gecko-dev/js/public/CharacterEncoding.h
2017-10-02 22:20:33 -07:00

342 lines
10 KiB
C++

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* vim: set ts=8 sts=4 et sw=4 tw=99:
* 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 js_CharacterEncoding_h
#define js_CharacterEncoding_h
#include "mozilla/Range.h"
#include "js/TypeDecls.h"
#include "js/Utility.h"
class JSFlatString;
namespace JS {
/*
* By default, all C/C++ 1-byte-per-character strings passed into the JSAPI
* are treated as ISO/IEC 8859-1, also known as Latin-1. That is, each
* byte is treated as a 2-byte character, and there is no way to pass in a
* string containing characters beyond U+00FF.
*/
class Latin1Chars : public mozilla::Range<Latin1Char>
{
typedef mozilla::Range<Latin1Char> Base;
public:
using CharT = Latin1Char;
Latin1Chars() : Base() {}
Latin1Chars(char* aBytes, size_t aLength) : Base(reinterpret_cast<Latin1Char*>(aBytes), aLength) {}
Latin1Chars(const Latin1Char* aBytes, size_t aLength)
: Base(const_cast<Latin1Char*>(aBytes), aLength)
{}
Latin1Chars(const char* aBytes, size_t aLength)
: Base(reinterpret_cast<Latin1Char*>(const_cast<char*>(aBytes)), aLength)
{}
};
/*
* A Latin1Chars, but with \0 termination for C compatibility.
*/
class Latin1CharsZ : public mozilla::RangedPtr<Latin1Char>
{
typedef mozilla::RangedPtr<Latin1Char> Base;
public:
using CharT = Latin1Char;
Latin1CharsZ() : Base(nullptr, 0) {}
Latin1CharsZ(char* aBytes, size_t aLength)
: Base(reinterpret_cast<Latin1Char*>(aBytes), aLength)
{
MOZ_ASSERT(aBytes[aLength] == '\0');
}
Latin1CharsZ(Latin1Char* aBytes, size_t aLength)
: Base(aBytes, aLength)
{
MOZ_ASSERT(aBytes[aLength] == '\0');
}
using Base::operator=;
char* c_str() { return reinterpret_cast<char*>(get()); }
};
class UTF8Chars : public mozilla::Range<unsigned char>
{
typedef mozilla::Range<unsigned char> Base;
public:
using CharT = unsigned char;
UTF8Chars() : Base() {}
UTF8Chars(char* aBytes, size_t aLength)
: Base(reinterpret_cast<unsigned char*>(aBytes), aLength)
{}
UTF8Chars(const char* aBytes, size_t aLength)
: Base(reinterpret_cast<unsigned char*>(const_cast<char*>(aBytes)), aLength)
{}
};
/*
* SpiderMonkey also deals directly with UTF-8 encoded text in some places.
*/
class UTF8CharsZ : public mozilla::RangedPtr<unsigned char>
{
typedef mozilla::RangedPtr<unsigned char> Base;
public:
using CharT = unsigned char;
UTF8CharsZ() : Base(nullptr, 0) {}
UTF8CharsZ(char* aBytes, size_t aLength)
: Base(reinterpret_cast<unsigned char*>(aBytes), aLength)
{
MOZ_ASSERT(aBytes[aLength] == '\0');
}
UTF8CharsZ(unsigned char* aBytes, size_t aLength)
: Base(aBytes, aLength)
{
MOZ_ASSERT(aBytes[aLength] == '\0');
}
using Base::operator=;
char* c_str() { return reinterpret_cast<char*>(get()); }
};
/*
* A wrapper for a "const char*" that is encoded using UTF-8.
* This class does not manage ownership of the data; that is left
* to others. This differs from UTF8CharsZ in that the chars are
* const and it allows assignment.
*/
class JS_PUBLIC_API(ConstUTF8CharsZ)
{
const char* data_;
public:
using CharT = unsigned char;
ConstUTF8CharsZ() : data_(nullptr)
{}
ConstUTF8CharsZ(const char* aBytes, size_t aLength)
: data_(aBytes)
{
MOZ_ASSERT(aBytes[aLength] == '\0');
#ifdef DEBUG
validate(aLength);
#endif
}
const void* get() const { return data_; }
const char* c_str() const { return data_; }
explicit operator bool() const { return data_ != nullptr; }
private:
#ifdef DEBUG
void validate(size_t aLength);
#endif
};
/*
* SpiderMonkey uses a 2-byte character representation: it is a
* 2-byte-at-a-time view of a UTF-16 byte stream. This is similar to UCS-2,
* but unlike UCS-2, we do not strip UTF-16 extension bytes. This allows a
* sufficiently dedicated JavaScript program to be fully unicode-aware by
* manually interpreting UTF-16 extension characters embedded in the JS
* string.
*/
class TwoByteChars : public mozilla::Range<char16_t>
{
typedef mozilla::Range<char16_t> Base;
public:
using CharT = char16_t;
TwoByteChars() : Base() {}
TwoByteChars(char16_t* aChars, size_t aLength) : Base(aChars, aLength) {}
TwoByteChars(const char16_t* aChars, size_t aLength) : Base(const_cast<char16_t*>(aChars), aLength) {}
};
/*
* A TwoByteChars, but \0 terminated for compatibility with JSFlatString.
*/
class TwoByteCharsZ : public mozilla::RangedPtr<char16_t>
{
typedef mozilla::RangedPtr<char16_t> Base;
public:
using CharT = char16_t;
TwoByteCharsZ() : Base(nullptr, 0) {}
TwoByteCharsZ(char16_t* chars, size_t length)
: Base(chars, length)
{
MOZ_ASSERT(chars[length] == '\0');
}
using Base::operator=;
};
typedef mozilla::RangedPtr<const char16_t> ConstCharPtr;
/*
* Like TwoByteChars, but the chars are const.
*/
class ConstTwoByteChars : public mozilla::Range<const char16_t>
{
typedef mozilla::Range<const char16_t> Base;
public:
using CharT = char16_t;
ConstTwoByteChars() : Base() {}
ConstTwoByteChars(const char16_t* aChars, size_t aLength) : Base(aChars, aLength) {}
};
/*
* Convert a 2-byte character sequence to "ISO-Latin-1". This works by
* truncating each 2-byte pair in the sequence to a 1-byte pair. If the source
* contains any UTF-16 extension characters, then this may give invalid Latin1
* output. The returned string is zero terminated. The returned string or the
* returned string's |start()| must be freed with JS_free or js_free,
* respectively. If allocation fails, an OOM error will be set and the method
* will return a nullptr chars (which can be tested for with the ! operator).
* This method cannot trigger GC.
*/
extern Latin1CharsZ
LossyTwoByteCharsToNewLatin1CharsZ(JSContext* cx,
const mozilla::Range<const char16_t> tbchars);
inline Latin1CharsZ
LossyTwoByteCharsToNewLatin1CharsZ(JSContext* cx, const char16_t* begin, size_t length)
{
const mozilla::Range<const char16_t> tbchars(begin, length);
return JS::LossyTwoByteCharsToNewLatin1CharsZ(cx, tbchars);
}
template <typename CharT>
extern UTF8CharsZ
CharsToNewUTF8CharsZ(JSContext* maybeCx, const mozilla::Range<CharT> chars);
JS_PUBLIC_API(uint32_t)
Utf8ToOneUcs4Char(const uint8_t* utf8Buffer, int utf8Length);
/*
* Inflate bytes in UTF-8 encoding to char16_t.
* - On error, returns an empty TwoByteCharsZ.
* - On success, returns a malloc'd TwoByteCharsZ, and updates |outlen| to hold
* its length; the length value excludes the trailing null.
*/
extern JS_PUBLIC_API(TwoByteCharsZ)
UTF8CharsToNewTwoByteCharsZ(JSContext* cx, const UTF8Chars utf8, size_t* outlen);
/*
* Like UTF8CharsToNewTwoByteCharsZ, but for ConstUTF8CharsZ.
*/
extern JS_PUBLIC_API(TwoByteCharsZ)
UTF8CharsToNewTwoByteCharsZ(JSContext* cx, const ConstUTF8CharsZ& utf8, size_t* outlen);
/*
* The same as UTF8CharsToNewTwoByteCharsZ(), except that any malformed UTF-8 characters
* will be replaced by \uFFFD. No exception will be thrown for malformed UTF-8
* input.
*/
extern JS_PUBLIC_API(TwoByteCharsZ)
LossyUTF8CharsToNewTwoByteCharsZ(JSContext* cx, const UTF8Chars utf8, size_t* outlen);
extern JS_PUBLIC_API(TwoByteCharsZ)
LossyUTF8CharsToNewTwoByteCharsZ(JSContext* cx, const ConstUTF8CharsZ& utf8, size_t* outlen);
/*
* Returns the length of the char buffer required to encode |s| as UTF8.
* Does not include the null-terminator.
*/
JS_PUBLIC_API(size_t)
GetDeflatedUTF8StringLength(JSFlatString* s);
/*
* Encode |src| as UTF8. The caller must either ensure |dst| has enough space
* to encode the entire string or pass the length of the buffer as |dstlenp|,
* in which case the function will encode characters from the string until
* the buffer is exhausted. Does not write the null terminator.
*
* If |dstlenp| is provided, it will be updated to hold the number of bytes
* written to the buffer. If |numcharsp| is provided, it will be updated to hold
* the number of Unicode characters written to the buffer (which can be less
* than the length of the string, if the buffer is exhausted before the string
* is fully encoded).
*/
JS_PUBLIC_API(void)
DeflateStringToUTF8Buffer(JSFlatString* src, mozilla::RangedPtr<char> dst,
size_t* dstlenp = nullptr, size_t* numcharsp = nullptr);
/*
* The smallest character encoding capable of fully representing a particular
* string.
*/
enum class SmallestEncoding {
ASCII,
Latin1,
UTF16
};
/*
* Returns the smallest encoding possible for the given string: if all
* codepoints are <128 then ASCII, otherwise if all codepoints are <256
* Latin-1, else UTF16.
*/
JS_PUBLIC_API(SmallestEncoding)
FindSmallestEncoding(UTF8Chars utf8);
/*
* Return a null-terminated Latin-1 string copied from the input string,
* storing its length (excluding null terminator) in |*outlen|. Fail and
* report an error if the string contains non-Latin-1 codepoints. Returns
* Latin1CharsZ() on failure.
*/
extern JS_PUBLIC_API(Latin1CharsZ)
UTF8CharsToNewLatin1CharsZ(JSContext* cx, const UTF8Chars utf8, size_t* outlen);
/*
* Return a null-terminated Latin-1 string copied from the input string,
* storing its length (excluding null terminator) in |*outlen|. Non-Latin-1
* codepoints are replaced by '?'. Returns Latin1CharsZ() on failure.
*/
extern JS_PUBLIC_API(Latin1CharsZ)
LossyUTF8CharsToNewLatin1CharsZ(JSContext* cx, const UTF8Chars utf8, size_t* outlen);
/*
* Returns true if all characters in the given null-terminated string are
* ASCII, i.e. < 0x80, false otherwise.
*/
extern JS_PUBLIC_API(bool)
StringIsASCII(const char* s);
/*
* Returns true if the given length-delimited string is a valid UTF-8 string,
* false otherwise.
*/
extern JS_PUBLIC_API(bool)
StringIsUTF8(const uint8_t* s, uint32_t length);
} // namespace JS
inline void JS_free(JS::Latin1CharsZ& ptr) { js_free((void*)ptr.get()); }
inline void JS_free(JS::UTF8CharsZ& ptr) { js_free((void*)ptr.get()); }
#endif /* js_CharacterEncoding_h */