ed5015939f
Implement .zip() specialization for Map and Cloned. The crucial thing for transparent specialization is that we want to preserve the potential side effects. The simplest example is that in this code snippet: `(0..6).map(f).zip((0..4).map(g)).count()` `f` will be called five times, and `g` four times. The last time for `f` is when the other iterator is at its end, so this element is unused. This side effect can be preserved without disturbing code generation for simple uses of `.map()`. The `Zip::next_back()` case is even more complicated, unfortunately.
32 lines
890 B
Rust
32 lines
890 B
Rust
// Copyright 2016 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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// compile-flags: -C no-prepopulate-passes -O
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#![crate_type = "lib"]
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// CHECK-LABEL: @zip_copy
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#[no_mangle]
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pub fn zip_copy(xs: &[u8], ys: &mut [u8]) {
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// CHECK: memcpy
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for (x, y) in xs.iter().zip(ys) {
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*y = *x;
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}
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}
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// CHECK-LABEL: @zip_copy_mapped
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#[no_mangle]
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pub fn zip_copy_mapped(xs: &[u8], ys: &mut [u8]) {
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// CHECK: memcpy
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for (x, y) in xs.iter().map(|&x| x).zip(ys) {
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*y = x;
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}
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}
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