aboutsummaryrefslogtreecommitdiff
path: root/crates/ra_analysis/src/completion/completion_context.rs
blob: 064fbc6f7be89751ea910863e9b784e3224691b3 (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
use ra_editor::find_node_at_offset;
use ra_text_edit::AtomTextEdit;
use ra_syntax::{
    algo::find_leaf_at_offset,
    ast,
    AstNode,
    SyntaxNodeRef,
    SourceFileNode,
    TextUnit,
    SyntaxKind::*,
};
use hir::source_binder;

use crate::{db, FilePosition, Cancelable};

/// `CompletionContext` is created early during completion to figure out, where
/// exactly is the cursor, syntax-wise.
#[derive(Debug)]
pub(super) struct CompletionContext<'a> {
    pub(super) db: &'a db::RootDatabase,
    pub(super) offset: TextUnit,
    pub(super) leaf: SyntaxNodeRef<'a>,
    pub(super) module: Option<hir::Module>,
    pub(super) enclosing_fn: Option<ast::FnDef<'a>>,
    pub(super) is_param: bool,
    /// A single-indent path, like `foo`.
    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,
    pub(super) is_stmt: bool,
    /// Something is typed at the "top" level, in module or impl/trait.
    pub(super) is_new_item: bool,
}

impl<'a> CompletionContext<'a> {
    pub(super) fn new(
        db: &'a db::RootDatabase,
        original_file: &'a SourceFileNode,
        position: FilePosition,
    ) -> Cancelable<Option<CompletionContext<'a>>> {
        let module = source_binder::module_from_position(db, position)?;
        let leaf =
            ctry!(find_leaf_at_offset(original_file.syntax(), position.offset).left_biased());
        let mut ctx = CompletionContext {
            db,
            leaf,
            offset: position.offset,
            module,
            enclosing_fn: None,
            is_param: false,
            is_trivial_path: false,
            path_prefix: None,
            after_if: false,
            is_stmt: false,
            is_new_item: false,
        };
        ctx.fill(original_file, position.offset);
        Ok(Some(ctx))
    }

    fn fill(&mut self, original_file: &SourceFileNode, offset: TextUnit) {
        // 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 = {
            let edit = AtomTextEdit::insert(offset, "intellijRulezz".to_string());
            original_file.reparse(&edit)
        };

        // First, let's try to complete a reference to some declaration.
        if let Some(name_ref) = find_node_at_offset::<ast::NameRef>(file.syntax(), 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;
            }
            self.classify_name_ref(&file, name_ref);
        }

        // 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.syntax(), offset) {
            if is_node::<ast::Param>(name.syntax()) {
                self.is_param = true;
                return;
            }
        }
    }
    fn classify_name_ref(&mut self, file: &SourceFileNode, name_ref: ast::NameRef) {
        let name_range = name_ref.syntax().range();
        let top_node = name_ref
            .syntax()
            .ancestors()
            .take_while(|it| it.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;
            }
            _ => (),
        }

        let parent = match name_ref.syntax().parent() {
            Some(it) => it,
            None => return,
        };
        if let Some(segment) = ast::PathSegment::cast(parent) {
            let path = segment.parent_path();
            if let Some(mut path) = hir::Path::from_ast(path) {
                if !path.is_ident() {
                    path.segments.pop().unwrap();
                    self.path_prefix = Some(path);
                    return;
                }
            }
            if path.qualifier().is_none() {
                self.is_trivial_path = true;
                self.enclosing_fn = self
                    .leaf
                    .ancestors()
                    .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
                    .find_map(ast::FnDef::cast);

                self.is_stmt = match name_ref
                    .syntax()
                    .ancestors()
                    .filter_map(ast::ExprStmt::cast)
                    .next()
                {
                    None => false,
                    Some(expr_stmt) => expr_stmt.syntax().range() == name_ref.syntax().range(),
                };

                if let Some(off) = name_ref.syntax().range().start().checked_sub(2.into()) {
                    if let Some(if_expr) = find_node_at_offset::<ast::IfExpr>(file.syntax(), off) {
                        if if_expr.syntax().range().end() < name_ref.syntax().range().start() {
                            self.after_if = true;
                        }
                    }
                }
            }
        }
    }
}

fn is_node<'a, N: AstNode<'a>>(node: SyntaxNodeRef<'a>) -> bool {
    match node.ancestors().filter_map(N::cast).next() {
        None => false,
        Some(n) => n.syntax().range() == node.range(),
    }
}