mirror of
https://github.com/postgres/postgres.git
synced 2025-06-29 10:41:53 +03:00
Improve implementation of btrim/ltrim/rtrim: provide a special case for
single-byte encodings, and a direct C implementation of the single-argument forms (where spaces are always what gets trimmed). This is in preparation for using rtrim1() as the bpchar-to-text cast operator, but is a useful performance improvement even if we decide not to do that.
This commit is contained in:
Tom Lane
@ -2,26 +2,30 @@
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* oracle_compat.c
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* Oracle compatible functions.
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*
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* Copyright (c) 1996-2001, PostgreSQL Global Development Group
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* Copyright (c) 1996-2003, PostgreSQL Global Development Group
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*
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* Author: Edmund Mergl <E.Mergl@bawue.de>
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* Multibyte enhancement: Tatsuo Ishii <ishii@postgresql.org>
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/utils/adt/oracle_compat.c,v 1.43 2002/09/04 20:31:28 momjian Exp $
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* $Header: /cvsroot/pgsql/src/backend/utils/adt/oracle_compat.c,v 1.44 2003/05/23 22:33:20 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include <ctype.h>
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#include "utils/builtins.h"
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#include "mb/pg_wchar.h"
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static text *dotrim(const char *string, int stringlen,
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const char *set, int setlen,
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bool doltrim, bool dortrim);
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/********************************************************************
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*
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* lower
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@ -349,88 +353,194 @@ btrim(PG_FUNCTION_ARGS)
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text *string = PG_GETARG_TEXT_P(0);
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text *set = PG_GETARG_TEXT_P(1);
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text *ret;
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char *ptr,
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*end,
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*ptr2,
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*end2;
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int m;
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char **mp;
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int mplen;
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char *p;
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int mblen;
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int len;
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if ((m = VARSIZE(string) - VARHDRSZ) <= 0 ||
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(VARSIZE(set) - VARHDRSZ) <= 0)
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PG_RETURN_TEXT_P(string);
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ptr = VARDATA(string);
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len = m;
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mp = (char **) palloc(len * sizeof(char *));
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p = ptr;
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mplen = 0;
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/* build the mb pointer array */
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while (len > 0)
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{
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mp[mplen++] = p;
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mblen = pg_mblen(p);
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p += mblen;
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len -= mblen;
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}
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mplen--;
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end2 = VARDATA(set) + VARSIZE(set) - VARHDRSZ - 1;
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while (m > 0)
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{
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int str_len = pg_mblen(ptr);
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ptr2 = VARDATA(set);
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while (ptr2 <= end2)
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{
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int set_len = pg_mblen(ptr2);
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if (str_len == set_len &&
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memcmp(ptr, ptr2, str_len) == 0)
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break;
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ptr2 += set_len;
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}
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if (ptr2 > end2)
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break;
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ptr += str_len;
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m -= str_len;
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}
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while (m > 0)
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{
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int str_len;
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end = mp[mplen--];
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str_len = pg_mblen(end);
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ptr2 = VARDATA(set);
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while (ptr2 <= end2)
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{
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int set_len = pg_mblen(ptr2);
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if (str_len == set_len &&
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memcmp(end, ptr2, str_len) == 0)
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break;
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ptr2 += set_len;
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}
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if (ptr2 > end2)
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break;
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m -= str_len;
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}
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pfree(mp);
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ret = (text *) palloc(VARHDRSZ + m);
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VARATT_SIZEP(ret) = VARHDRSZ + m;
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memcpy(VARDATA(ret), ptr, m);
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ret = dotrim(VARDATA(string), VARSIZE(string) - VARHDRSZ,
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VARDATA(set), VARSIZE(set) - VARHDRSZ,
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true, true);
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PG_RETURN_TEXT_P(ret);
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}
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/********************************************************************
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*
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* btrim1 --- btrim with set fixed as ' '
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*
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********************************************************************/
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Datum
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btrim1(PG_FUNCTION_ARGS)
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{
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text *string = PG_GETARG_TEXT_P(0);
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text *ret;
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ret = dotrim(VARDATA(string), VARSIZE(string) - VARHDRSZ,
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" ", 1,
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true, true);
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PG_RETURN_TEXT_P(ret);
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}
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/*
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* Common implementation for btrim, ltrim, rtrim
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*/
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static text *
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dotrim(const char *string, int stringlen,
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const char *set, int setlen,
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bool doltrim, bool dortrim)
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{
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text *result;
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int i;
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/* Nothing to do if either string or set is empty */
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if (stringlen > 0 && setlen > 0)
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{
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if (pg_database_encoding_max_length() > 1)
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{
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/*
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* In the multibyte-encoding case, build arrays of pointers to
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* character starts, so that we can avoid inefficient checks in
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* the inner loops.
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*/
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const char **stringchars;
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const char **setchars;
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int *stringmblen;
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int *setmblen;
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int stringnchars;
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int setnchars;
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int resultndx;
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int resultnchars;
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const char *p;
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int len;
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int mblen;
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const char *str_pos;
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int str_len;
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stringchars = (const char **) palloc(stringlen * sizeof(char *));
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stringmblen = (int *) palloc(stringlen * sizeof(int));
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stringnchars = 0;
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p = string;
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len = stringlen;
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while (len > 0)
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{
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stringchars[stringnchars] = p;
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stringmblen[stringnchars] = mblen = pg_mblen(p);
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stringnchars++;
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p += mblen;
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len -= mblen;
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}
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setchars = (const char **) palloc(setlen * sizeof(char *));
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setmblen = (int *) palloc(setlen * sizeof(int));
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setnchars = 0;
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p = set;
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len = setlen;
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while (len > 0)
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{
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setchars[setnchars] = p;
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setmblen[setnchars] = mblen = pg_mblen(p);
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setnchars++;
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p += mblen;
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len -= mblen;
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}
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resultndx = 0; /* index in stringchars[] */
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resultnchars = stringnchars;
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if (doltrim)
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{
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while (resultnchars > 0)
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{
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str_pos = stringchars[resultndx];
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str_len = stringmblen[resultndx];
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for (i = 0; i < setnchars; i++)
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{
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if (str_len == setmblen[i] &&
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memcmp(str_pos, setchars[i], str_len) == 0)
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break;
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}
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if (i >= setnchars)
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break; /* no match here */
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string += str_len;
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stringlen -= str_len;
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resultndx++;
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resultnchars--;
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}
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}
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if (dortrim)
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{
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while (resultnchars > 0)
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{
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str_pos = stringchars[resultndx + resultnchars - 1];
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str_len = stringmblen[resultndx + resultnchars - 1];
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for (i = 0; i < setnchars; i++)
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{
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if (str_len == setmblen[i] &&
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memcmp(str_pos, setchars[i], str_len) == 0)
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break;
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}
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if (i >= setnchars)
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break; /* no match here */
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stringlen -= str_len;
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resultnchars--;
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}
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}
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pfree(stringchars);
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pfree(stringmblen);
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pfree(setchars);
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pfree(setmblen);
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}
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else
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{
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/*
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* In the single-byte-encoding case, we don't need such overhead.
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*/
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if (doltrim)
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{
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while (stringlen > 0)
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{
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char str_ch = *string;
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for (i = 0; i < setlen; i++)
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{
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if (str_ch == set[i])
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break;
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}
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if (i >= setlen)
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break; /* no match here */
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string++;
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stringlen--;
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}
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}
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if (dortrim)
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{
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while (stringlen > 0)
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{
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char str_ch = string[stringlen - 1];
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for (i = 0; i < setlen; i++)
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{
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if (str_ch == set[i])
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break;
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}
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if (i >= setlen)
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break; /* no match here */
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stringlen--;
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}
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}
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}
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}
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/* Return selected portion of string */
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result = (text *) palloc(VARHDRSZ + stringlen);
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VARATT_SIZEP(result) = VARHDRSZ + stringlen;
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memcpy(VARDATA(result), string, stringlen);
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return result;
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}
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/********************************************************************
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*
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* byteatrim
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@ -525,44 +635,32 @@ ltrim(PG_FUNCTION_ARGS)
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text *string = PG_GETARG_TEXT_P(0);
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text *set = PG_GETARG_TEXT_P(1);
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text *ret;
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char *ptr,
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*ptr2,
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*end2;
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int m;
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if ((m = VARSIZE(string) - VARHDRSZ) <= 0 ||
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(VARSIZE(set) - VARHDRSZ) <= 0)
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PG_RETURN_TEXT_P(string);
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ptr = VARDATA(string);
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end2 = VARDATA(set) + VARSIZE(set) - VARHDRSZ - 1;
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while (m > 0)
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{
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int str_len = pg_mblen(ptr);
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ptr2 = VARDATA(set);
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while (ptr2 <= end2)
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{
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int set_len = pg_mblen(ptr2);
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if (str_len == set_len &&
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memcmp(ptr, ptr2, str_len) == 0)
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break;
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ptr2 += set_len;
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}
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if (ptr2 > end2)
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break;
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ptr += str_len;
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m -= str_len;
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}
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ret = (text *) palloc(VARHDRSZ + m);
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VARATT_SIZEP(ret) = VARHDRSZ + m;
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memcpy(VARDATA(ret), ptr, m);
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ret = dotrim(VARDATA(string), VARSIZE(string) - VARHDRSZ,
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VARDATA(set), VARSIZE(set) - VARHDRSZ,
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true, false);
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PG_RETURN_TEXT_P(ret);
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}
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/********************************************************************
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*
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* ltrim1 --- ltrim with set fixed as ' '
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*
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********************************************************************/
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Datum
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ltrim1(PG_FUNCTION_ARGS)
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{
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text *string = PG_GETARG_TEXT_P(0);
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text *ret;
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ret = dotrim(VARDATA(string), VARSIZE(string) - VARHDRSZ,
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" ", 1,
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true, false);
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PG_RETURN_TEXT_P(ret);
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}
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/********************************************************************
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*
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@ -586,64 +684,28 @@ rtrim(PG_FUNCTION_ARGS)
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text *set = PG_GETARG_TEXT_P(1);
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text *ret;
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char *ptr,
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*end,
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*ptr2,
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*end2;
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int m;
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ret = dotrim(VARDATA(string), VARSIZE(string) - VARHDRSZ,
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VARDATA(set), VARSIZE(set) - VARHDRSZ,
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false, true);
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char **mp;
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int mplen;
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char *p;
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int mblen;
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int len;
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PG_RETURN_TEXT_P(ret);
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}
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if ((m = VARSIZE(string) - VARHDRSZ) <= 0 ||
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(VARSIZE(set) - VARHDRSZ) <= 0)
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PG_RETURN_TEXT_P(string);
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/********************************************************************
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*
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* rtrim1 --- rtrim with set fixed as ' '
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*
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********************************************************************/
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ptr = VARDATA(string);
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Datum
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rtrim1(PG_FUNCTION_ARGS)
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{
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text *string = PG_GETARG_TEXT_P(0);
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text *ret;
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len = m;
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mp = (char **) palloc(len * sizeof(char *));
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p = ptr;
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mplen = 0;
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/* build the mb pointer array */
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while (len > 0)
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{
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mp[mplen++] = p;
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mblen = pg_mblen(p);
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p += mblen;
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len -= mblen;
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}
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mplen--;
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end2 = VARDATA(set) + VARSIZE(set) - VARHDRSZ - 1;
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while (m > 0)
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{
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int str_len;
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end = mp[mplen--];
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str_len = pg_mblen(end);
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ptr2 = VARDATA(set);
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while (ptr2 <= end2)
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{
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int set_len = pg_mblen(ptr2);
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if (str_len == set_len &&
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memcmp(end, ptr2, str_len) == 0)
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break;
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ptr2 += set_len;
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}
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if (ptr2 > end2)
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break;
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m -= str_len;
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}
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pfree(mp);
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ret = (text *) palloc(VARHDRSZ + m);
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VARATT_SIZEP(ret) = VARHDRSZ + m;
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memcpy(VARDATA(ret), ptr, m);
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ret = dotrim(VARDATA(string), VARSIZE(string) - VARHDRSZ,
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" ", 1,
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false, true);
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PG_RETURN_TEXT_P(ret);
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}
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