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Auto merge of #48813 - sinkuu:build_in_assert_macro, r=alexcrichton
Make `assert` a built-in procedural macro Makes `assert` macro a built-in one without touching its functionality. This is a prerequisite for RFC 2011 (#44838).
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// Copyright 2018 The Rust Project Developers. See the COPYRIGHT | ||
// file at the top-level directory of this distribution and at | ||
// http://rust-lang.org/COPYRIGHT. | ||
// | ||
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or | ||
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license | ||
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your | ||
// option. This file may not be copied, modified, or distributed | ||
// except according to those terms. | ||
|
||
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::tokenstream::{TokenStream, TokenTree}; | ||
use syntax_pos::{Span, DUMMY_SP}; | ||
|
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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 | ||
}; | ||
|
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let sp = sp.with_ctxt(sp.ctxt().apply_mark(cx.current_expansion.mark)); | ||
let panic_call = Mac_ { | ||
path: Path::from_ident(sp, Ident::from_str("panic")), | ||
tts: if let Some(ts) = custom_msg_args { | ||
ts.into() | ||
} else { | ||
// `expr_to_string` escapes the string literals with `.escape_default()` | ||
// which escapes all non-ASCII characters with `\u`. | ||
let escaped_expr = escape_format_string(&unescape_printable_unicode( | ||
&pprust::expr_to_string(&cond_expr), | ||
)); | ||
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TokenStream::from(TokenTree::Token( | ||
DUMMY_SP, | ||
token::Literal( | ||
token::Lit::Str_(Name::intern(&format!("assertion failed: {}", escaped_expr))), | ||
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) | ||
} | ||
|
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/// Escapes a string for use as a formatting string. | ||
fn escape_format_string(s: &str) -> String { | ||
let mut res = String::with_capacity(s.len()); | ||
for c in s.chars() { | ||
res.extend(c.escape_debug()); | ||
match c { | ||
'{' | '}' => res.push(c), | ||
_ => {} | ||
} | ||
} | ||
res | ||
} | ||
|
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#[test] | ||
fn test_escape_format_string() { | ||
assert!(escape_format_string(r"foo{}\") == r"foo{{}}\\"); | ||
} | ||
|
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/// Unescapes the escaped unicodes (`\u{...}`) that are printable. | ||
fn unescape_printable_unicode(mut s: &str) -> String { | ||
use std::{char, u32}; | ||
|
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let mut res = String::with_capacity(s.len()); | ||
|
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loop { | ||
if let Some(start) = s.find(r"\u{") { | ||
res.push_str(&s[0..start]); | ||
s = &s[start..]; | ||
s.find('}') | ||
.and_then(|end| { | ||
let v = u32::from_str_radix(&s[3..end], 16).ok()?; | ||
let c = char::from_u32(v)?; | ||
// Escape unprintable characters. | ||
res.extend(c.escape_debug()); | ||
s = &s[end + 1..]; | ||
Some(()) | ||
}) | ||
.expect("lexer should have rejected invalid escape sequences"); | ||
} else { | ||
res.push_str(s); | ||
return res; | ||
} | ||
} | ||
} | ||
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#[test] | ||
fn test_unescape_printable_unicode() { | ||
assert!(unescape_printable_unicode(r"\u{2603}\n\u{0}") == r"☃\n\u{0}"); | ||
} |
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@@ -0,0 +1,13 @@ | ||
// Copyright 2018 The Rust Project Developers. See the COPYRIGHT | ||
// file at the top-level directory of this distribution and at | ||
// http://rust-lang.org/COPYRIGHT. | ||
// | ||
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or | ||
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license | ||
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your | ||
// option. This file may not be copied, modified, or distributed | ||
// except according to those terms. | ||
|
||
fn main() { | ||
assert!(r#"☃\backslash"#.contains("\\")); | ||
} |
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|
@@ -10,4 +10,5 @@ | |
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fn main() { | ||
assert!("foo"); | ||
//~^ ERROR cannot apply unary operator `!` | ||
} |
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