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First cut at an implementation of the REPLACE() function. We might yet

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make this a compile-time option or move it into a separate source file. (CVS 3697)

FossilOrigin-Name: c2fe746ea782f84e850aaf3af7f5536b027a19a1
This commit is contained in:
drh
2007-03-17 13:27:54 +00:00
parent 06f52cb936
commit 26b6d90d74
4 changed files with 118 additions and 13 deletions
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66
src/func.c
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@@ -16,7 +16,7 @@
** sqliteRegisterBuildinFunctions() found at the bottom of the file.
** All other code has file scope.
**
** $Id: func.c,v 1.136 2007/01/29 17:58:28 drh Exp $
** $Id: func.c,v 1.137 2007/03/17 13:27:55 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>
@@ -669,6 +669,65 @@ static void hexFunc(
sqlite3_result_text(context, zHex, n*2, sqlite3_free);
}
/*
** The replace() function. Three arguments are all strings: call
** them A, B, and C. The result is also a string which is derived
** from A by replacing every occurance of B with C. The match
** must be exact. Collating sequences are not used.
*/
static void replaceFunc(
sqlite3_context *context,
int argc,
sqlite3_value **argv
){
const unsigned char *zStr; /* The input string A */
const unsigned char *zPattern; /* The pattern string B */
const unsigned char *zRep; /* The replacement string C */
unsigned char *zOut; /* The output */
int nStr; /* Size of zStr */
int nPattern; /* Size of zPattern */
int nRep; /* Size of zRep */
int nOut; /* Maximum size of zOut */
int loopLimit; /* Last zStr[] that might match zPattern[] */
int i, j; /* Loop counters */
assert( argc==3 );
if( sqlite3_value_type(argv[0])==SQLITE_NULL ||
sqlite3_value_type(argv[1])==SQLITE_NULL ||
sqlite3_value_type(argv[2])==SQLITE_NULL ){
return;
}
nStr = sqlite3_value_bytes(argv[0]);
zStr = sqlite3_value_text(argv[0]);
nPattern = sqlite3_value_bytes(argv[1]);
zPattern = sqlite3_value_text(argv[1]);
nRep = sqlite3_value_bytes(argv[2]);
zRep = sqlite3_value_text(argv[2]);
if( nPattern>=nRep ){
nOut = nStr;
}else{
nOut = (nStr/nPattern + 1)*nRep;
}
zOut = sqlite3_malloc(nOut+1);
if( zOut==0 ) return;
loopLimit = nStr - nPattern;
for(i=j=0; i<=loopLimit; i++){
if( zStr[i]!=zPattern[0] || memcmp(&zStr[i], zPattern, nPattern) ){
zOut[j++] = zStr[i];
}else{
memcpy(&zOut[j], zRep, nRep);
j += nRep;
i += nPattern-1;
}
}
memcpy(&zOut[j], &zStr[i], nStr-i);
j += nStr - i;
assert( j<=nOut );
zOut[j] = 0;
sqlite3_result_text(context, (char*)zOut, j, sqlite3_free);
}
#ifdef SQLITE_SOUNDEX
/*
** Compute the soundex encoding of a word.
@@ -1081,8 +1140,9 @@ void sqlite3RegisterBuiltinFunctions(sqlite3 *db){
{ "sqlite_version", 0, 0, SQLITE_UTF8, 0, versionFunc},
{ "quote", 1, 0, SQLITE_UTF8, 0, quoteFunc },
{ "last_insert_rowid", 0, 1, SQLITE_UTF8, 0, last_insert_rowid },
{ "changes", 0, 1, SQLITE_UTF8, 0, changes },
{ "total_changes", 0, 1, SQLITE_UTF8, 0, total_changes },
{ "changes", 0, 1, SQLITE_UTF8, 0, changes },
{ "total_changes", 0, 1, SQLITE_UTF8, 0, total_changes },
{ "replace", 3, 0, SQLITE_UTF8, 0, replaceFunc },
#ifdef SQLITE_SOUNDEX
{ "soundex", 1, 0, SQLITE_UTF8, 0, soundexFunc},
#endif