aboutsummaryrefslogtreecommitdiff
path: root/crates/ra_ssr/src/resolving.rs
blob: 6f62000f4a731d749d128b2da3e2ea9836abc333 (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
//! This module is responsible for resolving paths within rules.

use crate::errors::error;
use crate::{parsing, SsrError};
use parsing::Placeholder;
use ra_db::FilePosition;
use ra_syntax::{ast, SmolStr, SyntaxKind, SyntaxNode, SyntaxToken};
use rustc_hash::{FxHashMap, FxHashSet};
use test_utils::mark;

pub(crate) struct ResolutionScope<'db> {
    scope: hir::SemanticsScope<'db>,
    hygiene: hir::Hygiene,
}

pub(crate) struct ResolvedRule {
    pub(crate) pattern: ResolvedPattern,
    pub(crate) template: Option<ResolvedPattern>,
    pub(crate) index: usize,
}

pub(crate) struct ResolvedPattern {
    pub(crate) placeholders_by_stand_in: FxHashMap<SmolStr, parsing::Placeholder>,
    pub(crate) node: SyntaxNode,
    // Paths in `node` that we've resolved.
    pub(crate) resolved_paths: FxHashMap<SyntaxNode, ResolvedPath>,
    pub(crate) ufcs_function_calls: FxHashMap<SyntaxNode, hir::Function>,
}

pub(crate) struct ResolvedPath {
    pub(crate) resolution: hir::PathResolution,
    /// The depth of the ast::Path that was resolved within the pattern.
    pub(crate) depth: u32,
}

impl ResolvedRule {
    pub(crate) fn new(
        rule: parsing::ParsedRule,
        resolution_scope: &ResolutionScope,
        index: usize,
    ) -> Result<ResolvedRule, SsrError> {
        let resolver =
            Resolver { resolution_scope, placeholders_by_stand_in: rule.placeholders_by_stand_in };
        let resolved_template = if let Some(template) = rule.template {
            Some(resolver.resolve_pattern_tree(template)?)
        } else {
            None
        };
        Ok(ResolvedRule {
            pattern: resolver.resolve_pattern_tree(rule.pattern)?,
            template: resolved_template,
            index,
        })
    }

    pub(crate) fn get_placeholder(&self, token: &SyntaxToken) -> Option<&Placeholder> {
        if token.kind() != SyntaxKind::IDENT {
            return None;
        }
        self.pattern.placeholders_by_stand_in.get(token.text())
    }
}

struct Resolver<'a, 'db> {
    resolution_scope: &'a ResolutionScope<'db>,
    placeholders_by_stand_in: FxHashMap<SmolStr, parsing::Placeholder>,
}

impl Resolver<'_, '_> {
    fn resolve_pattern_tree(&self, pattern: SyntaxNode) -> Result<ResolvedPattern, SsrError> {
        let mut resolved_paths = FxHashMap::default();
        self.resolve(pattern.clone(), 0, &mut resolved_paths)?;
        let ufcs_function_calls = resolved_paths
            .iter()
            .filter_map(|(path_node, resolved)| {
                if let Some(grandparent) = path_node.parent().and_then(|parent| parent.parent()) {
                    if grandparent.kind() == SyntaxKind::CALL_EXPR {
                        if let hir::PathResolution::AssocItem(hir::AssocItem::Function(function)) =
                            &resolved.resolution
                        {
                            return Some((grandparent, *function));
                        }
                    }
                }
                None
            })
            .collect();
        Ok(ResolvedPattern {
            node: pattern,
            resolved_paths,
            placeholders_by_stand_in: self.placeholders_by_stand_in.clone(),
            ufcs_function_calls,
        })
    }

    fn resolve(
        &self,
        node: SyntaxNode,
        depth: u32,
        resolved_paths: &mut FxHashMap<SyntaxNode, ResolvedPath>,
    ) -> Result<(), SsrError> {
        use ra_syntax::ast::AstNode;
        if let Some(path) = ast::Path::cast(node.clone()) {
            // Check if this is an appropriate place in the path to resolve. If the path is
            // something like `a::B::<i32>::c` then we want to resolve `a::B`. If the path contains
            // a placeholder. e.g. `a::$b::c` then we want to resolve `a`.
            if !path_contains_type_arguments(path.qualifier())
                && !self.path_contains_placeholder(&path)
            {
                let resolution = self
                    .resolution_scope
                    .resolve_path(&path)
                    .ok_or_else(|| error!("Failed to resolve path `{}`", node.text()))?;
                resolved_paths.insert(node, ResolvedPath { resolution, depth });
                return Ok(());
            }
        }
        for node in node.children() {
            self.resolve(node, depth + 1, resolved_paths)?;
        }
        Ok(())
    }

    /// Returns whether `path` contains a placeholder, but ignores any placeholders within type
    /// arguments.
    fn path_contains_placeholder(&self, path: &ast::Path) -> bool {
        if let Some(segment) = path.segment() {
            if let Some(name_ref) = segment.name_ref() {
                if self.placeholders_by_stand_in.contains_key(name_ref.text()) {
                    return true;
                }
            }
        }
        if let Some(qualifier) = path.qualifier() {
            return self.path_contains_placeholder(&qualifier);
        }
        false
    }
}

impl<'db> ResolutionScope<'db> {
    pub(crate) fn new(
        sema: &hir::Semantics<'db, ra_ide_db::RootDatabase>,
        resolve_context: FilePosition,
    ) -> ResolutionScope<'db> {
        use ra_syntax::ast::AstNode;
        let file = sema.parse(resolve_context.file_id);
        // Find a node at the requested position, falling back to the whole file.
        let node = file
            .syntax()
            .token_at_offset(resolve_context.offset)
            .left_biased()
            .map(|token| token.parent())
            .unwrap_or_else(|| file.syntax().clone());
        let node = pick_node_for_resolution(node);
        let scope = sema.scope(&node);
        ResolutionScope {
            scope,
            hygiene: hir::Hygiene::new(sema.db, resolve_context.file_id.into()),
        }
    }

    fn resolve_path(&self, path: &ast::Path) -> Option<hir::PathResolution> {
        let hir_path = hir::Path::from_src(path.clone(), &self.hygiene)?;
        // First try resolving the whole path. This will work for things like
        // `std::collections::HashMap`, but will fail for things like
        // `std::collections::HashMap::new`.
        if let Some(resolution) = self.scope.resolve_hir_path(&hir_path) {
            return Some(resolution);
        }
        // Resolution failed, try resolving the qualifier (e.g. `std::collections::HashMap` and if
        // that succeeds, then iterate through the candidates on the resolved type with the provided
        // name.
        let resolved_qualifier = self.scope.resolve_hir_path_qualifier(&hir_path.qualifier()?)?;
        if let hir::PathResolution::Def(hir::ModuleDef::Adt(adt)) = resolved_qualifier {
            adt.ty(self.scope.db).iterate_path_candidates(
                self.scope.db,
                self.scope.module()?.krate(),
                &FxHashSet::default(),
                Some(hir_path.segments().last()?.name),
                |_ty, assoc_item| Some(hir::PathResolution::AssocItem(assoc_item)),
            )
        } else {
            None
        }
    }
}

/// Returns a suitable node for resolving paths in the current scope. If we create a scope based on
/// a statement node, then we can't resolve local variables that were defined in the current scope
/// (only in parent scopes). So we find another node, ideally a child of the statement where local
/// variable resolution is permitted.
fn pick_node_for_resolution(node: SyntaxNode) -> SyntaxNode {
    match node.kind() {
        SyntaxKind::EXPR_STMT => {
            if let Some(n) = node.first_child() {
                mark::hit!(cursor_after_semicolon);
                return n;
            }
        }
        SyntaxKind::LET_STMT | SyntaxKind::IDENT_PAT => {
            if let Some(next) = node.next_sibling() {
                return pick_node_for_resolution(next);
            }
        }
        SyntaxKind::NAME => {
            if let Some(parent) = node.parent() {
                return pick_node_for_resolution(parent);
            }
        }
        _ => {}
    }
    node
}

/// Returns whether `path` or any of its qualifiers contains type arguments.
fn path_contains_type_arguments(path: Option<ast::Path>) -> bool {
    if let Some(path) = path {
        if let Some(segment) = path.segment() {
            if segment.generic_arg_list().is_some() {
                mark::hit!(type_arguments_within_path);
                return true;
            }
        }
        return path_contains_type_arguments(path.qualifier());
    }
    false
}