Macro into_hset 

macro_rules! into_hset {
    (
  $( $key: expr ),* $( , )?
 ) => { ... };
}

Function and structures to work with collections. Creates a HashSet from a list of elements.

The into_hset macro allows for convenient creation of a HashSet with initial elements. Elements passed to the macro are automatically converted into the set’s element type using .into(), facilitating the use of literals or values of different, but convertible types.

Note: The into_hset macro relies on the .into() method to convert each element into the target type of the HashSet. This means that the elements must be compatible with the Into< T > trait for the type T used in the HashSet. Also, this means that sometimes you must specify the type of collection’s items.

Origin

This collection can be reexported from different crates :

• from std, if use_std is on ( no_std flag if off )
• from hashbrown, if use_alloc flag if on

Syntax

The macro can be called with a comma-separated list of elements. A trailing comma is optional.

// HashSet of &str
let set1: HashSet< &str > = into_hset!( "a", "b", "c" );

// HashSet of String
let set2: HashSet< String > = into_hset!{ "a".to_string(), "b", "c" };

// With trailing comma
let set3: HashSet< i32 > = into_hset!( 1, 2, 3, );

Parameters

• $( $key: expr ),* $( , )? : A comma-separated list of elements to insert into the HashSet. Each element can be of any type that implements the Into< T > trait, where T is the type stored in the HashSet.

Returns

Returns a HashSet containing all the specified elements. The capacity of the set is automatically determined based on the number of elements provided.

Example

Basic usage with string slices :

let set: HashSet< &str > = into_hset!( "one", "two", "three" );
assert!( set.contains( "one" ) );
assert!( set.contains( "two" ) );
assert!( set.contains( "three" ) );
assert_eq!( set.len(), 3 );

Example

Using with different types that implement Into< T > :

let numbers: HashSet< i32 > = into_hset!( 1, 2, 3 );
assert!( numbers.contains( &1 ) );
assert!( numbers.contains( &2 ) );
assert!( numbers.contains( &3 ) );

Example

Creating a HashSet of String from string literals :

let s: HashSet< String > = into_hset!{ "value" };
assert_eq!( s.get( "value" ), Some( &"value".to_string() ) );