wchar2mb-0.2.patch

*** a/src/backend/utils/mb/mbutils.c
--- b/src/backend/utils/mb/mbutils.c
***************
*** 710,715 **** pg_encoding_mb2wchar_with_len(int encoding,
--- 710,737 ----
  	return (*pg_wchar_table[encoding].mb2wchar_with_len) ((const unsigned char *) from, to, len);
  }
  
+ /* convert a wchar string to a multibyte */
+ int
+ pg_wchar2mb(const pg_wchar *from, char *to)
+ {
+ 	return (*pg_wchar_table[DatabaseEncoding->encoding].wchar2mb_with_len) (from, (unsigned char *)to, pg_wchar_strlen(from));
+ }
+ 
+ /* convert a wchar string to a multibyte with a limited length */
+ int
+ pg_wchar2mb_with_len(const pg_wchar *from, char *to, int len)
+ {
+ 	return (*pg_wchar_table[DatabaseEncoding->encoding].wchar2mb_with_len) (from, (unsigned char *)to, len);
+ }
+ 
+ /* same, with any encoding */
+ int
+ pg_encoding_wchar2mb_with_len(int encoding,
+ 							  const pg_wchar *from, char *to, int len)
+ {
+ 	return (*pg_wchar_table[encoding].wchar2mb_with_len) (from, (unsigned char *)to, len);
+ }
+ 
  /* returns the byte length of a multibyte character */
  int
  pg_mblen(const char *mbstr)
*** a/src/backend/utils/mb/wchar.c
--- b/src/backend/utils/mb/wchar.c
***************
*** 340,345 **** pg_euctw_dsplen(const unsigned char *s)
--- 340,391 ----
  }
  
  /*
+  * Convert pg_wchar to EUC_* encoding. 
+  * caller must allocate enough space for "to", including a trailing zero!
+  * len: length of from.
+  * "from" not necessarily null terminated.
+  */
+ static int
+ pg_wchar2euc_with_len(const pg_wchar *from, unsigned char *to, int len)
+ {
+ 	int			cnt = 0;
+ 
+ 	while (len > 0 && *from)
+ 	{
+ 		if (*from >> 24)
+ 		{
+ 			*to++ = *from >> 24;
+ 			*to++ = (*from >> 16) & 0xff;
+ 			*to++ = (*from >> 8) & 0xff;
+ 			*to++ = *from & 0xff;
+ 			cnt += 4;
+ 		}
+ 		else if (*from >> 16)
+ 		{
+ 			*to++ = *from >> 16;
+ 			*to++ = (*from >> 8) & 0xff;
+ 			*to++ = *from & 0xff;
+ 			cnt += 3;
+ 		}
+ 		else if (*from >> 8)
+ 		{
+ 			*to++ = *from >> 8;
+ 			*to++ = *from & 0xff;
+ 			cnt += 2;
+ 		}
+ 		else
+ 		{
+ 			*to++ = *from;
+ 			cnt++;
+ 		}		
+ 		len--;
+ 	}
+ 	*to = 0;
+ 	return cnt;
+ }
+ 
+ 
+ /*
   * JOHAB
   */
  static int
***************
*** 453,458 **** unicode_to_utf8(pg_wchar c, unsigned char *utf8string)
--- 499,525 ----
  	return utf8string;
  }
  
+ /*
+  * Trivial conversion from pg_wchar to UTF-8.
+  * caller should allocate enough space for "to"
+  * len: length of from.
+  * "from" not necessarily null terminated.
+  */
+ static int
+ pg_wchar2utf_with_len(const pg_wchar *from, unsigned char *to, int len)
+ {
+ 	int			cnt = 0;
+ 
+ 	while (len > 0 && *from)
+ 	{
+ 		unsigned char *next = unicode_to_utf8(*from, to);		
+ 		len--;
+ 		cnt += (next - to);
+ 		to = next;
+ 	}
+ 	*to = 0;
+ 	return cnt;
+ }
  
  /*
   * Return the byte length of a UTF8 character pointed to by s
***************
*** 719,724 **** pg_mule2wchar_with_len(const unsigned char *from, pg_wchar *to, int len)
--- 786,843 ----
  	return cnt;
  }
  
+ /*
+  * convert pg_wchar to mule internal code
+  * caller should allocate enough space for "to"
+  * len: length of from.
+  * "from" not necessarily null terminated.
+  */
+ static int
+ pg_wchar2mule_with_len(const pg_wchar *from, unsigned char *to, int len)
+ {
+ 	int			cnt = 0;
+ 	unsigned char lb;
+ 
+ 	while (len > 0 && *from)
+ 	{
+ 		/*
+ 		 * LBPRV1 is not used in any PostgreSQL supported encodings, it can be
+ 		 * safely ignored. LCPRV2 is only used for Chinese encodings (EUC_TW
+ 		 * and BIG5), so prefix byte is 0x9d.
+ 		 */
+ 		lb = (*from >> 16) & 0xff;
+ 		if (IS_LC1(lb))
+ 		{
+ 			*to++ = lb;
+ 			*to++ = *from & 0xff;
+ 			cnt += 2;
+ 		}
+ 		else if (IS_LC2(lb))
+ 		{
+ 			*to++ = lb;
+ 			*to++ = (*from >> 8) & 0xff;
+ 			*to++ = *from & 0xff;
+ 			cnt += 3;
+ 		}
+ 		else if (IS_LBPRV2(lb))
+ 		{
+ 			*to++ = 0x9d;
+ 			*to++ = lb;
+ 			*to++ = (*from >> 8) & 0xff;
+ 			*to++ = *from & 0xff;
+ 			cnt += 4;
+ 		}
+ 		else
+ 		{
+ 			*to++ = lb;
+ 			cnt += 1;
+ 		}
+ 		len--;
+ 	}
+ 	*to = 0;
+ 	return cnt;
+ }
+ 
  int
  pg_mule_mblen(const unsigned char *s)
  {
***************
*** 774,779 **** pg_latin12wchar_with_len(const unsigned char *from, pg_wchar *to, int len)
--- 893,920 ----
  	return cnt;
  }
  
+ /*
+  * Trivial conversion from pg_wchar to single byte encoding. Just ignores
+  * high bits.
+  * caller should allocate enough space for "to"
+  * len: length of from.
+  * "from" not necessarily null terminated.
+  */
+ static int
+ pg_wchar2single_with_len(const pg_wchar *from, unsigned char *to, int len)
+ {
+ 	int			cnt = 0;
+ 
+ 	while (len > 0 && *from)
+ 	{
+ 		*to++ = *from++;
+ 		len--;
+ 		cnt++;
+ 	}
+ 	*to = 0;
+ 	return cnt;
+ }
+ 
  static int
  pg_latin1_mblen(const unsigned char *s)
  {
***************
*** 1551,1598 **** pg_eucjp_increment(unsigned char *charptr, int length)
   *-------------------------------------------------------------------
   */
  pg_wchar_tbl pg_wchar_table[] = {
! 	{pg_ascii2wchar_with_len, pg_ascii_mblen, pg_ascii_dsplen, pg_ascii_verifier, 1},	/* PG_SQL_ASCII */
! 	{pg_eucjp2wchar_with_len, pg_eucjp_mblen, pg_eucjp_dsplen, pg_eucjp_verifier, 3},	/* PG_EUC_JP */
! 	{pg_euccn2wchar_with_len, pg_euccn_mblen, pg_euccn_dsplen, pg_euccn_verifier, 2},	/* PG_EUC_CN */
! 	{pg_euckr2wchar_with_len, pg_euckr_mblen, pg_euckr_dsplen, pg_euckr_verifier, 3},	/* PG_EUC_KR */
! 	{pg_euctw2wchar_with_len, pg_euctw_mblen, pg_euctw_dsplen, pg_euctw_verifier, 4},	/* PG_EUC_TW */
! 	{pg_eucjp2wchar_with_len, pg_eucjp_mblen, pg_eucjp_dsplen, pg_eucjp_verifier, 3},	/* PG_EUC_JIS_2004 */
! 	{pg_utf2wchar_with_len, pg_utf_mblen, pg_utf_dsplen, pg_utf8_verifier, 4},	/* PG_UTF8 */
! 	{pg_mule2wchar_with_len, pg_mule_mblen, pg_mule_dsplen, pg_mule_verifier, 4},		/* PG_MULE_INTERNAL */
! 	{pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_LATIN1 */
! 	{pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_LATIN2 */
! 	{pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_LATIN3 */
! 	{pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_LATIN4 */
! 	{pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_LATIN5 */
! 	{pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_LATIN6 */
! 	{pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_LATIN7 */
! 	{pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_LATIN8 */
! 	{pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_LATIN9 */
! 	{pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_LATIN10 */
! 	{pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_WIN1256 */
! 	{pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_WIN1258 */
! 	{pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_WIN866 */
! 	{pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_WIN874 */
! 	{pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_KOI8R */
! 	{pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_WIN1251 */
! 	{pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_WIN1252 */
! 	{pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* ISO-8859-5 */
! 	{pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* ISO-8859-6 */
! 	{pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* ISO-8859-7 */
! 	{pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* ISO-8859-8 */
! 	{pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_WIN1250 */
! 	{pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_WIN1253 */
! 	{pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_WIN1254 */
! 	{pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_WIN1255 */
! 	{pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_WIN1257 */
! 	{pg_latin12wchar_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_KOI8U */
! 	{0, pg_sjis_mblen, pg_sjis_dsplen, pg_sjis_verifier, 2},	/* PG_SJIS */
! 	{0, pg_big5_mblen, pg_big5_dsplen, pg_big5_verifier, 2},	/* PG_BIG5 */
! 	{0, pg_gbk_mblen, pg_gbk_dsplen, pg_gbk_verifier, 2},		/* PG_GBK */
! 	{0, pg_uhc_mblen, pg_uhc_dsplen, pg_uhc_verifier, 2},		/* PG_UHC */
! 	{0, pg_gb18030_mblen, pg_gb18030_dsplen, pg_gb18030_verifier, 4},	/* PG_GB18030 */
! 	{0, pg_johab_mblen, pg_johab_dsplen, pg_johab_verifier, 3}, /* PG_JOHAB */
! 	{0, pg_sjis_mblen, pg_sjis_dsplen, pg_sjis_verifier, 2}		/* PG_SHIFT_JIS_2004 */
  };
  
  /* returns the byte length of a word for mule internal code */
--- 1692,1739 ----
   *-------------------------------------------------------------------
   */
  pg_wchar_tbl pg_wchar_table[] = {
! 	{pg_ascii2wchar_with_len, pg_wchar2single_with_len, pg_ascii_mblen, pg_ascii_dsplen, pg_ascii_verifier, 1},	/* PG_SQL_ASCII */
! 	{pg_eucjp2wchar_with_len, pg_wchar2euc_with_len, pg_eucjp_mblen, pg_eucjp_dsplen, pg_eucjp_verifier, 3},	/* PG_EUC_JP */
! 	{pg_euccn2wchar_with_len, pg_wchar2euc_with_len, pg_euccn_mblen, pg_euccn_dsplen, pg_euccn_verifier, 2},	/* PG_EUC_CN */
! 	{pg_euckr2wchar_with_len, pg_wchar2euc_with_len, pg_euckr_mblen, pg_euckr_dsplen, pg_euckr_verifier, 3},	/* PG_EUC_KR */
! 	{pg_euctw2wchar_with_len, pg_wchar2euc_with_len, pg_euctw_mblen, pg_euctw_dsplen, pg_euctw_verifier, 4},	/* PG_EUC_TW */
! 	{pg_eucjp2wchar_with_len, pg_wchar2euc_with_len, pg_eucjp_mblen, pg_eucjp_dsplen, pg_eucjp_verifier, 3},	/* PG_EUC_JIS_2004 */
! 	{pg_utf2wchar_with_len, pg_wchar2utf_with_len, pg_utf_mblen, pg_utf_dsplen, pg_utf8_verifier, 4},	/* PG_UTF8 */
! 	{pg_mule2wchar_with_len, pg_wchar2mule_with_len, pg_mule_mblen, pg_mule_dsplen, pg_mule_verifier, 4},		/* PG_MULE_INTERNAL */
! 	{pg_latin12wchar_with_len, pg_wchar2single_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_LATIN1 */
! 	{pg_latin12wchar_with_len, pg_wchar2single_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_LATIN2 */
! 	{pg_latin12wchar_with_len, pg_wchar2single_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_LATIN3 */
! 	{pg_latin12wchar_with_len, pg_wchar2single_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_LATIN4 */
! 	{pg_latin12wchar_with_len, pg_wchar2single_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_LATIN5 */
! 	{pg_latin12wchar_with_len, pg_wchar2single_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_LATIN6 */
! 	{pg_latin12wchar_with_len, pg_wchar2single_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_LATIN7 */
! 	{pg_latin12wchar_with_len, pg_wchar2single_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_LATIN8 */
! 	{pg_latin12wchar_with_len, pg_wchar2single_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_LATIN9 */
! 	{pg_latin12wchar_with_len, pg_wchar2single_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_LATIN10 */
! 	{pg_latin12wchar_with_len, pg_wchar2single_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_WIN1256 */
! 	{pg_latin12wchar_with_len, pg_wchar2single_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_WIN1258 */
! 	{pg_latin12wchar_with_len, pg_wchar2single_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_WIN866 */
! 	{pg_latin12wchar_with_len, pg_wchar2single_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_WIN874 */
! 	{pg_latin12wchar_with_len, pg_wchar2single_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_KOI8R */
! 	{pg_latin12wchar_with_len, pg_wchar2single_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_WIN1251 */
! 	{pg_latin12wchar_with_len, pg_wchar2single_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_WIN1252 */
! 	{pg_latin12wchar_with_len, pg_wchar2single_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* ISO-8859-5 */
! 	{pg_latin12wchar_with_len, pg_wchar2single_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* ISO-8859-6 */
! 	{pg_latin12wchar_with_len, pg_wchar2single_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* ISO-8859-7 */
! 	{pg_latin12wchar_with_len, pg_wchar2single_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* ISO-8859-8 */
! 	{pg_latin12wchar_with_len, pg_wchar2single_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_WIN1250 */
! 	{pg_latin12wchar_with_len, pg_wchar2single_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_WIN1253 */
! 	{pg_latin12wchar_with_len, pg_wchar2single_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_WIN1254 */
! 	{pg_latin12wchar_with_len, pg_wchar2single_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_WIN1255 */
! 	{pg_latin12wchar_with_len, pg_wchar2single_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_WIN1257 */
! 	{pg_latin12wchar_with_len, pg_wchar2single_with_len, pg_latin1_mblen, pg_latin1_dsplen, pg_latin1_verifier, 1},		/* PG_KOI8U */
! 	{0, 0, pg_sjis_mblen, pg_sjis_dsplen, pg_sjis_verifier, 2},	/* PG_SJIS */
! 	{0, 0, pg_big5_mblen, pg_big5_dsplen, pg_big5_verifier, 2},	/* PG_BIG5 */
! 	{0, 0, pg_gbk_mblen, pg_gbk_dsplen, pg_gbk_verifier, 2},		/* PG_GBK */
! 	{0, 0, pg_uhc_mblen, pg_uhc_dsplen, pg_uhc_verifier, 2},		/* PG_UHC */
! 	{0, 0, pg_gb18030_mblen, pg_gb18030_dsplen, pg_gb18030_verifier, 4},	/* PG_GB18030 */
! 	{0, 0, pg_johab_mblen, pg_johab_dsplen, pg_johab_verifier, 3}, /* PG_JOHAB */
! 	{0, 0, pg_sjis_mblen, pg_sjis_dsplen, pg_sjis_verifier, 2}		/* PG_SHIFT_JIS_2004 */
  };
  
  /* returns the byte length of a word for mule internal code */
*** a/src/include/mb/pg_wchar.h
--- b/src/include/mb/pg_wchar.h
***************
*** 58,63 **** typedef unsigned int pg_wchar;
--- 58,67 ----
   * Is a prefix byte for "private" multibyte encodings?
   */
  #define IS_LCPRV2(c)	((unsigned char)(c) == 0x9c || (unsigned char)(c) == 0x9d)
+ /*
+  * Is a leading byte for "private" multibyte encodings?
+  */
+ #define IS_LBPRV2(c)	((unsigned char)(c) >= 0xf0)
  
  /*----------------------------------------------------
   * leading characters
***************
*** 277,283 **** extern pg_enc2gettext pg_enc2gettext_tbl[];
   * pg_wchar stuff
   */
  typedef int (*mb2wchar_with_len_converter) (const unsigned char *from,
! 														pg_wchar *to,
  														int len);
  
  typedef int (*mblen_converter) (const unsigned char *mbstr);
--- 281,291 ----
   * pg_wchar stuff
   */
  typedef int (*mb2wchar_with_len_converter) (const unsigned char *from,
! 													pg_wchar *to,
! 													int len);
! 
! typedef int (*wchar2mb_with_len_converter) (const pg_wchar *from,
! 														unsigned char *to,
  														int len);
  
  typedef int (*mblen_converter) (const unsigned char *mbstr);
***************
*** 290,297 **** typedef int (*mbverifier) (const unsigned char *mbstr, int len);
  
  typedef struct
  {
! 	mb2wchar_with_len_converter mb2wchar_with_len;		/* convert a multibyte
! 														 * string to a wchar */
  	mblen_converter mblen;		/* get byte length of a char */
  	mbdisplaylen_converter dsplen;		/* get display width of a char */
  	mbverifier	mbverify;		/* verify multibyte sequence */
--- 298,307 ----
  
  typedef struct
  {
! 	mb2wchar_with_len_converter mb2wchar_with_len;	/* convert a multibyte
! 													 * string to a wchar */
! 	wchar2mb_with_len_converter wchar2mb_with_len;	/* convert a wchar
! 													 * string to a multibyte */
  	mblen_converter mblen;		/* get byte length of a char */
  	mbdisplaylen_converter dsplen;		/* get display width of a char */
  	mbverifier	mbverify;		/* verify multibyte sequence */
***************
*** 372,377 **** extern int	pg_mb2wchar(const char *from, pg_wchar *to);
--- 382,391 ----
  extern int	pg_mb2wchar_with_len(const char *from, pg_wchar *to, int len);
  extern int pg_encoding_mb2wchar_with_len(int encoding,
  							  const char *from, pg_wchar *to, int len);
+ extern int	pg_wchar2mb(const pg_wchar *from, char *to);
+ extern int	pg_wchar2mb_with_len(const pg_wchar *from, char *to, int len);
+ extern int pg_encoding_wchar2mb_with_len(int encoding,
+ 							  const pg_wchar *from, char *to, int len);
  extern int	pg_char_and_wchar_strcmp(const char *s1, const pg_wchar *s2);
  extern int	pg_wchar_strncmp(const pg_wchar *s1, const pg_wchar *s2, size_t n);
  extern int	pg_char_and_wchar_strncmp(const char *s1, const pg_wchar *s2, size_t n);