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
|
use proc_macro2::TokenStream;
use quote::ToTokens;
use syn::{token, Token};
pub enum Fragment {
/// Tokens that can be used as an expression.
Expr(TokenStream),
/// Tokens that can be used inside a block. The surrounding curly braces are
/// not part of these tokens.
Block(TokenStream),
}
macro_rules! quote_expr {
($($tt:tt)*) => {
$crate::fragment::Fragment::Expr(quote!($($tt)*))
}
}
macro_rules! quote_block {
($($tt:tt)*) => {
$crate::fragment::Fragment::Block(quote!($($tt)*))
}
}
/// Interpolate a fragment in place of an expression. This involves surrounding
/// Block fragments in curly braces.
pub struct Expr(pub Fragment);
impl ToTokens for Expr {
fn to_tokens(&self, out: &mut TokenStream) {
match &self.0 {
Fragment::Expr(expr) => expr.to_tokens(out),
Fragment::Block(block) => {
token::Brace::default().surround(out, |out| block.to_tokens(out));
}
}
}
}
/// Interpolate a fragment as the statements of a block.
pub struct Stmts(pub Fragment);
impl ToTokens for Stmts {
fn to_tokens(&self, out: &mut TokenStream) {
match &self.0 {
Fragment::Expr(expr) => expr.to_tokens(out),
Fragment::Block(block) => block.to_tokens(out),
}
}
}
/// Interpolate a fragment as the value part of a `match` expression. This
/// involves putting a comma after expressions and curly braces around blocks.
pub struct Match(pub Fragment);
impl ToTokens for Match {
fn to_tokens(&self, out: &mut TokenStream) {
match &self.0 {
Fragment::Expr(expr) => {
expr.to_tokens(out);
<Token![,]>::default().to_tokens(out);
}
Fragment::Block(block) => {
token::Brace::default().surround(out, |out| block.to_tokens(out));
}
}
}
}
impl AsRef<TokenStream> for Fragment {
fn as_ref(&self) -> &TokenStream {
match self {
Fragment::Expr(expr) => expr,
Fragment::Block(block) => block,
}
}
}
|
