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-rw-r--r--crates/hir_expand/src/proc_macro.rs102
1 files changed, 102 insertions, 0 deletions
diff --git a/crates/hir_expand/src/proc_macro.rs b/crates/hir_expand/src/proc_macro.rs
index d5643393a..75e950816 100644
--- a/crates/hir_expand/src/proc_macro.rs
+++ b/crates/hir_expand/src/proc_macro.rs
@@ -2,6 +2,7 @@
2 2
3use crate::db::AstDatabase; 3use crate::db::AstDatabase;
4use base_db::{CrateId, ProcMacroId}; 4use base_db::{CrateId, ProcMacroId};
5use tt::buffer::{Cursor, TokenBuffer};
5 6
6#[derive(Debug, Clone, Copy, Eq, PartialEq, Hash)] 7#[derive(Debug, Clone, Copy, Eq, PartialEq, Hash)]
7pub struct ProcMacroExpander { 8pub struct ProcMacroExpander {
@@ -43,6 +44,9 @@ impl ProcMacroExpander {
43 .clone() 44 .clone()
44 .ok_or_else(|| err!("No derive macro found."))?; 45 .ok_or_else(|| err!("No derive macro found."))?;
45 46
47 let tt = remove_derive_attrs(tt)
48 .ok_or_else(|| err!("Fail to remove derive for custom derive"))?;
49
46 // Proc macros have access to the environment variables of the invoking crate. 50 // Proc macros have access to the environment variables of the invoking crate.
47 let env = &krate_graph[calling_crate].env; 51 let env = &krate_graph[calling_crate].env;
48 52
@@ -52,3 +56,101 @@ impl ProcMacroExpander {
52 } 56 }
53 } 57 }
54} 58}
59
60fn eat_punct(cursor: &mut Cursor, c: char) -> bool {
61 if let Some(tt::buffer::TokenTreeRef::Leaf(tt::Leaf::Punct(punct), _)) = cursor.token_tree() {
62 if punct.char == c {
63 *cursor = cursor.bump();
64 return true;
65 }
66 }
67 false
68}
69
70fn eat_subtree(cursor: &mut Cursor, kind: tt::DelimiterKind) -> bool {
71 if let Some(tt::buffer::TokenTreeRef::Subtree(subtree, _)) = cursor.token_tree() {
72 if Some(kind) == subtree.delimiter_kind() {
73 *cursor = cursor.bump_subtree();
74 return true;
75 }
76 }
77 false
78}
79
80fn eat_ident(cursor: &mut Cursor, t: &str) -> bool {
81 if let Some(tt::buffer::TokenTreeRef::Leaf(tt::Leaf::Ident(ident), _)) = cursor.token_tree() {
82 if t == ident.text.as_str() {
83 *cursor = cursor.bump();
84 return true;
85 }
86 }
87 false
88}
89
90fn remove_derive_attrs(tt: &tt::Subtree) -> Option<tt::Subtree> {
91 let buffer = TokenBuffer::from_tokens(&tt.token_trees);
92 let mut p = buffer.begin();
93 let mut result = tt::Subtree::default();
94
95 while !p.eof() {
96 let curr = p;
97
98 if eat_punct(&mut p, '#') {
99 eat_punct(&mut p, '!');
100 let parent = p;
101 if eat_subtree(&mut p, tt::DelimiterKind::Bracket) {
102 if eat_ident(&mut p, "derive") {
103 p = parent.bump();
104 continue;
105 }
106 }
107 }
108
109 result.token_trees.push(curr.token_tree()?.cloned());
110 p = curr.bump();
111 }
112
113 Some(result)
114}
115
116#[cfg(test)]
117mod tests {
118 use super::*;
119 use test_utils::assert_eq_text;
120
121 #[test]
122 fn test_remove_derive_attrs() {
123 let tt = mbe::parse_to_token_tree(
124 r#"
125 #[allow(unused)]
126 #[derive(Copy)]
127 #[derive(Hello)]
128 struct A {
129 bar: u32
130 }
131"#,
132 )
133 .unwrap()
134 .0;
135 let result = format!("{:#?}", remove_derive_attrs(&tt).unwrap());
136
137 assert_eq_text!(
138 r#"
139SUBTREE $
140 PUNCH # [alone] 0
141 SUBTREE [] 1
142 IDENT allow 2
143 SUBTREE () 3
144 IDENT unused 4
145 IDENT struct 15
146 IDENT A 16
147 SUBTREE {} 17
148 IDENT bar 18
149 PUNCH : [alone] 19
150 IDENT u32 20
151"#
152 .trim(),
153 &result
154 );
155 }
156}