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zig/lib/std/array_hash_map.zig
Andrew Kelley eab934814f docs: ArrayHashMap: warn against the shrink footgun
2024-07-26 15:24:25 -07:00

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const std = @import("std.zig");
const debug = std.debug;
const assert = debug.assert;
const testing = std.testing;
const math = std.math;
const mem = std.mem;
const autoHash = std.hash.autoHash;
const Wyhash = std.hash.Wyhash;
const Allocator = mem.Allocator;
const hash_map = @This();
/// An `ArrayHashMap` with default hash and equal functions.
///
/// See `AutoContext` for a description of the hash and equal implementations.
pub fn AutoArrayHashMap(comptime K: type, comptime V: type) type {
return ArrayHashMap(K, V, AutoContext(K), !autoEqlIsCheap(K));
}
/// An `ArrayHashMapUnmanaged` with default hash and equal functions.
///
/// See `AutoContext` for a description of the hash and equal implementations.
pub fn AutoArrayHashMapUnmanaged(comptime K: type, comptime V: type) type {
return ArrayHashMapUnmanaged(K, V, AutoContext(K), !autoEqlIsCheap(K));
}
/// An `ArrayHashMap` with strings as keys.
pub fn StringArrayHashMap(comptime V: type) type {
return ArrayHashMap([]const u8, V, StringContext, true);
}
/// An `ArrayHashMapUnmanaged` with strings as keys.
pub fn StringArrayHashMapUnmanaged(comptime V: type) type {
return ArrayHashMapUnmanaged([]const u8, V, StringContext, true);
}
pub const StringContext = struct {
pub fn hash(self: @This(), s: []const u8) u32 {
_ = self;
return hashString(s);
}
pub fn eql(self: @This(), a: []const u8, b: []const u8, b_index: usize) bool {
_ = self;
_ = b_index;
return eqlString(a, b);
}
};
pub fn eqlString(a: []const u8, b: []const u8) bool {
return mem.eql(u8, a, b);
}
pub fn hashString(s: []const u8) u32 {
return @as(u32, @truncate(std.hash.Wyhash.hash(0, s)));
}
/// A hash table of keys and values, each stored sequentially.
///
/// Insertion order is preserved. In general, this data structure supports the same
/// operations as `std.ArrayList`.
///
/// Deletion operations:
/// * `swapRemove` - O(1)
/// * `orderedRemove` - O(N)
///
/// Modifying the hash map while iterating is allowed, however, one must understand
/// the (well defined) behavior when mixing insertions and deletions with iteration.
///
/// See `ArrayHashMapUnmanaged` for a variant of this data structure that accepts an
/// `Allocator` as a parameter when needed rather than storing it.
pub fn ArrayHashMap(
comptime K: type,
comptime V: type,
/// A namespace that provides these two functions:
/// * `pub fn hash(self, K) u32`
/// * `pub fn eql(self, K, K) bool`
///
comptime Context: type,
/// When `false`, this data structure is biased towards cheap `eql`
/// functions and avoids storing each key's hash in the table. Setting
/// `store_hash` to `true` incurs more memory cost but limits `eql` to
/// being called only once per insertion/deletion (provided there are no
/// hash collisions).
comptime store_hash: bool,
) type {
return struct {
unmanaged: Unmanaged,
allocator: Allocator,
ctx: Context,
/// The ArrayHashMapUnmanaged type using the same settings as this managed map.
pub const Unmanaged = ArrayHashMapUnmanaged(K, V, Context, store_hash);
/// Pointers to a key and value in the backing store of this map.
/// Modifying the key is allowed only if it does not change the hash.
/// Modifying the value is allowed.
/// Entry pointers become invalid whenever this ArrayHashMap is modified,
/// unless `ensureTotalCapacity`/`ensureUnusedCapacity` was previously used.
pub const Entry = Unmanaged.Entry;
/// A KV pair which has been copied out of the backing store
pub const KV = Unmanaged.KV;
/// The Data type used for the MultiArrayList backing this map
pub const Data = Unmanaged.Data;
/// The MultiArrayList type backing this map
pub const DataList = Unmanaged.DataList;
/// The stored hash type, either u32 or void.
pub const Hash = Unmanaged.Hash;
/// getOrPut variants return this structure, with pointers
/// to the backing store and a flag to indicate whether an
/// existing entry was found.
/// Modifying the key is allowed only if it does not change the hash.
/// Modifying the value is allowed.
/// Entry pointers become invalid whenever this ArrayHashMap is modified,
/// unless `ensureTotalCapacity`/`ensureUnusedCapacity` was previously used.
pub const GetOrPutResult = Unmanaged.GetOrPutResult;
/// An Iterator over Entry pointers.
pub const Iterator = Unmanaged.Iterator;
const Self = @This();
/// Create an ArrayHashMap instance which will use a specified allocator.
pub fn init(allocator: Allocator) Self {
if (@sizeOf(Context) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call initContext instead.");
return initContext(allocator, undefined);
}
pub fn initContext(allocator: Allocator, ctx: Context) Self {
return .{
.unmanaged = .{},
.allocator = allocator,
.ctx = ctx,
};
}
/// Frees the backing allocation and leaves the map in an undefined state.
/// Note that this does not free keys or values. You must take care of that
/// before calling this function, if it is needed.
pub fn deinit(self: *Self) void {
self.unmanaged.deinit(self.allocator);
self.* = undefined;
}
/// Puts the hash map into a state where any method call that would
/// cause an existing key or value pointer to become invalidated will
/// instead trigger an assertion.
///
/// An additional call to `lockPointers` in such state also triggers an
/// assertion.
///
/// `unlockPointers` returns the hash map to the previous state.
pub fn lockPointers(self: *Self) void {
self.unmanaged.lockPointers();
}
/// Undoes a call to `lockPointers`.
pub fn unlockPointers(self: *Self) void {
self.unmanaged.unlockPointers();
}
/// Clears the map but retains the backing allocation for future use.
pub fn clearRetainingCapacity(self: *Self) void {
return self.unmanaged.clearRetainingCapacity();
}
/// Clears the map and releases the backing allocation
pub fn clearAndFree(self: *Self) void {
return self.unmanaged.clearAndFree(self.allocator);
}
/// Returns the number of KV pairs stored in this map.
pub fn count(self: Self) usize {
return self.unmanaged.count();
}
/// Returns the backing array of keys in this map. Modifying the map may
/// invalidate this array. Modifying this array in a way that changes
/// key hashes or key equality puts the map into an unusable state until
/// `reIndex` is called.
pub fn keys(self: Self) []K {
return self.unmanaged.keys();
}
/// Returns the backing array of values in this map. Modifying the map
/// may invalidate this array. It is permitted to modify the values in
/// this array.
pub fn values(self: Self) []V {
return self.unmanaged.values();
}
/// Returns an iterator over the pairs in this map.
/// Modifying the map may invalidate this iterator.
pub fn iterator(self: *const Self) Iterator {
return self.unmanaged.iterator();
}
/// If key exists this function cannot fail.
/// If there is an existing item with `key`, then the result
/// `Entry` pointer points to it, and found_existing is true.
/// Otherwise, puts a new item with undefined value, and
/// the `Entry` pointer points to it. Caller should then initialize
/// the value (but not the key).
pub fn getOrPut(self: *Self, key: K) !GetOrPutResult {
return self.unmanaged.getOrPutContext(self.allocator, key, self.ctx);
}
pub fn getOrPutAdapted(self: *Self, key: anytype, ctx: anytype) !GetOrPutResult {
return self.unmanaged.getOrPutContextAdapted(self.allocator, key, ctx, self.ctx);
}
/// If there is an existing item with `key`, then the result
/// `Entry` pointer points to it, and found_existing is true.
/// Otherwise, puts a new item with undefined value, and
/// the `Entry` pointer points to it. Caller should then initialize
/// the value (but not the key).
/// If a new entry needs to be stored, this function asserts there
/// is enough capacity to store it.
pub fn getOrPutAssumeCapacity(self: *Self, key: K) GetOrPutResult {
return self.unmanaged.getOrPutAssumeCapacityContext(key, self.ctx);
}
pub fn getOrPutAssumeCapacityAdapted(self: *Self, key: anytype, ctx: anytype) GetOrPutResult {
return self.unmanaged.getOrPutAssumeCapacityAdapted(key, ctx);
}
pub fn getOrPutValue(self: *Self, key: K, value: V) !GetOrPutResult {
return self.unmanaged.getOrPutValueContext(self.allocator, key, value, self.ctx);
}
/// Increases capacity, guaranteeing that insertions up until the
/// `expected_count` will not cause an allocation, and therefore cannot fail.
pub fn ensureTotalCapacity(self: *Self, new_capacity: usize) !void {
return self.unmanaged.ensureTotalCapacityContext(self.allocator, new_capacity, self.ctx);
}
/// Increases capacity, guaranteeing that insertions up until
/// `additional_count` **more** items will not cause an allocation, and
/// therefore cannot fail.
pub fn ensureUnusedCapacity(self: *Self, additional_count: usize) !void {
return self.unmanaged.ensureUnusedCapacityContext(self.allocator, additional_count, self.ctx);
}
/// Returns the number of total elements which may be present before it is
/// no longer guaranteed that no allocations will be performed.
pub fn capacity(self: Self) usize {
return self.unmanaged.capacity();
}
/// Clobbers any existing data. To detect if a put would clobber
/// existing data, see `getOrPut`.
pub fn put(self: *Self, key: K, value: V) !void {
return self.unmanaged.putContext(self.allocator, key, value, self.ctx);
}
/// Inserts a key-value pair into the hash map, asserting that no previous
/// entry with the same key is already present
pub fn putNoClobber(self: *Self, key: K, value: V) !void {
return self.unmanaged.putNoClobberContext(self.allocator, key, value, self.ctx);
}
/// Asserts there is enough capacity to store the new key-value pair.
/// Clobbers any existing data. To detect if a put would clobber
/// existing data, see `getOrPutAssumeCapacity`.
pub fn putAssumeCapacity(self: *Self, key: K, value: V) void {
return self.unmanaged.putAssumeCapacityContext(key, value, self.ctx);
}
/// Asserts there is enough capacity to store the new key-value pair.
/// Asserts that it does not clobber any existing data.
/// To detect if a put would clobber existing data, see `getOrPutAssumeCapacity`.
pub fn putAssumeCapacityNoClobber(self: *Self, key: K, value: V) void {
return self.unmanaged.putAssumeCapacityNoClobberContext(key, value, self.ctx);
}
/// Inserts a new `Entry` into the hash map, returning the previous one, if any.
pub fn fetchPut(self: *Self, key: K, value: V) !?KV {
return self.unmanaged.fetchPutContext(self.allocator, key, value, self.ctx);
}
/// Inserts a new `Entry` into the hash map, returning the previous one, if any.
/// If insertion happuns, asserts there is enough capacity without allocating.
pub fn fetchPutAssumeCapacity(self: *Self, key: K, value: V) ?KV {
return self.unmanaged.fetchPutAssumeCapacityContext(key, value, self.ctx);
}
/// Finds pointers to the key and value storage associated with a key.
pub fn getEntry(self: Self, key: K) ?Entry {
return self.unmanaged.getEntryContext(key, self.ctx);
}
pub fn getEntryAdapted(self: Self, key: anytype, ctx: anytype) ?Entry {
return self.unmanaged.getEntryAdapted(key, ctx);
}
/// Finds the index in the `entries` array where a key is stored
pub fn getIndex(self: Self, key: K) ?usize {
return self.unmanaged.getIndexContext(key, self.ctx);
}
pub fn getIndexAdapted(self: Self, key: anytype, ctx: anytype) ?usize {
return self.unmanaged.getIndexAdapted(key, ctx);
}
/// Find the value associated with a key
pub fn get(self: Self, key: K) ?V {
return self.unmanaged.getContext(key, self.ctx);
}
pub fn getAdapted(self: Self, key: anytype, ctx: anytype) ?V {
return self.unmanaged.getAdapted(key, ctx);
}
/// Find a pointer to the value associated with a key
pub fn getPtr(self: Self, key: K) ?*V {
return self.unmanaged.getPtrContext(key, self.ctx);
}
pub fn getPtrAdapted(self: Self, key: anytype, ctx: anytype) ?*V {
return self.unmanaged.getPtrAdapted(key, ctx);
}
/// Find the actual key associated with an adapted key
pub fn getKey(self: Self, key: K) ?K {
return self.unmanaged.getKeyContext(key, self.ctx);
}
pub fn getKeyAdapted(self: Self, key: anytype, ctx: anytype) ?K {
return self.unmanaged.getKeyAdapted(key, ctx);
}
/// Find a pointer to the actual key associated with an adapted key
pub fn getKeyPtr(self: Self, key: K) ?*K {
return self.unmanaged.getKeyPtrContext(key, self.ctx);
}
pub fn getKeyPtrAdapted(self: Self, key: anytype, ctx: anytype) ?*K {
return self.unmanaged.getKeyPtrAdapted(key, ctx);
}
/// Check whether a key is stored in the map
pub fn contains(self: Self, key: K) bool {
return self.unmanaged.containsContext(key, self.ctx);
}
pub fn containsAdapted(self: Self, key: anytype, ctx: anytype) bool {
return self.unmanaged.containsAdapted(key, ctx);
}
/// If there is an `Entry` with a matching key, it is deleted from
/// the hash map, and then returned from this function. The entry is
/// removed from the underlying array by swapping it with the last
/// element.
pub fn fetchSwapRemove(self: *Self, key: K) ?KV {
return self.unmanaged.fetchSwapRemoveContext(key, self.ctx);
}
pub fn fetchSwapRemoveAdapted(self: *Self, key: anytype, ctx: anytype) ?KV {
return self.unmanaged.fetchSwapRemoveContextAdapted(key, ctx, self.ctx);
}
/// If there is an `Entry` with a matching key, it is deleted from
/// the hash map, and then returned from this function. The entry is
/// removed from the underlying array by shifting all elements forward
/// thereby maintaining the current ordering.
pub fn fetchOrderedRemove(self: *Self, key: K) ?KV {
return self.unmanaged.fetchOrderedRemoveContext(key, self.ctx);
}
pub fn fetchOrderedRemoveAdapted(self: *Self, key: anytype, ctx: anytype) ?KV {
return self.unmanaged.fetchOrderedRemoveContextAdapted(key, ctx, self.ctx);
}
/// If there is an `Entry` with a matching key, it is deleted from
/// the hash map. The entry is removed from the underlying array
/// by swapping it with the last element. Returns true if an entry
/// was removed, false otherwise.
pub fn swapRemove(self: *Self, key: K) bool {
return self.unmanaged.swapRemoveContext(key, self.ctx);
}
pub fn swapRemoveAdapted(self: *Self, key: anytype, ctx: anytype) bool {
return self.unmanaged.swapRemoveContextAdapted(key, ctx, self.ctx);
}
/// If there is an `Entry` with a matching key, it is deleted from
/// the hash map. The entry is removed from the underlying array
/// by shifting all elements forward, thereby maintaining the
/// current ordering. Returns true if an entry was removed, false otherwise.
pub fn orderedRemove(self: *Self, key: K) bool {
return self.unmanaged.orderedRemoveContext(key, self.ctx);
}
pub fn orderedRemoveAdapted(self: *Self, key: anytype, ctx: anytype) bool {
return self.unmanaged.orderedRemoveContextAdapted(key, ctx, self.ctx);
}
/// Deletes the item at the specified index in `entries` from
/// the hash map. The entry is removed from the underlying array
/// by swapping it with the last element.
pub fn swapRemoveAt(self: *Self, index: usize) void {
self.unmanaged.swapRemoveAtContext(index, self.ctx);
}
/// Deletes the item at the specified index in `entries` from
/// the hash map. The entry is removed from the underlying array
/// by shifting all elements forward, thereby maintaining the
/// current ordering.
pub fn orderedRemoveAt(self: *Self, index: usize) void {
self.unmanaged.orderedRemoveAtContext(index, self.ctx);
}
/// Create a copy of the hash map which can be modified separately.
/// The copy uses the same context and allocator as this instance.
pub fn clone(self: Self) !Self {
var other = try self.unmanaged.cloneContext(self.allocator, self.ctx);
return other.promoteContext(self.allocator, self.ctx);
}
/// Create a copy of the hash map which can be modified separately.
/// The copy uses the same context as this instance, but the specified
/// allocator.
pub fn cloneWithAllocator(self: Self, allocator: Allocator) !Self {
var other = try self.unmanaged.cloneContext(allocator, self.ctx);
return other.promoteContext(allocator, self.ctx);
}
/// Create a copy of the hash map which can be modified separately.
/// The copy uses the same allocator as this instance, but the
/// specified context.
pub fn cloneWithContext(self: Self, ctx: anytype) !ArrayHashMap(K, V, @TypeOf(ctx), store_hash) {
var other = try self.unmanaged.cloneContext(self.allocator, ctx);
return other.promoteContext(self.allocator, ctx);
}
/// Create a copy of the hash map which can be modified separately.
/// The copy uses the specified allocator and context.
pub fn cloneWithAllocatorAndContext(self: Self, allocator: Allocator, ctx: anytype) !ArrayHashMap(K, V, @TypeOf(ctx), store_hash) {
var other = try self.unmanaged.cloneContext(allocator, ctx);
return other.promoteContext(allocator, ctx);
}
/// Set the map to an empty state, making deinitialization a no-op, and
/// returning a copy of the original.
pub fn move(self: *Self) Self {
self.unmanaged.pointer_stability.assertUnlocked();
const result = self.*;
self.unmanaged = .{};
return result;
}
/// Recomputes stored hashes and rebuilds the key indexes. If the
/// underlying keys have been modified directly, call this method to
/// recompute the denormalized metadata necessary for the operation of
/// the methods of this map that lookup entries by key.
///
/// One use case for this is directly calling `entries.resize()` to grow
/// the underlying storage, and then setting the `keys` and `values`
/// directly without going through the methods of this map.
///
/// The time complexity of this operation is O(n).
pub fn reIndex(self: *Self) !void {
return self.unmanaged.reIndexContext(self.allocator, self.ctx);
}
/// Sorts the entries and then rebuilds the index.
/// `sort_ctx` must have this method:
/// `fn lessThan(ctx: @TypeOf(ctx), a_index: usize, b_index: usize) bool`
pub fn sort(self: *Self, sort_ctx: anytype) void {
return self.unmanaged.sortContext(sort_ctx, self.ctx);
}
/// Shrinks the underlying `Entry` array to `new_len` elements and
/// discards any associated index entries. Keeps capacity the same.
///
/// Asserts the discarded entries remain initialized and capable of
/// performing hash and equality checks. Any deinitialization of
/// discarded entries must take place *after* calling this function.
pub fn shrinkRetainingCapacity(self: *Self, new_len: usize) void {
return self.unmanaged.shrinkRetainingCapacityContext(new_len, self.ctx);
}
/// Shrinks the underlying `Entry` array to `new_len` elements and
/// discards any associated index entries. Reduces allocated capacity.
///
/// Asserts the discarded entries remain initialized and capable of
/// performing hash and equality checks. It is a bug to call this
/// function if the discarded entries require deinitialization. For
/// that use case, `shrinkRetainingCapacity` can be used instead.
pub fn shrinkAndFree(self: *Self, new_len: usize) void {
return self.unmanaged.shrinkAndFreeContext(self.allocator, new_len, self.ctx);
}
/// Removes the last inserted `Entry` in the hash map and returns it.
pub fn pop(self: *Self) KV {
return self.unmanaged.popContext(self.ctx);
}
/// Removes the last inserted `Entry` in the hash map and returns it if count is nonzero.
/// Otherwise returns null.
pub fn popOrNull(self: *Self) ?KV {
return self.unmanaged.popOrNullContext(self.ctx);
}
};
}
/// A hash table of keys and values, each stored sequentially.
///
/// Insertion order is preserved. In general, this data structure supports the same
/// operations as `std.ArrayListUnmanaged`.
///
/// Deletion operations:
/// * `swapRemove` - O(1)
/// * `orderedRemove` - O(N)
///
/// Modifying the hash map while iterating is allowed, however, one must understand
/// the (well defined) behavior when mixing insertions and deletions with iteration.
///
/// This type does not store an `Allocator` field - the `Allocator` must be passed in
/// with each function call that requires it. See `ArrayHashMap` for a type that stores
/// an `Allocator` field for convenience.
///
/// Can be initialized directly using the default field values.
///
/// This type is designed to have low overhead for small numbers of entries. When
/// `store_hash` is `false` and the number of entries in the map is less than 9,
/// the overhead cost of using `ArrayHashMapUnmanaged` rather than `std.ArrayList` is
/// only a single pointer-sized integer.
pub fn ArrayHashMapUnmanaged(
comptime K: type,
comptime V: type,
/// A namespace that provides these two functions:
/// * `pub fn hash(self, K) u32`
/// * `pub fn eql(self, K, K) bool`
comptime Context: type,
/// When `false`, this data structure is biased towards cheap `eql`
/// functions and avoids storing each key's hash in the table. Setting
/// `store_hash` to `true` incurs more memory cost but limits `eql` to
/// being called only once per insertion/deletion (provided there are no
/// hash collisions).
comptime store_hash: bool,
) type {
return struct {
/// It is permitted to access this field directly.
/// After any modification to the keys, consider calling `reIndex`.
entries: DataList = .{},
/// When entries length is less than `linear_scan_max`, this remains `null`.
/// Once entries length grows big enough, this field is allocated. There is
/// an IndexHeader followed by an array of Index(I) structs, where I is defined
/// by how many total indexes there are.
index_header: ?*IndexHeader = null,
/// Used to detect memory safety violations.
pointer_stability: std.debug.SafetyLock = .{},
/// Modifying the key is allowed only if it does not change the hash.
/// Modifying the value is allowed.
/// Entry pointers become invalid whenever this ArrayHashMap is modified,
/// unless `ensureTotalCapacity`/`ensureUnusedCapacity` was previously used.
pub const Entry = struct {
key_ptr: *K,
value_ptr: *V,
};
/// A KV pair which has been copied out of the backing store
pub const KV = struct {
key: K,
value: V,
};
/// The Data type used for the MultiArrayList backing this map
pub const Data = struct {
hash: Hash,
key: K,
value: V,
};
/// The MultiArrayList type backing this map
pub const DataList = std.MultiArrayList(Data);
/// The stored hash type, either u32 or void.
pub const Hash = if (store_hash) u32 else void;
/// getOrPut variants return this structure, with pointers
/// to the backing store and a flag to indicate whether an
/// existing entry was found.
/// Modifying the key is allowed only if it does not change the hash.
/// Modifying the value is allowed.
/// Entry pointers become invalid whenever this ArrayHashMap is modified,
/// unless `ensureTotalCapacity`/`ensureUnusedCapacity` was previously used.
pub const GetOrPutResult = struct {
key_ptr: *K,
value_ptr: *V,
found_existing: bool,
index: usize,
};
/// The ArrayHashMap type using the same settings as this managed map.
pub const Managed = ArrayHashMap(K, V, Context, store_hash);
/// Some functions require a context only if hashes are not stored.
/// To keep the api simple, this type is only used internally.
const ByIndexContext = if (store_hash) void else Context;
const Self = @This();
const linear_scan_max = 8;
const RemovalType = enum {
swap,
ordered,
};
/// Convert from an unmanaged map to a managed map. After calling this,
/// the promoted map should no longer be used.
pub fn promote(self: Self, allocator: Allocator) Managed {
if (@sizeOf(Context) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call promoteContext instead.");
return self.promoteContext(allocator, undefined);
}
pub fn promoteContext(self: Self, allocator: Allocator, ctx: Context) Managed {
return .{
.unmanaged = self,
.allocator = allocator,
.ctx = ctx,
};
}
pub fn init(allocator: Allocator, key_list: []const K, value_list: []const V) !Self {
var self: Self = .{};
try self.entries.resize(allocator, key_list.len);
errdefer self.entries.deinit(allocator);
@memcpy(self.keys(), key_list);
if (@sizeOf(V) != 0) {
assert(key_list.len == value_list.len);
@memcpy(self.values(), value_list);
}
try self.reIndex(allocator);
return self;
}
/// Frees the backing allocation and leaves the map in an undefined state.
/// Note that this does not free keys or values. You must take care of that
/// before calling this function, if it is needed.
pub fn deinit(self: *Self, allocator: Allocator) void {
self.pointer_stability.assertUnlocked();
self.entries.deinit(allocator);
if (self.index_header) |header| {
header.free(allocator);
}
self.* = undefined;
}
/// Puts the hash map into a state where any method call that would
/// cause an existing key or value pointer to become invalidated will
/// instead trigger an assertion.
///
/// An additional call to `lockPointers` in such state also triggers an
/// assertion.
///
/// `unlockPointers` returns the hash map to the previous state.
pub fn lockPointers(self: *Self) void {
self.pointer_stability.lock();
}
/// Undoes a call to `lockPointers`.
pub fn unlockPointers(self: *Self) void {
self.pointer_stability.unlock();
}
/// Clears the map but retains the backing allocation for future use.
pub fn clearRetainingCapacity(self: *Self) void {
self.pointer_stability.lock();
defer self.pointer_stability.unlock();
self.entries.len = 0;
if (self.index_header) |header| {
switch (header.capacityIndexType()) {
.u8 => @memset(header.indexes(u8), Index(u8).empty),
.u16 => @memset(header.indexes(u16), Index(u16).empty),
.u32 => @memset(header.indexes(u32), Index(u32).empty),
}
}
}
/// Clears the map and releases the backing allocation
pub fn clearAndFree(self: *Self, allocator: Allocator) void {
self.pointer_stability.lock();
defer self.pointer_stability.unlock();
self.entries.shrinkAndFree(allocator, 0);
if (self.index_header) |header| {
header.free(allocator);
self.index_header = null;
}
}
/// Returns the number of KV pairs stored in this map.
pub fn count(self: Self) usize {
return self.entries.len;
}
/// Returns the backing array of keys in this map. Modifying the map may
/// invalidate this array. Modifying this array in a way that changes
/// key hashes or key equality puts the map into an unusable state until
/// `reIndex` is called.
pub fn keys(self: Self) []K {
return self.entries.items(.key);
}
/// Returns the backing array of values in this map. Modifying the map
/// may invalidate this array. It is permitted to modify the values in
/// this array.
pub fn values(self: Self) []V {
return self.entries.items(.value);
}
/// Returns an iterator over the pairs in this map.
/// Modifying the map may invalidate this iterator.
pub fn iterator(self: Self) Iterator {
const slice = self.entries.slice();
return .{
.keys = slice.items(.key).ptr,
.values = slice.items(.value).ptr,
.len = @as(u32, @intCast(slice.len)),
};
}
pub const Iterator = struct {
keys: [*]K,
values: [*]V,
len: u32,
index: u32 = 0,
pub fn next(it: *Iterator) ?Entry {
if (it.index >= it.len) return null;
const result = Entry{
.key_ptr = &it.keys[it.index],
// workaround for #6974
.value_ptr = if (@sizeOf(*V) == 0) undefined else &it.values[it.index],
};
it.index += 1;
return result;
}
/// Reset the iterator to the initial index
pub fn reset(it: *Iterator) void {
it.index = 0;
}
};
/// If key exists this function cannot fail.
/// If there is an existing item with `key`, then the result
/// `Entry` pointer points to it, and found_existing is true.
/// Otherwise, puts a new item with undefined value, and
/// the `Entry` pointer points to it. Caller should then initialize
/// the value (but not the key).
pub fn getOrPut(self: *Self, allocator: Allocator, key: K) !GetOrPutResult {
if (@sizeOf(Context) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call getOrPutContext instead.");
return self.getOrPutContext(allocator, key, undefined);
}
pub fn getOrPutContext(self: *Self, allocator: Allocator, key: K, ctx: Context) !GetOrPutResult {
const gop = try self.getOrPutContextAdapted(allocator, key, ctx, ctx);
if (!gop.found_existing) {
gop.key_ptr.* = key;
}
return gop;
}
pub fn getOrPutAdapted(self: *Self, allocator: Allocator, key: anytype, key_ctx: anytype) !GetOrPutResult {
if (@sizeOf(Context) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call getOrPutContextAdapted instead.");
return self.getOrPutContextAdapted(allocator, key, key_ctx, undefined);
}
pub fn getOrPutContextAdapted(self: *Self, allocator: Allocator, key: anytype, key_ctx: anytype, ctx: Context) !GetOrPutResult {
self.ensureTotalCapacityContext(allocator, self.entries.len + 1, ctx) catch |err| {
// "If key exists this function cannot fail."
const index = self.getIndexAdapted(key, key_ctx) orelse return err;
const slice = self.entries.slice();
return GetOrPutResult{
.key_ptr = &slice.items(.key)[index],
// workaround for #6974
.value_ptr = if (@sizeOf(*V) == 0) undefined else &slice.items(.value)[index],
.found_existing = true,
.index = index,
};
};
return self.getOrPutAssumeCapacityAdapted(key, key_ctx);
}
/// If there is an existing item with `key`, then the result
/// `Entry` pointer points to it, and found_existing is true.
/// Otherwise, puts a new item with undefined value, and
/// the `Entry` pointer points to it. Caller should then initialize
/// the value (but not the key).
/// If a new entry needs to be stored, this function asserts there
/// is enough capacity to store it.
pub fn getOrPutAssumeCapacity(self: *Self, key: K) GetOrPutResult {
if (@sizeOf(Context) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call getOrPutAssumeCapacityContext instead.");
return self.getOrPutAssumeCapacityContext(key, undefined);
}
pub fn getOrPutAssumeCapacityContext(self: *Self, key: K, ctx: Context) GetOrPutResult {
const gop = self.getOrPutAssumeCapacityAdapted(key, ctx);
if (!gop.found_existing) {
gop.key_ptr.* = key;
}
return gop;
}
/// If there is an existing item with `key`, then the result
/// `Entry` pointers point to it, and found_existing is true.
/// Otherwise, puts a new item with undefined key and value, and
/// the `Entry` pointers point to it. Caller must then initialize
/// both the key and the value.
/// If a new entry needs to be stored, this function asserts there
/// is enough capacity to store it.
pub fn getOrPutAssumeCapacityAdapted(self: *Self, key: anytype, ctx: anytype) GetOrPutResult {
const header = self.index_header orelse {
// Linear scan.
const h = if (store_hash) checkedHash(ctx, key) else {};
const slice = self.entries.slice();
const hashes_array = slice.items(.hash);
const keys_array = slice.items(.key);
for (keys_array, 0..) |*item_key, i| {
if (hashes_array[i] == h and checkedEql(ctx, key, item_key.*, i)) {
return GetOrPutResult{
.key_ptr = item_key,
// workaround for #6974
.value_ptr = if (@sizeOf(*V) == 0) undefined else &slice.items(.value)[i],
.found_existing = true,
.index = i,
};
}
}
const index = self.entries.addOneAssumeCapacity();
// The slice length changed, so we directly index the pointer.
if (store_hash) hashes_array.ptr[index] = h;
return GetOrPutResult{
.key_ptr = &keys_array.ptr[index],
// workaround for #6974
.value_ptr = if (@sizeOf(*V) == 0) undefined else &slice.items(.value).ptr[index],
.found_existing = false,
.index = index,
};
};
switch (header.capacityIndexType()) {
.u8 => return self.getOrPutInternal(key, ctx, header, u8),
.u16 => return self.getOrPutInternal(key, ctx, header, u16),
.u32 => return self.getOrPutInternal(key, ctx, header, u32),
}
}
pub fn getOrPutValue(self: *Self, allocator: Allocator, key: K, value: V) !GetOrPutResult {
if (@sizeOf(Context) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call getOrPutValueContext instead.");
return self.getOrPutValueContext(allocator, key, value, undefined);
}
pub fn getOrPutValueContext(self: *Self, allocator: Allocator, key: K, value: V, ctx: Context) !GetOrPutResult {
const res = try self.getOrPutContextAdapted(allocator, key, ctx, ctx);
if (!res.found_existing) {
res.key_ptr.* = key;
res.value_ptr.* = value;
}
return res;
}
/// Increases capacity, guaranteeing that insertions up until the
/// `expected_count` will not cause an allocation, and therefore cannot fail.
pub fn ensureTotalCapacity(self: *Self, allocator: Allocator, new_capacity: usize) !void {
if (@sizeOf(ByIndexContext) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call ensureTotalCapacityContext instead.");
return self.ensureTotalCapacityContext(allocator, new_capacity, undefined);
}
pub fn ensureTotalCapacityContext(self: *Self, allocator: Allocator, new_capacity: usize, ctx: Context) !void {
self.pointer_stability.lock();
defer self.pointer_stability.unlock();
if (new_capacity <= linear_scan_max) {
try self.entries.ensureTotalCapacity(allocator, new_capacity);
return;
}
if (self.index_header) |header| {
if (new_capacity <= header.capacity()) {
try self.entries.ensureTotalCapacity(allocator, new_capacity);
return;
}
}
try self.entries.ensureTotalCapacity(allocator, new_capacity);
const new_bit_index = try IndexHeader.findBitIndex(new_capacity);
const new_header = try IndexHeader.alloc(allocator, new_bit_index);
if (self.index_header) |old_header| old_header.free(allocator);
self.insertAllEntriesIntoNewHeader(if (store_hash) {} else ctx, new_header);
self.index_header = new_header;
}
/// Increases capacity, guaranteeing that insertions up until
/// `additional_count` **more** items will not cause an allocation, and
/// therefore cannot fail.
pub fn ensureUnusedCapacity(
self: *Self,
allocator: Allocator,
additional_capacity: usize,
) !void {
if (@sizeOf(Context) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call ensureTotalCapacityContext instead.");
return self.ensureUnusedCapacityContext(allocator, additional_capacity, undefined);
}
pub fn ensureUnusedCapacityContext(
self: *Self,
allocator: Allocator,
additional_capacity: usize,
ctx: Context,
) !void {
return self.ensureTotalCapacityContext(allocator, self.count() + additional_capacity, ctx);
}
/// Returns the number of total elements which may be present before it is
/// no longer guaranteed that no allocations will be performed.
pub fn capacity(self: Self) usize {
const entry_cap = self.entries.capacity;
const header = self.index_header orelse return @min(linear_scan_max, entry_cap);
const indexes_cap = header.capacity();
return @min(entry_cap, indexes_cap);
}
/// Clobbers any existing data. To detect if a put would clobber
/// existing data, see `getOrPut`.
pub fn put(self: *Self, allocator: Allocator, key: K, value: V) !void {
if (@sizeOf(Context) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call putContext instead.");
return self.putContext(allocator, key, value, undefined);
}
pub fn putContext(self: *Self, allocator: Allocator, key: K, value: V, ctx: Context) !void {
const result = try self.getOrPutContext(allocator, key, ctx);
result.value_ptr.* = value;
}
/// Inserts a key-value pair into the hash map, asserting that no previous
/// entry with the same key is already present
pub fn putNoClobber(self: *Self, allocator: Allocator, key: K, value: V) !void {
if (@sizeOf(Context) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call putNoClobberContext instead.");
return self.putNoClobberContext(allocator, key, value, undefined);
}
pub fn putNoClobberContext(self: *Self, allocator: Allocator, key: K, value: V, ctx: Context) !void {
const result = try self.getOrPutContext(allocator, key, ctx);
assert(!result.found_existing);
result.value_ptr.* = value;
}
/// Asserts there is enough capacity to store the new key-value pair.
/// Clobbers any existing data. To detect if a put would clobber
/// existing data, see `getOrPutAssumeCapacity`.
pub fn putAssumeCapacity(self: *Self, key: K, value: V) void {
if (@sizeOf(Context) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call putAssumeCapacityContext instead.");
return self.putAssumeCapacityContext(key, value, undefined);
}
pub fn putAssumeCapacityContext(self: *Self, key: K, value: V, ctx: Context) void {
const result = self.getOrPutAssumeCapacityContext(key, ctx);
result.value_ptr.* = value;
}
/// Asserts there is enough capacity to store the new key-value pair.
/// Asserts that it does not clobber any existing data.
/// To detect if a put would clobber existing data, see `getOrPutAssumeCapacity`.
pub fn putAssumeCapacityNoClobber(self: *Self, key: K, value: V) void {
if (@sizeOf(Context) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call putAssumeCapacityNoClobberContext instead.");
return self.putAssumeCapacityNoClobberContext(key, value, undefined);
}
pub fn putAssumeCapacityNoClobberContext(self: *Self, key: K, value: V, ctx: Context) void {
const result = self.getOrPutAssumeCapacityContext(key, ctx);
assert(!result.found_existing);
result.value_ptr.* = value;
}
/// Inserts a new `Entry` into the hash map, returning the previous one, if any.
pub fn fetchPut(self: *Self, allocator: Allocator, key: K, value: V) !?KV {
if (@sizeOf(Context) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call fetchPutContext instead.");
return self.fetchPutContext(allocator, key, value, undefined);
}
pub fn fetchPutContext(self: *Self, allocator: Allocator, key: K, value: V, ctx: Context) !?KV {
const gop = try self.getOrPutContext(allocator, key, ctx);
var result: ?KV = null;
if (gop.found_existing) {
result = KV{
.key = gop.key_ptr.*,
.value = gop.value_ptr.*,
};
}
gop.value_ptr.* = value;
return result;
}
/// Inserts a new `Entry` into the hash map, returning the previous one, if any.
/// If insertion happens, asserts there is enough capacity without allocating.
pub fn fetchPutAssumeCapacity(self: *Self, key: K, value: V) ?KV {
if (@sizeOf(Context) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call fetchPutAssumeCapacityContext instead.");
return self.fetchPutAssumeCapacityContext(key, value, undefined);
}
pub fn fetchPutAssumeCapacityContext(self: *Self, key: K, value: V, ctx: Context) ?KV {
const gop = self.getOrPutAssumeCapacityContext(key, ctx);
var result: ?KV = null;
if (gop.found_existing) {
result = KV{
.key = gop.key_ptr.*,
.value = gop.value_ptr.*,
};
}
gop.value_ptr.* = value;
return result;
}
/// Finds pointers to the key and value storage associated with a key.
pub fn getEntry(self: Self, key: K) ?Entry {
if (@sizeOf(Context) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call getEntryContext instead.");
return self.getEntryContext(key, undefined);
}
pub fn getEntryContext(self: Self, key: K, ctx: Context) ?Entry {
return self.getEntryAdapted(key, ctx);
}
pub fn getEntryAdapted(self: Self, key: anytype, ctx: anytype) ?Entry {
const index = self.getIndexAdapted(key, ctx) orelse return null;
const slice = self.entries.slice();
return Entry{
.key_ptr = &slice.items(.key)[index],
// workaround for #6974
.value_ptr = if (@sizeOf(*V) == 0) undefined else &slice.items(.value)[index],
};
}
/// Finds the index in the `entries` array where a key is stored
pub fn getIndex(self: Self, key: K) ?usize {
if (@sizeOf(Context) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call getIndexContext instead.");
return self.getIndexContext(key, undefined);
}
pub fn getIndexContext(self: Self, key: K, ctx: Context) ?usize {
return self.getIndexAdapted(key, ctx);
}
pub fn getIndexAdapted(self: Self, key: anytype, ctx: anytype) ?usize {
const header = self.index_header orelse {
// Linear scan.
const h = if (store_hash) checkedHash(ctx, key) else {};
const slice = self.entries.slice();
const hashes_array = slice.items(.hash);
const keys_array = slice.items(.key);
for (keys_array, 0..) |*item_key, i| {
if (hashes_array[i] == h and checkedEql(ctx, key, item_key.*, i)) {
return i;
}
}
return null;
};
switch (header.capacityIndexType()) {
.u8 => return self.getIndexWithHeaderGeneric(key, ctx, header, u8),
.u16 => return self.getIndexWithHeaderGeneric(key, ctx, header, u16),
.u32 => return self.getIndexWithHeaderGeneric(key, ctx, header, u32),
}
}
fn getIndexWithHeaderGeneric(self: Self, key: anytype, ctx: anytype, header: *IndexHeader, comptime I: type) ?usize {
const indexes = header.indexes(I);
const slot = self.getSlotByKey(key, ctx, header, I, indexes) orelse return null;
return indexes[slot].entry_index;
}
/// Find the value associated with a key
pub fn get(self: Self, key: K) ?V {
if (@sizeOf(Context) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call getContext instead.");
return self.getContext(key, undefined);
}
pub fn getContext(self: Self, key: K, ctx: Context) ?V {
return self.getAdapted(key, ctx);
}
pub fn getAdapted(self: Self, key: anytype, ctx: anytype) ?V {
const index = self.getIndexAdapted(key, ctx) orelse return null;
return self.values()[index];
}
/// Find a pointer to the value associated with a key
pub fn getPtr(self: Self, key: K) ?*V {
if (@sizeOf(Context) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call getPtrContext instead.");
return self.getPtrContext(key, undefined);
}
pub fn getPtrContext(self: Self, key: K, ctx: Context) ?*V {
return self.getPtrAdapted(key, ctx);
}
pub fn getPtrAdapted(self: Self, key: anytype, ctx: anytype) ?*V {
const index = self.getIndexAdapted(key, ctx) orelse return null;
// workaround for #6974
return if (@sizeOf(*V) == 0) @as(*V, undefined) else &self.values()[index];
}
/// Find the actual key associated with an adapted key
pub fn getKey(self: Self, key: K) ?K {
if (@sizeOf(Context) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call getKeyContext instead.");
return self.getKeyContext(key, undefined);
}
pub fn getKeyContext(self: Self, key: K, ctx: Context) ?K {
return self.getKeyAdapted(key, ctx);
}
pub fn getKeyAdapted(self: Self, key: anytype, ctx: anytype) ?K {
const index = self.getIndexAdapted(key, ctx) orelse return null;
return self.keys()[index];
}
/// Find a pointer to the actual key associated with an adapted key
pub fn getKeyPtr(self: Self, key: K) ?*K {
if (@sizeOf(Context) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call getKeyPtrContext instead.");
return self.getKeyPtrContext(key, undefined);
}
pub fn getKeyPtrContext(self: Self, key: K, ctx: Context) ?*K {
return self.getKeyPtrAdapted(key, ctx);
}
pub fn getKeyPtrAdapted(self: Self, key: anytype, ctx: anytype) ?*K {
const index = self.getIndexAdapted(key, ctx) orelse return null;
return &self.keys()[index];
}
/// Check whether a key is stored in the map
pub fn contains(self: Self, key: K) bool {
if (@sizeOf(Context) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call containsContext instead.");
return self.containsContext(key, undefined);
}
pub fn containsContext(self: Self, key: K, ctx: Context) bool {
return self.containsAdapted(key, ctx);
}
pub fn containsAdapted(self: Self, key: anytype, ctx: anytype) bool {
return self.getIndexAdapted(key, ctx) != null;
}
/// If there is an `Entry` with a matching key, it is deleted from
/// the hash map, and then returned from this function. The entry is
/// removed from the underlying array by swapping it with the last
/// element.
pub fn fetchSwapRemove(self: *Self, key: K) ?KV {
if (@sizeOf(Context) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call fetchSwapRemoveContext instead.");
return self.fetchSwapRemoveContext(key, undefined);
}
pub fn fetchSwapRemoveContext(self: *Self, key: K, ctx: Context) ?KV {
return self.fetchSwapRemoveContextAdapted(key, ctx, ctx);
}
pub fn fetchSwapRemoveAdapted(self: *Self, key: anytype, ctx: anytype) ?KV {
if (@sizeOf(ByIndexContext) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call fetchSwapRemoveContextAdapted instead.");
return self.fetchSwapRemoveContextAdapted(key, ctx, undefined);
}
pub fn fetchSwapRemoveContextAdapted(self: *Self, key: anytype, key_ctx: anytype, ctx: Context) ?KV {
self.pointer_stability.lock();
defer self.pointer_stability.unlock();
return self.fetchRemoveByKey(key, key_ctx, if (store_hash) {} else ctx, .swap);
}
/// If there is an `Entry` with a matching key, it is deleted from
/// the hash map, and then returned from this function. The entry is
/// removed from the underlying array by shifting all elements forward
/// thereby maintaining the current ordering.
pub fn fetchOrderedRemove(self: *Self, key: K) ?KV {
if (@sizeOf(Context) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call fetchOrderedRemoveContext instead.");
return self.fetchOrderedRemoveContext(key, undefined);
}
pub fn fetchOrderedRemoveContext(self: *Self, key: K, ctx: Context) ?KV {
return self.fetchOrderedRemoveContextAdapted(key, ctx, ctx);
}
pub fn fetchOrderedRemoveAdapted(self: *Self, key: anytype, ctx: anytype) ?KV {
if (@sizeOf(ByIndexContext) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call fetchOrderedRemoveContextAdapted instead.");
return self.fetchOrderedRemoveContextAdapted(key, ctx, undefined);
}
pub fn fetchOrderedRemoveContextAdapted(self: *Self, key: anytype, key_ctx: anytype, ctx: Context) ?KV {
self.pointer_stability.lock();
defer self.pointer_stability.unlock();
return self.fetchRemoveByKey(key, key_ctx, if (store_hash) {} else ctx, .ordered);
}
/// If there is an `Entry` with a matching key, it is deleted from
/// the hash map. The entry is removed from the underlying array
/// by swapping it with the last element. Returns true if an entry
/// was removed, false otherwise.
pub fn swapRemove(self: *Self, key: K) bool {
if (@sizeOf(Context) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call swapRemoveContext instead.");
return self.swapRemoveContext(key, undefined);
}
pub fn swapRemoveContext(self: *Self, key: K, ctx: Context) bool {
return self.swapRemoveContextAdapted(key, ctx, ctx);
}
pub fn swapRemoveAdapted(self: *Self, key: anytype, ctx: anytype) bool {
if (@sizeOf(ByIndexContext) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call swapRemoveContextAdapted instead.");
return self.swapRemoveContextAdapted(key, ctx, undefined);
}
pub fn swapRemoveContextAdapted(self: *Self, key: anytype, key_ctx: anytype, ctx: Context) bool {
self.pointer_stability.lock();
defer self.pointer_stability.unlock();
return self.removeByKey(key, key_ctx, if (store_hash) {} else ctx, .swap);
}
/// If there is an `Entry` with a matching key, it is deleted from
/// the hash map. The entry is removed from the underlying array
/// by shifting all elements forward, thereby maintaining the
/// current ordering. Returns true if an entry was removed, false otherwise.
pub fn orderedRemove(self: *Self, key: K) bool {
if (@sizeOf(Context) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call orderedRemoveContext instead.");
return self.orderedRemoveContext(key, undefined);
}
pub fn orderedRemoveContext(self: *Self, key: K, ctx: Context) bool {
return self.orderedRemoveContextAdapted(key, ctx, ctx);
}
pub fn orderedRemoveAdapted(self: *Self, key: anytype, ctx: anytype) bool {
if (@sizeOf(ByIndexContext) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call orderedRemoveContextAdapted instead.");
return self.orderedRemoveContextAdapted(key, ctx, undefined);
}
pub fn orderedRemoveContextAdapted(self: *Self, key: anytype, key_ctx: anytype, ctx: Context) bool {
self.pointer_stability.lock();
defer self.pointer_stability.unlock();
return self.removeByKey(key, key_ctx, if (store_hash) {} else ctx, .ordered);
}
/// Deletes the item at the specified index in `entries` from
/// the hash map. The entry is removed from the underlying array
/// by swapping it with the last element.
pub fn swapRemoveAt(self: *Self, index: usize) void {
if (@sizeOf(ByIndexContext) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call swapRemoveAtContext instead.");
return self.swapRemoveAtContext(index, undefined);
}
pub fn swapRemoveAtContext(self: *Self, index: usize, ctx: Context) void {
self.pointer_stability.lock();
defer self.pointer_stability.unlock();
self.removeByIndex(index, if (store_hash) {} else ctx, .swap);
}
/// Deletes the item at the specified index in `entries` from
/// the hash map. The entry is removed from the underlying array
/// by shifting all elements forward, thereby maintaining the
/// current ordering.
pub fn orderedRemoveAt(self: *Self, index: usize) void {
if (@sizeOf(ByIndexContext) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call orderedRemoveAtContext instead.");
return self.orderedRemoveAtContext(index, undefined);
}
pub fn orderedRemoveAtContext(self: *Self, index: usize, ctx: Context) void {
self.pointer_stability.lock();
defer self.pointer_stability.unlock();
self.removeByIndex(index, if (store_hash) {} else ctx, .ordered);
}
/// Create a copy of the hash map which can be modified separately.
/// The copy uses the same context as this instance, but is allocated
/// with the provided allocator.
pub fn clone(self: Self, allocator: Allocator) !Self {
if (@sizeOf(ByIndexContext) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call cloneContext instead.");
return self.cloneContext(allocator, undefined);
}
pub fn cloneContext(self: Self, allocator: Allocator, ctx: Context) !Self {
var other: Self = .{};
other.entries = try self.entries.clone(allocator);
errdefer other.entries.deinit(allocator);
if (self.index_header) |header| {
// TODO: I'm pretty sure this could be memcpy'd instead of
// doing all this work.
const new_header = try IndexHeader.alloc(allocator, header.bit_index);
other.insertAllEntriesIntoNewHeader(if (store_hash) {} else ctx, new_header);
other.index_header = new_header;
}
return other;
}
/// Set the map to an empty state, making deinitialization a no-op, and
/// returning a copy of the original.
pub fn move(self: *Self) Self {
self.pointer_stability.assertUnlocked();
const result = self.*;
self.* = .{};
return result;
}
/// Recomputes stored hashes and rebuilds the key indexes. If the
/// underlying keys have been modified directly, call this method to
/// recompute the denormalized metadata necessary for the operation of
/// the methods of this map that lookup entries by key.
///
/// One use case for this is directly calling `entries.resize()` to grow
/// the underlying storage, and then setting the `keys` and `values`
/// directly without going through the methods of this map.
///
/// The time complexity of this operation is O(n).
pub fn reIndex(self: *Self, allocator: Allocator) !void {
if (@sizeOf(ByIndexContext) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call reIndexContext instead.");
return self.reIndexContext(allocator, undefined);
}
pub fn reIndexContext(self: *Self, allocator: Allocator, ctx: Context) !void {
// Recompute all hashes.
if (store_hash) {
for (self.keys(), self.entries.items(.hash)) |key, *hash| {
const h = checkedHash(ctx, key);
hash.* = h;
}
}
// Rebuild the index.
if (self.entries.capacity > linear_scan_max) {
// We're going to rebuild the index header and replace the existing one (if any). The
// indexes should sized such that they will be at most 60% full.
const bit_index = try IndexHeader.findBitIndex(self.entries.capacity);
const new_header = try IndexHeader.alloc(allocator, bit_index);
if (self.index_header) |header| header.free(allocator);
self.insertAllEntriesIntoNewHeader(if (store_hash) {} else ctx, new_header);
self.index_header = new_header;
}
}
/// Sorts the entries and then rebuilds the index.
/// `sort_ctx` must have this method:
/// `fn lessThan(ctx: @TypeOf(ctx), a_index: usize, b_index: usize) bool`
/// Uses a stable sorting algorithm.
pub inline fn sort(self: *Self, sort_ctx: anytype) void {
if (@sizeOf(ByIndexContext) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call sortContext instead.");
return sortContextInternal(self, .stable, sort_ctx, undefined);
}
/// Sorts the entries and then rebuilds the index.
/// `sort_ctx` must have this method:
/// `fn lessThan(ctx: @TypeOf(ctx), a_index: usize, b_index: usize) bool`
/// Uses an unstable sorting algorithm.
pub inline fn sortUnstable(self: *Self, sort_ctx: anytype) void {
if (@sizeOf(ByIndexContext) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call sortUnstableContext instead.");
return self.sortContextInternal(.unstable, sort_ctx, undefined);
}
pub inline fn sortContext(self: *Self, sort_ctx: anytype, ctx: Context) void {
return sortContextInternal(self, .stable, sort_ctx, ctx);
}
pub inline fn sortUnstableContext(self: *Self, sort_ctx: anytype, ctx: Context) void {
return sortContextInternal(self, .unstable, sort_ctx, ctx);
}
fn sortContextInternal(
self: *Self,
comptime mode: std.sort.Mode,
sort_ctx: anytype,
ctx: Context,
) void {
self.pointer_stability.lock();
defer self.pointer_stability.unlock();
switch (mode) {
.stable => self.entries.sort(sort_ctx),
.unstable => self.entries.sortUnstable(sort_ctx),
}
const header = self.index_header orelse return;
header.reset();
self.insertAllEntriesIntoNewHeader(if (store_hash) {} else ctx, header);
}
/// Shrinks the underlying `Entry` array to `new_len` elements and
/// discards any associated index entries. Keeps capacity the same.
///
/// Asserts the discarded entries remain initialized and capable of
/// performing hash and equality checks. Any deinitialization of
/// discarded entries must take place *after* calling this function.
pub fn shrinkRetainingCapacity(self: *Self, new_len: usize) void {
if (@sizeOf(ByIndexContext) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call shrinkRetainingCapacityContext instead.");
return self.shrinkRetainingCapacityContext(new_len, undefined);
}
/// Shrinks the underlying `Entry` array to `new_len` elements and
/// discards any associated index entries. Keeps capacity the same.
///
/// Asserts the discarded entries remain initialized and capable of
/// performing hash and equality checks. Any deinitialization of
/// discarded entries must take place *after* calling this function.
pub fn shrinkRetainingCapacityContext(self: *Self, new_len: usize, ctx: Context) void {
self.pointer_stability.lock();
defer self.pointer_stability.unlock();
// Remove index entries from the new length onwards.
// Explicitly choose to ONLY remove index entries and not the underlying array list
// entries as we're going to remove them in the subsequent shrink call.
if (self.index_header) |header| {
var i: usize = new_len;
while (i < self.entries.len) : (i += 1)
self.removeFromIndexByIndex(i, if (store_hash) {} else ctx, header);
}
self.entries.shrinkRetainingCapacity(new_len);
}
/// Shrinks the underlying `Entry` array to `new_len` elements and
/// discards any associated index entries. Reduces allocated capacity.
///
/// Asserts the discarded entries remain initialized and capable of
/// performing hash and equality checks. It is a bug to call this
/// function if the discarded entries require deinitialization. For
/// that use case, `shrinkRetainingCapacity` can be used instead.
pub fn shrinkAndFree(self: *Self, allocator: Allocator, new_len: usize) void {
if (@sizeOf(ByIndexContext) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call shrinkAndFreeContext instead.");
return self.shrinkAndFreeContext(allocator, new_len, undefined);
}
/// Shrinks the underlying `Entry` array to `new_len` elements and
/// discards any associated index entries. Reduces allocated capacity.
///
/// Asserts the discarded entries remain initialized and capable of
/// performing hash and equality checks. It is a bug to call this
/// function if the discarded entries require deinitialization. For
/// that use case, `shrinkRetainingCapacityContext` can be used
/// instead.
pub fn shrinkAndFreeContext(self: *Self, allocator: Allocator, new_len: usize, ctx: Context) void {
self.pointer_stability.lock();
defer self.pointer_stability.unlock();
// Remove index entries from the new length onwards.
// Explicitly choose to ONLY remove index entries and not the underlying array list
// entries as we're going to remove them in the subsequent shrink call.
if (self.index_header) |header| {
var i: usize = new_len;
while (i < self.entries.len) : (i += 1)
self.removeFromIndexByIndex(i, if (store_hash) {} else ctx, header);
}
self.entries.shrinkAndFree(allocator, new_len);
}
/// Removes the last inserted `Entry` in the hash map and returns it.
pub fn pop(self: *Self) KV {
if (@sizeOf(ByIndexContext) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call popContext instead.");
return self.popContext(undefined);
}
pub fn popContext(self: *Self, ctx: Context) KV {
self.pointer_stability.lock();
defer self.pointer_stability.unlock();
const item = self.entries.get(self.entries.len - 1);
if (self.index_header) |header|
self.removeFromIndexByIndex(self.entries.len - 1, if (store_hash) {} else ctx, header);
self.entries.len -= 1;
return .{
.key = item.key,
.value = item.value,
};
}
/// Removes the last inserted `Entry` in the hash map and returns it if count is nonzero.
/// Otherwise returns null.
pub fn popOrNull(self: *Self) ?KV {
if (@sizeOf(ByIndexContext) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call popContext instead.");
return self.popOrNullContext(undefined);
}
pub fn popOrNullContext(self: *Self, ctx: Context) ?KV {
return if (self.entries.len == 0) null else self.popContext(ctx);
}
fn fetchRemoveByKey(
self: *Self,
key: anytype,
key_ctx: anytype,
ctx: ByIndexContext,
comptime removal_type: RemovalType,
) ?KV {
const header = self.index_header orelse {
// Linear scan.
const key_hash = if (store_hash) key_ctx.hash(key) else {};
const slice = self.entries.slice();
const hashes_array = if (store_hash) slice.items(.hash) else {};
const keys_array = slice.items(.key);
for (keys_array, 0..) |*item_key, i| {
const hash_match = if (store_hash) hashes_array[i] == key_hash else true;
if (hash_match and key_ctx.eql(key, item_key.*, i)) {
const removed_entry: KV = .{
.key = keys_array[i],
.value = slice.items(.value)[i],
};
switch (removal_type) {
.swap => self.entries.swapRemove(i),
.ordered => self.entries.orderedRemove(i),
}
return removed_entry;
}
}
return null;
};
return switch (header.capacityIndexType()) {
.u8 => self.fetchRemoveByKeyGeneric(key, key_ctx, ctx, header, u8, removal_type),
.u16 => self.fetchRemoveByKeyGeneric(key, key_ctx, ctx, header, u16, removal_type),
.u32 => self.fetchRemoveByKeyGeneric(key, key_ctx, ctx, header, u32, removal_type),
};
}
fn fetchRemoveByKeyGeneric(
self: *Self,
key: anytype,
key_ctx: anytype,
ctx: ByIndexContext,
header: *IndexHeader,
comptime I: type,
comptime removal_type: RemovalType,
) ?KV {
const indexes = header.indexes(I);
const entry_index = self.removeFromIndexByKey(key, key_ctx, header, I, indexes) orelse return null;
const slice = self.entries.slice();
const removed_entry: KV = .{
.key = slice.items(.key)[entry_index],
.value = slice.items(.value)[entry_index],
};
self.removeFromArrayAndUpdateIndex(entry_index, ctx, header, I, indexes, removal_type);
return removed_entry;
}
fn removeByKey(
self: *Self,
key: anytype,
key_ctx: anytype,
ctx: ByIndexContext,
comptime removal_type: RemovalType,
) bool {
const header = self.index_header orelse {
// Linear scan.
const key_hash = if (store_hash) key_ctx.hash(key) else {};
const slice = self.entries.slice();
const hashes_array = if (store_hash) slice.items(.hash) else {};
const keys_array = slice.items(.key);
for (keys_array, 0..) |*item_key, i| {
const hash_match = if (store_hash) hashes_array[i] == key_hash else true;
if (hash_match and key_ctx.eql(key, item_key.*, i)) {
switch (removal_type) {
.swap => self.entries.swapRemove(i),
.ordered => self.entries.orderedRemove(i),
}
return true;
}
}
return false;
};
return switch (header.capacityIndexType()) {
.u8 => self.removeByKeyGeneric(key, key_ctx, ctx, header, u8, removal_type),
.u16 => self.removeByKeyGeneric(key, key_ctx, ctx, header, u16, removal_type),
.u32 => self.removeByKeyGeneric(key, key_ctx, ctx, header, u32, removal_type),
};
}
fn removeByKeyGeneric(self: *Self, key: anytype, key_ctx: anytype, ctx: ByIndexContext, header: *IndexHeader, comptime I: type, comptime removal_type: RemovalType) bool {
const indexes = header.indexes(I);
const entry_index = self.removeFromIndexByKey(key, key_ctx, header, I, indexes) orelse return false;
self.removeFromArrayAndUpdateIndex(entry_index, ctx, header, I, indexes, removal_type);
return true;
}
fn removeByIndex(self: *Self, entry_index: usize, ctx: ByIndexContext, comptime removal_type: RemovalType) void {
assert(entry_index < self.entries.len);
const header = self.index_header orelse {
switch (removal_type) {
.swap => self.entries.swapRemove(entry_index),
.ordered => self.entries.orderedRemove(entry_index),
}
return;
};
switch (header.capacityIndexType()) {
.u8 => self.removeByIndexGeneric(entry_index, ctx, header, u8, removal_type),
.u16 => self.removeByIndexGeneric(entry_index, ctx, header, u16, removal_type),
.u32 => self.removeByIndexGeneric(entry_index, ctx, header, u32, removal_type),
}
}
fn removeByIndexGeneric(self: *Self, entry_index: usize, ctx: ByIndexContext, header: *IndexHeader, comptime I: type, comptime removal_type: RemovalType) void {
const indexes = header.indexes(I);
self.removeFromIndexByIndexGeneric(entry_index, ctx, header, I, indexes);
self.removeFromArrayAndUpdateIndex(entry_index, ctx, header, I, indexes, removal_type);
}
fn removeFromArrayAndUpdateIndex(self: *Self, entry_index: usize, ctx: ByIndexContext, header: *IndexHeader, comptime I: type, indexes: []Index(I), comptime removal_type: RemovalType) void {
const last_index = self.entries.len - 1; // overflow => remove from empty map
switch (removal_type) {
.swap => {
if (last_index != entry_index) {
// Because of the swap remove, now we need to update the index that was
// pointing to the last entry and is now pointing to this removed item slot.
self.updateEntryIndex(header, last_index, entry_index, ctx, I, indexes);
}
// updateEntryIndex reads from the old entry index,
// so it needs to run before removal.
self.entries.swapRemove(entry_index);
},
.ordered => {
var i: usize = entry_index;
while (i < last_index) : (i += 1) {
// Because of the ordered remove, everything from the entry index onwards has
// been shifted forward so we'll need to update the index entries.
self.updateEntryIndex(header, i + 1, i, ctx, I, indexes);
}
// updateEntryIndex reads from the old entry index,
// so it needs to run before removal.
self.entries.orderedRemove(entry_index);
},
}
}
fn updateEntryIndex(
self: *Self,
header: *IndexHeader,
old_entry_index: usize,
new_entry_index: usize,
ctx: ByIndexContext,
comptime I: type,
indexes: []Index(I),
) void {
const slot = self.getSlotByIndex(old_entry_index, ctx, header, I, indexes);
indexes[slot].entry_index = @as(I, @intCast(new_entry_index));
}
fn removeFromIndexByIndex(self: *Self, entry_index: usize, ctx: ByIndexContext, header: *IndexHeader) void {
switch (header.capacityIndexType()) {
.u8 => self.removeFromIndexByIndexGeneric(entry_index, ctx, header, u8, header.indexes(u8)),
.u16 => self.removeFromIndexByIndexGeneric(entry_index, ctx, header, u16, header.indexes(u16)),
.u32 => self.removeFromIndexByIndexGeneric(entry_index, ctx, header, u32, header.indexes(u32)),
}
}
fn removeFromIndexByIndexGeneric(self: *Self, entry_index: usize, ctx: ByIndexContext, header: *IndexHeader, comptime I: type, indexes: []Index(I)) void {
const slot = self.getSlotByIndex(entry_index, ctx, header, I, indexes);
removeSlot(slot, header, I, indexes);
}
fn removeFromIndexByKey(self: *Self, key: anytype, ctx: anytype, header: *IndexHeader, comptime I: type, indexes: []Index(I)) ?usize {
const slot = self.getSlotByKey(key, ctx, header, I, indexes) orelse return null;
const removed_entry_index = indexes[slot].entry_index;
removeSlot(slot, header, I, indexes);
return removed_entry_index;
}
fn removeSlot(removed_slot: usize, header: *IndexHeader, comptime I: type, indexes: []Index(I)) void {
const start_index = removed_slot +% 1;
const end_index = start_index +% indexes.len;
var last_slot = removed_slot;
var index: usize = start_index;
while (index != end_index) : (index +%= 1) {
const slot = header.constrainIndex(index);
const slot_data = indexes[slot];
if (slot_data.isEmpty() or slot_data.distance_from_start_index == 0) {
indexes[last_slot].setEmpty();
return;
}
indexes[last_slot] = .{
.entry_index = slot_data.entry_index,
.distance_from_start_index = slot_data.distance_from_start_index - 1,
};
last_slot = slot;
}
unreachable;
}
fn getSlotByIndex(self: *Self, entry_index: usize, ctx: ByIndexContext, header: *IndexHeader, comptime I: type, indexes: []Index(I)) usize {
const slice = self.entries.slice();
const h = if (store_hash) slice.items(.hash)[entry_index] else checkedHash(ctx, slice.items(.key)[entry_index]);
const start_index = safeTruncate(usize, h);
const end_index = start_index +% indexes.len;
var index = start_index;
var distance_from_start_index: I = 0;
while (index != end_index) : ({
index +%= 1;
distance_from_start_index += 1;
}) {
const slot = header.constrainIndex(index);
const slot_data = indexes[slot];
// This is the fundamental property of the array hash map index. If this
// assert fails, it probably means that the entry was not in the index.
assert(!slot_data.isEmpty());
assert(slot_data.distance_from_start_index >= distance_from_start_index);
if (slot_data.entry_index == entry_index) {
return slot;
}
}
unreachable;
}
/// Must `ensureTotalCapacity`/`ensureUnusedCapacity` before calling this.
fn getOrPutInternal(self: *Self, key: anytype, ctx: anytype, header: *IndexHeader, comptime I: type) GetOrPutResult {
const slice = self.entries.slice();
const hashes_array = if (store_hash) slice.items(.hash) else {};
const keys_array = slice.items(.key);
const values_array = slice.items(.value);
const indexes = header.indexes(I);
const h = checkedHash(ctx, key);
const start_index = safeTruncate(usize, h);
const end_index = start_index +% indexes.len;
var index = start_index;
var distance_from_start_index: I = 0;
while (index != end_index) : ({
index +%= 1;
distance_from_start_index += 1;
}) {
var slot = header.constrainIndex(index);
var slot_data = indexes[slot];
// If the slot is empty, there can be no more items in this run.
// We didn't find a matching item, so this must be new.
// Put it in the empty slot.
if (slot_data.isEmpty()) {
const new_index = self.entries.addOneAssumeCapacity();
indexes[slot] = .{
.distance_from_start_index = distance_from_start_index,
.entry_index = @as(I, @intCast(new_index)),
};
// update the hash if applicable
if (store_hash) hashes_array.ptr[new_index] = h;
return .{
.found_existing = false,
.key_ptr = &keys_array.ptr[new_index],
// workaround for #6974
.value_ptr = if (@sizeOf(*V) == 0) undefined else &values_array.ptr[new_index],
.index = new_index,
};
}
// This pointer survives the following append because we call
// entries.ensureTotalCapacity before getOrPutInternal.
const i = slot_data.entry_index;
const hash_match = if (store_hash) h == hashes_array[i] else true;
if (hash_match and checkedEql(ctx, key, keys_array[i], i)) {
return .{
.found_existing = true,
.key_ptr = &keys_array[slot_data.entry_index],
// workaround for #6974
.value_ptr = if (@sizeOf(*V) == 0) undefined else &values_array[slot_data.entry_index],
.index = slot_data.entry_index,
};
}
// If the entry is closer to its target than our current distance,
// the entry we are looking for does not exist. It would be in
// this slot instead if it was here. So stop looking, and switch
// to insert mode.
if (slot_data.distance_from_start_index < distance_from_start_index) {
// In this case, we did not find the item. We will put a new entry.
// However, we will use this index for the new entry, and move
// the previous index down the line, to keep the max distance_from_start_index
// as small as possible.
const new_index = self.entries.addOneAssumeCapacity();
if (store_hash) hashes_array.ptr[new_index] = h;
indexes[slot] = .{
.entry_index = @as(I, @intCast(new_index)),
.distance_from_start_index = distance_from_start_index,
};
distance_from_start_index = slot_data.distance_from_start_index;
var displaced_index = slot_data.entry_index;
// Find somewhere to put the index we replaced by shifting
// following indexes backwards.
index +%= 1;
distance_from_start_index += 1;
while (index != end_index) : ({
index +%= 1;
distance_from_start_index += 1;
}) {
slot = header.constrainIndex(index);
slot_data = indexes[slot];
if (slot_data.isEmpty()) {
indexes[slot] = .{
.entry_index = displaced_index,
.distance_from_start_index = distance_from_start_index,
};
return .{
.found_existing = false,
.key_ptr = &keys_array.ptr[new_index],
// workaround for #6974
.value_ptr = if (@sizeOf(*V) == 0) undefined else &values_array.ptr[new_index],
.index = new_index,
};
}
if (slot_data.distance_from_start_index < distance_from_start_index) {
indexes[slot] = .{
.entry_index = displaced_index,
.distance_from_start_index = distance_from_start_index,
};
displaced_index = slot_data.entry_index;
distance_from_start_index = slot_data.distance_from_start_index;
}
}
unreachable;
}
}
unreachable;
}
fn getSlotByKey(self: Self, key: anytype, ctx: anytype, header: *IndexHeader, comptime I: type, indexes: []Index(I)) ?usize {
const slice = self.entries.slice();
const hashes_array = if (store_hash) slice.items(.hash) else {};
const keys_array = slice.items(.key);
const h = checkedHash(ctx, key);
const start_index = safeTruncate(usize, h);
const end_index = start_index +% indexes.len;
var index = start_index;
var distance_from_start_index: I = 0;
while (index != end_index) : ({
index +%= 1;
distance_from_start_index += 1;
}) {
const slot = header.constrainIndex(index);
const slot_data = indexes[slot];
if (slot_data.isEmpty() or slot_data.distance_from_start_index < distance_from_start_index)
return null;
const i = slot_data.entry_index;
const hash_match = if (store_hash) h == hashes_array[i] else true;
if (hash_match and checkedEql(ctx, key, keys_array[i], i))
return slot;
}
unreachable;
}
fn insertAllEntriesIntoNewHeader(self: *Self, ctx: ByIndexContext, header: *IndexHeader) void {
switch (header.capacityIndexType()) {
.u8 => return self.insertAllEntriesIntoNewHeaderGeneric(ctx, header, u8),
.u16 => return self.insertAllEntriesIntoNewHeaderGeneric(ctx, header, u16),
.u32 => return self.insertAllEntriesIntoNewHeaderGeneric(ctx, header, u32),
}
}
fn insertAllEntriesIntoNewHeaderGeneric(self: *Self, ctx: ByIndexContext, header: *IndexHeader, comptime I: type) void {
const slice = self.entries.slice();
const items = if (store_hash) slice.items(.hash) else slice.items(.key);
const indexes = header.indexes(I);
entry_loop: for (items, 0..) |key, i| {
const h = if (store_hash) key else checkedHash(ctx, key);
const start_index = safeTruncate(usize, h);
const end_index = start_index +% indexes.len;
var index = start_index;
var entry_index = @as(I, @intCast(i));
var distance_from_start_index: I = 0;
while (index != end_index) : ({
index +%= 1;
distance_from_start_index += 1;
}) {
const slot = header.constrainIndex(index);
const next_index = indexes[slot];
if (next_index.isEmpty()) {
indexes[slot] = .{
.distance_from_start_index = distance_from_start_index,
.entry_index = entry_index,
};
continue :entry_loop;
}
if (next_index.distance_from_start_index < distance_from_start_index) {
indexes[slot] = .{
.distance_from_start_index = distance_from_start_index,
.entry_index = entry_index,
};
distance_from_start_index = next_index.distance_from_start_index;
entry_index = next_index.entry_index;
}
}
unreachable;
}
}
fn checkedHash(ctx: anytype, key: anytype) u32 {
// If you get a compile error on the next line, it means that your
// generic hash function doesn't accept your key.
return ctx.hash(key);
}
fn checkedEql(ctx: anytype, a: anytype, b: K, b_index: usize) bool {
// If you get a compile error on the next line, it means that your
// generic eql function doesn't accept (self, adapt key, K, index).
return ctx.eql(a, b, b_index);
}
fn dumpState(self: Self, comptime keyFmt: []const u8, comptime valueFmt: []const u8) void {
if (@sizeOf(ByIndexContext) != 0)
@compileError("Cannot infer context " ++ @typeName(Context) ++ ", call dumpStateContext instead.");
self.dumpStateContext(keyFmt, valueFmt, undefined);
}
fn dumpStateContext(self: Self, comptime keyFmt: []const u8, comptime valueFmt: []const u8, ctx: Context) void {
const p = std.debug.print;
p("{s}:\n", .{@typeName(Self)});
const slice = self.entries.slice();
const hash_status = if (store_hash) "stored" else "computed";
p(" len={} capacity={} hashes {s}\n", .{ slice.len, slice.capacity, hash_status });
var i: usize = 0;
const mask: u32 = if (self.index_header) |header| header.mask() else ~@as(u32, 0);
while (i < slice.len) : (i += 1) {
const hash = if (store_hash) slice.items(.hash)[i] else checkedHash(ctx, slice.items(.key)[i]);
if (store_hash) {
p(
" [{}]: key=" ++ keyFmt ++ " value=" ++ valueFmt ++ " hash=0x{x} slot=[0x{x}]\n",
.{ i, slice.items(.key)[i], slice.items(.value)[i], hash, hash & mask },
);
} else {
p(
" [{}]: key=" ++ keyFmt ++ " value=" ++ valueFmt ++ " slot=[0x{x}]\n",
.{ i, slice.items(.key)[i], slice.items(.value)[i], hash & mask },
);
}
}
if (self.index_header) |header| {
p("\n", .{});
switch (header.capacityIndexType()) {
.u8 => dumpIndex(header, u8),
.u16 => dumpIndex(header, u16),
.u32 => dumpIndex(header, u32),
}
}
}
fn dumpIndex(header: *IndexHeader, comptime I: type) void {
const p = std.debug.print;
p(" index len=0x{x} type={}\n", .{ header.length(), header.capacityIndexType() });
const indexes = header.indexes(I);
if (indexes.len == 0) return;
var is_empty = false;
for (indexes, 0..) |idx, i| {
if (idx.isEmpty()) {
is_empty = true;
} else {
if (is_empty) {
is_empty = false;
p(" ...\n", .{});
}
p(" [0x{x}]: [{}] +{}\n", .{ i, idx.entry_index, idx.distance_from_start_index });
}
}
if (is_empty) {
p(" ...\n", .{});
}
}
};
}
const CapacityIndexType = enum { u8, u16, u32 };
fn capacityIndexType(bit_index: u8) CapacityIndexType {
if (bit_index <= 8)
return .u8;
if (bit_index <= 16)
return .u16;
assert(bit_index <= 32);
return .u32;
}
fn capacityIndexSize(bit_index: u8) usize {
switch (capacityIndexType(bit_index)) {
.u8 => return @sizeOf(Index(u8)),
.u16 => return @sizeOf(Index(u16)),
.u32 => return @sizeOf(Index(u32)),
}
}
/// @truncate fails if the target type is larger than the
/// target value. This causes problems when one of the types
/// is usize, which may be larger or smaller than u32 on different
/// systems. This version of truncate is safe to use if either
/// parameter has dynamic size, and will perform widening conversion
/// when needed. Both arguments must have the same signedness.
fn safeTruncate(comptime T: type, val: anytype) T {
if (@bitSizeOf(T) >= @bitSizeOf(@TypeOf(val)))
return val;
return @as(T, @truncate(val));
}
/// A single entry in the lookup acceleration structure. These structs
/// are found in an array after the IndexHeader. Hashes index into this
/// array, and linear probing is used for collisions.
fn Index(comptime I: type) type {
return extern struct {
const Self = @This();
/// The index of this entry in the backing store. If the index is
/// empty, this is empty_sentinel.
entry_index: I,
/// The distance between this slot and its ideal placement. This is
/// used to keep maximum scan length small. This value is undefined
/// if the index is empty.
distance_from_start_index: I,
/// The special entry_index value marking an empty slot.
const empty_sentinel = ~@as(I, 0);
/// A constant empty index
const empty = Self{
.entry_index = empty_sentinel,
.distance_from_start_index = undefined,
};
/// Checks if a slot is empty
fn isEmpty(idx: Self) bool {
return idx.entry_index == empty_sentinel;
}
/// Sets a slot to empty
fn setEmpty(idx: *Self) void {
idx.entry_index = empty_sentinel;
idx.distance_from_start_index = undefined;
}
};
}
/// the byte size of the index must fit in a usize. This is a power of two
/// length * the size of an Index(u32). The index is 8 bytes (3 bits repr)
/// and max_usize + 1 is not representable, so we need to subtract out 4 bits.
const max_representable_index_len = @bitSizeOf(usize) - 4;
const max_bit_index = @min(32, max_representable_index_len);
const min_bit_index = 5;
const max_capacity = (1 << max_bit_index) - 1;
const index_capacities = blk: {
var caps: [max_bit_index + 1]u32 = undefined;
for (caps[0..max_bit_index], 0..) |*item, i| {
item.* = (1 << i) * 3 / 5;
}
caps[max_bit_index] = max_capacity;
break :blk caps;
};
/// This struct is trailed by two arrays of length indexes_len
/// of integers, whose integer size is determined by indexes_len.
/// These arrays are indexed by constrainIndex(hash). The
/// entryIndexes array contains the index in the dense backing store
/// where the entry's data can be found. Entries which are not in
/// use have their index value set to emptySentinel(I).
/// The entryDistances array stores the distance between an entry
/// and its ideal hash bucket. This is used when adding elements
/// to balance the maximum scan length.
const IndexHeader = struct {
/// This field tracks the total number of items in the arrays following
/// this header. It is the bit index of the power of two number of indices.
/// This value is between min_bit_index and max_bit_index, inclusive.
bit_index: u8 align(@alignOf(u32)),
/// Map from an incrementing index to an index slot in the attached arrays.
fn constrainIndex(header: IndexHeader, i: usize) usize {
// This is an optimization for modulo of power of two integers;
// it requires `indexes_len` to always be a power of two.
return @as(usize, @intCast(i & header.mask()));
}
/// Returns the attached array of indexes. I must match the type
/// returned by capacityIndexType.
fn indexes(header: *IndexHeader, comptime I: type) []Index(I) {
const start_ptr: [*]Index(I) = @alignCast(@ptrCast(@as([*]u8, @ptrCast(header)) + @sizeOf(IndexHeader)));
return start_ptr[0..header.length()];
}
/// Returns the type used for the index arrays.
fn capacityIndexType(header: IndexHeader) CapacityIndexType {
return hash_map.capacityIndexType(header.bit_index);
}
fn capacity(self: IndexHeader) u32 {
return index_capacities[self.bit_index];
}
fn length(self: IndexHeader) usize {
return @as(usize, 1) << @as(math.Log2Int(usize), @intCast(self.bit_index));
}
fn mask(self: IndexHeader) u32 {
return @as(u32, @intCast(self.length() - 1));
}
fn findBitIndex(desired_capacity: usize) !u8 {
if (desired_capacity > max_capacity) return error.OutOfMemory;
var new_bit_index = @as(u8, @intCast(std.math.log2_int_ceil(usize, desired_capacity)));
if (desired_capacity > index_capacities[new_bit_index]) new_bit_index += 1;
if (new_bit_index < min_bit_index) new_bit_index = min_bit_index;
assert(desired_capacity <= index_capacities[new_bit_index]);
return new_bit_index;
}
/// Allocates an index header, and fills the entryIndexes array with empty.
/// The distance array contents are undefined.
fn alloc(allocator: Allocator, new_bit_index: u8) !*IndexHeader {
const len = @as(usize, 1) << @as(math.Log2Int(usize), @intCast(new_bit_index));
const index_size = hash_map.capacityIndexSize(new_bit_index);
const nbytes = @sizeOf(IndexHeader) + index_size * len;
const bytes = try allocator.alignedAlloc(u8, @alignOf(IndexHeader), nbytes);
@memset(bytes[@sizeOf(IndexHeader)..], 0xff);
const result: *IndexHeader = @alignCast(@ptrCast(bytes.ptr));
result.* = .{
.bit_index = new_bit_index,
};
return result;
}
/// Releases the memory for a header and its associated arrays.
fn free(header: *IndexHeader, allocator: Allocator) void {
const index_size = hash_map.capacityIndexSize(header.bit_index);
const ptr: [*]align(@alignOf(IndexHeader)) u8 = @ptrCast(header);
const slice = ptr[0 .. @sizeOf(IndexHeader) + header.length() * index_size];
allocator.free(slice);
}
/// Puts an IndexHeader into the state that it would be in after being freshly allocated.
fn reset(header: *IndexHeader) void {
const index_size = hash_map.capacityIndexSize(header.bit_index);
const ptr: [*]align(@alignOf(IndexHeader)) u8 = @ptrCast(header);
const nbytes = @sizeOf(IndexHeader) + header.length() * index_size;
@memset(ptr[@sizeOf(IndexHeader)..nbytes], 0xff);
}
// Verify that the header has sufficient alignment to produce aligned arrays.
comptime {
if (@alignOf(u32) > @alignOf(IndexHeader))
@compileError("IndexHeader must have a larger alignment than its indexes!");
}
};
test "basic hash map usage" {
var map = AutoArrayHashMap(i32, i32).init(std.testing.allocator);
defer map.deinit();
try testing.expect((try map.fetchPut(1, 11)) == null);
try testing.expect((try map.fetchPut(2, 22)) == null);
try testing.expect((try map.fetchPut(3, 33)) == null);
try testing.expect((try map.fetchPut(4, 44)) == null);
try map.putNoClobber(5, 55);
try testing.expect((try map.fetchPut(5, 66)).?.value == 55);
try testing.expect((try map.fetchPut(5, 55)).?.value == 66);
const gop1 = try map.getOrPut(5);
try testing.expect(gop1.found_existing == true);
try testing.expect(gop1.value_ptr.* == 55);
try testing.expect(gop1.index == 4);
gop1.value_ptr.* = 77;
try testing.expect(map.getEntry(5).?.value_ptr.* == 77);
const gop2 = try map.getOrPut(99);
try testing.expect(gop2.found_existing == false);
try testing.expect(gop2.index == 5);
gop2.value_ptr.* = 42;
try testing.expect(map.getEntry(99).?.value_ptr.* == 42);
const gop3 = try map.getOrPutValue(5, 5);
try testing.expect(gop3.value_ptr.* == 77);
const gop4 = try map.getOrPutValue(100, 41);
try testing.expect(gop4.value_ptr.* == 41);
try testing.expect(map.contains(2));
try testing.expect(map.getEntry(2).?.value_ptr.* == 22);
try testing.expect(map.get(2).? == 22);
const rmv1 = map.fetchSwapRemove(2);
try testing.expect(rmv1.?.key == 2);
try testing.expect(rmv1.?.value == 22);
try testing.expect(map.fetchSwapRemove(2) == null);
try testing.expect(map.swapRemove(2) == false);
try testing.expect(map.getEntry(2) == null);
try testing.expect(map.get(2) == null);
// Since we've used `swapRemove` above, the index of this entry should remain unchanged.
try testing.expect(map.getIndex(100).? == 1);
const gop5 = try map.getOrPut(5);
try testing.expect(gop5.found_existing == true);
try testing.expect(gop5.value_ptr.* == 77);
try testing.expect(gop5.index == 4);
// Whereas, if we do an `orderedRemove`, it should move the index forward one spot.
const rmv2 = map.fetchOrderedRemove(100);
try testing.expect(rmv2.?.key == 100);
try testing.expect(rmv2.?.value == 41);
try testing.expect(map.fetchOrderedRemove(100) == null);
try testing.expect(map.orderedRemove(100) == false);
try testing.expect(map.getEntry(100) == null);
try testing.expect(map.get(100) == null);
const gop6 = try map.getOrPut(5);
try testing.expect(gop6.found_existing == true);
try testing.expect(gop6.value_ptr.* == 77);
try testing.expect(gop6.index == 3);
try testing.expect(map.swapRemove(3));
}
test "iterator hash map" {
var reset_map = AutoArrayHashMap(i32, i32).init(std.testing.allocator);
defer reset_map.deinit();
// test ensureTotalCapacity with a 0 parameter
try reset_map.ensureTotalCapacity(0);
try reset_map.putNoClobber(0, 11);
try reset_map.putNoClobber(1, 22);
try reset_map.putNoClobber(2, 33);
const keys = [_]i32{
0, 2, 1,
};
const values = [_]i32{
11, 33, 22,
};
var buffer = [_]i32{
0, 0, 0,
};
var it = reset_map.iterator();
const first_entry = it.next().?;
it.reset();
var count: usize = 0;
while (it.next()) |entry| : (count += 1) {
buffer[@as(usize, @intCast(entry.key_ptr.*))] = entry.value_ptr.*;
}
try testing.expect(count == 3);
try testing.expect(it.next() == null);
for (buffer, 0..) |_, i| {
try testing.expect(buffer[@as(usize, @intCast(keys[i]))] == values[i]);
}
it.reset();
count = 0;
while (it.next()) |entry| {
buffer[@as(usize, @intCast(entry.key_ptr.*))] = entry.value_ptr.*;
count += 1;
if (count >= 2) break;
}
for (buffer[0..2], 0..) |_, i| {
try testing.expect(buffer[@as(usize, @intCast(keys[i]))] == values[i]);
}
it.reset();
const entry = it.next().?;
try testing.expect(entry.key_ptr.* == first_entry.key_ptr.*);
try testing.expect(entry.value_ptr.* == first_entry.value_ptr.*);
}
test "ensure capacity" {
var map = AutoArrayHashMap(i32, i32).init(std.testing.allocator);
defer map.deinit();
try map.ensureTotalCapacity(20);
const initial_capacity = map.capacity();
try testing.expect(initial_capacity >= 20);
var i: i32 = 0;
while (i < 20) : (i += 1) {
try testing.expect(map.fetchPutAssumeCapacity(i, i + 10) == null);
}
// shouldn't resize from putAssumeCapacity
try testing.expect(initial_capacity == map.capacity());
}
test "ensure capacity leak" {
try testing.checkAllAllocationFailures(std.testing.allocator, struct {
pub fn f(allocator: Allocator) !void {
var map = AutoArrayHashMap(i32, i32).init(allocator);
defer map.deinit();
var i: i32 = 0;
// put more than `linear_scan_max` in so index_header gets allocated.
while (i <= 20) : (i += 1) try map.put(i, i);
}
}.f, .{});
}
test "big map" {
var map = AutoArrayHashMap(i32, i32).init(std.testing.allocator);
defer map.deinit();
var i: i32 = 0;
while (i < 8) : (i += 1) {
try map.put(i, i + 10);
}
i = 0;
while (i < 8) : (i += 1) {
try testing.expectEqual(@as(?i32, i + 10), map.get(i));
}
while (i < 16) : (i += 1) {
try testing.expectEqual(@as(?i32, null), map.get(i));
}
i = 4;
while (i < 12) : (i += 1) {
try map.put(i, i + 12);
}
i = 0;
while (i < 4) : (i += 1) {
try testing.expectEqual(@as(?i32, i + 10), map.get(i));
}
while (i < 12) : (i += 1) {
try testing.expectEqual(@as(?i32, i + 12), map.get(i));
}
while (i < 16) : (i += 1) {
try testing.expectEqual(@as(?i32, null), map.get(i));
}
i = 0;
while (i < 4) : (i += 1) {
try testing.expect(map.orderedRemove(i));
}
while (i < 8) : (i += 1) {
try testing.expect(map.swapRemove(i));
}
i = 0;
while (i < 8) : (i += 1) {
try testing.expectEqual(@as(?i32, null), map.get(i));
}
while (i < 12) : (i += 1) {
try testing.expectEqual(@as(?i32, i + 12), map.get(i));
}
while (i < 16) : (i += 1) {
try testing.expectEqual(@as(?i32, null), map.get(i));
}
}
test "clone" {
var original = AutoArrayHashMap(i32, i32).init(std.testing.allocator);
defer original.deinit();
// put more than `linear_scan_max` so we can test that the index header is properly cloned
var i: u8 = 0;
while (i < 10) : (i += 1) {
try original.putNoClobber(i, i * 10);
}
var copy = try original.clone();
defer copy.deinit();
i = 0;
while (i < 10) : (i += 1) {
try testing.expect(original.get(i).? == i * 10);
try testing.expect(copy.get(i).? == i * 10);
try testing.expect(original.getPtr(i).? != copy.getPtr(i).?);
}
while (i < 20) : (i += 1) {
try testing.expect(original.get(i) == null);
try testing.expect(copy.get(i) == null);
}
}
test "shrink" {
var map = AutoArrayHashMap(i32, i32).init(std.testing.allocator);
defer map.deinit();
// This test is more interesting if we insert enough entries to allocate the index header.
const num_entries = 20;
var i: i32 = 0;
while (i < num_entries) : (i += 1)
try testing.expect((try map.fetchPut(i, i * 10)) == null);
try testing.expect(map.unmanaged.index_header != null);
try testing.expect(map.count() == num_entries);
// Test `shrinkRetainingCapacity`.
map.shrinkRetainingCapacity(17);
try testing.expect(map.count() == 17);
try testing.expect(map.capacity() == 20);
i = 0;
while (i < num_entries) : (i += 1) {
const gop = try map.getOrPut(i);
if (i < 17) {
try testing.expect(gop.found_existing == true);
try testing.expect(gop.value_ptr.* == i * 10);
} else try testing.expect(gop.found_existing == false);
}
// Test `shrinkAndFree`.
map.shrinkAndFree(15);
try testing.expect(map.count() == 15);
try testing.expect(map.capacity() == 15);
i = 0;
while (i < num_entries) : (i += 1) {
const gop = try map.getOrPut(i);
if (i < 15) {
try testing.expect(gop.found_existing == true);
try testing.expect(gop.value_ptr.* == i * 10);
} else try testing.expect(gop.found_existing == false);
}
}
test "pop" {
var map = AutoArrayHashMap(i32, i32).init(std.testing.allocator);
defer map.deinit();
// Insert just enough entries so that the map expands. Afterwards,
// pop all entries out of the map.
var i: i32 = 0;
while (i < 9) : (i += 1) {
try testing.expect((try map.fetchPut(i, i)) == null);
}
while (i > 0) : (i -= 1) {
const pop = map.pop();
try testing.expect(pop.key == i - 1 and pop.value == i - 1);
}
}
test "popOrNull" {
var map = AutoArrayHashMap(i32, i32).init(std.testing.allocator);
defer map.deinit();
// Insert just enough entries so that the map expands. Afterwards,
// pop all entries out of the map.
var i: i32 = 0;
while (i < 9) : (i += 1) {
try testing.expect((try map.fetchPut(i, i)) == null);
}
while (map.popOrNull()) |pop| {
try testing.expect(pop.key == i - 1 and pop.value == i - 1);
i -= 1;
}
try testing.expect(map.count() == 0);
}
test "reIndex" {
var map = ArrayHashMap(i32, i32, AutoContext(i32), true).init(std.testing.allocator);
defer map.deinit();
// Populate via the API.
const num_indexed_entries = 20;
var i: i32 = 0;
while (i < num_indexed_entries) : (i += 1)
try testing.expect((try map.fetchPut(i, i * 10)) == null);
// Make sure we allocated an index header.
try testing.expect(map.unmanaged.index_header != null);
// Now write to the arrays directly.
const num_unindexed_entries = 20;
try map.unmanaged.entries.resize(std.testing.allocator, num_indexed_entries + num_unindexed_entries);
for (map.keys()[num_indexed_entries..], map.values()[num_indexed_entries..], num_indexed_entries..) |*key, *value, j| {
key.* = @intCast(j);
value.* = @intCast(j * 10);
}
// After reindexing, we should see everything.
try map.reIndex();
i = 0;
while (i < num_indexed_entries + num_unindexed_entries) : (i += 1) {
const gop = try map.getOrPut(i);
try testing.expect(gop.found_existing == true);
try testing.expect(gop.value_ptr.* == i * 10);
try testing.expect(gop.index == i);
}
}
test "auto store_hash" {
const HasCheapEql = AutoArrayHashMap(i32, i32);
const HasExpensiveEql = AutoArrayHashMap([32]i32, i32);
try testing.expect(std.meta.fieldInfo(HasCheapEql.Data, .hash).type == void);
try testing.expect(std.meta.fieldInfo(HasExpensiveEql.Data, .hash).type != void);
const HasCheapEqlUn = AutoArrayHashMapUnmanaged(i32, i32);
const HasExpensiveEqlUn = AutoArrayHashMapUnmanaged([32]i32, i32);
try testing.expect(std.meta.fieldInfo(HasCheapEqlUn.Data, .hash).type == void);
try testing.expect(std.meta.fieldInfo(HasExpensiveEqlUn.Data, .hash).type != void);
}
test "sort" {
var map = AutoArrayHashMap(i32, i32).init(std.testing.allocator);
defer map.deinit();
for ([_]i32{ 8, 3, 12, 10, 2, 4, 9, 5, 6, 13, 14, 15, 16, 1, 11, 17, 7 }) |x| {
try map.put(x, x * 3);
}
const C = struct {
keys: []i32,
pub fn lessThan(ctx: @This(), a_index: usize, b_index: usize) bool {
return ctx.keys[a_index] < ctx.keys[b_index];
}
};
map.sort(C{ .keys = map.keys() });
var x: i32 = 1;
for (map.keys(), 0..) |key, i| {
try testing.expect(key == x);
try testing.expect(map.values()[i] == x * 3);
x += 1;
}
}
test "0 sized key" {
var map = AutoArrayHashMap(u0, i32).init(std.testing.allocator);
defer map.deinit();
try testing.expectEqual(map.get(0), null);
try map.put(0, 5);
try testing.expectEqual(map.get(0), 5);
try map.put(0, 10);
try testing.expectEqual(map.get(0), 10);
try testing.expectEqual(map.swapRemove(0), true);
try testing.expectEqual(map.get(0), null);
}
test "0 sized key and 0 sized value" {
var map = AutoArrayHashMap(u0, u0).init(std.testing.allocator);
defer map.deinit();
try testing.expectEqual(map.get(0), null);
try map.put(0, 0);
try testing.expectEqual(map.get(0), 0);
try testing.expectEqual(map.swapRemove(0), true);
try testing.expectEqual(map.get(0), null);
}
pub fn getHashPtrAddrFn(comptime K: type, comptime Context: type) (fn (Context, K) u32) {
return struct {
fn hash(ctx: Context, key: K) u32 {
_ = ctx;
return getAutoHashFn(usize, void)({}, @intFromPtr(key));
}
}.hash;
}
pub fn getTrivialEqlFn(comptime K: type, comptime Context: type) (fn (Context, K, K) bool) {
return struct {
fn eql(ctx: Context, a: K, b: K) bool {
_ = ctx;
return a == b;
}
}.eql;
}
pub fn AutoContext(comptime K: type) type {
return struct {
pub const hash = getAutoHashFn(K, @This());
pub const eql = getAutoEqlFn(K, @This());
};
}
pub fn getAutoHashFn(comptime K: type, comptime Context: type) (fn (Context, K) u32) {
return struct {
fn hash(ctx: Context, key: K) u32 {
_ = ctx;
if (std.meta.hasUniqueRepresentation(K)) {
return @truncate(Wyhash.hash(0, std.mem.asBytes(&key)));
} else {
var hasher = Wyhash.init(0);
autoHash(&hasher, key);
return @truncate(hasher.final());
}
}
}.hash;
}
pub fn getAutoEqlFn(comptime K: type, comptime Context: type) (fn (Context, K, K, usize) bool) {
return struct {
fn eql(ctx: Context, a: K, b: K, b_index: usize) bool {
_ = b_index;
_ = ctx;
return std.meta.eql(a, b);
}
}.eql;
}
pub fn autoEqlIsCheap(comptime K: type) bool {
return switch (@typeInfo(K)) {
.Bool,
.Int,
.Float,
.Pointer,
.ComptimeFloat,
.ComptimeInt,
.Enum,
.Fn,
.ErrorSet,
.AnyFrame,
.EnumLiteral,
=> true,
else => false,
};
}
pub fn getAutoHashStratFn(comptime K: type, comptime Context: type, comptime strategy: std.hash.Strategy) (fn (Context, K) u32) {
return struct {
fn hash(ctx: Context, key: K) u32 {
_ = ctx;
var hasher = Wyhash.init(0);
std.hash.autoHashStrat(&hasher, key, strategy);
return @as(u32, @truncate(hasher.final()));
}
}.hash;
}
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