CreateHashMap

Module std.collections

import std.collections;

Public declaration contracts and authored examples. A page can document several related symbols. Implementation bodies are excluded.

CreateHashMap

pub fn CreateHashMap<K, V>() -> HashMap<K, V>
    where K: BuiltinHashKey, Movable where V: Movable

Creates an empty hash map using built-in logical key hashing.

Construction allocates nothing. The returned owner allocates on fallible reserve/insertion; borrowed text keys still require their backing owner to outlive storage. Custom key types must supply an explicit policy through the HashMap constructor. Floating keys use canonical signed-zero/NaN equality. K: Supported built-in key representation, movable into storage. V: Movable owned value representation. Return: Empty owning table with the default allocator and safe hash functions.

CreateHashMap

pub fn CreateHashMap<K, V, A>(mut AllocatorValue: A) -> HashMap<K, V, HashPolicy<K>, A>
    where K: BuiltinHashKey, Movable where V: Movable where A: Allocator, Defaultable, Movable

Creates an empty default-hash map with a transferred allocator.

Both table arrays remain owned by this allocator; failed insertion retains the input key and value. Construction allocates nothing and retains no external borrow. K: Supported built-in movable key representation. V: Movable owned value representation. A: Movable Defaultable allocator type owning future table allocations. AllocatorValue: Allocator transferred into the returned table. Return: Empty table owning its allocator and default safe hash/equality policy.

Example

module example.default_hash_allocator;
from std.collections import CreateHashMap, CreateHashSet;
from std.memory import DefaultAllocator;
fn Main() -> i32 {
    var Values = CreateHashMap<u32, i32>(default(DefaultAllocator));
    var Keys = CreateHashSet<u32>(default(DefaultAllocator));
    if Values.TryReserve(2) is .Err { Error = _ } { return 1; }
    if Keys.TryReserve(2) is .Err { Error = _ } { return 2; }
    if Values.TryInsert(7, 42) is .Err { Error = _ } { return 3; }
    if Keys.TryInsert(7) is .Err { Error = _ } { return 4; }
    if !Keys.Contains(7) || Values.Find(7).Unwrap() != 42 { return 5; }
    Values.Clear(); Keys.Clear();
    if Values.TryShrinkToFit() is .Err { Error = _ } { return 6; }
    if Keys.TryShrinkToFit() is .Err { Error = _ } { return 7; }
    return 0;
}