gecko/xpcom/ds/nsPersistentProperties.cpp
Nicholas Nethercote c2df231328 Bug 1174625 - Overhaul PLDHashTable's iterator. r=froydnj.
This change splits PLDHashTable::Iterator::NextEntry() into two separate
functions, which allow you to get the current element and advance the iterator
separately, which means you can use a for-loop to iterate instead of a
while-loop.

As part of this change, the internals of PLDHashTable::Iterator were
significantly changed and simplified (and modelled after js::HashTable's
equivalent code). It's no longer duplicating code from PL_DHashTableEnumerator.
The chaos mode code was a casualty of this, but given how unreliable that code
has proven to be (see bug 1173212, bug 1174046) this is for the best. (We can
reimplement chaos mode once PLDHashTable::Iterator is back on more solid
footing again, if we think it's important.)

All these changes will make it much easier to add an alternative Iterator that
removes elements, which was turning out to be difficult with the prior code.

In order to make the for-loop header usually fit on a single line, I
deliberately renamed a bunch of things to have shorter names.

In summary, you used to write this:

  PLDHashTable::Iterator iter(&table);
  while (iter.HasMoreEntries()) {
    auto entry = static_cast<FooEntry*>(iter.NextEntry());
    // ... do stuff with |entry| ...
  }
  // iter's scope extends beyond here

and now you write this:

  for (auto iter = table.Iter(); !iter.Done(); iter.Next()) {
    auto entry = static_cast<FooEntry*>(iter.Get());
    // ... do stuff with |entry| ...
  }
  // iter's scope doesn't reach here
2015-06-11 21:19:53 -07:00

670 lines
19 KiB
C++

/* -*- 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/. */
#include "nsArrayEnumerator.h"
#include "nsID.h"
#include "nsCOMArray.h"
#include "nsUnicharInputStream.h"
#include "nsPrintfCString.h"
#include "nsAutoPtr.h"
#define PL_ARENA_CONST_ALIGN_MASK 3
#include "nsPersistentProperties.h"
#include "nsIProperties.h"
struct PropertyTableEntry : public PLDHashEntryHdr
{
// both of these are arena-allocated
const char* mKey;
const char16_t* mValue;
};
static char16_t*
ArenaStrdup(const nsAFlatString& aString, PLArenaPool* aArena)
{
void* mem;
// add one to include the null terminator
int32_t len = (aString.Length() + 1) * sizeof(char16_t);
PL_ARENA_ALLOCATE(mem, aArena, len);
NS_ASSERTION(mem, "Couldn't allocate space!\n");
if (mem) {
memcpy(mem, aString.get(), len);
}
return static_cast<char16_t*>(mem);
}
static char*
ArenaStrdup(const nsAFlatCString& aString, PLArenaPool* aArena)
{
void* mem;
// add one to include the null terminator
int32_t len = (aString.Length() + 1) * sizeof(char);
PL_ARENA_ALLOCATE(mem, aArena, len);
NS_ASSERTION(mem, "Couldn't allocate space!\n");
if (mem) {
memcpy(mem, aString.get(), len);
}
return static_cast<char*>(mem);
}
static const struct PLDHashTableOps property_HashTableOps = {
PL_DHashStringKey,
PL_DHashMatchStringKey,
PL_DHashMoveEntryStub,
PL_DHashClearEntryStub,
nullptr,
};
//
// parser stuff
//
enum EParserState
{
eParserState_AwaitingKey,
eParserState_Key,
eParserState_AwaitingValue,
eParserState_Value,
eParserState_Comment
};
enum EParserSpecial
{
eParserSpecial_None, // not parsing a special character
eParserSpecial_Escaped, // awaiting a special character
eParserSpecial_Unicode // parsing a \Uxxx value
};
class MOZ_STACK_CLASS nsPropertiesParser
{
public:
explicit nsPropertiesParser(nsIPersistentProperties* aProps)
: mHaveMultiLine(false)
, mState(eParserState_AwaitingKey)
, mProps(aProps)
{
}
void FinishValueState(nsAString& aOldValue)
{
static const char trimThese[] = " \t";
mKey.Trim(trimThese, false, true);
// This is really ugly hack but it should be fast
char16_t backup_char;
uint32_t minLength = mMinLength;
if (minLength) {
backup_char = mValue[minLength - 1];
mValue.SetCharAt('x', minLength - 1);
}
mValue.Trim(trimThese, false, true);
if (minLength) {
mValue.SetCharAt(backup_char, minLength - 1);
}
mProps->SetStringProperty(NS_ConvertUTF16toUTF8(mKey), mValue, aOldValue);
mSpecialState = eParserSpecial_None;
WaitForKey();
}
EParserState GetState() { return mState; }
static NS_METHOD SegmentWriter(nsIUnicharInputStream* aStream,
void* aClosure,
const char16_t* aFromSegment,
uint32_t aToOffset,
uint32_t aCount,
uint32_t* aWriteCount);
nsresult ParseBuffer(const char16_t* aBuffer, uint32_t aBufferLength);
private:
bool ParseValueCharacter(
char16_t aChar, // character that is just being parsed
const char16_t* aCur, // pointer to character aChar in the buffer
const char16_t*& aTokenStart, // string copying is done in blocks as big as
// possible, aTokenStart points to the beginning
// of this block
nsAString& aOldValue); // when duplicate property is found, new value
// is stored into hashtable and the old one is
// placed in this variable
void WaitForKey()
{
mState = eParserState_AwaitingKey;
}
void EnterKeyState()
{
mKey.Truncate();
mState = eParserState_Key;
}
void WaitForValue()
{
mState = eParserState_AwaitingValue;
}
void EnterValueState()
{
mValue.Truncate();
mMinLength = 0;
mState = eParserState_Value;
mSpecialState = eParserSpecial_None;
}
void EnterCommentState()
{
mState = eParserState_Comment;
}
nsAutoString mKey;
nsAutoString mValue;
uint32_t mUnicodeValuesRead; // should be 4!
char16_t mUnicodeValue; // currently parsed unicode value
bool mHaveMultiLine; // is TRUE when last processed characters form
// any of following sequences:
// - "\\\r"
// - "\\\n"
// - "\\\r\n"
// - any sequence above followed by any
// combination of ' ' and '\t'
bool mMultiLineCanSkipN; // TRUE if "\\\r" was detected
uint32_t mMinLength; // limit right trimming at the end to not trim
// escaped whitespaces
EParserState mState;
// if we see a '\' then we enter this special state
EParserSpecial mSpecialState;
nsCOMPtr<nsIPersistentProperties> mProps;
};
inline bool
IsWhiteSpace(char16_t aChar)
{
return (aChar == ' ') || (aChar == '\t') ||
(aChar == '\r') || (aChar == '\n');
}
inline bool
IsEOL(char16_t aChar)
{
return (aChar == '\r') || (aChar == '\n');
}
bool
nsPropertiesParser::ParseValueCharacter(char16_t aChar, const char16_t* aCur,
const char16_t*& aTokenStart,
nsAString& aOldValue)
{
switch (mSpecialState) {
// the normal state - look for special characters
case eParserSpecial_None:
switch (aChar) {
case '\\':
if (mHaveMultiLine) {
// there is nothing to append to mValue yet
mHaveMultiLine = false;
} else {
mValue += Substring(aTokenStart, aCur);
}
mSpecialState = eParserSpecial_Escaped;
break;
case '\n':
// if we detected multiline and got only "\\\r" ignore next "\n" if any
if (mHaveMultiLine && mMultiLineCanSkipN) {
// but don't allow another '\n' to be skipped
mMultiLineCanSkipN = false;
// Now there is nothing to append to the mValue since we are skipping
// whitespaces at the beginning of the new line of the multiline
// property. Set aTokenStart properly to ensure that nothing is appended
// if we find regular line-end or the end of the buffer.
aTokenStart = aCur + 1;
break;
}
// no break
case '\r':
// we're done! We have a key and value
mValue += Substring(aTokenStart, aCur);
FinishValueState(aOldValue);
mHaveMultiLine = false;
break;
default:
// there is nothing to do with normal characters,
// but handle multilines correctly
if (mHaveMultiLine) {
if (aChar == ' ' || aChar == '\t') {
// don't allow another '\n' to be skipped
mMultiLineCanSkipN = false;
// Now there is nothing to append to the mValue since we are skipping
// whitespaces at the beginning of the new line of the multiline
// property. Set aTokenStart properly to ensure that nothing is appended
// if we find regular line-end or the end of the buffer.
aTokenStart = aCur + 1;
break;
}
mHaveMultiLine = false;
aTokenStart = aCur;
}
break; // from switch on (aChar)
}
break; // from switch on (mSpecialState)
// saw a \ character, so parse the character after that
case eParserSpecial_Escaped:
// probably want to start parsing at the next token
// other characters, like 'u' might override this
aTokenStart = aCur + 1;
mSpecialState = eParserSpecial_None;
switch (aChar) {
// the easy characters - \t, \n, and so forth
case 't':
mValue += char16_t('\t');
mMinLength = mValue.Length();
break;
case 'n':
mValue += char16_t('\n');
mMinLength = mValue.Length();
break;
case 'r':
mValue += char16_t('\r');
mMinLength = mValue.Length();
break;
case '\\':
mValue += char16_t('\\');
break;
// switch to unicode mode!
case 'u':
case 'U':
mSpecialState = eParserSpecial_Unicode;
mUnicodeValuesRead = 0;
mUnicodeValue = 0;
break;
// a \ immediately followed by a newline means we're going multiline
case '\r':
case '\n':
mHaveMultiLine = true;
mMultiLineCanSkipN = (aChar == '\r');
mSpecialState = eParserSpecial_None;
break;
default:
// don't recognize the character, so just append it
mValue += aChar;
break;
}
break;
// we're in the middle of parsing a 4-character unicode value
// like \u5f39
case eParserSpecial_Unicode:
if ('0' <= aChar && aChar <= '9') {
mUnicodeValue =
(mUnicodeValue << 4) | (aChar - '0');
} else if ('a' <= aChar && aChar <= 'f') {
mUnicodeValue =
(mUnicodeValue << 4) | (aChar - 'a' + 0x0a);
} else if ('A' <= aChar && aChar <= 'F') {
mUnicodeValue =
(mUnicodeValue << 4) | (aChar - 'A' + 0x0a);
} else {
// non-hex character. Append what we have, and move on.
mValue += mUnicodeValue;
mMinLength = mValue.Length();
mSpecialState = eParserSpecial_None;
// leave aTokenStart at this unknown character, so it gets appended
aTokenStart = aCur;
// ensure parsing this non-hex character again
return false;
}
if (++mUnicodeValuesRead >= 4) {
aTokenStart = aCur + 1;
mSpecialState = eParserSpecial_None;
mValue += mUnicodeValue;
mMinLength = mValue.Length();
}
break;
}
return true;
}
NS_METHOD
nsPropertiesParser::SegmentWriter(nsIUnicharInputStream* aStream,
void* aClosure,
const char16_t* aFromSegment,
uint32_t aToOffset,
uint32_t aCount,
uint32_t* aWriteCount)
{
nsPropertiesParser* parser = static_cast<nsPropertiesParser*>(aClosure);
parser->ParseBuffer(aFromSegment, aCount);
*aWriteCount = aCount;
return NS_OK;
}
nsresult
nsPropertiesParser::ParseBuffer(const char16_t* aBuffer,
uint32_t aBufferLength)
{
const char16_t* cur = aBuffer;
const char16_t* end = aBuffer + aBufferLength;
// points to the start/end of the current key or value
const char16_t* tokenStart = nullptr;
// if we're in the middle of parsing a key or value, make sure
// the current token points to the beginning of the current buffer
if (mState == eParserState_Key ||
mState == eParserState_Value) {
tokenStart = aBuffer;
}
nsAutoString oldValue;
while (cur != end) {
char16_t c = *cur;
switch (mState) {
case eParserState_AwaitingKey:
if (c == '#' || c == '!') {
EnterCommentState();
}
else if (!IsWhiteSpace(c)) {
// not a comment, not whitespace, we must have found a key!
EnterKeyState();
tokenStart = cur;
}
break;
case eParserState_Key:
if (c == '=' || c == ':') {
mKey += Substring(tokenStart, cur);
WaitForValue();
}
break;
case eParserState_AwaitingValue:
if (IsEOL(c)) {
// no value at all! mimic the normal value-ending
EnterValueState();
FinishValueState(oldValue);
}
// ignore white space leading up to the value
else if (!IsWhiteSpace(c)) {
tokenStart = cur;
EnterValueState();
// make sure to handle this first character
if (ParseValueCharacter(c, cur, tokenStart, oldValue)) {
cur++;
}
// If the character isn't consumed, don't do cur++ and parse
// the character again. This can happen f.e. for char 'X' in sequence
// "\u00X". This character can be control character and must be
// processed again.
continue;
}
break;
case eParserState_Value:
if (ParseValueCharacter(c, cur, tokenStart, oldValue)) {
cur++;
}
// See few lines above for reason of doing this
continue;
case eParserState_Comment:
// stay in this state till we hit EOL
if (c == '\r' || c == '\n') {
WaitForKey();
}
break;
}
// finally, advance to the next character
cur++;
}
// if we're still parsing the value and are in eParserSpecial_None, then
// append whatever we have..
if (mState == eParserState_Value && tokenStart &&
mSpecialState == eParserSpecial_None) {
mValue += Substring(tokenStart, cur);
}
// if we're still parsing the key, then append whatever we have..
else if (mState == eParserState_Key && tokenStart) {
mKey += Substring(tokenStart, cur);
}
return NS_OK;
}
nsPersistentProperties::nsPersistentProperties()
: mIn(nullptr)
, mTable(&property_HashTableOps, sizeof(PropertyTableEntry), 16)
{
PL_INIT_ARENA_POOL(&mArena, "PersistentPropertyArena", 2048);
}
nsPersistentProperties::~nsPersistentProperties()
{
PL_FinishArenaPool(&mArena);
}
nsresult
nsPersistentProperties::Create(nsISupports* aOuter, REFNSIID aIID,
void** aResult)
{
if (aOuter) {
return NS_ERROR_NO_AGGREGATION;
}
nsRefPtr<nsPersistentProperties> props = new nsPersistentProperties();
return props->QueryInterface(aIID, aResult);
}
NS_IMPL_ISUPPORTS(nsPersistentProperties, nsIPersistentProperties, nsIProperties)
NS_IMETHODIMP
nsPersistentProperties::Load(nsIInputStream* aIn)
{
nsresult rv = nsSimpleUnicharStreamFactory::GetInstance()->
CreateInstanceFromUTF8Stream(aIn, getter_AddRefs(mIn));
if (rv != NS_OK) {
NS_WARNING("Error creating UnicharInputStream");
return NS_ERROR_FAILURE;
}
nsPropertiesParser parser(this);
uint32_t nProcessed;
// If this 4096 is changed to some other value, make sure to adjust
// the bug121341.properties test file accordingly.
while (NS_SUCCEEDED(rv = mIn->ReadSegments(nsPropertiesParser::SegmentWriter,
&parser, 4096, &nProcessed)) &&
nProcessed != 0);
mIn = nullptr;
if (NS_FAILED(rv)) {
return rv;
}
// We may have an unprocessed value at this point
// if the last line did not have a proper line ending.
if (parser.GetState() == eParserState_Value) {
nsAutoString oldValue;
parser.FinishValueState(oldValue);
}
return NS_OK;
}
NS_IMETHODIMP
nsPersistentProperties::SetStringProperty(const nsACString& aKey,
const nsAString& aNewValue,
nsAString& aOldValue)
{
const nsAFlatCString& flatKey = PromiseFlatCString(aKey);
PropertyTableEntry* entry = static_cast<PropertyTableEntry*>(
PL_DHashTableAdd(&mTable, flatKey.get(), mozilla::fallible));
if (entry->mKey) {
aOldValue = entry->mValue;
NS_WARNING(nsPrintfCString("the property %s already exists\n",
flatKey.get()).get());
} else {
aOldValue.Truncate();
}
entry->mKey = ArenaStrdup(flatKey, &mArena);
entry->mValue = ArenaStrdup(PromiseFlatString(aNewValue), &mArena);
return NS_OK;
}
NS_IMETHODIMP
nsPersistentProperties::Save(nsIOutputStream* aOut, const nsACString& aHeader)
{
return NS_ERROR_NOT_IMPLEMENTED;
}
NS_IMETHODIMP
nsPersistentProperties::GetStringProperty(const nsACString& aKey,
nsAString& aValue)
{
const nsAFlatCString& flatKey = PromiseFlatCString(aKey);
PropertyTableEntry* entry = static_cast<PropertyTableEntry*>(
PL_DHashTableSearch(&mTable, flatKey.get()));
if (!entry) {
return NS_ERROR_FAILURE;
}
aValue = entry->mValue;
return NS_OK;
}
NS_IMETHODIMP
nsPersistentProperties::Enumerate(nsISimpleEnumerator** aResult)
{
nsCOMArray<nsIPropertyElement> props;
// We know the necessary size; we can avoid growing it while adding elements
props.SetCapacity(mTable.EntryCount());
// Step through hash entries populating a transient array
for (auto iter = mTable.Iter(); !iter.Done(); iter.Next()) {
auto entry = static_cast<PropertyTableEntry*>(iter.Get());
nsRefPtr<nsPropertyElement> element =
new nsPropertyElement(nsDependentCString(entry->mKey),
nsDependentString(entry->mValue));
if (!props.AppendObject(element)) {
return NS_ERROR_OUT_OF_MEMORY;
}
}
return NS_NewArrayEnumerator(aResult, props);
}
////////////////////////////////////////////////////////////////////////////////
// XXX Some day we'll unify the nsIPersistentProperties interface with
// nsIProperties, but until now...
NS_IMETHODIMP
nsPersistentProperties::Get(const char* aProp, const nsIID& aUUID,
void** aResult)
{
return NS_ERROR_NOT_IMPLEMENTED;
}
NS_IMETHODIMP
nsPersistentProperties::Set(const char* aProp, nsISupports* value)
{
return NS_ERROR_NOT_IMPLEMENTED;
}
NS_IMETHODIMP
nsPersistentProperties::Undefine(const char* aProp)
{
return NS_ERROR_NOT_IMPLEMENTED;
}
NS_IMETHODIMP
nsPersistentProperties::Has(const char* aProp, bool* aResult)
{
*aResult = !!PL_DHashTableSearch(&mTable, aProp);
return NS_OK;
}
NS_IMETHODIMP
nsPersistentProperties::GetKeys(uint32_t* aCount, char*** aKeys)
{
return NS_ERROR_NOT_IMPLEMENTED;
}
////////////////////////////////////////////////////////////////////////////////
// PropertyElement
////////////////////////////////////////////////////////////////////////////////
NS_METHOD
nsPropertyElement::Create(nsISupports* aOuter, REFNSIID aIID, void** aResult)
{
if (aOuter) {
return NS_ERROR_NO_AGGREGATION;
}
nsRefPtr<nsPropertyElement> propElem = new nsPropertyElement();
return propElem->QueryInterface(aIID, aResult);
}
NS_IMPL_ISUPPORTS(nsPropertyElement, nsIPropertyElement)
NS_IMETHODIMP
nsPropertyElement::GetKey(nsACString& aReturnKey)
{
aReturnKey = mKey;
return NS_OK;
}
NS_IMETHODIMP
nsPropertyElement::GetValue(nsAString& aReturnValue)
{
aReturnValue = mValue;
return NS_OK;
}
NS_IMETHODIMP
nsPropertyElement::SetKey(const nsACString& aKey)
{
mKey = aKey;
return NS_OK;
}
NS_IMETHODIMP
nsPropertyElement::SetValue(const nsAString& aValue)
{
mValue = aValue;
return NS_OK;
}
////////////////////////////////////////////////////////////////////////////////