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### Multiple branches
All of these matches are equivalent, each written in a different style:
```rust
use E::*;
enum E { A, B, C, D }
match foo {
A | B => println!("Give me A | B!"),
C | D => println!("Give me C | D!"),
}
match foo {
| A | B => println!("Give me A...
...Usage let matcher = regex_filtered::Builder::new() .push("foo")? .push("bar")? .push("baz")? .push("quux")? .build()?; assert!(matcher.is_match("bar")); assert_eq!(matcher.matching("baz").count(), 1); assert_eq!(matcher.matching("foo quux").count(), 2); # Ok::<(), Box<dyn std::error::Error>>(()) [ Regexes::is_match ] returns whether any pattern in...
Simple string matching with single- and multi-character wildcard operator. wildmatch Match strings against a simple wildcard pattern. Tests a wildcard pattern p against an input string s . Returns true only when p matches the entirety of s . See also the example described on wikipedia for matching wildcards. ? matches exactly...
## Summary
[summary]: #summary
Better ergonomics for pattern-matching on references.
Currently, matching on references requires a bit of a dance using
`ref` and `&` patterns:
```rust
let x: &Option<_> = &Some(0);
match x {
&Some(ref y) => { ... },
&None => { ... },
}
// or using `*`:
match *x {
Some(ref x) => { ... },
None => { ... },
}
```
After this RFC, the above form...
core::str::trim_right_matches
Deprecated
pub fn trim_right_matches<P>(&self, pat: P) -> &strstr::trim_right_matches — Returns a string slice with all suffixes that match a pattern repeatedly removed.
The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.
Text directionality
A string is a sequence of bytes. 'Right' in...
## Summary
[summary]: #summary
Allow `if let` guards in `match` expressions.
## Motivation
[motivation]: #motivation
This feature would greatly simplify some logic where we must match a pattern iff some value computed from the `match`-bound values has a certain form, where said value may be costly or impossible (due to affine...
pub fn trim_end_matches<P>(&self, pat: P) -> &strstr::trim_end_matches — Returns a string slice with all suffixes that match a pattern repeatedly removed.
The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.
Text directionality
A string is a sequence of bytes. end in...
The match Control Flow Construct
Rust has an extremely powerful control flow construct called match that allows you to compare a value against a series of patterns and then execute code based on which pattern matches. Patterns can be made up of literal values, variable names, wildcards, and many other...
core::str::trim_left_matches
Deprecated
pub fn trim_left_matches<P>(&self, pat: P) -> &strstr::trim_left_matches — Returns a string slice with all prefixes that match a pattern repeatedly removed.
The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.
Text directionality
A string is a sequence of bytes. 'Left' in...
pub fn trim_start_matches<P>(&self, pat: P) -> &strstr::trim_start_matches — Returns a string slice with all prefixes that match a pattern repeatedly removed.
The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.
Text directionality
A string is a sequence of bytes. start in...
pub fn matches<P>(&self, pat: P) -> Matches<'_, P>str::matches — Returns an iterator over the disjoint matches of a pattern within the given string slice.
The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.
Iterator behavior
The returned iterator will be a DoubleEndedIterator if the...
...Void) {
match v { }
}
In effect, this match serves as a kind of assertion. You are saying
“because v can never be instantiated, foo could never actually be
called, and therefore – when I match against it – this match must
be dead code”. Since the match is dead code, you don’t...
## Summary
Change array/slice patterns in the following ways:
- Make them only match on arrays (`[T; n]` and `[T]`), not slices;
- Make subslice matching yield a value of type `[T; n]` or `[T]`, not `&[T]` or
`&mut [T]`;
- Allow multiple mutable references to be made to different parts of the...
...For example, these two matches on x: &i32 are equivalent:
let int_reference = &3;
let a = match *int_reference { 0 => "zero", _ => "some" };
let b = match int_reference { &0 => "zero", _ => "some" };
assert_eq!(a, b);
The grammar production for reference patterns has to match the token && to match a reference to...
...For example, if we have a pattern ab?c and a single match which has matched a in the input then we can fork and one match will attempt to match b then c, and one will just match c.
One interesting aspect of matching is handling metavariable matching in...
if let
For some use cases, when matching enums, match is awkward. For example:
// Make `optional` of type `Option<i32>`
let optional = Some(7);
match optional {
Some(i) => println!("This is a really long string and `{:?}`", i),
_ => {},
// ^ Required because `match` is exhaustive. Doesn't it seem
// like wasted space?
};
if...
Rust is one of those nice languages with pattern matching.
If you don’t know, it can be thought of as a generalization of the switch statement:
comparing objects not just by value (or overloaded equality operator, etc.)
but by structure:
match hashmap.get(&key) {
Some(value) => do_something_with...
...match Arms
As discussed in Chapter 6, we use patterns in the arms of match expressions. Formally, match expressions are defined as the keyword match, a value to match on, and one or more match arms that consist of a pattern and an expression to run if the value matches...
...let mut router = Router::new(); router.insert("/{{hello}}", true)?; router.insert("/{hello}", true)?; // Match the static route. let matched = router.at("/{hello}")?; assert!(matched.params.is_empty()); // Match the dynamic route. let matched = router.at("/hello")?; assert_eq!(matched.params.get("hello"), Some("hello")); Conflict Rules Static and dynamic route...
...extern crate clap; extern crate sys_mount; use clap::{App, Arg}; use sys_mount::{Mount, MountFlags, SupportedFilesystems}; use std::process::exit; fn main() { let matches = App::new("mount") .arg(Arg::with_name("source").required(true)) .arg(Arg::with_name("directory").required(true)) .get_matches(); let src = matches.value_of("source...
"Why do I use the letter ‘o’ for my generic closure param name? [...] I recently realized that since Rust uses pipes to enclose a param block, usin..."