532 lines
18 KiB
Zig
532 lines
18 KiB
Zig
const std = @import("index.zig");
|
|
const debug = std.debug;
|
|
const assert = debug.assert;
|
|
const math = std.math;
|
|
const mem = std.mem;
|
|
const Allocator = mem.Allocator;
|
|
const builtin = @import("builtin");
|
|
|
|
const want_modification_safety = builtin.mode != builtin.Mode.ReleaseFast;
|
|
const debug_u32 = if (want_modification_safety) u32 else void;
|
|
|
|
pub fn AutoHashMap(comptime K: type, comptime V: type) type {
|
|
return HashMap(K, V, getAutoHashFn(K), getAutoEqlFn(K));
|
|
}
|
|
|
|
pub fn HashMap(comptime K: type, comptime V: type, comptime hash: fn (key: K) u32, comptime eql: fn (a: K, b: K) bool) type {
|
|
return struct {
|
|
entries: []Entry,
|
|
size: usize,
|
|
max_distance_from_start_index: usize,
|
|
allocator: *Allocator,
|
|
// this is used to detect bugs where a hashtable is edited while an iterator is running.
|
|
modification_count: debug_u32,
|
|
|
|
const Self = this;
|
|
|
|
pub const KV = struct {
|
|
key: K,
|
|
value: V,
|
|
};
|
|
|
|
const Entry = struct {
|
|
used: bool,
|
|
distance_from_start_index: usize,
|
|
kv: KV,
|
|
};
|
|
|
|
pub const GetOrPutResult = struct {
|
|
kv: *KV,
|
|
found_existing: bool,
|
|
};
|
|
|
|
pub const Iterator = struct {
|
|
hm: *const Self,
|
|
// how many items have we returned
|
|
count: usize,
|
|
// iterator through the entry array
|
|
index: usize,
|
|
// used to detect concurrent modification
|
|
initial_modification_count: debug_u32,
|
|
|
|
pub fn next(it: *Iterator) ?*KV {
|
|
if (want_modification_safety) {
|
|
assert(it.initial_modification_count == it.hm.modification_count); // concurrent modification
|
|
}
|
|
if (it.count >= it.hm.size) return null;
|
|
while (it.index < it.hm.entries.len) : (it.index += 1) {
|
|
const entry = &it.hm.entries[it.index];
|
|
if (entry.used) {
|
|
it.index += 1;
|
|
it.count += 1;
|
|
return &entry.kv;
|
|
}
|
|
}
|
|
unreachable; // no next item
|
|
}
|
|
|
|
// Reset the iterator to the initial index
|
|
pub fn reset(it: *Iterator) void {
|
|
it.count = 0;
|
|
it.index = 0;
|
|
// Resetting the modification count too
|
|
it.initial_modification_count = it.hm.modification_count;
|
|
}
|
|
};
|
|
|
|
pub fn init(allocator: *Allocator) Self {
|
|
return Self{
|
|
.entries = []Entry{},
|
|
.allocator = allocator,
|
|
.size = 0,
|
|
.max_distance_from_start_index = 0,
|
|
.modification_count = if (want_modification_safety) 0 else {},
|
|
};
|
|
}
|
|
|
|
pub fn deinit(hm: Self) void {
|
|
hm.allocator.free(hm.entries);
|
|
}
|
|
|
|
pub fn clear(hm: *Self) void {
|
|
for (hm.entries) |*entry| {
|
|
entry.used = false;
|
|
}
|
|
hm.size = 0;
|
|
hm.max_distance_from_start_index = 0;
|
|
hm.incrementModificationCount();
|
|
}
|
|
|
|
pub fn count(self: Self) usize {
|
|
return self.size;
|
|
}
|
|
|
|
/// If key exists this function cannot fail.
|
|
/// If there is an existing item with `key`, then the result
|
|
/// kv pointer points to it, and found_existing is true.
|
|
/// Otherwise, puts a new item with undefined value, and
|
|
/// the kv pointer points to it. Caller should then initialize
|
|
/// the data.
|
|
pub fn getOrPut(self: *Self, key: K) !GetOrPutResult {
|
|
// TODO this implementation can be improved - we should only
|
|
// have to hash once and find the entry once.
|
|
if (self.get(key)) |kv| {
|
|
return GetOrPutResult{
|
|
.kv = kv,
|
|
.found_existing = true,
|
|
};
|
|
}
|
|
self.incrementModificationCount();
|
|
try self.ensureCapacity();
|
|
const put_result = self.internalPut(key);
|
|
assert(put_result.old_kv == null);
|
|
return GetOrPutResult{
|
|
.kv = &put_result.new_entry.kv,
|
|
.found_existing = false,
|
|
};
|
|
}
|
|
|
|
fn ensureCapacity(self: *Self) !void {
|
|
if (self.entries.len == 0) {
|
|
return self.initCapacity(16);
|
|
}
|
|
|
|
// if we get too full (60%), double the capacity
|
|
if (self.size * 5 >= self.entries.len * 3) {
|
|
const old_entries = self.entries;
|
|
try self.initCapacity(self.entries.len * 2);
|
|
// dump all of the old elements into the new table
|
|
for (old_entries) |*old_entry| {
|
|
if (old_entry.used) {
|
|
self.internalPut(old_entry.kv.key).new_entry.kv.value = old_entry.kv.value;
|
|
}
|
|
}
|
|
self.allocator.free(old_entries);
|
|
}
|
|
}
|
|
|
|
/// Returns the kv pair that was already there.
|
|
pub fn put(self: *Self, key: K, value: V) !?KV {
|
|
self.incrementModificationCount();
|
|
try self.ensureCapacity();
|
|
|
|
const put_result = self.internalPut(key);
|
|
put_result.new_entry.kv.value = value;
|
|
return put_result.old_kv;
|
|
}
|
|
|
|
pub fn get(hm: *const Self, key: K) ?*KV {
|
|
if (hm.entries.len == 0) {
|
|
return null;
|
|
}
|
|
return hm.internalGet(key);
|
|
}
|
|
|
|
pub fn contains(hm: *const Self, key: K) bool {
|
|
return hm.get(key) != null;
|
|
}
|
|
|
|
pub fn remove(hm: *Self, key: K) ?*KV {
|
|
if (hm.entries.len == 0) return null;
|
|
hm.incrementModificationCount();
|
|
const start_index = hm.keyToIndex(key);
|
|
{
|
|
var roll_over: usize = 0;
|
|
while (roll_over <= hm.max_distance_from_start_index) : (roll_over += 1) {
|
|
const index = (start_index + roll_over) % hm.entries.len;
|
|
var entry = &hm.entries[index];
|
|
|
|
if (!entry.used) return null;
|
|
|
|
if (!eql(entry.kv.key, key)) continue;
|
|
|
|
while (roll_over < hm.entries.len) : (roll_over += 1) {
|
|
const next_index = (start_index + roll_over + 1) % hm.entries.len;
|
|
const next_entry = &hm.entries[next_index];
|
|
if (!next_entry.used or next_entry.distance_from_start_index == 0) {
|
|
entry.used = false;
|
|
hm.size -= 1;
|
|
return &entry.kv;
|
|
}
|
|
entry.* = next_entry.*;
|
|
entry.distance_from_start_index -= 1;
|
|
entry = next_entry;
|
|
}
|
|
unreachable; // shifting everything in the table
|
|
}
|
|
}
|
|
return null;
|
|
}
|
|
|
|
pub fn iterator(hm: *const Self) Iterator {
|
|
return Iterator{
|
|
.hm = hm,
|
|
.count = 0,
|
|
.index = 0,
|
|
.initial_modification_count = hm.modification_count,
|
|
};
|
|
}
|
|
|
|
pub fn clone(self: Self) !Self {
|
|
var other = Self.init(self.allocator);
|
|
try other.initCapacity(self.entries.len);
|
|
var it = self.iterator();
|
|
while (it.next()) |entry| {
|
|
assert((try other.put(entry.key, entry.value)) == null);
|
|
}
|
|
return other;
|
|
}
|
|
|
|
fn initCapacity(hm: *Self, capacity: usize) !void {
|
|
hm.entries = try hm.allocator.alloc(Entry, capacity);
|
|
hm.size = 0;
|
|
hm.max_distance_from_start_index = 0;
|
|
for (hm.entries) |*entry| {
|
|
entry.used = false;
|
|
}
|
|
}
|
|
|
|
fn incrementModificationCount(hm: *Self) void {
|
|
if (want_modification_safety) {
|
|
hm.modification_count +%= 1;
|
|
}
|
|
}
|
|
|
|
const InternalPutResult = struct {
|
|
new_entry: *Entry,
|
|
old_kv: ?KV,
|
|
};
|
|
|
|
/// Returns a pointer to the new entry.
|
|
/// Asserts that there is enough space for the new item.
|
|
fn internalPut(self: *Self, orig_key: K) InternalPutResult {
|
|
var key = orig_key;
|
|
var value: V = undefined;
|
|
const start_index = self.keyToIndex(key);
|
|
var roll_over: usize = 0;
|
|
var distance_from_start_index: usize = 0;
|
|
var got_result_entry = false;
|
|
var result = InternalPutResult{
|
|
.new_entry = undefined,
|
|
.old_kv = null,
|
|
};
|
|
while (roll_over < self.entries.len) : ({
|
|
roll_over += 1;
|
|
distance_from_start_index += 1;
|
|
}) {
|
|
const index = (start_index + roll_over) % self.entries.len;
|
|
const entry = &self.entries[index];
|
|
|
|
if (entry.used and !eql(entry.kv.key, key)) {
|
|
if (entry.distance_from_start_index < distance_from_start_index) {
|
|
// robin hood to the rescue
|
|
const tmp = entry.*;
|
|
self.max_distance_from_start_index = math.max(self.max_distance_from_start_index, distance_from_start_index);
|
|
if (!got_result_entry) {
|
|
got_result_entry = true;
|
|
result.new_entry = entry;
|
|
}
|
|
entry.* = Entry{
|
|
.used = true,
|
|
.distance_from_start_index = distance_from_start_index,
|
|
.kv = KV{
|
|
.key = key,
|
|
.value = value,
|
|
},
|
|
};
|
|
key = tmp.kv.key;
|
|
value = tmp.kv.value;
|
|
distance_from_start_index = tmp.distance_from_start_index;
|
|
}
|
|
continue;
|
|
}
|
|
|
|
if (entry.used) {
|
|
result.old_kv = entry.kv;
|
|
} else {
|
|
// adding an entry. otherwise overwriting old value with
|
|
// same key
|
|
self.size += 1;
|
|
}
|
|
|
|
self.max_distance_from_start_index = math.max(distance_from_start_index, self.max_distance_from_start_index);
|
|
if (!got_result_entry) {
|
|
result.new_entry = entry;
|
|
}
|
|
entry.* = Entry{
|
|
.used = true,
|
|
.distance_from_start_index = distance_from_start_index,
|
|
.kv = KV{
|
|
.key = key,
|
|
.value = value,
|
|
},
|
|
};
|
|
return result;
|
|
}
|
|
unreachable; // put into a full map
|
|
}
|
|
|
|
fn internalGet(hm: Self, key: K) ?*KV {
|
|
const start_index = hm.keyToIndex(key);
|
|
{
|
|
var roll_over: usize = 0;
|
|
while (roll_over <= hm.max_distance_from_start_index) : (roll_over += 1) {
|
|
const index = (start_index + roll_over) % hm.entries.len;
|
|
const entry = &hm.entries[index];
|
|
|
|
if (!entry.used) return null;
|
|
if (eql(entry.kv.key, key)) return &entry.kv;
|
|
}
|
|
}
|
|
return null;
|
|
}
|
|
|
|
fn keyToIndex(hm: Self, key: K) usize {
|
|
return usize(hash(key)) % hm.entries.len;
|
|
}
|
|
};
|
|
}
|
|
|
|
test "basic hash map usage" {
|
|
var direct_allocator = std.heap.DirectAllocator.init();
|
|
defer direct_allocator.deinit();
|
|
|
|
var map = AutoHashMap(i32, i32).init(&direct_allocator.allocator);
|
|
defer map.deinit();
|
|
|
|
assert((try map.put(1, 11)) == null);
|
|
assert((try map.put(2, 22)) == null);
|
|
assert((try map.put(3, 33)) == null);
|
|
assert((try map.put(4, 44)) == null);
|
|
assert((try map.put(5, 55)) == null);
|
|
|
|
assert((try map.put(5, 66)).?.value == 55);
|
|
assert((try map.put(5, 55)).?.value == 66);
|
|
|
|
const gop1 = try map.getOrPut(5);
|
|
assert(gop1.found_existing == true);
|
|
assert(gop1.kv.value == 55);
|
|
gop1.kv.value = 77;
|
|
assert(map.get(5).?.value == 77);
|
|
|
|
const gop2 = try map.getOrPut(99);
|
|
assert(gop2.found_existing == false);
|
|
gop2.kv.value = 42;
|
|
assert(map.get(99).?.value == 42);
|
|
|
|
assert(map.contains(2));
|
|
assert(map.get(2).?.value == 22);
|
|
_ = map.remove(2);
|
|
assert(map.remove(2) == null);
|
|
assert(map.get(2) == null);
|
|
}
|
|
|
|
test "iterator hash map" {
|
|
var direct_allocator = std.heap.DirectAllocator.init();
|
|
defer direct_allocator.deinit();
|
|
|
|
var reset_map = AutoHashMap(i32, i32).init(&direct_allocator.allocator);
|
|
defer reset_map.deinit();
|
|
|
|
assert((try reset_map.put(1, 11)) == null);
|
|
assert((try reset_map.put(2, 22)) == null);
|
|
assert((try reset_map.put(3, 33)) == null);
|
|
|
|
var keys = []i32{
|
|
1,
|
|
2,
|
|
3,
|
|
};
|
|
var values = []i32{
|
|
11,
|
|
22,
|
|
33,
|
|
};
|
|
|
|
var it = reset_map.iterator();
|
|
var count: usize = 0;
|
|
while (it.next()) |next| {
|
|
assert(next.key == keys[count]);
|
|
assert(next.value == values[count]);
|
|
count += 1;
|
|
}
|
|
|
|
assert(count == 3);
|
|
assert(it.next() == null);
|
|
it.reset();
|
|
count = 0;
|
|
while (it.next()) |next| {
|
|
assert(next.key == keys[count]);
|
|
assert(next.value == values[count]);
|
|
count += 1;
|
|
if (count == 2) break;
|
|
}
|
|
|
|
it.reset();
|
|
var entry = it.next().?;
|
|
assert(entry.key == keys[0]);
|
|
assert(entry.value == values[0]);
|
|
}
|
|
|
|
pub fn getAutoHashFn(comptime K: type) (fn (K) u32) {
|
|
return struct {
|
|
fn hash(key: K) u32 {
|
|
comptime var rng = comptime std.rand.DefaultPrng.init(0);
|
|
return autoHash(key, &rng.random, u32);
|
|
}
|
|
}.hash;
|
|
}
|
|
|
|
pub fn getAutoEqlFn(comptime K: type) (fn (K, K) bool) {
|
|
return struct {
|
|
fn eql(a: K, b: K) bool {
|
|
return autoEql(a, b);
|
|
}
|
|
}.eql;
|
|
}
|
|
|
|
// TODO improve these hash functions
|
|
pub fn autoHash(key: var, comptime rng: *std.rand.Random, comptime HashInt: type) HashInt {
|
|
switch (@typeInfo(@typeOf(key))) {
|
|
builtin.TypeId.NoReturn,
|
|
builtin.TypeId.Opaque,
|
|
builtin.TypeId.Undefined,
|
|
builtin.TypeId.ArgTuple,
|
|
=> @compileError("cannot hash this type"),
|
|
|
|
builtin.TypeId.Void,
|
|
builtin.TypeId.Null,
|
|
=> return 0,
|
|
|
|
builtin.TypeId.Int => |info| {
|
|
const unsigned_x = @bitCast(@IntType(false, info.bits), key);
|
|
if (info.bits <= HashInt.bit_count) {
|
|
return HashInt(unsigned_x) ^ comptime rng.scalar(HashInt);
|
|
} else {
|
|
return @truncate(HashInt, unsigned_x ^ comptime rng.scalar(@typeOf(unsigned_x)));
|
|
}
|
|
},
|
|
|
|
builtin.TypeId.Float => |info| {
|
|
return autoHash(@bitCast(@IntType(false, info.bits), key), rng);
|
|
},
|
|
builtin.TypeId.Bool => return autoHash(@boolToInt(key), rng),
|
|
builtin.TypeId.Enum => return autoHash(@enumToInt(key), rng),
|
|
builtin.TypeId.ErrorSet => return autoHash(@errorToInt(key), rng),
|
|
builtin.TypeId.Promise, builtin.TypeId.Fn => return autoHash(@ptrToInt(key), rng),
|
|
|
|
builtin.TypeId.Namespace,
|
|
builtin.TypeId.Block,
|
|
builtin.TypeId.BoundFn,
|
|
builtin.TypeId.ComptimeFloat,
|
|
builtin.TypeId.ComptimeInt,
|
|
builtin.TypeId.Type,
|
|
=> return 0,
|
|
|
|
builtin.TypeId.Pointer => |info| switch (info.size) {
|
|
builtin.TypeInfo.Pointer.Size.One => @compileError("TODO auto hash for single item pointers"),
|
|
builtin.TypeInfo.Pointer.Size.Many => @compileError("TODO auto hash for many item pointers"),
|
|
builtin.TypeInfo.Pointer.Size.Slice => {
|
|
const interval = std.math.max(1, key.len / 256);
|
|
var i: usize = 0;
|
|
var h = comptime rng.scalar(HashInt);
|
|
while (i < key.len) : (i += interval) {
|
|
h ^= autoHash(key[i], rng, HashInt);
|
|
}
|
|
return h;
|
|
},
|
|
},
|
|
|
|
builtin.TypeId.Optional => @compileError("TODO auto hash for optionals"),
|
|
builtin.TypeId.Array => @compileError("TODO auto hash for arrays"),
|
|
builtin.TypeId.Struct => @compileError("TODO auto hash for structs"),
|
|
builtin.TypeId.Union => @compileError("TODO auto hash for unions"),
|
|
builtin.TypeId.ErrorUnion => @compileError("TODO auto hash for unions"),
|
|
}
|
|
}
|
|
|
|
pub fn autoEql(a: var, b: @typeOf(a)) bool {
|
|
switch (@typeInfo(@typeOf(a))) {
|
|
builtin.TypeId.NoReturn,
|
|
builtin.TypeId.Opaque,
|
|
builtin.TypeId.Undefined,
|
|
builtin.TypeId.ArgTuple,
|
|
=> @compileError("cannot test equality of this type"),
|
|
builtin.TypeId.Void,
|
|
builtin.TypeId.Null,
|
|
=> return true,
|
|
builtin.TypeId.Bool,
|
|
builtin.TypeId.Int,
|
|
builtin.TypeId.Float,
|
|
builtin.TypeId.ComptimeFloat,
|
|
builtin.TypeId.ComptimeInt,
|
|
builtin.TypeId.Namespace,
|
|
builtin.TypeId.Block,
|
|
builtin.TypeId.Promise,
|
|
builtin.TypeId.Enum,
|
|
builtin.TypeId.BoundFn,
|
|
builtin.TypeId.Fn,
|
|
builtin.TypeId.ErrorSet,
|
|
builtin.TypeId.Type,
|
|
=> return a == b,
|
|
|
|
builtin.TypeId.Pointer => |info| switch (info.size) {
|
|
builtin.TypeInfo.Pointer.Size.One => @compileError("TODO auto eql for single item pointers"),
|
|
builtin.TypeInfo.Pointer.Size.Many => @compileError("TODO auto eql for many item pointers"),
|
|
builtin.TypeInfo.Pointer.Size.Slice => {
|
|
if (a.len != b.len) return false;
|
|
for (a) |a_item, i| {
|
|
if (!autoEql(a_item, b[i])) return false;
|
|
}
|
|
return true;
|
|
},
|
|
},
|
|
|
|
builtin.TypeId.Optional => @compileError("TODO auto eql for optionals"),
|
|
builtin.TypeId.Array => @compileError("TODO auto eql for arrays"),
|
|
builtin.TypeId.Struct => @compileError("TODO auto eql for structs"),
|
|
builtin.TypeId.Union => @compileError("TODO auto eql for unions"),
|
|
builtin.TypeId.ErrorUnion => @compileError("TODO auto eql for unions"),
|
|
}
|
|
}
|