64 lines
1.3 KiB
Rust
64 lines
1.3 KiB
Rust
// Copyright 2014-2018 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution.
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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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fn some_func(a: Option<u32>) -> Option<u32> {
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if a.is_none() {
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return None;
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}
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a
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}
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pub enum SeemsOption<T> {
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Some(T),
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None,
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}
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impl<T> SeemsOption<T> {
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pub fn is_none(&self) -> bool {
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match *self {
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SeemsOption::None => true,
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SeemsOption::Some(_) => false,
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}
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}
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}
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fn returns_something_similar_to_option(a: SeemsOption<u32>) -> SeemsOption<u32> {
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if a.is_none() {
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return SeemsOption::None;
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}
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a
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}
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pub struct SomeStruct {
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pub opt: Option<u32>,
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}
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impl SomeStruct {
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pub fn func(&self) -> Option<u32> {
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if (self.opt).is_none() {
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return None;
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}
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self.opt
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}
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}
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fn main() {
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some_func(Some(42));
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some_func(None);
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let some_struct = SomeStruct { opt: Some(54) };
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some_struct.func();
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let so = SeemsOption::Some(45);
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returns_something_similar_to_option(so);
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}
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