diff options
Diffstat (limited to 'xpcom/ds/nsStaticNameTable.cpp')
| -rw-r--r-- | xpcom/ds/nsStaticNameTable.cpp | 180 |
1 files changed, 180 insertions, 0 deletions
diff --git a/xpcom/ds/nsStaticNameTable.cpp b/xpcom/ds/nsStaticNameTable.cpp new file mode 100644 index 0000000000..2ee731c153 --- /dev/null +++ b/xpcom/ds/nsStaticNameTable.cpp @@ -0,0 +1,180 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ +/* vim: set ts=8 sts=2 et sw=2 tw=80: */ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +/* Class to manage lookup of static names in a table. */ + +#include "mozilla/HashFunctions.h" +#include "mozilla/TextUtils.h" + +#include "nsCRT.h" + +#include "nscore.h" +#include "nsISupportsImpl.h" + +#include "nsStaticNameTable.h" + +using namespace mozilla; + +struct NameTableKey { + NameTableKey(const nsDependentCString aNameArray[], const nsCString* aKeyStr) + : mNameArray(aNameArray), mIsUnichar(false) { + mKeyStr.m1b = aKeyStr; + } + + NameTableKey(const nsDependentCString aNameArray[], const nsString* aKeyStr) + : mNameArray(aNameArray), mIsUnichar(true) { + mKeyStr.m2b = aKeyStr; + } + + const nsDependentCString* mNameArray; + union { + const nsCString* m1b; + const nsString* m2b; + } mKeyStr; + bool mIsUnichar; +}; + +struct NameTableEntry : public PLDHashEntryHdr { + int32_t mIndex; +}; + +static bool matchNameKeysCaseInsensitive(const PLDHashEntryHdr* aHdr, + const void* aVoidKey) { + auto entry = static_cast<const NameTableEntry*>(aHdr); + auto key = static_cast<const NameTableKey*>(aVoidKey); + const nsDependentCString* name = &key->mNameArray[entry->mIndex]; + + return key->mIsUnichar ? key->mKeyStr.m2b->LowerCaseEqualsASCII( + name->get(), name->Length()) + : key->mKeyStr.m1b->LowerCaseEqualsASCII( + name->get(), name->Length()); +} + +/* + * caseInsensitiveHashKey is just like PLDHashTable::HashStringKey except it + * uses (*s & ~0x20) instead of simply *s. This means that "aFOO" and + * "afoo" and "aFoo" will all hash to the same thing. It also means + * that some strings that aren't case-insensensitively equal will hash + * to the same value, but it's just a hash function so it doesn't + * matter. + */ +static PLDHashNumber caseInsensitiveStringHashKey(const void* aKey) { + PLDHashNumber h = 0; + const NameTableKey* tableKey = static_cast<const NameTableKey*>(aKey); + if (tableKey->mIsUnichar) { + for (const char16_t* s = tableKey->mKeyStr.m2b->get(); *s != '\0'; s++) { + h = AddToHash(h, *s & ~0x20); + } + } else { + for (const unsigned char* s = reinterpret_cast<const unsigned char*>( + tableKey->mKeyStr.m1b->get()); + *s != '\0'; s++) { + h = AddToHash(h, *s & ~0x20); + } + } + return h; +} + +static const struct PLDHashTableOps nametable_CaseInsensitiveHashTableOps = { + caseInsensitiveStringHashKey, + matchNameKeysCaseInsensitive, + PLDHashTable::MoveEntryStub, + PLDHashTable::ClearEntryStub, + nullptr, +}; + +nsStaticCaseInsensitiveNameTable::nsStaticCaseInsensitiveNameTable( + const char* const aNames[], int32_t aLength) + : mNameArray(nullptr), + mNameTable(&nametable_CaseInsensitiveHashTableOps, sizeof(NameTableEntry), + aLength), + mNullStr("") { + MOZ_COUNT_CTOR(nsStaticCaseInsensitiveNameTable); + + MOZ_ASSERT(aNames, "null name table"); + MOZ_ASSERT(aLength, "0 length"); + + mNameArray = + (nsDependentCString*)moz_xmalloc(aLength * sizeof(nsDependentCString)); + + for (int32_t index = 0; index < aLength; ++index) { + const char* raw = aNames[index]; +#ifdef DEBUG + { + // verify invariants of contents + nsAutoCString temp1(raw); + nsDependentCString temp2(raw); + ToLowerCase(temp1); + MOZ_ASSERT(temp1.Equals(temp2), "upper case char in table"); + MOZ_ASSERT(IsAsciiNullTerminated(raw), + "non-ascii string in table -- " + "case-insensitive matching won't work right"); + } +#endif + // use placement-new to initialize the string object + nsDependentCString* strPtr = &mNameArray[index]; + new (strPtr) nsDependentCString(raw); + + NameTableKey key(mNameArray, strPtr); + + auto entry = static_cast<NameTableEntry*>(mNameTable.Add(&key, fallible)); + if (!entry) { + continue; + } + + // If the entry already exists it's unlikely but possible that its index is + // zero, in which case this assertion won't fail. But if the index is + // non-zero (highly likely) then it will fail. In other words, this + // assertion is likely but not guaranteed to detect if an entry is already + // used. + MOZ_ASSERT(entry->mIndex == 0, "Entry already exists!"); + + entry->mIndex = index; + } + mNameTable.MarkImmutable(); +} + +nsStaticCaseInsensitiveNameTable::~nsStaticCaseInsensitiveNameTable() { + // manually call the destructor on placement-new'ed objects + for (uint32_t index = 0; index < mNameTable.EntryCount(); index++) { + mNameArray[index].~nsDependentCString(); + } + free((void*)mNameArray); + MOZ_COUNT_DTOR(nsStaticCaseInsensitiveNameTable); +} + +int32_t nsStaticCaseInsensitiveNameTable::Lookup( + const nsACString& aName) const { + NS_ASSERTION(mNameArray, "not inited"); + + const nsCString& str = PromiseFlatCString(aName); + + NameTableKey key(mNameArray, &str); + auto entry = static_cast<NameTableEntry*>(mNameTable.Search(&key)); + + return entry ? entry->mIndex : nsStaticCaseInsensitiveNameTable::NOT_FOUND; +} + +int32_t nsStaticCaseInsensitiveNameTable::Lookup(const nsAString& aName) const { + NS_ASSERTION(mNameArray, "not inited"); + + const nsString& str = PromiseFlatString(aName); + + NameTableKey key(mNameArray, &str); + auto entry = static_cast<NameTableEntry*>(mNameTable.Search(&key)); + + return entry ? entry->mIndex : nsStaticCaseInsensitiveNameTable::NOT_FOUND; +} + +const nsCString& nsStaticCaseInsensitiveNameTable::GetStringValue( + int32_t aIndex) { + NS_ASSERTION(mNameArray, "not inited"); + + if ((NOT_FOUND < aIndex) && ((uint32_t)aIndex < mNameTable.EntryCount())) { + return mNameArray[aIndex]; + } + return mNullStr; +} |