1 //! Utilities for formatting macro expanded nodes until we get a proper formatter.
2 use syntax::{
3 ast::make,
4 ted::{self, Position},
5 NodeOrToken,
6 SyntaxKind::{self, *},
7 SyntaxNode, SyntaxToken, WalkEvent, T,
8 };
9
10 // FIXME: It would also be cool to share logic here and in the mbe tests,
11 // which are pretty unreadable at the moment.
12 /// Renders a [`SyntaxNode`] with whitespace inserted between tokens that require them.
insert_ws_into(syn: SyntaxNode) -> SyntaxNode13 pub fn insert_ws_into(syn: SyntaxNode) -> SyntaxNode {
14 let mut indent = 0;
15 let mut last: Option<SyntaxKind> = None;
16 let mut mods = Vec::new();
17 let syn = syn.clone_subtree().clone_for_update();
18
19 let before = Position::before;
20 let after = Position::after;
21
22 let do_indent = |pos: fn(_) -> Position, token: &SyntaxToken, indent| {
23 (pos(token.clone()), make::tokens::whitespace(&" ".repeat(2 * indent)))
24 };
25 let do_ws = |pos: fn(_) -> Position, token: &SyntaxToken| {
26 (pos(token.clone()), make::tokens::single_space())
27 };
28 let do_nl = |pos: fn(_) -> Position, token: &SyntaxToken| {
29 (pos(token.clone()), make::tokens::single_newline())
30 };
31
32 for event in syn.preorder_with_tokens() {
33 let token = match event {
34 WalkEvent::Enter(NodeOrToken::Token(token)) => token,
35 WalkEvent::Leave(NodeOrToken::Node(node))
36 if matches!(node.kind(), ATTR | MATCH_ARM | STRUCT | ENUM | UNION | FN | IMPL) =>
37 {
38 if indent > 0 {
39 mods.push((
40 Position::after(node.clone()),
41 make::tokens::whitespace(&" ".repeat(2 * indent)),
42 ));
43 }
44 if node.parent().is_some() {
45 mods.push((Position::after(node), make::tokens::single_newline()));
46 }
47 continue;
48 }
49 _ => continue,
50 };
51 let tok = &token;
52
53 let is_next = |f: fn(SyntaxKind) -> bool, default| -> bool {
54 tok.next_token().map(|it| f(it.kind())).unwrap_or(default)
55 };
56 let is_last =
57 |f: fn(SyntaxKind) -> bool, default| -> bool { last.map(f).unwrap_or(default) };
58
59 match tok.kind() {
60 k if is_text(k) && is_next(|it| !it.is_punct(), true) => {
61 mods.push(do_ws(after, tok));
62 }
63 L_CURLY if is_next(|it| it != R_CURLY, true) => {
64 indent += 1;
65 if is_last(is_text, false) {
66 mods.push(do_ws(before, tok));
67 }
68
69 if indent > 0 {
70 mods.push(do_indent(after, tok, indent));
71 }
72 mods.push(do_nl(after, &tok));
73 }
74 R_CURLY if is_last(|it| it != L_CURLY, true) => {
75 indent = indent.saturating_sub(1);
76
77 if indent > 0 {
78 mods.push(do_indent(before, tok, indent));
79 }
80 mods.push(do_nl(before, tok));
81 }
82 R_CURLY => {
83 if indent > 0 {
84 mods.push(do_indent(after, tok, indent));
85 }
86 mods.push(do_nl(after, tok));
87 }
88 LIFETIME_IDENT if is_next(|it| is_text(it), true) => {
89 mods.push(do_ws(after, tok));
90 }
91 AS_KW => {
92 mods.push(do_ws(after, tok));
93 }
94 T![;] => {
95 if indent > 0 {
96 mods.push(do_indent(after, tok, indent));
97 }
98 mods.push(do_nl(after, tok));
99 }
100 T![->] | T![=] | T![=>] => {
101 mods.push(do_ws(before, tok));
102 mods.push(do_ws(after, tok));
103 }
104 _ => (),
105 }
106
107 last = Some(tok.kind());
108 }
109
110 for (pos, insert) in mods {
111 ted::insert(pos, insert);
112 }
113
114 syn
115 }
116
is_text(k: SyntaxKind) -> bool117 fn is_text(k: SyntaxKind) -> bool {
118 k.is_keyword() || k.is_literal() || k == IDENT
119 }
120