379 lines
9.8 KiB
V
379 lines
9.8 KiB
V
// Copyright (c) 2019-2020 Alexander Medvednikov. All rights reserved.
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// Use of this source code is governed by an MIT license
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// that can be found in the LICENSE file.
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module builtin
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import (
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strings
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hash.wyhash
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)
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const (
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// Number of bits from the hash stored for each entry
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hashbits = 24
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// Number of bits from the hash stored for rehasing
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cached_hashbits = 16
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// Initial log-number of buckets in the hashtable
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init_log_capicity = 5
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// Initial number of buckets in the hashtable
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init_capicity = 1<<init_log_capicity
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// Initial load-factor
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init_load_factor = 0.8
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// Initial range cap
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init_range_cap = init_capicity - 1
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// Bitmask to select all the hashbits
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hash_mask = u32(0x00FFFFFF)
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// Used for incrementing the probe-count
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probe_inc = u32(0x01000000)
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// Bitmask for maximum probe count
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max_probe = u32(0xFF000000)
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)
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pub struct map {
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// Byte size of value
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value_bytes int
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mut:
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// Index of the highest index in the hashtable
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range_cap u32
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// Number of cached hashbits left for rehasing
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window byte
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// Used for right-shifting out used hashbits
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shift byte
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// Pointer to Key-value memory
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key_values &KeyValue
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// Pointer to probe_hash memory. Each Key-value has a
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// corresponding probe_hash-DWORD. Upper-bits are the
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// probe-count and lower-bits are bits from the hash.
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probe_hash &u32
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// Measure that decides when to increase the capacity
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load_factor f32
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pub mut:
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// Number of key-values currently in the hashmap
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size int
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}
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struct KeyValue {
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key string
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mut:
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value voidptr
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}
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fn new_map(n, value_bytes int) map {
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probe_hash_bytes := sizeof(u32) * init_capicity
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key_value_bytes := sizeof(KeyValue) * init_capicity
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memory := vcalloc(key_value_bytes + probe_hash_bytes)
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return map{
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value_bytes: value_bytes
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range_cap: init_range_cap
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shift: init_log_capicity
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window: cached_hashbits
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key_values: &KeyValue(memory)
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probe_hash: &u32(memory + key_value_bytes)
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load_factor: init_load_factor
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size: 0
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}
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}
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fn new_map_init(n, value_bytes int, keys &string, values voidptr) map {
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mut out := new_map(n, value_bytes)
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for i in 0 .. n {
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out.set(keys[i], values + i * value_bytes)
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}
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return out
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}
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fn (m mut map) set(key string, value voidptr) {
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// load_factor can be adjusted.
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if (f32(m.size) / f32(m.range_cap)) > m.load_factor {
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m.expand()
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}
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hash := wyhash.wyhash_c(key.str, u64(key.len), 0)
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mut probe_hash := u32(((hash>>m.shift) & hash_mask) | probe_inc)
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mut index := hash & m.range_cap
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// While probe count is less
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for probe_hash < m.probe_hash[index] {
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index = (index + 1) & m.range_cap
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probe_hash += probe_inc
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}
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// While we might have a match
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for probe_hash == m.probe_hash[index] {
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if key == m.key_values[index].key {
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C.memcpy(m.key_values[index].value, value, m.value_bytes)
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return
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}
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index = (index + 1) & m.range_cap
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probe_hash += probe_inc
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}
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// Match is not possible anymore.
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// Probe until an empty index is found.
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// Swap when probe count is higher/richer (Robin Hood).
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mut current_kv := KeyValue{
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key:key
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value:malloc(m.value_bytes)
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}
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C.memcpy(current_kv.value, value, m.value_bytes)
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for m.probe_hash[index] != 0 {
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if probe_hash > m.probe_hash[index] {
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// Swap probe_hash
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tmp_probe_hash := m.probe_hash[index]
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m.probe_hash[index] = probe_hash
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probe_hash = tmp_probe_hash
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// Swap KeyValue
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tmp_kv := m.key_values[index]
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m.key_values[index] = current_kv
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current_kv = tmp_kv
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}
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index = (index + 1) & m.range_cap
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probe_hash += probe_inc
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}
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// Should almost never happen
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if (probe_hash & max_probe) == max_probe {
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m.expand()
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m.set(current_kv.key, current_kv.value)
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return
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}
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m.probe_hash[index] = probe_hash
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m.key_values[index] = current_kv
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m.size++
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}
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fn (m mut map) expand() {
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old_range_cap := m.range_cap
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// double the size of the hashmap
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m.range_cap = ((m.range_cap + 1)<<1) - 1
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// check if no hashbits are left
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if m.window == 0 {
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m.shift += cached_hashbits
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m.rehash(old_range_cap)
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m.window = cached_hashbits
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}
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else {
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m.cached_rehash(old_range_cap)
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}
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m.window--
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}
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fn (m mut map) rehash(old_range_cap u32) {
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probe_hash_bytes := sizeof(u32) * (m.range_cap + 1)
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key_value_bytes := sizeof(KeyValue) * (m.range_cap + 1)
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memory := vcalloc(probe_hash_bytes + key_value_bytes)
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mut new_key_values := &KeyValue(memory)
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mut new_probe_hash := &u32(memory + key_value_bytes)
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for i := u32(0); i < old_range_cap + 1; i++ {
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if m.probe_hash[i] != 0 {
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mut kv := m.key_values[i]
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hash := wyhash.wyhash_c(kv.key.str, u64(kv.key.len), 0)
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mut probe_hash := u32(((hash>>m.shift) & hash_mask) | probe_inc)
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mut index := hash & m.range_cap
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// While probe count is less
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for probe_hash < new_probe_hash[index] {
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index = (index + 1) & m.range_cap
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probe_hash += probe_inc
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}
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// Probe until an empty index is found.
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// Swap when probe count is higher/richer (Robin Hood).
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for new_probe_hash[index] != 0 {
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if probe_hash > new_probe_hash[index] {
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// Swap probe_hash
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tmp_probe_hash := new_probe_hash[index]
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new_probe_hash[index] = probe_hash
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probe_hash = tmp_probe_hash
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// Swap KeyValue
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tmp_kv := new_key_values[index]
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new_key_values[index] = kv
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kv = tmp_kv
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}
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index = (index + 1) & m.range_cap
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probe_hash += probe_inc
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}
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// Should almost never happen
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if (probe_hash & max_probe) == max_probe {
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m.expand()
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m.set(kv.key, kv.value)
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return
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}
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new_probe_hash[index] = probe_hash
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new_key_values[index] = kv
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}
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}
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unsafe{
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free(m.key_values)
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}
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m.key_values = new_key_values
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m.probe_hash = new_probe_hash
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}
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fn (m mut map) cached_rehash(old_range_cap u32) {
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probe_hash_bytes := sizeof(u32) * (m.range_cap + 1)
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key_value_bytes := sizeof(KeyValue) * (m.range_cap + 1)
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memory := vcalloc(probe_hash_bytes + key_value_bytes)
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mut new_probe_hash := &u32(memory + key_value_bytes)
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mut new_key_values := &KeyValue(memory)
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for i := u32(0); i < old_range_cap + 1; i++ {
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if m.probe_hash[i] != 0 {
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mut kv := m.key_values[i]
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mut probe_hash := m.probe_hash[i]
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original := u64(i - ((probe_hash>>hashbits) - 1)) & (m.range_cap>>1)
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hash := original | (probe_hash<<m.shift)
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probe_hash = (probe_hash & hash_mask) | probe_inc
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mut index := hash & m.range_cap
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// While probe count is less
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for probe_hash < new_probe_hash[index] {
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index = (index + 1) & m.range_cap
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probe_hash += probe_inc
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}
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// Probe until an empty index is found.
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// Swap when probe count is higher/richer (Robin Hood).
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for new_probe_hash[index] != 0 {
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if probe_hash > new_probe_hash[index] {
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// Swap probe_hash
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tmp_probe_hash := new_probe_hash[index]
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new_probe_hash[index] = probe_hash
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probe_hash = tmp_probe_hash
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// Swap KeyValue
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tmp_kv := new_key_values[index]
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new_key_values[index] = kv
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kv = tmp_kv
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}
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index = (index + 1) & m.range_cap
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probe_hash += probe_inc
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}
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// Should almost never happen
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if (probe_hash & max_probe) == max_probe {
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m.expand()
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m.set(kv.key, kv.value)
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return
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}
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new_probe_hash[index] = probe_hash
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new_key_values[index] = kv
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}
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}
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unsafe{
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free(m.key_values)
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}
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m.key_values = new_key_values
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m.probe_hash = new_probe_hash
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}
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pub fn (m mut map) delete(key string) {
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hash := wyhash.wyhash_c(key.str, u64(key.len), 0)
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mut index := hash & m.range_cap
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mut probe_hash := u32(((hash>>m.shift) & hash_mask) | probe_inc)
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for probe_hash < m.probe_hash[index] {
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index = (index + 1) & m.range_cap
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probe_hash += probe_inc
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}
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// Perform backwards shifting
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for probe_hash == m.probe_hash[index] {
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if key == m.key_values[index].key {
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mut old_index := index
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index = (index + 1) & m.range_cap
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mut current_probe_hash := m.probe_hash[index]
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for (current_probe_hash>>hashbits) > 1 {
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m.probe_hash[old_index] = current_probe_hash - probe_inc
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m.key_values[old_index] = m.key_values[index]
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old_index = index
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index = (index + 1) & m.range_cap
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current_probe_hash = m.probe_hash[index]
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}
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m.probe_hash[old_index] = 0
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m.size--
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return
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}
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index = (index + 1) & m.range_cap
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probe_hash += probe_inc
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}
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}
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fn (m map) get(key string, out voidptr) bool {
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hash := wyhash.wyhash_c(key.str, u64(key.len), 0)
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mut index := hash & m.range_cap
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mut probe_hash := u32(((hash>>m.shift) & hash_mask) | probe_inc)
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for probe_hash < m.probe_hash[index] {
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index = (index + 1) & m.range_cap
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probe_hash += probe_inc
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}
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for probe_hash == m.probe_hash[index] {
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if key == m.key_values[index].key {
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C.memcpy(out, m.key_values[index].value, m.value_bytes)
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return true
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}
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index = (index + 1) & m.range_cap
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probe_hash += probe_inc
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}
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return false
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}
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fn (m map) exists(key string) bool {
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if m.value_bytes == 0 {
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return false
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}
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hash := wyhash.wyhash_c(key.str, u64(key.len), 0)
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mut index := hash & m.range_cap
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mut probe_hash := u32(((hash>>m.shift) & hash_mask) | probe_inc)
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for probe_hash < m.probe_hash[index] {
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index = (index + 1) & m.range_cap
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probe_hash += probe_inc
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}
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for probe_hash == m.probe_hash[index] {
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if key == m.key_values[index].key {
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return true
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}
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index = (index + 1) & m.range_cap
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probe_hash += probe_inc
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}
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return false
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}
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pub fn (m &map) keys() []string {
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mut keys := [''].repeat(m.size)
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//mut keys := []string{len: m.size}
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if m.value_bytes == 0 {
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return keys
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}
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mut j := 0
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for i := u32(0); i < m.range_cap + 1; i++ {
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if m.probe_hash[i] != 0 {
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keys[j] = m.key_values[i].key
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j++
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}
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}
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return keys
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}
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pub fn (m mut map) set_load_factor(new_load_factor f32) {
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if new_load_factor > 1.0 {
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m.load_factor = 1.0
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}
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else if new_load_factor < 0.1 {
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m.load_factor = 0.1
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}
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else {
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m.load_factor = new_load_factor
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}
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}
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pub fn (m mut map) free() {
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unsafe{
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free(m.key_values)
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}
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}
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pub fn (m map) print() {
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println('TODO')
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}
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pub fn (m map_string) str() string {
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if m.size == 0 {
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return '{}'
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}
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mut sb := strings.new_builder(50)
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sb.writeln('{')
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for key, val in m {
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sb.writeln(' "$key" => "$val"')
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}
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sb.writeln('}')
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return sb.str()
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}
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