aboutsummaryrefslogtreecommitdiff
path: root/crates/ra_hir_expand/src/eager.rs
blob: 302d2b3e099c67afd2c2eb46beda4b0b142ef59c (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
//! Eager expansion related utils
//!
//! Here is a dump of a discussion from Vadim Petrochenkov about Eager Expansion and
//! Its name resolution :
//!
//! > Eagerly expanded macros (and also macros eagerly expanded by eagerly expanded macros,
//! > which actually happens in practice too!) are resolved at the location of the "root" macro
//! > that performs the eager expansion on its arguments.
//! > If some name cannot be resolved at the eager expansion time it's considered unresolved,
//! > even if becomes available later (e.g. from a glob import or other macro).
//!
//! > Eagerly expanded macros don't add anything to the module structure of the crate and
//! > don't build any speculative module structures, i.e. they are expanded in a "flat"
//! > way even if tokens in them look like modules.
//!
//! > In other words, it kinda works for simple cases for which it was originally intended,
//! > and we need to live with it because it's available on stable and widely relied upon.
//!
//!
//! See the full discussion : https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/Eager.20expansion.20of.20built-in.20macros

use crate::{
    ast::{self, AstNode},
    db::AstDatabase,
    EagerCallLoc, EagerMacroId, InFile, MacroCallId, MacroCallKind, MacroDefId, MacroDefKind,
};

use ra_db::CrateId;
use ra_parser::FragmentKind;
use ra_syntax::{algo::SyntaxRewriter, SyntaxNode};
use std::sync::Arc;

pub fn expand_eager_macro(
    db: &dyn AstDatabase,
    krate: CrateId,
    macro_call: InFile<ast::MacroCall>,
    def: MacroDefId,
    resolver: &dyn Fn(ast::Path) -> Option<MacroDefId>,
) -> Option<EagerMacroId> {
    let args = macro_call.value.token_tree()?;
    let parsed_args = mbe::ast_to_token_tree(&args)?.0;

    // Note:
    // When `lazy_expand` is called, its *parent* file must be already exists.
    // Here we store an eager macro id for the argument expanded subtree here
    // for that purpose.
    let arg_id = db.intern_eager_expansion({
        EagerCallLoc {
            def,
            fragment: FragmentKind::Expr,
            subtree: Arc::new(parsed_args.clone()),
            krate,
            file_id: macro_call.file_id,
        }
    });
    let arg_file_id: MacroCallId = arg_id.into();

    let parsed_args = mbe::token_tree_to_syntax_node(&parsed_args, FragmentKind::Expr).ok()?.0;
    let result = eager_macro_recur(
        db,
        InFile::new(arg_file_id.as_file(), parsed_args.syntax_node()),
        krate,
        resolver,
    )?;
    let subtree = to_subtree(&result)?;

    if let MacroDefKind::BuiltInEager(eager) = def.kind {
        let (subtree, fragment) = eager.expand(db, arg_id, &subtree).ok()?;
        let eager = EagerCallLoc {
            def,
            fragment,
            subtree: Arc::new(subtree),
            krate,
            file_id: macro_call.file_id,
        };

        Some(db.intern_eager_expansion(eager))
    } else {
        None
    }
}

fn to_subtree(node: &SyntaxNode) -> Option<tt::Subtree> {
    let mut subtree = mbe::syntax_node_to_token_tree(node)?.0;
    subtree.delimiter = None;
    Some(subtree)
}

fn lazy_expand(
    db: &dyn AstDatabase,
    def: &MacroDefId,
    macro_call: InFile<ast::MacroCall>,
    krate: CrateId,
) -> Option<InFile<SyntaxNode>> {
    let ast_id = db.ast_id_map(macro_call.file_id).ast_id(&macro_call.value);

    let id: MacroCallId =
        def.as_lazy_macro(db, krate, MacroCallKind::FnLike(macro_call.with_value(ast_id))).into();

    db.parse_or_expand(id.as_file()).map(|node| InFile::new(id.as_file(), node))
}

fn eager_macro_recur(
    db: &dyn AstDatabase,
    curr: InFile<SyntaxNode>,
    krate: CrateId,
    macro_resolver: &dyn Fn(ast::Path) -> Option<MacroDefId>,
) -> Option<SyntaxNode> {
    let original = curr.value.clone();

    let children = curr.value.descendants().filter_map(ast::MacroCall::cast);
    let mut rewriter = SyntaxRewriter::default();

    // Collect replacement
    for child in children {
        let def: MacroDefId = macro_resolver(child.path()?)?;
        let insert = match def.kind {
            MacroDefKind::BuiltInEager(_) => {
                let id: MacroCallId = expand_eager_macro(
                    db,
                    krate,
                    curr.with_value(child.clone()),
                    def,
                    macro_resolver,
                )?
                .into();
                db.parse_or_expand(id.as_file())?
            }
            MacroDefKind::Declarative
            | MacroDefKind::BuiltIn(_)
            | MacroDefKind::BuiltInDerive(_)
            | MacroDefKind::CustomDerive(_) => {
                let expanded = lazy_expand(db, &def, curr.with_value(child.clone()), krate)?;
                // replace macro inside
                eager_macro_recur(db, expanded, krate, macro_resolver)?
            }
        };

        rewriter.replace(child.syntax(), &insert);
    }

    let res = rewriter.rewrite(&original);
    Some(res)
}