gecko-dev/xpcom/ds/nsDoubleHashtable.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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 * The Original Code is Mozilla Communicator client code.
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#include "nsDoubleHashtable.h"
#include "nsISupports.h"
#include "nsString.h"
#include "nsReadableUtils.h"

//
// KEY String
//
class PLDHashStringEntry : public PLDHashEntryHdr
{
public:
  PLDHashStringEntry(const nsAString& aString) :
    mKey(aString) { }

  nsString mKey;
};

PR_STATIC_CALLBACK(const void *)
PLDHashStringGetKey(PLDHashTable *table, PLDHashEntryHdr *entry)
{
  PLDHashStringEntry *e = NS_STATIC_CAST(PLDHashStringEntry *, entry);

  return NS_STATIC_CAST(const nsAString *, &e->mKey);
}

PR_STATIC_CALLBACK(PLDHashNumber)
PLDHashStringHashKey(PLDHashTable *table, const void *key)
{
  const nsAString *str = NS_STATIC_CAST(const nsAString *, key);

  return HashString(*str);
}

PR_STATIC_CALLBACK(PRBool)
PLDHashStringMatchEntry(PLDHashTable *table, const PLDHashEntryHdr *entry,
                        const void *key)
{
  const PLDHashStringEntry *e =
    NS_STATIC_CAST(const PLDHashStringEntry *, entry);
  const nsAString *str = NS_STATIC_CAST(const nsAString *, key);

  return str->Equals(e->mKey);
}

//
// ENTRY StringSupports
//
class PLDHashStringSupportsEntry : public PLDHashStringEntry
{
public:
  PLDHashStringSupportsEntry(const nsAString& aString) :
    PLDHashStringEntry(aString)
  {
  }
  ~PLDHashStringSupportsEntry() {
  }
  nsCOMPtr<nsISupports> mVal;
};

PR_STATIC_CALLBACK(void)
PLDHashStringSupportsClearEntry(PLDHashTable *table, PLDHashEntryHdr *entry)
{
  PLDHashStringSupportsEntry *e = NS_STATIC_CAST(PLDHashStringSupportsEntry *,
                                                 entry);
  // An entry is being cleared, let the entry down its own cleanup.
  e->~PLDHashStringSupportsEntry();
}

PR_STATIC_CALLBACK(void)
PLDHashStringSupportsInitEntry(PLDHashTable *table, PLDHashEntryHdr *entry,
                           const void *key)
{
  const nsAString *keyStr = NS_STATIC_CAST(const nsAString *, key);
  // Initialize the entry with placement new
  new (entry) PLDHashStringSupportsEntry(*keyStr);
}


#define INIT_STRING_HASH(_HASHNAME_) \
static PLDHashTableOps hash_table_ops = \
{ \
  PL_DHashAllocTable, \
  PL_DHashFreeTable, \
  PLDHashStringGetKey, \
  PLDHashStringHashKey, \
  PLDHashStringMatchEntry, \
  PL_DHashMoveEntryStub, \
  _HASHNAME_##ClearEntry, \
  PL_DHashFinalizeStub, \
  _HASHNAME_##InitEntry \
}; \
if (!mHashTable.ops) { \
  PRBool isLive = PL_DHashTableInit(&mHashTable, \
                                    &hash_table_ops, nsnull, \
                                    sizeof(_HASHNAME_##Entry), 16); \
  if (!isLive) { \
    mHashTable.ops = nsnull; \
    return NS_ERROR_OUT_OF_MEMORY; \
  } \
}


//
// HASH StringSupports
//
nsDoubleHashtableStringSupports::nsDoubleHashtableStringSupports()
{
  // MUST init mHashTable.ops to nsnull so that we can detect that the
  // hashtable has not been initialized.
  mHashTable.ops = nsnull;
};

nsDoubleHashtableStringSupports::~nsDoubleHashtableStringSupports()
{
  if (mHashTable.ops) {
    PL_DHashTableFinish(&mHashTable);
  }
}

nsresult
nsDoubleHashtableStringSupports::Init()
{
  INIT_STRING_HASH(PLDHashStringSupports)
  return NS_OK;
}

already_AddRefed<nsISupports>
nsDoubleHashtableStringSupports::Get(const nsAString& aKey)
{
  PLDHashStringSupportsEntry * entry =
    NS_STATIC_CAST(PLDHashStringSupportsEntry *,
                   PL_DHashTableOperate(&mHashTable, &aKey,
                                        PL_DHASH_LOOKUP));
  if (!PL_DHASH_ENTRY_IS_LIVE(entry)) {
    return nsnull;
  }

  nsISupports* supports = entry->mVal;
  NS_IF_ADDREF(supports);
  return supports;
}

nsresult
nsDoubleHashtableStringSupports::Put(const nsAString& aKey,
                                     nsISupports* aResult)
{
  PLDHashStringSupportsEntry * entry =
    NS_STATIC_CAST(PLDHashStringSupportsEntry *,
                   PL_DHashTableOperate(&mHashTable, &aKey,
                                        PL_DHASH_ADD));

  NS_ENSURE_TRUE(entry, NS_ERROR_OUT_OF_MEMORY);

  //
  // Add the entry
  //
  entry->mVal = aResult;

  return NS_OK;
}

nsresult
nsDoubleHashtableStringSupports::Remove(nsAString& aKey)
{
  PL_DHashTableOperate(&mHashTable, &aKey, PL_DHASH_REMOVE);
  return NS_OK;
}