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Now uses the benefits of shared strings to simplify the hash table for value lookups.

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Added a more compact way of storing shared string hash chains.

git-svn-id: http://picoc.googlecode.com/svn/trunk@44 21eae674-98b7-11dd-bd71-f92a316d2d60
This commit is contained in:
zik.saleeba 2009-02-02 03:25:15 +00:00
parent 86af5318da
commit a9a93f3aa4
1 changed files with 35 additions and 20 deletions
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55
table.c
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@ -20,14 +20,14 @@ void TableInit(struct Table *Tbl, struct TableEntry **HashTable, int Size, int O
} }
/* check a hash table entry for a key */ /* check a hash table entry for a key */
static int TableSearch(struct Table *Tbl, const char *Key, int Len, int *AddAt) static int TableSearch(struct Table *Tbl, const char *Key, int *AddAt)
{ {
struct TableEntry *Entry; struct TableEntry *Entry;
int HashValue = TableHash(Key, Len) % Tbl->Size; int HashValue = ((unsigned long)Key) % Tbl->Size;
for (Entry = Tbl->HashTable[HashValue]; Entry != NULL; Entry = Entry->Next) for (Entry = Tbl->HashTable[HashValue]; Entry != NULL; Entry = Entry->Next)
{ {
if (strncmp(Entry->Key, Key, Len) == 0 && Entry->Key[Len] == '\0') if (Entry->p.v.Key == Key)
return HashValue; /* found */ return HashValue; /* found */
} }
@ -35,18 +35,18 @@ static int TableSearch(struct Table *Tbl, const char *Key, int Len, int *AddAt)
return -1; return -1;
} }
/* set an identifier to a value. returns FALSE if it already exists */ /* set an identifier to a value. returns FALSE if it already exists.
* Key must be a shared string from StrRegister() */
int TableSet(struct Table *Tbl, const char *Key, struct Value *Val) int TableSet(struct Table *Tbl, const char *Key, struct Value *Val)
{ {
int AddAt; int AddAt;
int KeyLen = strlen(Key); int HashPos = TableSearch(Tbl, Key, &AddAt);
int HashPos = TableSearch(Tbl, Key, KeyLen, &AddAt);
if (HashPos == -1) if (HashPos == -1)
{ /* add it to the table */ { /* add it to the table */
struct TableEntry *NewEntry = VariableAlloc(NULL, sizeof(struct TableEntry), Tbl->OnHeap); struct TableEntry *NewEntry = VariableAlloc(NULL, sizeof(struct TableEntry), Tbl->OnHeap);
NewEntry->Key = Key; NewEntry->p.v.Key = Key;
NewEntry->Val = Val; NewEntry->p.v.Val = Val;
NewEntry->Next = Tbl->HashTable[AddAt]; NewEntry->Next = Tbl->HashTable[AddAt];
Tbl->HashTable[AddAt] = NewEntry; Tbl->HashTable[AddAt] = NewEntry;
return TRUE; return TRUE;
@ -55,34 +55,49 @@ int TableSet(struct Table *Tbl, const char *Key, struct Value *Val)
return FALSE; return FALSE;
} }
/* find a value in a table. returns FALSE if not found */ /* find a value in a table. returns FALSE if not found.
* Key must be a shared string from StrRegister() */
int TableGet(struct Table *Tbl, const char *Key, struct Value **Val) int TableGet(struct Table *Tbl, const char *Key, struct Value **Val)
{ {
int AddAt; int AddAt;
int HashPos = TableSearch(Tbl, Key, strlen(Key), &AddAt); int HashPos = TableSearch(Tbl, Key, &AddAt);
if (HashPos == -1) if (HashPos == -1)
return FALSE; return FALSE;
*Val = Tbl->HashTable[HashPos]->Val; *Val = Tbl->HashTable[HashPos]->p.v.Val;
return TRUE; return TRUE;
} }
/* check a hash table entry for an identifier */
static int TableSearchIdentifier(struct Table *Tbl, const char *Key, int Len, int *AddAt)
{
struct TableEntry *Entry;
int HashValue = TableHash(Key, Len) % Tbl->Size;
for (Entry = Tbl->HashTable[HashValue]; Entry != NULL; Entry = Entry->Next)
{
if (strncmp(Entry->p.Key, Key, Len) == 0 && Entry->p.Key[Len] == '\0')
return HashValue; /* found */
}
*AddAt = HashValue; /* didn't find it in the chain */
return -1;
}
/* set an identifier and return the identifier. share if possible */ /* set an identifier and return the identifier. share if possible */
const char *TableSetKey(struct Table *Tbl, const char *Ident, int IdentLen) const char *TableSetIdentifier(struct Table *Tbl, const char *Ident, int IdentLen)
{ {
int AddAt; int AddAt;
int HashPos = TableSearch(Tbl, Ident, IdentLen, &AddAt); int HashPos = TableSearchIdentifier(Tbl, Ident, IdentLen, &AddAt);
if (HashPos != -1) if (HashPos != -1)
return Tbl->HashTable[HashPos]->Key; return Tbl->HashTable[HashPos]->p.Key;
else else
{ /* add it to the table */ { /* add it to the table - we economise by not allocating the whole structure here */
struct TableEntry *NewEntry = HeapAlloc(sizeof(struct TableEntry) + IdentLen + 1); struct TableEntry *NewEntry = HeapAlloc(sizeof(struct TableEntry *) + IdentLen + 1);
NewEntry->Key = (void *)NewEntry + sizeof(struct TableEntry); strncpy((char *)NewEntry->p.Key, Ident, IdentLen);
strncpy((char *)NewEntry->Key, Ident, IdentLen);
NewEntry->Val = NULL;
NewEntry->Next = Tbl->HashTable[AddAt]; NewEntry->Next = Tbl->HashTable[AddAt];
Tbl->HashTable[AddAt] = NewEntry; Tbl->HashTable[AddAt] = NewEntry;
return NewEntry->Key; return NewEntry->p.Key;
} }
} }