path: root/xpcom/string/nsReadableUtils.h

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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/. */
// IWYU pragma: private, include "nsString.h"

#ifndef nsReadableUtils_h___
#define nsReadableUtils_h___

/**
 * I guess all the routines in this file are all mis-named.
 * According to our conventions, they should be |NS_xxx|.
 */

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

#include "nsTArrayForwardDeclare.h"

inline size_t
Distance(const nsReadingIterator<char16_t>& aStart,
         const nsReadingIterator<char16_t>& aEnd)
{
  MOZ_ASSERT(aStart.get() <= aEnd.get());
  return static_cast<size_t>(aEnd.get() - aStart.get());
}
inline size_t
Distance(const nsReadingIterator<char>& aStart,
         const nsReadingIterator<char>& aEnd)
{
  MOZ_ASSERT(aStart.get() <= aEnd.get());
  return static_cast<size_t>(aEnd.get() - aStart.get());
}

void LossyCopyUTF16toASCII(const nsAString& aSource, nsACString& aDest);
void CopyASCIItoUTF16(const nsACString& aSource, nsAString& aDest);

void LossyCopyUTF16toASCII(const char16ptr_t aSource, nsACString& aDest);
void CopyASCIItoUTF16(const char* aSource, nsAString& aDest);

void CopyUTF16toUTF8(const nsAString& aSource, nsACString& aDest);
[[nodiscard]] bool CopyUTF16toUTF8(const nsAString& aSource, nsACString& aDest,
                                  const mozilla::fallible_t&);
void CopyUTF8toUTF16(const nsACString& aSource, nsAString& aDest);

void CopyUTF16toUTF8(const char16ptr_t aSource, nsACString& aDest);
void CopyUTF8toUTF16(const char* aSource, nsAString& aDest);

void LossyAppendUTF16toASCII(const nsAString& aSource, nsACString& aDest);
void AppendASCIItoUTF16(const nsACString& aSource, nsAString& aDest);
[[nodiscard]] bool AppendASCIItoUTF16(const nsACString& aSource,
                                     nsAString& aDest,
                                     const mozilla::fallible_t&);

void LossyAppendUTF16toASCII(const char16ptr_t aSource, nsACString& aDest);
[[nodiscard]] bool AppendASCIItoUTF16(const char* aSource,
                                     nsAString& aDest,
                                     const mozilla::fallible_t&);
void AppendASCIItoUTF16(const char* aSource, nsAString& aDest);

void AppendUTF16toUTF8(const nsAString& aSource, nsACString& aDest);
[[nodiscard]] bool AppendUTF16toUTF8(const nsAString& aSource,
                                    nsACString& aDest,
                                    const mozilla::fallible_t&);
void AppendUTF8toUTF16(const nsACString& aSource, nsAString& aDest);
[[nodiscard]] bool AppendUTF8toUTF16(const nsACString& aSource,
                                    nsAString& aDest,
                                    const mozilla::fallible_t&);

void AppendUTF16toUTF8(const char16ptr_t aSource, nsACString& aDest);
void AppendUTF8toUTF16(const char* aSource, nsAString& aDest);

/**
 * Returns a new |char| buffer containing a zero-terminated copy of |aSource|.
 *
 * Allocates and returns a new |char| buffer which you must free with |free|.
 * Performs a lossy encoding conversion by chopping 16-bit wide characters down to 8-bits wide while copying |aSource| to your new buffer.
 * This conversion is not well defined; but it reproduces legacy string behavior.
 * The new buffer is zero-terminated, but that may not help you if |aSource| contains embedded nulls.
 *
 * @param aSource a 16-bit wide string
 * @return a new |char| buffer you must free with |free|.
 */
char* ToNewCString(const nsAString& aSource);


/**
 * Returns a new |char| buffer containing a zero-terminated copy of |aSource|.
 *
 * Allocates and returns a new |char| buffer which you must free with |free|.
 * The new buffer is zero-terminated, but that may not help you if |aSource| contains embedded nulls.
 *
 * @param aSource an 8-bit wide string
 * @return a new |char| buffer you must free with |free|.
 */
char* ToNewCString(const nsACString& aSource);

/**
 * Returns a new |char| buffer containing a zero-terminated copy of |aSource|.
 *
 * Allocates and returns a new |char| buffer which you must free with
 * |free|.
 * Performs an encoding conversion from a UTF-16 string to a UTF-8 string
 * copying |aSource| to your new buffer.
 * The new buffer is zero-terminated, but that may not help you if |aSource|
 * contains embedded nulls.
 *
 * @param aSource a UTF-16 string (made of char16_t's)
 * @param aUTF8Count the number of 8-bit units that was returned
 * @return a new |char| buffer you must free with |free|.
 */

char* ToNewUTF8String(const nsAString& aSource, uint32_t* aUTF8Count = nullptr);


/**
 * Returns a new |char16_t| buffer containing a zero-terminated copy of
 * |aSource|.
 *
 * Allocates and returns a new |char16_t| buffer which you must free with
 * |free|.
 * The new buffer is zero-terminated, but that may not help you if |aSource|
 * contains embedded nulls.
 *
 * @param aSource a UTF-16 string
 * @return a new |char16_t| buffer you must free with |free|.
 */
char16_t* ToNewUnicode(const nsAString& aSource);


/**
 * Returns a new |char16_t| buffer containing a zero-terminated copy of |aSource|.
 *
 * Allocates and returns a new |char16_t| buffer which you must free with |free|.
 * Performs an encoding conversion by 0-padding 8-bit wide characters up to 16-bits wide while copying |aSource| to your new buffer.
 * This conversion is not well defined; but it reproduces legacy string behavior.
 * The new buffer is zero-terminated, but that may not help you if |aSource| contains embedded nulls.
 *
 * @param aSource an 8-bit wide string (a C-string, NOT UTF-8)
 * @return a new |char16_t| buffer you must free with |free|.
 */
char16_t* ToNewUnicode(const nsACString& aSource);

/**
 * Returns the required length for a char16_t buffer holding
 * a copy of aSource, using UTF-8 to UTF-16 conversion.
 * The length does NOT include any space for zero-termination.
 *
 * @param aSource an 8-bit wide string, UTF-8 encoded
 * @return length of UTF-16 encoded string copy, not zero-terminated
 */
uint32_t CalcUTF8ToUnicodeLength(const nsACString& aSource);

/**
 * Copies the source string into the specified buffer, converting UTF-8 to
 * UTF-16 in the process. The conversion is well defined for valid UTF-8
 * strings.
 * The copied string will be zero-terminated! Any embedded nulls will be
 * copied nonetheless. It is the caller's responsiblity to ensure the buffer
 * is large enough to hold the string copy plus one char16_t for
 * zero-termination!
 *
 * @see CalcUTF8ToUnicodeLength( const nsACString& )
 * @see UTF8ToNewUnicode( const nsACString&, uint32_t* )
 *
 * @param aSource an 8-bit wide string, UTF-8 encoded
 * @param aBuffer the buffer holding the converted string copy
 * @param aUTF16Count receiving optionally the number of 16-bit units that
 *                    were copied
 * @return aBuffer pointer, for convenience
 */
char16_t* UTF8ToUnicodeBuffer(const nsACString& aSource,
                              char16_t* aBuffer,
                              uint32_t* aUTF16Count = nullptr);

/**
 * Returns a new |char16_t| buffer containing a zero-terminated copy
 * of |aSource|.
 *
 * Allocates and returns a new |char| buffer which you must free with
 * |free|.  Performs an encoding conversion from UTF-8 to UTF-16
 * while copying |aSource| to your new buffer.  This conversion is well defined
 * for a valid UTF-8 string.  The new buffer is zero-terminated, but that
 * may not help you if |aSource| contains embedded nulls.
 *
 * @param aSource an 8-bit wide string, UTF-8 encoded
 * @param aUTF16Count the number of 16-bit units that was returned
 * @return a new |char16_t| buffer you must free with |free|.
 *         (UTF-16 encoded)
 */
char16_t* UTF8ToNewUnicode(const nsACString& aSource,
                           uint32_t* aUTF16Count = nullptr);

/**
 * Copies |aLength| 16-bit code units from the start of |aSource| to the
 * |char16_t| buffer |aDest|.
 *
 * After this operation |aDest| is not null terminated.
 *
 * @param aSource a UTF-16 string
 * @param aSrcOffset start offset in the source string
 * @param aDest a |char16_t| buffer
 * @param aLength the number of 16-bit code units to copy
 * @return pointer to destination buffer - identical to |aDest|
 */
char16_t* CopyUnicodeTo(const nsAString& aSource,
                        uint32_t aSrcOffset,
                        char16_t* aDest,
                        uint32_t aLength);


/**
 * Copies 16-bit characters between iterators |aSrcStart| and
 * |aSrcEnd| to the writable string |aDest|. Similar to the
 * |nsString::Mid| method.
 *
 * After this operation |aDest| is not null terminated.
 *
 * @param aSrcStart start source iterator
 * @param aSrcEnd end source iterator
 * @param aDest destination for the copy
 */
void CopyUnicodeTo(const nsAString::const_iterator& aSrcStart,
                   const nsAString::const_iterator& aSrcEnd,
                   nsAString& aDest);

/**
 * Appends 16-bit characters between iterators |aSrcStart| and
 * |aSrcEnd| to the writable string |aDest|.
 *
 * After this operation |aDest| is not null terminated.
 *
 * @param aSrcStart start source iterator
 * @param aSrcEnd end source iterator
 * @param aDest destination for the copy
 */
void AppendUnicodeTo(const nsAString::const_iterator& aSrcStart,
                     const nsAString::const_iterator& aSrcEnd,
                     nsAString& aDest);

/**
 * Returns |true| if |aString| contains only ASCII characters, that is, characters in the range (0x00, 0x7F).
 *
 * @param aString a 16-bit wide string to scan
 */
bool IsASCII(const nsAString& aString);

/**
 * Returns |true| if |aString| contains only ASCII characters, that is, characters in the range (0x00, 0x7F).
 *
 * @param aString a 8-bit wide string to scan
 */
bool IsASCII(const nsACString& aString);

/**
 * Returns |true| if |aString| is a valid UTF-8 string.
 * XXX This is not bullet-proof and nor an all-purpose UTF-8 validator.
 * It is mainly written to replace and roughly equivalent to
 *
 *    str.Equals(NS_ConvertUTF16toUTF8(NS_ConvertUTF8toUTF16(str)))
 *
 * (see bug 191541)
 * As such,  it does not check for non-UTF-8 7bit encodings such as
 * ISO-2022-JP and HZ.
 *
 * It rejects sequences with the following errors:
 *
 * byte sequences that cannot be decoded into characters according to
 *   UTF-8's rules (including cases where the input is part of a valid
 *   UTF-8 sequence but starts or ends mid-character)
 * overlong sequences (i.e., cases where a character was encoded
 *   non-canonically by using more bytes than necessary)
 * surrogate codepoints (i.e., the codepoints reserved for
     representing astral characters in UTF-16)
 * codepoints above the unicode range (i.e., outside the first 17
 *   planes; higher than U+10FFFF), in accordance with
 *   http://tools.ietf.org/html/rfc3629
 * when aRejectNonChar is true (the default), any codepoint whose low
 *   16 bits are 0xFFFE or 0xFFFF

 *
 * @param aString an 8-bit wide string to scan
 * @param aRejectNonChar a boolean to control the rejection of utf-8
 *        non characters
 */
bool IsUTF8(const nsACString& aString, bool aRejectNonChar = true);

bool ParseString(const nsACString& aAstring, char aDelimiter,
                 nsTArray<nsCString>& aArray);

/**
 * Converts case in place in the argument string.
 */
void ToUpperCase(nsACString&);

void ToLowerCase(nsACString&);

void ToUpperCase(nsCSubstring&);

void ToLowerCase(nsCSubstring&);

/**
 * Converts case from string aSource to aDest.
 */
void ToUpperCase(const nsACString& aSource, nsACString& aDest);

void ToLowerCase(const nsACString& aSource, nsACString& aDest);

/**
 * Finds the leftmost occurrence of |aPattern|, if any in the range |aSearchStart|..|aSearchEnd|.
 *
 * Returns |true| if a match was found, and adjusts |aSearchStart| and |aSearchEnd| to
 * point to the match.  If no match was found, returns |false| and makes |aSearchStart == aSearchEnd|.
 *
 * Currently, this is equivalent to the O(m*n) implementation previously on |ns[C]String|.
 * If we need something faster, then we can implement that later.
 */

bool FindInReadable(const nsAString& aPattern, nsAString::const_iterator&,
                    nsAString::const_iterator&,
                    const nsStringComparator& = nsDefaultStringComparator());
bool FindInReadable(const nsACString& aPattern, nsACString::const_iterator&,
                    nsACString::const_iterator&,
                    const nsCStringComparator& = nsDefaultCStringComparator());

/* sometimes we don't care about where the string was, just that we
 * found it or not */
inline bool
FindInReadable(const nsAString& aPattern, const nsAString& aSource,
               const nsStringComparator& aCompare = nsDefaultStringComparator())
{
  nsAString::const_iterator start, end;
  aSource.BeginReading(start);
  aSource.EndReading(end);
  return FindInReadable(aPattern, start, end, aCompare);
}

inline bool
FindInReadable(const nsACString& aPattern, const nsACString& aSource,
               const nsCStringComparator& aCompare = nsDefaultCStringComparator())
{
  nsACString::const_iterator start, end;
  aSource.BeginReading(start);
  aSource.EndReading(end);
  return FindInReadable(aPattern, start, end, aCompare);
}


bool CaseInsensitiveFindInReadable(const nsACString& aPattern,
                                   nsACString::const_iterator&,
                                   nsACString::const_iterator&);

/**
 * Finds the rightmost occurrence of |aPattern|
 * Returns |true| if a match was found, and adjusts |aSearchStart| and |aSearchEnd| to
 * point to the match.  If no match was found, returns |false| and makes |aSearchStart == aSearchEnd|.
 *
 */
bool RFindInReadable(const nsAString& aPattern, nsAString::const_iterator&,
                     nsAString::const_iterator&,
                     const nsStringComparator& = nsDefaultStringComparator());
bool RFindInReadable(const nsACString& aPattern, nsACString::const_iterator&,
                     nsACString::const_iterator&,
                     const nsCStringComparator& = nsDefaultCStringComparator());

/**
* Finds the leftmost occurrence of |aChar|, if any in the range
* |aSearchStart|..|aSearchEnd|.
*
* Returns |true| if a match was found, and adjusts |aSearchStart| to
* point to the match.  If no match was found, returns |false| and
* makes |aSearchStart == aSearchEnd|.
*/
bool FindCharInReadable(char16_t aChar, nsAString::const_iterator& aSearchStart,
                        const nsAString::const_iterator& aSearchEnd);
bool FindCharInReadable(char aChar, nsACString::const_iterator& aSearchStart,
                        const nsACString::const_iterator& aSearchEnd);

/**
* Finds the number of occurences of |aChar| in the string |aStr|
*/
uint32_t CountCharInReadable(const nsAString& aStr,
                             char16_t aChar);
uint32_t CountCharInReadable(const nsACString& aStr,
                             char aChar);

bool StringBeginsWith(const nsAString& aSource, const nsAString& aSubstring);
bool StringBeginsWith(const nsAString& aSource, const nsAString& aSubstring,
                      const nsStringComparator& aComparator);
bool StringBeginsWith(const nsACString& aSource, const nsACString& aSubstring);
bool StringBeginsWith(const nsACString& aSource, const nsACString& aSubstring,
                      const nsCStringComparator& aComparator);
bool StringEndsWith(const nsAString& aSource, const nsAString& aSubstring);
bool StringEndsWith(const nsAString& aSource, const nsAString& aSubstring,
                    const nsStringComparator& aComparator);
bool StringEndsWith(const nsACString& aSource, const nsACString& aSubstring);
bool StringEndsWith(const nsACString& aSource, const nsACString& aSubstring,
                    const nsCStringComparator& aComparator);

const nsAFlatString& EmptyString();
const nsAFlatCString& EmptyCString();

const nsAFlatString& NullString();
const nsAFlatCString& NullCString();

/**
* Compare a UTF-8 string to an UTF-16 string.
*
* Returns 0 if the strings are equal, -1 if aUTF8String is less
* than aUTF16Count, and 1 in the reverse case.  In case of fatal
* error (eg the strings are not valid UTF8 and UTF16 respectively),
* this method will return INT32_MIN.
*/
int32_t CompareUTF8toUTF16(const nsASingleFragmentCString& aUTF8String,
                           const nsASingleFragmentString& aUTF16String);

void AppendUCS4ToUTF16(const uint32_t aSource, nsAString& aDest);

template<class T>
inline bool
EnsureStringLength(T& aStr, uint32_t aLen)
{
  aStr.SetLength(aLen);
  return (aStr.Length() == aLen);
}

#endif // !defined(nsReadableUtils_h___)