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
use syntax::ast::*;
use syntax::codemap::Spanned;
use syntax::ext::base::*;
use syntax::ext::build::AstBuilder;
use syntax::parse::token;
use syntax::print::pprust;
use syntax::symbol::Symbol;
use syntax::tokenstream::{TokenStream, TokenTree};
use syntax_pos::{Span, DUMMY_SP};
pub fn expand_assert<'cx>(
cx: &'cx mut ExtCtxt,
sp: Span,
tts: &[TokenTree],
) -> Box<MacResult + 'cx> {
let mut parser = cx.new_parser_from_tts(tts);
let cond_expr = panictry!(parser.parse_expr());
let custom_msg_args = if parser.eat(&token::Comma) {
let ts = parser.parse_tokens();
if !ts.is_empty() {
Some(ts)
} else {
None
}
} else {
None
};
let sp = sp.apply_mark(cx.current_expansion.mark);
let panic_call = Mac_ {
path: Path::from_ident(Ident::new(Symbol::intern("panic"), sp)),
tts: if let Some(ts) = custom_msg_args {
ts.into()
} else {
TokenStream::from(TokenTree::Token(
DUMMY_SP,
token::Literal(
token::Lit::Str_(Name::intern(&format!(
"assertion failed: {}",
pprust::expr_to_string(&cond_expr).escape_debug()
))),
None,
),
)).into()
},
};
let if_expr = cx.expr_if(
sp,
cx.expr(sp, ExprKind::Unary(UnOp::Not, cond_expr)),
cx.expr(
sp,
ExprKind::Mac(Spanned {
span: sp,
node: panic_call,
}),
),
None,
);
MacEager::expr(if_expr)
}