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/* Copyright (C) 2010-2021 by The D Language Foundation, All Rights Reserved
* http://www.digitalmars.com
* Distributed under the Boost Software License, Version 1.0.
* (See accompanying file LICENSE or copy at http://www.boost.org/LICENSE_1_0.txt)
* https://github.com/D-Programming-Language/dmd/blob/master/src/root/aav.c
*/
/**
* Implementation of associative arrays.
*
*/
#include "dsystem.h"
#include "aav.h"
#include "rmem.h"
inline size_t hash(size_t a)
{
a ^= (a >> 20) ^ (a >> 12);
return a ^ (a >> 7) ^ (a >> 4);
}
struct aaA
{
aaA *next;
Key key;
Value value;
};
struct AA
{
aaA* *b;
size_t b_length;
size_t nodes; // total number of aaA nodes
aaA* binit[4]; // initial value of b[]
aaA aafirst; // a lot of these AA's have only one entry
};
/****************************************************
* Determine number of entries in associative array.
*/
size_t dmd_aaLen(AA* aa)
{
return aa ? aa->nodes : 0;
}
/*************************************************
* Get pointer to value in associative array indexed by key.
* Add entry for key if it is not already there, returning a pointer to a null Value.
* Create the associative array if it does not already exist.
*/
Value* dmd_aaGet(AA** paa, Key key)
{
//printf("paa = %p\n", paa);
if (!*paa)
{ AA *a = (AA *)mem.xmalloc(sizeof(AA));
a->b = (aaA**)a->binit;
a->b_length = 4;
a->nodes = 0;
a->binit[0] = NULL;
a->binit[1] = NULL;
a->binit[2] = NULL;
a->binit[3] = NULL;
*paa = a;
assert((*paa)->b_length == 4);
}
//printf("paa = %p, *paa = %p\n", paa, *paa);
assert((*paa)->b_length);
size_t i = hash((size_t)key) & ((*paa)->b_length - 1);
aaA** pe = &(*paa)->b[i];
aaA *e;
while ((e = *pe) != NULL)
{
if (key == e->key)
return &e->value;
pe = &e->next;
}
// Not found, create new elem
//printf("create new one\n");
size_t nodes = ++(*paa)->nodes;
e = (nodes != 1) ? (aaA *)mem.xmalloc(sizeof(aaA)) : &(*paa)->aafirst;
//e = new aaA();
e->next = NULL;
e->key = key;
e->value = NULL;
*pe = e;
//printf("length = %d, nodes = %d\n", (*paa)->b_length, nodes);
if (nodes > (*paa)->b_length * 2)
{
//printf("rehash\n");
dmd_aaRehash(paa);
}
return &e->value;
}
/*************************************************
* Get value in associative array indexed by key.
* Returns NULL if it is not already there.
*/
Value dmd_aaGetRvalue(AA* aa, Key key)
{
//printf("_aaGetRvalue(key = %p)\n", key);
if (aa)
{
size_t i;
size_t len = aa->b_length;
i = hash((size_t)key) & (len-1);
aaA* e = aa->b[i];
while (e)
{
if (key == e->key)
return e->value;
e = e->next;
}
}
return NULL; // not found
}
/********************************************
* Rehash an array.
*/
void dmd_aaRehash(AA** paa)
{
//printf("Rehash\n");
if (*paa)
{
AA *aa = *paa;
if (aa)
{
size_t len = aa->b_length;
if (len == 4)
len = 32;
else
len *= 4;
aaA** newb = (aaA**)mem.xmalloc(sizeof(aaA)*len);
memset(newb, 0, len * sizeof(aaA*));
for (size_t k = 0; k < aa->b_length; k++)
{ aaA *e = aa->b[k];
while (e)
{ aaA* enext = e->next;
size_t j = hash((size_t)e->key) & (len-1);
e->next = newb[j];
newb[j] = e;
e = enext;
}
}
if (aa->b != (aaA**)aa->binit)
mem.xfree(aa->b);
aa->b = newb;
aa->b_length = len;
}
}
}
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