mirror of
https://github.com/ziglang/zig.git
synced 2024-11-30 09:02:32 +00:00
260 lines
9.0 KiB
Zig
260 lines
9.0 KiB
Zig
const debug = @import("debug.zig");
|
|
const assert = debug.assert;
|
|
const math = @import("math/index.zig");
|
|
const mem = @import("mem.zig");
|
|
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 HashMap(comptime K: type, comptime V: type,
|
|
comptime hash: fn(key: K)->u32,
|
|
comptime eql: fn(a: K, b: K)->bool) -> type
|
|
{
|
|
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 Entry = struct {
|
|
used: bool,
|
|
distance_from_start_index: usize,
|
|
key: K,
|
|
value: V,
|
|
};
|
|
|
|
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) -> ?&Entry {
|
|
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;
|
|
}
|
|
}
|
|
unreachable // no next item
|
|
}
|
|
};
|
|
|
|
pub fn init(allocator: &Allocator) -> Self {
|
|
Self {
|
|
.entries = []Entry{},
|
|
.allocator = allocator,
|
|
.size = 0,
|
|
.max_distance_from_start_index = 0,
|
|
// it doesn't actually matter what we set this to since we use wrapping integer arithmetic
|
|
.modification_count = undefined,
|
|
}
|
|
}
|
|
|
|
pub fn deinit(hm: &Self) {
|
|
hm.allocator.free(hm.entries);
|
|
}
|
|
|
|
pub fn clear(hm: &Self) {
|
|
for (hm.entries) |*entry| {
|
|
entry.used = false;
|
|
}
|
|
hm.size = 0;
|
|
hm.max_distance_from_start_index = 0;
|
|
hm.incrementModificationCount();
|
|
}
|
|
|
|
/// Returns the value that was already there.
|
|
pub fn put(hm: &Self, key: K, value: &const V) -> %?V {
|
|
if (hm.entries.len == 0) {
|
|
%return hm.initCapacity(16);
|
|
}
|
|
hm.incrementModificationCount();
|
|
|
|
// if we get too full (60%), double the capacity
|
|
if (hm.size * 5 >= hm.entries.len * 3) {
|
|
const old_entries = hm.entries;
|
|
%return hm.initCapacity(hm.entries.len * 2);
|
|
// dump all of the old elements into the new table
|
|
for (old_entries) |*old_entry| {
|
|
if (old_entry.used) {
|
|
_ = hm.internalPut(old_entry.key, old_entry.value);
|
|
}
|
|
}
|
|
hm.allocator.free(old_entries);
|
|
}
|
|
|
|
return hm.internalPut(key, value);
|
|
}
|
|
|
|
pub fn get(hm: &Self, key: K) -> ?&Entry {
|
|
if (hm.entries.len == 0) {
|
|
return null;
|
|
}
|
|
return hm.internalGet(key);
|
|
}
|
|
|
|
pub fn remove(hm: &Self, key: K) -> ?&Entry {
|
|
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.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;
|
|
}
|
|
*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,
|
|
};
|
|
}
|
|
|
|
fn initCapacity(hm: &Self, capacity: usize) -> %void {
|
|
hm.entries = %return 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) {
|
|
if (want_modification_safety) {
|
|
hm.modification_count +%= 1;
|
|
}
|
|
}
|
|
|
|
/// Returns the value that was already there.
|
|
fn internalPut(hm: &Self, orig_key: K, orig_value: &const V) -> ?V {
|
|
var key = orig_key;
|
|
var value = *orig_value;
|
|
const start_index = hm.keyToIndex(key);
|
|
var roll_over: usize = 0;
|
|
var distance_from_start_index: usize = 0;
|
|
while (roll_over < hm.entries.len) : ({roll_over += 1; distance_from_start_index += 1}) {
|
|
const index = (start_index + roll_over) % hm.entries.len;
|
|
const entry = &hm.entries[index];
|
|
|
|
if (entry.used and !eql(entry.key, key)) {
|
|
if (entry.distance_from_start_index < distance_from_start_index) {
|
|
// robin hood to the rescue
|
|
const tmp = *entry;
|
|
hm.max_distance_from_start_index = math.max(hm.max_distance_from_start_index,
|
|
distance_from_start_index);
|
|
*entry = Entry {
|
|
.used = true,
|
|
.distance_from_start_index = distance_from_start_index,
|
|
.key = key,
|
|
.value = value,
|
|
};
|
|
key = tmp.key;
|
|
value = tmp.value;
|
|
distance_from_start_index = tmp.distance_from_start_index;
|
|
}
|
|
continue;
|
|
}
|
|
|
|
var result: ?V = null;
|
|
if (entry.used) {
|
|
result = entry.value;
|
|
} else {
|
|
// adding an entry. otherwise overwriting old value with
|
|
// same key
|
|
hm.size += 1;
|
|
}
|
|
|
|
hm.max_distance_from_start_index = math.max(distance_from_start_index, hm.max_distance_from_start_index);
|
|
*entry = Entry {
|
|
.used = true,
|
|
.distance_from_start_index = distance_from_start_index,
|
|
.key = key,
|
|
.value = value,
|
|
};
|
|
return result;
|
|
}
|
|
unreachable // put into a full map
|
|
}
|
|
|
|
fn internalGet(hm: &Self, key: K) -> ?&Entry {
|
|
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.key, key)) return entry;
|
|
}}
|
|
return null;
|
|
}
|
|
|
|
fn keyToIndex(hm: &Self, key: K) -> usize {
|
|
return usize(hash(key)) % hm.entries.len;
|
|
}
|
|
}
|
|
}
|
|
|
|
test "basicHashMapTest" {
|
|
var map = HashMap(i32, i32, hash_i32, eql_i32).init(&debug.global_allocator);
|
|
defer map.deinit();
|
|
|
|
assert(%%map.put(1, 11) == null);
|
|
assert(%%map.put(2, 22) == null);
|
|
assert(%%map.put(3, 33) == null);
|
|
assert(%%map.put(4, 44) == null);
|
|
assert(%%map.put(5, 55) == null);
|
|
|
|
assert(??%%map.put(5, 66) == 55);
|
|
assert(??%%map.put(5, 55) == 66);
|
|
|
|
assert((??map.get(2)).value == 22);
|
|
_ = map.remove(2);
|
|
assert(map.remove(2) == null);
|
|
assert(map.get(2) == null);
|
|
}
|
|
|
|
fn hash_i32(x: i32) -> u32 {
|
|
*@ptrCast(&u32, &x)
|
|
}
|
|
|
|
fn eql_i32(a: i32, b: i32) -> bool {
|
|
a == b
|
|
}
|