9b3f9d9444
Slice patterns are different from the rest in that a single slice pattern does not have a distinct constructor if it contains a variable-length subslice pattern. For example, the pattern [a, b, ..tail] can match a slice of length 2, 3, 4 and so on. As a result, the decision tree for exhaustiveness and redundancy analysis should explore each of those constructors separately to determine if the pattern could be useful when specialized for any of them.
83 lines
3.7 KiB
Rust
83 lines
3.7 KiB
Rust
// Copyright 2014 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 match_vecs<'a, T>(l1: &'a [T], l2: &'a [T]) -> &'static str {
|
|
match (l1, l2) {
|
|
([], []) => "both empty",
|
|
([], [..]) | ([..], []) => "one empty",
|
|
([..], [..]) => "both non-empty"
|
|
}
|
|
}
|
|
|
|
fn match_vecs_cons<'a, T>(l1: &'a [T], l2: &'a [T]) -> &'static str {
|
|
match (l1, l2) {
|
|
([], []) => "both empty",
|
|
([], [_, ..]) | ([_, ..], []) => "one empty",
|
|
([_, ..], [_, ..]) => "both non-empty"
|
|
}
|
|
}
|
|
|
|
fn match_vecs_snoc<'a, T>(l1: &'a [T], l2: &'a [T]) -> &'static str {
|
|
match (l1, l2) {
|
|
([], []) => "both empty",
|
|
([], [.., _]) | ([.., _], []) => "one empty",
|
|
([.., _], [.., _]) => "both non-empty"
|
|
}
|
|
}
|
|
|
|
fn match_nested_vecs_cons<'a, T>(l1: Option<&'a [T]>, l2: Result<&'a [T], ()>) -> &'static str {
|
|
match (l1, l2) {
|
|
(Some([]), Ok([])) => "Some(empty), Ok(empty)",
|
|
(Some([_, ..]), Ok(_)) | (Some([_, ..]), Err(())) => "Some(non-empty), any",
|
|
(None, Ok([])) | (None, Err(())) | (None, Ok([_])) => "None, Ok(less than one element)",
|
|
(None, Ok([_, _, ..])) => "None, Ok(at least two elements)",
|
|
_ => "other"
|
|
}
|
|
}
|
|
|
|
fn match_nested_vecs_snoc<'a, T>(l1: Option<&'a [T]>, l2: Result<&'a [T], ()>) -> &'static str {
|
|
match (l1, l2) {
|
|
(Some([]), Ok([])) => "Some(empty), Ok(empty)",
|
|
(Some([.., _]), Ok(_)) | (Some([.., _]), Err(())) => "Some(non-empty), any",
|
|
(None, Ok([])) | (None, Err(())) | (None, Ok([_])) => "None, Ok(less than one element)",
|
|
(None, Ok([.., _, _])) => "None, Ok(at least two elements)",
|
|
_ => "other"
|
|
}
|
|
}
|
|
|
|
fn main() {
|
|
assert_eq!(match_vecs(&[1i, 2], &[2i, 3]), "both non-empty");
|
|
assert_eq!(match_vecs(&[], &[1i, 2, 3, 4]), "one empty");
|
|
assert_eq!(match_vecs::<uint>(&[], &[]), "both empty");
|
|
assert_eq!(match_vecs(&[1i, 2, 3], &[]), "one empty");
|
|
|
|
assert_eq!(match_vecs_cons(&[1i, 2], &[2i, 3]), "both non-empty");
|
|
assert_eq!(match_vecs_cons(&[], &[1i, 2, 3, 4]), "one empty");
|
|
assert_eq!(match_vecs_cons::<uint>(&[], &[]), "both empty");
|
|
assert_eq!(match_vecs_cons(&[1i, 2, 3], &[]), "one empty");
|
|
|
|
assert_eq!(match_vecs_snoc(&[1i, 2], &[2i, 3]), "both non-empty");
|
|
assert_eq!(match_vecs_snoc(&[], &[1i, 2, 3, 4]), "one empty");
|
|
assert_eq!(match_vecs_snoc::<uint>(&[], &[]), "both empty");
|
|
assert_eq!(match_vecs_snoc(&[1i, 2, 3], &[]), "one empty");
|
|
|
|
assert_eq!(match_nested_vecs_cons(None, Ok(&[4u, 2u])), "None, Ok(at least two elements)");
|
|
assert_eq!(match_nested_vecs_cons::<uint>(None, Err(())), "None, Ok(less than one element)");
|
|
assert_eq!(match_nested_vecs_cons::<bool>(Some(&[]), Ok(&[])), "Some(empty), Ok(empty)");
|
|
assert_eq!(match_nested_vecs_cons(Some(&[1i]), Err(())), "Some(non-empty), any");
|
|
assert_eq!(match_nested_vecs_cons(Some(&[(42i, ())]), Ok(&[(1i, ())])), "Some(non-empty), any");
|
|
|
|
assert_eq!(match_nested_vecs_snoc(None, Ok(&[4u, 2u])), "None, Ok(at least two elements)");
|
|
assert_eq!(match_nested_vecs_snoc::<uint>(None, Err(())), "None, Ok(less than one element)");
|
|
assert_eq!(match_nested_vecs_snoc::<bool>(Some(&[]), Ok(&[])), "Some(empty), Ok(empty)");
|
|
assert_eq!(match_nested_vecs_snoc(Some(&[1i]), Err(())), "Some(non-empty), any");
|
|
assert_eq!(match_nested_vecs_snoc(Some(&[(42i, ())]), Ok(&[(1i, ())])), "Some(non-empty), any");
|
|
}
|