Macro deque 

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

Creates a VecDeque from a list of elements.

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

Note: The deque macro relies on the .into() method to convert each element into the target type of the VecDeque. This means that the elements must be compatible with the Into< T > trait for the type T used in the VecDeque.

Origin

This collection is reexported from alloc.

Syntax

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

// VecDeque of i32
let vd1 = deque!( 1, 2, 3, 4, 5 );

// VecDeque of String
let vd2 = deque!{ "hello", "world", "rust" };

// With trailing comma
let vd3 = deque!( 1.1, 2.2, 3.3, );

Parameters

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

Returns

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

Example

Basic usage with integers :

let vd: VecDeque< i32 > = deque!( 1, 2, 3 );
assert_eq!( vd.front(), Some( &1 ) ); // The first element is 1
assert_eq!( vd.back(), Some( &3 ) ); // The last element is 3

Example

Creating a VecDeque of &str from string literals :

let fruits = deque!{ "apple", "banana", "cherry" };
assert_eq!( fruits.front(), Some( &"apple" ) ); // The first element
assert_eq!( fruits.back(), Some( &"cherry" ) ); // The last element