63 lines
1.9 KiB
Rust
63 lines
1.9 KiB
Rust
// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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// Check usage and precedence of block arguments in expressions:
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pub fn main() {
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let v = ~[-1f, 0f, 1f, 2f, 3f];
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// Statement form does not require parentheses:
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for vec::each(v) |i| {
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info!("%?", *i);
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}
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// Usable at all:
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let mut any_negative = do vec::any(v) |e| { e.is_negative() };
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assert!(any_negative);
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// Higher precedence than assignments:
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any_negative = do vec::any(v) |e| { e.is_negative() };
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assert!(any_negative);
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// Higher precedence than unary operations:
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let abs_v = do vec::map(v) |e| { e.abs() };
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assert!(do vec::all(abs_v) |e| { e.is_positive() });
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assert!(!do vec::any(abs_v) |e| { e.is_negative() });
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// Usable in funny statement-like forms:
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if !do vec::any(v) |e| { e.is_positive() } {
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assert!(false);
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}
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match do vec::all(v) |e| { e.is_negative() } {
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true => { fail!("incorrect answer."); }
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false => { }
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}
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match 3 {
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_ if do vec::any(v) |e| { e.is_negative() } => {
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}
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_ => {
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fail!("wrong answer.");
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}
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}
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// Lower precedence than binary operations:
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let w = do vec::foldl(0f, v) |x, y| { x + *y } + 10f;
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let y = do vec::foldl(0f, v) |x, y| { x + *y } + 10f;
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let z = 10f + do vec::foldl(0f, v) |x, y| { x + *y };
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assert_eq!(w, y);
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assert_eq!(y, z);
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// In the tail of a block
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let w =
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if true { do vec::any(abs_v) |e| { e.is_positive() } }
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else { false };
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assert!(w);
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}
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