text: /*
   * Copyright (C) 2005 The Android Open Source Project
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  #ifndef ANDROID_UNICODE_H
  #define ANDROID_UNICODE_H
  
  #include <sys/types.h>
  #include <stdint.h>
  
  extern "C" {
  
  // Standard string functions on char16_t strings.
  int strcmp16(const char16_t *, const char16_t *);
  int strncmp16(const char16_t *s1, const char16_t *s2, size_t n);
  size_t strlen16(const char16_t *);
  size_t strnlen16(const char16_t *, size_t);
  char16_t *strcpy16(char16_t *, const char16_t *);
  char16_t *strncpy16(char16_t *, const char16_t *, size_t);
  char16_t *strstr16(const char16_t*, const char16_t*);
  
  // Version of comparison that supports embedded nulls.
  // This is different than strncmp() because we don't stop
  // at a nul character and consider the strings to be different
  // if the lengths are different (thus we need to supply the
  // lengths of both strings).  This can also be used when
  // your string is not nul-terminated as it will have the
  // equivalent result as strcmp16 (unlike strncmp16).
  int strzcmp16(const char16_t *s1, size_t n1, const char16_t *s2, size_t n2);
  
  // Version of strzcmp16 for comparing strings in different endianness.
  int strzcmp16_h_n(const char16_t *s1H, size_t n1, const char16_t *s2N, size_t n2);
  
  // Standard string functions on char32_t strings.
  size_t strlen32(const char32_t *);
  size_t strnlen32(const char32_t *, size_t);
  
  /**
   * Measure the length of a UTF-32 string in UTF-8. If the string is invalid
   * such as containing a surrogate character, -1 will be returned.
   */
  ssize_t utf32_to_utf8_length(const char32_t *src, size_t src_len);
  
  /**
   * Stores a UTF-8 string converted from "src" in "dst", if "dst_length" is not
   * large enough to store the string, the part of the "src" string is stored
   * into "dst" as much as possible. See the examples for more detail.
   * Returns the size actually used for storing the string.
   * dst" is not null-terminated when dst_len is fully used (like strncpy).
   *
   * Example 1
   * "src" == \u3042\u3044 (\xE3\x81\x82\xE3\x81\x84)
   * "src_len" == 2
   * "dst_len" >= 7
   * ->
   * Returned value == 6
   * "dst" becomes \xE3\x81\x82\xE3\x81\x84\0
   * (note that "dst" is null-terminated)
   *
   * Example 2
   * "src" == \u3042\u3044 (\xE3\x81\x82\xE3\x81\x84)
   * "src_len" == 2
   * "dst_len" == 5
   * ->
   * Returned value == 3
   * "dst" becomes \xE3\x81\x82\0
   * (note that "dst" is null-terminated, but \u3044 is not stored in "dst"
   * since "dst" does not have enough size to store the character)
   *
   * Example 3
   * "src" == \u3042\u3044 (\xE3\x81\x82\xE3\x81\x84)
   * "src_len" == 2
   * "dst_len" == 6
   * ->
   * Returned value == 6
   * "dst" becomes \xE3\x81\x82\xE3\x81\x84
   * (note that "dst" is NOT null-terminated, like strncpy)
   */
  void utf32_to_utf8(const char32_t* src, size_t src_len, char* dst, size_t dst_len);
  
  /**
   * Returns the unicode value at "index".
   * Returns -1 when the index is invalid (equals to or more than "src_len").
   * If returned value is positive, it is able to be converted to char32_t, which
   * is unsigned. Then, if "next_index" is not NULL, the next index to be used is
   * stored in "next_index". "next_index" can be NULL.
   */
  int32_t utf32_from_utf8_at(const char *src, size_t src_len, size_t index, size_t *next_index);
  
  
  /**
   * Returns the UTF-8 length of UTF-16 string "src".
   */
  ssize_t utf16_to_utf8_length(const char16_t *src, size_t src_len);
  
  /**
   * Converts a UTF-16 string to UTF-8. The destination buffer must be large
   * enough to fit the UTF-16 as measured by utf16_to_utf8_length with an added
   * NULL terminator.
   */
  void utf16_to_utf8(const char16_t* src, size_t src_len, char* dst, size_t dst_len);
  
  /**
   * Returns the length of "src" when "src" is valid UTF-8 string.
   * Returns 0 if src is NULL or 0-length string. Returns -1 when the source
   * is an invalid string.
   *
   * This function should be used to determine whether "src" is valid UTF-8
   * characters with valid unicode codepoints. "src" must be null-terminated.
   *
   * If you are going to use other utf8_to_... functions defined in this header
   * with string which may not be valid UTF-8 with valid codepoint (form 0 to
   * 0x10FFFF), you should use this function before calling others, since the
   * other functions do not check whether the string is valid UTF-8 or not.
   *
   * If you do not care whether "src" is valid UTF-8 or not, you should use
   * strlen() as usual, which should be much faster.
   */
  ssize_t utf8_length(const char *src);
  
  /**
   * Measure the length of a UTF-32 string.
   */
  size_t utf8_to_utf32_length(const char *src, size_t src_len);
  
  /**
   * Stores a UTF-32 string converted from "src" in "dst". "dst" must be large
   * enough to store the entire converted string as measured by
   * utf8_to_utf32_length plus space for a NULL terminator.
   */
  void utf8_to_utf32(const char* src, size_t src_len, char32_t* dst);
  
  /**
   * Returns the UTF-16 length of UTF-8 string "src".
   */
  ssize_t utf8_to_utf16_length(const uint8_t* src, size_t srcLen);
  
  /**
   * Convert UTF-8 to UTF-16 including surrogate pairs.
   * Returns a pointer to the end of the string (where a null terminator might go
   * if you wanted to add one).
   */
  char16_t* utf8_to_utf16_no_null_terminator(const uint8_t* src, size_t srcLen, char16_t* dst);
  
  /**
   * Convert UTF-8 to UTF-16 including surrogate pairs. The destination buffer
   * must be large enough to hold the result as measured by utf8_to_utf16_length
   * plus an added NULL terminator.
   */
  void utf8_to_utf16(const uint8_t* src, size_t srcLen, char16_t* dst);
  
  /**
   * Like utf8_to_utf16_no_null_terminator, but you can supply a maximum length of the
   * decoded string.  The decoded string will fill up to that length; if it is longer
   * the returned pointer will be to the character after dstLen.
   */
  char16_t* utf8_to_utf16_n(const uint8_t* src, size_t srcLen, char16_t* dst, size_t dstLen);
  
  }
  
  #endif
  