true;
                return;
            }
            // FIXME: remove this (^) duplication and make the check more precise
            if name.syntax().ancestors().find_map(ast::RecordFieldPatList::cast).is_some() {
                self.record_pat_syntax =
                    self.sema.find_node_at_offset_with_macros(&original_file, offset);
            }
        }
    }

    fn classify_name_ref(
        &mut self,
        original_file: &SyntaxNode,
        name_ref: ast::NameRef,
        offset: TextSize,
    ) {
        self.name_ref_syntax =
            find_node_at_offset(&original_file, name_ref.syntax().text_range().start());
        let name_range = name_ref.syntax().text_range();
        if ast::RecordField::for_field_name(&name_ref).is_some() {
            self.record_lit_syntax =
                self.sema.find_node_at_offset_with_macros(&original_file, offset);
        }

        self.impl_def = self
            .sema
            .ancestors_with_macros(self.token.parent())
            .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
            .find_map(ast::ImplDef::cast);

        let top_node = name_ref
            .syntax()
            .ancestors()
            .take_while(|it| it.text_range() == name_range)
            .last()
            .unwrap();

        match top_node.parent().map(|it| it.kind()) {
            Some(SOURCE_FILE) | Some(ITEM_LIST) => {
                self.is_new_item = true;
                return;
            }
            _ => (),
        }

        self.use_item_syntax =
            self.sema.ancestors_with_macros(self.token.parent()).find_map(ast::UseItem::cast);

        self.function_syntax = self
            .sema
            .ancestors_with_macros(self.token.parent())
            .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
            .find_map(ast::FnDef::cast);

        self.record_field_syntax = self
            .sema
            .ancestors_with_macros(self.token.parent())
            .take_while(|it| {
                it.kind() != SOURCE_FILE && it.kind() != MODULE && it.kind() != CALL_EXPR
            })
            .find_map(ast::RecordField::cast);

        let parent = match name_ref.syntax().parent() {
            Some(it) => it,
            None => return,
        };

        if let Some(segment) = ast::PathSegment::cast(parent.clone()) {
            let path = segment.parent_path();
            self.is_call = path
                .syntax()
                .parent()
                .and_then(ast::PathExpr::cast)
                .and_then(|it| it.syntax().parent().and_then(ast::CallExpr::cast))
                .is_some();
            self.is_macro_call = path.syntax().parent().and_then(ast::MacroCall::cast).is_some();

            self.is_path_type = path.syntax().parent().and_then(ast::PathType::cast).is_some();
            self.has_type_args = segment.type_arg_list().is_some();

            if let Some(path) = hir::Path::from_ast(path.clone()) {
                if let Some(path_prefix) = path.qualifier() {
                    self.path_prefix = Some(path_prefix);
                    return;
                }
            }

            if path.qualifier().is_none() {
                self.is_trivial_path = true;

                // Find either enclosing expr statement (thing with `;`) or a
                // block. If block, check that we are the last expr.
                self.can_be_stmt = name_ref
                    .syntax()
                    .ancestors()
                    .find_map(|node| {
                        if let Some(stmt) = ast::ExprStmt::cast(node.clone()) {
                            return Some(
                                stmt.syntax().text_range() == name_ref.syntax().text_range(),
                            );
                        }
                        if let Some(block) = ast::BlockExpr::cast(node) {
                            return Some(
                                block.expr().map(|e| e.syntax().text_range())
                                    == Some(name_ref.syntax().text_range()),
                            );
                        }
                        None
                    })
                    .unwrap_or(false);

                if let Some(off) = name_ref.syntax().text_range().start().checked_sub(2.into()) {
                    if let Some(if_expr) =
                        self.sema.find_node_at_offset_with_macros::<ast::IfExpr>(original_file, off)
                    {
                        if if_expr.syntax().text_range().end()
                            < name_ref.syntax().text_range().start()
                        {
                            self.after_if = true;
                        }
                    }
                }
            }
        }
        if let Some(field_expr) = ast::FieldExpr::cast(parent.clone()) {
            // The receiver comes before the point of insertion of the fake
            // ident, so it should have the same range in the non-modified file
            self.dot_receiver = field_expr
                .expr()
                .map(|e| e.syntax().text_range())
                .and_then(|r| find_node_with_range(original_file, r));
            self.dot_receiver_is_ambiguous_float_literal =
                if let Some(ast::Expr::Literal(l)) = &self.dot_receiver {
                    match l.kind() {
                        ast::LiteralKind::FloatNumber { .. } => l.token().text().ends_with('.'),
                        _ => false,
                    }
                } else {
                    false
                }
        }
        if let Some(method_call_expr) = ast::MethodCallExpr::cast(parent) {
            // As above
            self.dot_receiver = method_call_expr
                .expr()
                .map(|e| e.syntax().text_range())
                .and_then(|r| find_node_with_range(original_file, r));
            self.is_call = true;
        }
    }
}

fn find_node_with_range<N: AstNode>(syntax: &SyntaxNode, range: TextRange) -> Option<N> {
    find_covering_element(syntax, range).ancestors().find_map(N::cast)
}

fn is_node<N: AstNode>(node: &SyntaxNode) -> bool {
    match node.ancestors().find_map(N::cast) {
        None => false,
        Some(n) => n.syntax().text_range() == node.text_range(),
    }
}