tor-browser

TextUtils.h (8938B)

---

/* -*- 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/. */

/* Character/text operations. */

#ifndef mozilla_TextUtils_h
#define mozilla_TextUtils_h

#include "mozilla/Assertions.h"
#include "mozilla/Latin1.h"

#ifdef MOZ_HAS_JSRUST
// Can't include mozilla/Encoding.h here.
extern "C" {
// Declared as uint8_t instead of char to match declaration in another header.
size_t encoding_ascii_valid_up_to(uint8_t const* buffer, size_t buffer_len);
}
#endif

namespace mozilla {

// See Utf8.h for IsUtf8() and conversions between UTF-8 and UTF-16.
// See Latin1.h for testing UTF-16 and UTF-8 for Latin1ness and
// for conversions to and from Latin1.

// The overloads below are not templated in order to make
// implicit conversions to span work as expected for the Span
// overloads.

/** Returns true iff |aChar| is ASCII, i.e. in the range [0, 0x80). */
inline constexpr bool IsAscii(unsigned char aChar) { return aChar < 0x80; }

/** Returns true iff |aChar| is ASCII, i.e. in the range [0, 0x80). */
inline constexpr bool IsAscii(signed char aChar) {
 return IsAscii(static_cast<unsigned char>(aChar));
}

/** Returns true iff |aChar| is ASCII, i.e. in the range [0, 0x80). */
inline constexpr bool IsAscii(char aChar) {
 return IsAscii(static_cast<unsigned char>(aChar));
}

#ifdef __cpp_char8_t
/** Returns true iff |aChar| is ASCII, i.e. in the range [0, 0x80). */
inline constexpr bool IsAscii(char8_t aChar) {
 return IsAscii(static_cast<unsigned char>(aChar));
}
#endif

/** Returns true iff |aChar| is ASCII, i.e. in the range [0, 0x80). */
inline constexpr bool IsAscii(char16_t aChar) { return aChar < 0x80; }

/** Returns true iff |aChar| is ASCII, i.e. in the range [0, 0x80). */
inline constexpr bool IsAscii(char32_t aChar) { return aChar < 0x80; }

/**
* Returns |true| iff |aString| contains only ASCII characters, that is,
* characters in the range [0x00, 0x80).
*
* @param aString a 8-bit wide string to scan
*/
inline bool IsAscii(mozilla::Span<const char> aString) {
#if MOZ_HAS_JSRUST()
 size_t length = aString.Length();
 const char* ptr = aString.Elements();
 // For short strings, avoid the function call, since, the SIMD
 // code won't have a chance to kick in anyway.
 if (length < mozilla::detail::kShortStringLimitForInlinePaths) {
   const uint8_t* uptr = reinterpret_cast<const uint8_t*>(ptr);
   uint8_t accu = 0;
   for (size_t i = 0; i < length; i++) {
     accu |= uptr[i];
   }
   return accu < 0x80;
 }
 return encoding_mem_is_ascii(ptr, length);
#else
 for (char c : aString) {
   if (!IsAscii(c)) {
     return false;
   }
 }
 return true;
#endif
}

/**
* Returns |true| iff |aString| contains only ASCII characters, that is,
* characters in the range [0x00, 0x80).
*
* @param aString a 16-bit wide string to scan
*/
inline bool IsAscii(mozilla::Span<const char16_t> aString) {
#if MOZ_HAS_JSRUST()
 size_t length = aString.Length();
 const char16_t* ptr = aString.Elements();
 // For short strings, calling into Rust is a pessimization, and the SIMD
 // code won't have a chance to kick in anyway.
 // 16 is a bit larger than logically necessary for this function alone,
 // but it's important that the limit here matches the limit used in
 // LossyConvertUtf16toLatin1!
 if (length < mozilla::detail::kShortStringLimitForInlinePaths) {
   char16_t accu = 0;
   for (size_t i = 0; i < length; i++) {
     accu |= ptr[i];
   }
   return accu < 0x80;
 }
 return encoding_mem_is_basic_latin(ptr, length);
#else
 for (char16_t c : aString) {
   if (!IsAscii(c)) {
     return false;
   }
 }
 return true;
#endif
}

/**
* Returns true iff every character in the null-terminated string pointed to by
* |aChar| is ASCII, i.e. in the range [0, 0x80).
*/
template <typename Char>
constexpr bool IsAsciiNullTerminated(const Char* aChar) {
 while (Char c = *aChar++) {
   if (!IsAscii(c)) {
     return false;
   }
 }
 return true;
}

#if MOZ_HAS_JSRUST()
/**
* Returns the index of the first non-ASCII byte or
* the length of the string if there are none.
*/
inline size_t AsciiValidUpTo(mozilla::Span<const char> aString) {
 return encoding_ascii_valid_up_to(
     reinterpret_cast<const uint8_t*>(aString.Elements()), aString.Length());
}

/**
* Returns the index of the first unpaired surrogate or
* the length of the string if there are none.
*/
inline size_t Utf16ValidUpTo(mozilla::Span<const char16_t> aString) {
 return encoding_mem_utf16_valid_up_to(aString.Elements(), aString.Length());
}

/**
* Replaces unpaired surrogates with U+FFFD in the argument.
*
* Note: If you have an nsAString, use EnsureUTF16Validity() from
* nsReadableUtils.h instead to avoid unsharing a valid shared
* string.
*/
inline void EnsureUtf16ValiditySpan(mozilla::Span<char16_t> aString) {
 encoding_mem_ensure_utf16_validity(aString.Elements(), aString.Length());
}

/**
* Convert ASCII to UTF-16. In debug builds, assert that the input is
* ASCII.
*
* The length of aDest must not be less than the length of aSource.
*/
inline void ConvertAsciitoUtf16(mozilla::Span<const char> aSource,
                               mozilla::Span<char16_t> aDest) {
 MOZ_ASSERT(IsAscii(aSource));
 ConvertLatin1toUtf16(aSource, aDest);
}

#endif  // MOZ_HAS_JSRUST

/**
* Returns true iff |aChar| matches Ascii Whitespace.
*
* This function is intended to match the Infra standard
* (https://infra.spec.whatwg.org/#ascii-whitespace)
*/
template <typename Char>
constexpr bool IsAsciiWhitespace(Char aChar) {
 using UnsignedChar = typename detail::MakeUnsignedChar<Char>::Type;
 auto uc = static_cast<UnsignedChar>(aChar);
 return uc == 0x9 || uc == 0xA || uc == 0xC || uc == 0xD || uc == 0x20;
}

/**
* Returns true iff |aChar| matches [a-z].
*
* This function is basically what you thought islower was, except its behavior
* doesn't depend on the user's current locale.
*/
template <typename Char>
constexpr bool IsAsciiLowercaseAlpha(Char aChar) {
 using UnsignedChar = typename detail::MakeUnsignedChar<Char>::Type;
 auto uc = static_cast<UnsignedChar>(aChar);
 return 'a' <= uc && uc <= 'z';
}

/**
* Returns true iff |aChar| matches [A-Z].
*
* This function is basically what you thought isupper was, except its behavior
* doesn't depend on the user's current locale.
*/
template <typename Char>
constexpr bool IsAsciiUppercaseAlpha(Char aChar) {
 using UnsignedChar = typename detail::MakeUnsignedChar<Char>::Type;
 auto uc = static_cast<UnsignedChar>(aChar);
 return 'A' <= uc && uc <= 'Z';
}

/**
* Returns true iff |aChar| matches [a-zA-Z].
*
* This function is basically what you thought isalpha was, except its behavior
* doesn't depend on the user's current locale.
*/
template <typename Char>
constexpr bool IsAsciiAlpha(Char aChar) {
 return IsAsciiLowercaseAlpha(aChar) || IsAsciiUppercaseAlpha(aChar);
}

/**
* Returns true iff |aChar| matches [0-9].
*
* This function is basically what you thought isdigit was, except its behavior
* doesn't depend on the user's current locale.
*/
template <typename Char>
constexpr bool IsAsciiDigit(Char aChar) {
 using UnsignedChar = typename detail::MakeUnsignedChar<Char>::Type;
 auto uc = static_cast<UnsignedChar>(aChar);
 return '0' <= uc && uc <= '9';
}

/**
* Returns true iff |aChar| matches [0-9a-fA-F].
*
* This function is basically isxdigit, but guaranteed to be only for ASCII.
*/
template <typename Char>
constexpr bool IsAsciiHexDigit(Char aChar) {
 using UnsignedChar = typename detail::MakeUnsignedChar<Char>::Type;
 auto uc = static_cast<UnsignedChar>(aChar);
 return ('0' <= uc && uc <= '9') || ('a' <= uc && uc <= 'f') ||
        ('A' <= uc && uc <= 'F');
}

/**
* Returns true iff |aChar| matches [a-zA-Z0-9].
*
* This function is basically what you thought isalnum was, except its behavior
* doesn't depend on the user's current locale.
*/
template <typename Char>
constexpr bool IsAsciiAlphanumeric(Char aChar) {
 return IsAsciiDigit(aChar) || IsAsciiAlpha(aChar);
}

/**
* Converts an ASCII alphanumeric digit [0-9a-zA-Z] to number as if in base-36.
* (This function therefore works for decimal, hexadecimal, etc.).
*/
template <typename Char>
constexpr uint8_t AsciiAlphanumericToNumber(Char aChar) {
 using UnsignedChar = typename detail::MakeUnsignedChar<Char>::Type;
 auto uc = static_cast<UnsignedChar>(aChar);

 if ('0' <= uc && uc <= '9') {
   return uc - '0';
 }

 if ('A' <= uc && uc <= 'Z') {
   return uc - 'A' + 10;
 }

 MOZ_ASSERT(IsAsciiLowercaseAlpha(aChar),
            "non-ASCII alphanumeric character can't be converted to number");
 return uc - 'a' + 10;
}

}  // namespace mozilla

#endif /* mozilla_TextUtils_h */