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Change functions to handle NULLs correctly. Added the NULLIF() function. (CVS 590)

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FossilOrigin-Name: 46ce1a9ab6e527958ebc757fa2175c488299cd84
This commit is contained in:
drh
2002-05-26 21:34:58 +00:00
parent f5905aa7be
commit 8912d106e1
4 changed files with 63 additions and 45 deletions
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88
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 1.16 2002/04/20 14:24:42 drh Exp $
** $Id: func.c,v 1.17 2002/05/26 21:34:58 drh Exp $
*/
#include <ctype.h>
#include <math.h>
@@ -33,7 +33,9 @@ static void minFunc(sqlite_func *context, int argc, const char **argv){
if( argc==0 ) return;
zBest = argv[0];
if( zBest==0 ) return;
for(i=1; i<argc; i++){
if( argv[i]==0 ) return;
if( sqliteCompare(argv[i], zBest)<0 ){
zBest = argv[i];
}
@@ -46,7 +48,9 @@ static void maxFunc(sqlite_func *context, int argc, const char **argv){
if( argc==0 ) return;
zBest = argv[0];
if( zBest==0 ) return;
for(i=1; i<argc; i++){
if( argv[i]==0 ) return;
if( sqliteCompare(argv[i], zBest)>0 ){
zBest = argv[i];
}
@@ -63,15 +67,12 @@ static void lengthFunc(sqlite_func *context, int argc, const char **argv){
assert( argc==1 );
z = argv[0];
if( z==0 ){
len = 0;
}else{
if( z==0 ) return;
#ifdef SQLITE_UTF8
for(len=0; *z; z++){ if( (0xc0&*z)!=0x80 ) len++; }
for(len=0; *z; z++){ if( (0xc0&*z)!=0x80 ) len++; }
#else
len = strlen(z);
len = strlen(z);
#endif
}
sqlite_set_result_int(context, len);
}
@@ -82,7 +83,8 @@ static void absFunc(sqlite_func *context, int argc, const char **argv){
const char *z;
assert( argc==1 );
z = argv[0];
if( z && z[0]=='-' && isdigit(z[1]) ) z++;
if( z==0 ) return;
if( z[0]=='-' && isdigit(z[1]) ) z++;
sqlite_set_result_string(context, z, -1);
}
@@ -142,10 +144,11 @@ static void roundFunc(sqlite_func *context, int argc, const char **argv){
double r;
char zBuf[100];
assert( argc==1 || argc==2 );
n = argc==2 && argv[1] ? atoi(argv[1]) : 0;
if( argv[0]==0 || (argc==2 && argv[1]==0) ) return;
n = argc==2 ? atoi(argv[1]) : 0;
if( n>30 ) n = 30;
if( n<0 ) n = 0;
r = argv[0] ? atof(argv[0]) : 0.0;
r = atof(argv[0]);
sprintf(zBuf,"%.*f",n,r);
sqlite_set_result_string(context, zBuf, -1);
}
@@ -215,8 +218,8 @@ static void last_insert_rowid(sqlite_func *context, int arg, const char **argv){
** is implemented as like(A,B).
*/
static void likeFunc(sqlite_func *context, int arg, const char **argv){
sqlite_set_result_int(context,
sqliteLikeCompare(argv[0] ? argv[0] : "",argv[1] ? argv[1] : ""));
if( argv[0]==0 || argv[1]==0 ) return;
sqlite_set_result_int(context, sqliteLikeCompare(argv[0], argv[1]));
}
/*
@@ -229,8 +232,19 @@ static void likeFunc(sqlite_func *context, int arg, const char **argv){
** is implemented as glob(A,B).
*/
static void globFunc(sqlite_func *context, int arg, const char **argv){
sqlite_set_result_int(context,
sqliteGlobCompare(argv[0] ? argv[0] : "",argv[1] ? argv[1] : ""));
if( argv[0]==0 || argv[1]==0 ) return;
sqlite_set_result_int(context, sqliteGlobCompare(argv[0], argv[1]));
}
/*
** Implementation of the NULLIF(x,y) function. The result is the first
** argument if the arguments are different. The result is NULL if the
** arguments are equal to each other.
*/
static void nullifFunc(sqlite_func *context, int argc, const char **argv){
if( argv[0]!=0 && sqliteCompare(argv[0],argv[1])!=0 ){
sqlite_set_result_string(context, argv[0], -1);
}
}
/*
@@ -334,6 +348,7 @@ static void countFinalize(sqlite_func *context){
*/
typedef struct MinMaxCtx MinMaxCtx;
struct MinMaxCtx {
int isNull; /* True if the result should be NULL */
char *z; /* The best so far */
char zBuf[28]; /* Space that can be used for storage */
};
@@ -345,50 +360,52 @@ static void minStep(sqlite_func *context, int argc, const char **argv){
MinMaxCtx *p;
p = sqlite_aggregate_context(context, sizeof(*p));
if( p==0 || argc<1 ) return;
if( argv[0]==0 || p->isNull ){
p->isNull = 1;
return;
}
if( sqlite_aggregate_count(context)==1 || sqliteCompare(argv[0],p->z)<0 ){
int len;
if( p->z && p->z!=p->zBuf ){
sqliteFree(p->z);
}
if( argv[0] ){
int len = strlen(argv[0]);
if( len < sizeof(p->zBuf) ){
p->z = p->zBuf;
}else{
p->z = sqliteMalloc( len+1 );
if( p->z==0 ) return;
}
strcpy(p->z, argv[0]);
len = strlen(argv[0]);
if( len < sizeof(p->zBuf) ){
p->z = p->zBuf;
}else{
p->z = 0;
p->z = sqliteMalloc( len+1 );
if( p->z==0 ) return;
}
strcpy(p->z, argv[0]);
}
}
static void maxStep(sqlite_func *context, int argc, const char **argv){
MinMaxCtx *p;
p = sqlite_aggregate_context(context, sizeof(*p));
if( p==0 || argc<1 ) return;
if( argv[0]==0 || p->isNull ){
p->isNull = 1;
return;
}
if( sqlite_aggregate_count(context)==1 || sqliteCompare(argv[0],p->z)>0 ){
int len;
if( p->z && p->z!=p->zBuf ){
sqliteFree(p->z);
}
if( argv[0] ){
int len = strlen(argv[0]);
if( len < sizeof(p->zBuf) ){
p->z = p->zBuf;
}else{
p->z = sqliteMalloc( len+1 );
if( p->z==0 ) return;
}
strcpy(p->z, argv[0]);
len = strlen(argv[0]);
if( len < sizeof(p->zBuf) ){
p->z = p->zBuf;
}else{
p->z = 0;
p->z = sqliteMalloc( len+1 );
if( p->z==0 ) return;
}
strcpy(p->z, argv[0]);
}
}
static void minMaxFinalize(sqlite_func *context){
MinMaxCtx *p;
p = sqlite_aggregate_context(context, sizeof(*p));
if( p && p->z ){
if( p && p->z && !p->isNull ){
sqlite_set_result_string(context, p->z, strlen(p->z));
}
if( p && p->z && p->z!=p->zBuf ){
@@ -424,6 +441,7 @@ void sqliteRegisterBuildinFunctions(sqlite *db){
{ "random", -1, randomFunc },
{ "like", 2, likeFunc },
{ "glob", 2, globFunc },
{ "nullif", 2, nullifFunc },
};
static struct {
char *zName;