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stringtable.d
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stringtable.d
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/**
* Compiler implementation of the D programming language
* http://dlang.org
*
* Copyright: Copyright (C) 1999-2018 by The D Language Foundation, All Rights Reserved
* Authors: Walter Bright, http://www.digitalmars.com
* License: $(LINK2 http://www.boost.org/LICENSE_1_0.txt, Boost License 1.0)
* Source: $(LINK2 https://github.com/dlang/dmd/blob/master/src/dmd/root/stringtable.d, root/_stringtable.d)
* Documentation: https://dlang.org/phobos/dmd_root_stringtable.html
* Coverage: https://codecov.io/gh/dlang/dmd/src/master/src/dmd/root/stringtable.d
*/
module dmd.root.stringtable;
import core.stdc.string;
import dmd.root.rmem, dmd.root.hash;
enum POOL_BITS = 12;
enum POOL_SIZE = (1U << POOL_BITS);
private size_t nextpow2(size_t val) pure nothrow @nogc @safe
{
size_t res = 1;
while (res < val)
res <<= 1;
return res;
}
enum loadFactor = 0.8;
struct StringEntry
{
uint hash;
uint vptr;
}
// StringValue is a variable-length structure. It has neither proper c'tors nor a
// factory method because the only thing which should be creating these is StringTable.
struct StringValue
{
void* ptrvalue;
size_t length;
nothrow:
pure:
extern (C++) char* lstring()
{
return cast(char*)(&this + 1);
}
extern (C++) size_t len() const
{
return length;
}
extern (C++) const(char)* toDchars() const
{
return cast(const(char)*)(&this + 1);
}
}
struct StringTable
{
private:
StringEntry* table;
size_t tabledim;
ubyte** pools;
size_t npools;
size_t nfill;
size_t count;
public:
extern (C++) void _init(size_t size = 0) nothrow
{
size = nextpow2(cast(size_t)(size / loadFactor));
if (size < 32)
size = 32;
table = cast(StringEntry*)mem.xcalloc(size, (table[0]).sizeof);
tabledim = size;
pools = null;
npools = nfill = 0;
count = 0;
}
extern (C++) void reset(size_t size = 0) nothrow
{
for (size_t i = 0; i < npools; ++i)
mem.xfree(pools[i]);
mem.xfree(table);
mem.xfree(pools);
table = null;
pools = null;
_init(size);
}
extern (C++) ~this() nothrow
{
for (size_t i = 0; i < npools; ++i)
mem.xfree(pools[i]);
mem.xfree(table);
mem.xfree(pools);
table = null;
pools = null;
}
extern (C++) inout(StringValue)* lookup(const(char)* s, size_t length) inout nothrow pure
{
const(hash_t) hash = calcHash(s, length);
const(size_t) i = findSlot(hash, s, length);
// printf("lookup %.*s %p\n", (int)length, s, table[i].value ?: NULL);
return getValue(table[i].vptr);
}
extern (C++) StringValue* insert(const(char)* s, size_t length, void* ptrvalue) nothrow
{
const(hash_t) hash = calcHash(s, length);
size_t i = findSlot(hash, s, length);
if (table[i].vptr)
return null; // already in table
if (++count > tabledim * loadFactor)
{
grow();
i = findSlot(hash, s, length);
}
table[i].hash = hash;
table[i].vptr = allocValue(s, length, ptrvalue);
// printf("insert %.*s %p\n", (int)length, s, table[i].value ?: NULL);
return getValue(table[i].vptr);
}
extern (C++) StringValue* update(const(char)* s, size_t length) nothrow
{
const(hash_t) hash = calcHash(s, length);
size_t i = findSlot(hash, s, length);
if (!table[i].vptr)
{
if (++count > tabledim * loadFactor)
{
grow();
i = findSlot(hash, s, length);
}
table[i].hash = hash;
table[i].vptr = allocValue(s, length, null);
}
// printf("update %.*s %p\n", (int)length, s, table[i].value ?: NULL);
return getValue(table[i].vptr);
}
/********************************
* Walk the contents of the string table,
* calling fp for each entry.
* Params:
* fp = function to call. Returns !=0 to stop
* Returns:
* last return value of fp call
*/
extern (C++) int apply(int function(const(StringValue)*) fp)
{
foreach (const se; table[0 .. tabledim])
{
if (!se.vptr)
continue;
const sv = getValue(se.vptr);
int result = (*fp)(sv);
if (result)
return result;
}
return 0;
}
StringValue* update(const(char)[] name) nothrow
{
return update(name.ptr, name.length);
}
private:
nothrow:
uint allocValue(const(char)* s, size_t length, void* ptrvalue)
{
const(size_t) nbytes = StringValue.sizeof + length + 1;
if (!npools || nfill + nbytes > POOL_SIZE)
{
pools = cast(ubyte**)mem.xrealloc(pools, ++npools * (pools[0]).sizeof);
pools[npools - 1] = cast(ubyte*)mem.xmalloc(nbytes > POOL_SIZE ? nbytes : POOL_SIZE);
nfill = 0;
}
StringValue* sv = cast(StringValue*)&pools[npools - 1][nfill];
sv.ptrvalue = ptrvalue;
sv.length = length;
.memcpy(sv.lstring(), s, length);
sv.lstring()[length] = 0;
const(uint) vptr = cast(uint)(npools << POOL_BITS | nfill);
nfill += nbytes + (-nbytes & 7); // align to 8 bytes
return vptr;
}
inout(StringValue)* getValue(uint vptr) inout pure
{
if (!vptr)
return null;
const(size_t) idx = (vptr >> POOL_BITS) - 1;
const(size_t) off = vptr & POOL_SIZE - 1;
return cast(inout(StringValue)*)&pools[idx][off];
}
size_t findSlot(hash_t hash, const(char)* s, size_t length) const pure
{
// quadratic probing using triangular numbers
// http://stackoverflow.com/questions/2348187/moving-from-linear-probing-to-quadratic-probing-hash-collisons/2349774#2349774
for (size_t i = hash & (tabledim - 1), j = 1;; ++j)
{
const(StringValue)* sv;
auto vptr = table[i].vptr;
if (!vptr || table[i].hash == hash && (sv = getValue(vptr)).length == length && .memcmp(s, sv.toDchars(), length) == 0)
return i;
i = (i + j) & (tabledim - 1);
}
}
void grow()
{
const odim = tabledim;
auto otab = table;
tabledim *= 2;
table = cast(StringEntry*)mem.xcalloc(tabledim, (table[0]).sizeof);
foreach (const se; otab[0 .. odim])
{
if (!se.vptr)
continue;
const sv = getValue(se.vptr);
table[findSlot(se.hash, sv.toDchars(), sv.length)] = se;
}
mem.xfree(otab);
}
}