gecko-dev/dom/encoding/EncodingUtils.cpp

85 lines
2.3 KiB
C++

/* 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 "mozilla/dom/EncodingUtils.h"
#include "mozilla/Util.h" // ArrayLength
#include "nsUConvPropertySearch.h"
namespace mozilla {
namespace dom {
static const char* labelsEncodings[][3] = {
#include "labelsencodings.properties.h"
};
uint32_t
EncodingUtils::IdentifyDataOffset(const char* aData,
const uint32_t aLength,
nsACString& aRetval)
{
// Truncating to pre-clear return value in case of failure.
aRetval.Truncate();
// Minimum bytes in input stream data that represents
// the Byte Order Mark is 2. Max is 3.
if (aLength < 2) {
return 0;
}
if (aData[0] == '\xFF' && aData[1] == '\xFE') {
aRetval.AssignLiteral("UTF-16LE");
return 2;
}
if (aData[0] == '\xFE' && aData[1] == '\xFF') {
aRetval.AssignLiteral("UTF-16BE");
return 2;
}
// Checking utf-8 byte order mark.
// Minimum bytes in input stream data that represents
// the Byte Order Mark for utf-8 is 3.
if (aLength < 3) {
return 0;
}
if (aData[0] == '\xEF' && aData[1] == '\xBB' && aData[2] == '\xBF') {
aRetval.AssignLiteral("UTF-8");
return 3;
}
return 0;
}
bool
EncodingUtils::FindEncodingForLabel(const nsACString& aLabel,
nsACString& aOutEncoding)
{
// Save aLabel first because it may refer the same string as aOutEncoding.
nsCString label(aLabel);
EncodingUtils::TrimSpaceCharacters(label);
if (label.IsEmpty()) {
aOutEncoding.Truncate();
return false;
}
ToLowerCase(label);
return NS_SUCCEEDED(nsUConvPropertySearch::SearchPropertyValue(
labelsEncodings, ArrayLength(labelsEncodings), label, aOutEncoding));
}
bool
EncodingUtils::IsAsciiCompatible(const nsACString& aPreferredName)
{
return !(aPreferredName.LowerCaseEqualsLiteral("utf-16") ||
aPreferredName.LowerCaseEqualsLiteral("utf-16be") ||
aPreferredName.LowerCaseEqualsLiteral("utf-16le") ||
aPreferredName.LowerCaseEqualsLiteral("utf-7") ||
aPreferredName.LowerCaseEqualsLiteral("x-imap4-modified-utf7"));
}
} // namespace dom
} // namespace mozilla