Struct Arm 

pub struct Arm { /* private fields */ }

One arm of a match: a pattern, and whether the arm has a guard.

A guard is treated as possibly failing: a guarded arm never makes later arms unreachable and never counts toward exhaustiveness, but it is itself reachable whenever a value matching its pattern can get past the earlier unguarded arms. With an or-pattern, the guard is assumed to be tried again for each alternative that matches, so alternatives of a guarded arm never make each other redundant.

Examples

use match_lang::{Arm, Pat};

let plain = Arm::new(Pat::wild());
let guarded = Arm::guarded(Pat::int(0));
assert!(!plain.is_guarded());
assert!(guarded.is_guarded());
assert_eq!(guarded.pat().to_string(), "0");

Implementations

impl Arm

pub fn new(pat: Pat) -> Arm

An arm without a guard.

Examples

use match_lang::{Arm, Pat};

let arm = Arm::new(Pat::bool(true));
assert!(!arm.is_guarded());

pub fn guarded(pat: Pat) -> Arm

An arm with a guard (pat if condition). The condition itself is not analysed.

Examples

use match_lang::{Arm, Pat};

let arm = Arm::guarded(Pat::wild());
assert!(arm.is_guarded());

pub fn pat(&self) -> &Pat

The arm’s pattern.

Examples

use match_lang::{Arm, Pat};

assert_eq!(Arm::new(Pat::int(3)).pat().to_string(), "3");

pub fn is_guarded(&self) -> bool

Whether the arm has a guard.

Examples

use match_lang::{Arm, Pat};

assert!(Arm::guarded(Pat::wild()).is_guarded());

Trait Implementations

impl Clone for Arm

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Arm

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.