gecko-dev/dom/encoding/EncodingUtils.h

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/* 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/. */
#ifndef mozilla_dom_encodingutils_h_
#define mozilla_dom_encodingutils_h_
#include "nsDataHashtable.h"
#include "nsString.h"
class nsIUnicodeDecoder;
class nsIUnicodeEncoder;
namespace mozilla {
namespace dom {
class EncodingUtils
{
public:
/**
* Implements get an encoding algorithm from Encoding spec.
* http://encoding.spec.whatwg.org/#concept-encoding-get
* Given a label, this function returns the corresponding encoding or a
* false.
* The returned name may not be lowercased due to compatibility with
* our internal implementations.
*
* @param aLabel, incoming label describing charset to be decoded.
* @param aOutEncoding, returning corresponding encoding for label.
* @return false if no encoding was found for label.
* true if valid encoding found.
*/
static bool FindEncodingForLabel(const nsACString& aLabel,
nsACString& aOutEncoding);
static bool FindEncodingForLabel(const nsAString& aLabel,
nsACString& aOutEncoding)
{
return FindEncodingForLabel(NS_ConvertUTF16toUTF8(aLabel), aOutEncoding);
}
/**
* Like FindEncodingForLabel() except labels that map to "replacement"
* are treated as unknown.
*
* @param aLabel, incoming label describing charset to be decoded.
* @param aOutEncoding, returning corresponding encoding for label.
* @return false if no encoding was found for label.
* true if valid encoding found.
*/
static bool FindEncodingForLabelNoReplacement(const nsACString& aLabel,
nsACString& aOutEncoding);
static bool FindEncodingForLabelNoReplacement(const nsAString& aLabel,
nsACString& aOutEncoding)
{
return FindEncodingForLabelNoReplacement(NS_ConvertUTF16toUTF8(aLabel),
aOutEncoding);
}
/**
* Remove any leading and trailing space characters, following the
* definition of space characters from Encoding spec.
* http://encoding.spec.whatwg.org/#terminology
* Note that nsAString::StripWhitespace() doesn't exactly match the
* definition. It also removes all matching chars in the string,
* not just leading and trailing.
*
* @param aString, string to be trimmed.
*/
template<class T>
static void TrimSpaceCharacters(T& aString)
{
aString.Trim(" \t\n\f\r");
}
/**
* Check is the encoding is ASCII-compatible in the sense that Basic Latin
* encodes to ASCII bytes. (The reverse may not be true!)
*
* @param aPreferredName a preferred encoding label
* @return whether the encoding is ASCII-compatible
*/
static bool IsAsciiCompatible(const nsACString& aPreferredName);
/**
* Instantiates a decoder for an encoding. The input must be a
* Gecko-canonical encoding name.
* @param aEncoding a Gecko-canonical encoding name
* @return a decoder
*/
static already_AddRefed<nsIUnicodeDecoder>
DecoderForEncoding(const char* aEncoding)
{
nsDependentCString encoding(aEncoding);
return DecoderForEncoding(encoding);
}
/**
* Instantiates a decoder for an encoding. The input must be a
* Gecko-canonical encoding name
* @param aEncoding a Gecko-canonical encoding name
* @return a decoder
*/
static already_AddRefed<nsIUnicodeDecoder>
DecoderForEncoding(const nsACString& aEncoding);
/**
* Instantiates an encoder for an encoding. The input must be a
* Gecko-canonical encoding name.
* @param aEncoding a Gecko-canonical encoding name
* @return an encoder
*/
static already_AddRefed<nsIUnicodeEncoder>
EncoderForEncoding(const char* aEncoding)
{
nsDependentCString encoding(aEncoding);
return EncoderForEncoding(encoding);
}
/**
* Instantiates an encoder for an encoding. The input must be a
* Gecko-canonical encoding name.
* @param aEncoding a Gecko-canonical encoding name
* @return an encoder
*/
static already_AddRefed<nsIUnicodeEncoder>
EncoderForEncoding(const nsACString& aEncoding);
/**
* Finds a Gecko language group string (e.g. x-western) for a Gecko-canonical
* encoding name.
*
* @param aEncoding, incoming label describing charset to be decoded.
* @param aOutGroup, returning corresponding language group.
*/
static void LangGroupForEncoding(const nsACString& aEncoding,
nsACString& aOutGroup);
private:
EncodingUtils() = delete;
};
} // dom
} // mozilla
#endif // mozilla_dom_encodingutils_h_