rust/src/test/run-pass/block-arg.rs

63 lines
2.0 KiB
Rust

// Copyright 2012 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.
// Check usage and precedence of block arguments in expressions:
pub fn main() {
let v = ~[-1f, 0f, 1f, 2f, 3f];
// Statement form does not require parentheses:
for vec::each(v) |i| {
log(info, *i);
}
// Usable at all:
let mut any_negative = do vec::any(v) |e| { float::is_negative(*e) };
assert any_negative;
// Higher precedence than assignments:
any_negative = do vec::any(v) |e| { float::is_negative(*e) };
assert any_negative;
// Higher precedence than unary operations:
let abs_v = do vec::map(v) |e| { float::abs(*e) };
assert do vec::all(abs_v) |e| { float::is_nonnegative(*e) };
assert !do vec::any(abs_v) |e| { float::is_negative(*e) };
// Usable in funny statement-like forms:
if !do vec::any(v) |e| { float::is_positive(*e) } {
assert false;
}
match do vec::all(v) |e| { float::is_negative(*e) } {
true => { fail!(~"incorrect answer."); }
false => { }
}
match 3 {
_ if do vec::any(v) |e| { float::is_negative(*e) } => {
}
_ => {
fail!(~"wrong answer.");
}
}
// Lower precedence than binary operations:
let w = do vec::foldl(0f, v) |x, y| { x + *y } + 10f;
let y = do vec::foldl(0f, v) |x, y| { x + *y } + 10f;
let z = 10f + do vec::foldl(0f, v) |x, y| { x + *y };
assert w == y;
assert y == z;
// In the tail of a block
let w =
if true { do vec::any(abs_v) |e| { float::is_nonnegative(*e) } }
else { false };
assert w;
}