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Added length() and substr() functions (CVS 143)

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FossilOrigin-Name: 0eef538f3de66fede7c88f8be8c3458d84107c3f
This commit is contained in:
drh
2000-08-28 15:51:43 +00:00
parent 3d441f8082
commit 6ec2733b44
6 changed files with 150 additions and 24 deletions
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88
src/vdbe.c
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@@ -41,7 +41,7 @@
** But other routines are also provided to help in building up
** a program instruction by instruction.
**
** $Id: vdbe.c,v 1.38 2000/08/02 12:26:29 drh Exp $
** $Id: vdbe.c,v 1.39 2000/08/28 15:51:44 drh Exp $
*/
#include "sqliteInt.h"
#include <unistd.h>
@@ -788,6 +788,7 @@ static char *zOpName[] = { 0,
"Lt", "Le", "Gt", "Ge",
"IsNull", "NotNull", "Negative", "And",
"Or", "Not", "Concat", "Noop",
"Strlen", "Substr",
};
/*
@@ -3130,6 +3131,91 @@ int sqliteVdbeExec(
break;
}
/* Opcode: Length * * *
**
** Interpret the top of the stack as a string. Replace the top of
** stack with an integer which is the length of the string.
*/
case OP_Strlen: {
int tos = p->tos;
int len;
if( tos<0 ) goto not_enough_stack;
Stringify(p, tos);
len = p->aStack[tos].n-1;
PopStack(p, 1);
p->tos++;
p->aStack[tos].i = len;
p->aStack[tos].flags = STK_Int;
break;
}
/* Opcode: Substr P1 P2 *
**
** This operation pops between 1 and 3 elements from the stack and
** pushes back a single element. The bottom-most element popped from
** the stack is a string and the element pushed back is also a string.
** The other two elements popped are integers. The integers are taken
** from the stack only if P1 and/or P2 are 0. When P1 or P2 are
** not zero, the value of the operand is used rather than the integer
** from the stack. In the sequel, we will use P1 and P2 to describe
** the two integers, even if those integers are really taken from the
** stack.
**
** The string pushed back onto the stack is a substring of the string
** that was popped. There are P2 characters in the substring. The
** first character of the substring is the P1-th character of the
** original string where the left-most character is 1 (not 0). If P1
** is negative, then counting begins at the right instead of at the
** left.
*/
case OP_Substr: {
int cnt;
int start;
int n;
char *z;
if( pOp->p2==0 ){
if( p->tos<0 ) goto not_enough_stack;
Integerify(p, p->tos);
cnt = p->aStack[p->tos].i;
PopStack(p, 1);
}else{
cnt = pOp->p2;
}
if( pOp->p1==0 ){
if( p->tos<0 ) goto not_enough_stack;
Integerify(p, p->tos);
start = p->aStack[p->tos].i;
PopStack(p, 1);
}else{
start = pOp->p1;
}
if( p->tos<0 ) goto not_enough_stack;
Stringify(p, p->tos);
n = p->aStack[p->tos].n - 1;
if( start<0 ){
start += n;
if( start<0 ){
cnt += start;
start = 0;
}
}
if( cnt<0 ) cnt = 0;
if( cnt > n ){
cnt = n;
}
z = sqliteMalloc( cnt+1 );
if( z==0 ) goto no_mem;
strncpy(z, p->zStack[p->tos], cnt);
z[cnt] = 0;
PopStack(p, 1);
p->tos++;
p->zStack[p->tos] = z;
p->aStack[p->tos].n = cnt + 1;
p->aStack[p->tos].flags = STK_Str|STK_Dyn;
break;
}
/* An other opcode is illegal...
*/
default: {