vdbe.c

SQLite 2.8.6 源代码,用来在Linux/Unix/Windows上编译安装.它是一个小型的数据库,但是非常好用,速度也快,一般的数据库查询之类的操作据统计比MySQL,PostgreSQL

  if( x<0 && (-x)<=p->nLabel && p->aOp ){
    if( p->aLabel[-1-x]==p->nOp ) return;
    assert( p->aLabel[-1-x]<0 );
    p->aLabel[-1-x] = p->nOp;
    for(j=0; j<p->nOp; j++){
      if( p->aOp[j].p2==x ) p->aOp[j].p2 = p->nOp;
    }
  }
}

/*
** Return the address of the next instruction to be inserted.
*/
int sqliteVdbeCurrentAddr(Vdbe *p){
  assert( p->magic==VDBE_MAGIC_INIT );
  return p->nOp;
}

/*
** Add a whole list of operations to the operation stack.  Return the
** address of the first operation added.
*/
int sqliteVdbeAddOpList(Vdbe *p, int nOp, VdbeOp const *aOp){
  int addr;
  assert( p->magic==VDBE_MAGIC_INIT );
  if( p->nOp + nOp >= p->nOpAlloc ){
    int oldSize = p->nOpAlloc;
    Op *aNew;
    p->nOpAlloc = p->nOpAlloc*2 + nOp + 10;
    aNew = sqliteRealloc(p->aOp, p->nOpAlloc*sizeof(Op));
    if( aNew==0 ){
      p->nOpAlloc = oldSize;
      return 0;
    }
    p->aOp = aNew;
    memset(&p->aOp[oldSize], 0, (p->nOpAlloc-oldSize)*sizeof(Op));
  }
  addr = p->nOp;
  if( nOp>0 ){
    int i;
    for(i=0; i<nOp; i++){
      int p2 = aOp[i].p2;
      p->aOp[i+addr] = aOp[i];
      if( p2<0 ) p->aOp[i+addr].p2 = addr + ADDR(p2);
      p->aOp[i+addr].p3type = aOp[i].p3 ? P3_STATIC : P3_NOTUSED;
#ifndef NDEBUG
      if( sqlite_vdbe_addop_trace ) vdbePrintOp(0, i+addr, &p->aOp[i+addr]);
#endif
    }
    p->nOp += nOp;
  }
  return addr;
}

/*
** Change the value of the P1 operand for a specific instruction.
** This routine is useful when a large program is loaded from a
** static array using sqliteVdbeAddOpList but we want to make a
** few minor changes to the program.
*/
void sqliteVdbeChangeP1(Vdbe *p, int addr, int val){
  assert( p->magic==VDBE_MAGIC_INIT );
  if( p && addr>=0 && p->nOp>addr && p->aOp ){
    p->aOp[addr].p1 = val;
  }
}

/*
** Change the value of the P2 operand for a specific instruction.
** This routine is useful for setting a jump destination.
*/
void sqliteVdbeChangeP2(Vdbe *p, int addr, int val){
  assert( val>=0 );
  assert( p->magic==VDBE_MAGIC_INIT );
  if( p && addr>=0 && p->nOp>addr && p->aOp ){
    p->aOp[addr].p2 = val;
  }
}

/*
** Change the value of the P3 operand for a specific instruction.
** This routine is useful when a large program is loaded from a
** static array using sqliteVdbeAddOpList but we want to make a
** few minor changes to the program.
**
** If n>=0 then the P3 operand is dynamic, meaning that a copy of
** the string is made into memory obtained from sqliteMalloc().
** A value of n==0 means copy bytes of zP3 up to and including the
** first null byte.  If n>0 then copy n+1 bytes of zP3.
**
** If n==P3_STATIC  it means that zP3 is a pointer to a constant static
** string and we can just copy the pointer.  n==P3_POINTER means zP3 is
** a pointer to some object other than a string.
**
** If addr<0 then change P3 on the most recently inserted instruction.
*/
void sqliteVdbeChangeP3(Vdbe *p, int addr, const char *zP3, int n){
  Op *pOp;
  assert( p->magic==VDBE_MAGIC_INIT );
  if( p==0 || p->aOp==0 ) return;
  if( addr<0 || addr>=p->nOp ){
    addr = p->nOp - 1;
    if( addr<0 ) return;
  }
  pOp = &p->aOp[addr];
  if( pOp->p3 && pOp->p3type==P3_DYNAMIC ){
    sqliteFree(pOp->p3);
    pOp->p3 = 0;
  }
  if( zP3==0 ){
    pOp->p3 = 0;
    pOp->p3type = P3_NOTUSED;
  }else if( n<0 ){
    pOp->p3 = (char*)zP3;
    pOp->p3type = n;
  }else{
    sqliteSetNString(&pOp->p3, zP3, n, 0);
    pOp->p3type = P3_DYNAMIC;
  }
}

/*
** If the P3 operand to the specified instruction appears
** to be a quoted string token, then this procedure removes 
** the quotes.
**
** The quoting operator can be either a grave ascent (ASCII 0x27)
** or a double quote character (ASCII 0x22).  Two quotes in a row
** resolve to be a single actual quote character within the string.
*/
void sqliteVdbeDequoteP3(Vdbe *p, int addr){
  Op *pOp;
  assert( p->magic==VDBE_MAGIC_INIT );
  if( p->aOp==0 || addr<0 || addr>=p->nOp ) return;
  pOp = &p->aOp[addr];
  if( pOp->p3==0 || pOp->p3[0]==0 ) return;
  if( pOp->p3type==P3_POINTER ) return;
  if( pOp->p3type!=P3_DYNAMIC ){
    pOp->p3 = sqliteStrDup(pOp->p3);
    pOp->p3type = P3_DYNAMIC;
  }
  sqliteDequote(pOp->p3);
}

/*
** On the P3 argument of the given instruction, change all
** strings of whitespace characters into a single space and
** delete leading and trailing whitespace.
*/
void sqliteVdbeCompressSpace(Vdbe *p, int addr){
  char *z;
  int i, j;
  Op *pOp;
  assert( p->magic==VDBE_MAGIC_INIT );
  if( p->aOp==0 || addr<0 || addr>=p->nOp ) return;
  pOp = &p->aOp[addr];
  if( pOp->p3type==P3_POINTER ){
    return;
  }
  if( pOp->p3type!=P3_DYNAMIC ){
    pOp->p3 = sqliteStrDup(pOp->p3);
    pOp->p3type = P3_DYNAMIC;
  }
  z = pOp->p3;
  if( z==0 ) return;
  i = j = 0;
  while( isspace(z[i]) ){ i++; }
  while( z[i] ){
    if( isspace(z[i]) ){
      z[j++] = ' ';
      while( isspace(z[++i]) ){}
    }else{
      z[j++] = z[i++];
    }
  }
  while( j>0 && isspace(z[j-1]) ){ j--; }
  z[j] = 0;
}

/*
** Search for the current program for the given opcode and P2
** value.  Return the address plus 1 if found and 0 if not found.
*/
int sqliteVdbeFindOp(Vdbe *p, int op, int p2){
  int i;
  assert( p->magic==VDBE_MAGIC_INIT );
  for(i=0; i<p->nOp; i++){
    if( p->aOp[i].opcode==op && p->aOp[i].p2==p2 ) return i+1;
  }
  return 0;
}

/*
** Return the opcode for a given address.
*/
VdbeOp *sqliteVdbeGetOp(Vdbe *p, int addr){
  assert( p->magic==VDBE_MAGIC_INIT );
  assert( addr>=0 && addr<p->nOp );
  return &p->aOp[addr];
}

/*
** The following group or routines are employed by installable functions
** to return their results.
**
** The sqlite_set_result_string() routine can be used to return a string
** value or to return a NULL.  To return a NULL, pass in NULL for zResult.
** A copy is made of the string before this routine returns so it is safe
** to pass in an ephemeral string.
**
** sqlite_set_result_error() works like sqlite_set_result_string() except
** that it signals a fatal error.  The string argument, if any, is the
** error message.  If the argument is NULL a generic substitute error message
** is used.
**
** The sqlite_set_result_int() and sqlite_set_result_double() set the return
** value of the user function to an integer or a double.
**
** These routines are defined here in vdbe.c because they depend on knowing
** the internals of the sqlite_func structure which is only defined in 
** this source file.
*/
char *sqlite_set_result_string(sqlite_func *p, const char *zResult, int n){
  assert( !p->isStep );
  if( p->s.flags & STK_Dyn ){
    sqliteFree(p->z);
  }
  if( zResult==0 ){
    p->s.flags = STK_Null;
    n = 0;
    p->z = 0;
    p->s.n = 0;
  }else{
    if( n<0 ) n = strlen(zResult);
    if( n<NBFS-1 ){
      memcpy(p->s.z, zResult, n);
      p->s.z[n] = 0;
      p->s.flags = STK_Str;
      p->z = p->s.z;
    }else{
      p->z = sqliteMallocRaw( n+1 );
      if( p->z ){
        memcpy(p->z, zResult, n);
        p->z[n] = 0;
      }
      p->s.flags = STK_Str | STK_Dyn;
    }
    p->s.n = n+1;
  }
  return p->z;
}
void sqlite_set_result_int(sqlite_func *p, int iResult){
  assert( !p->isStep );
  if( p->s.flags & STK_Dyn ){
    sqliteFree(p->z);
  }
  p->s.i = iResult;
  p->s.flags = STK_Int;
}
void sqlite_set_result_double(sqlite_func *p, double rResult){
  assert( !p->isStep );
  if( p->s.flags & STK_Dyn ){
    sqliteFree(p->z);
  }
  p->s.r = rResult;
  p->s.flags = STK_Real;
}
void sqlite_set_result_error(sqlite_func *p, const char *zMsg, int n){
  assert( !p->isStep );
  sqlite_set_result_string(p, zMsg, n);
  p->isError = 1;
}

/*
** Extract the user data from a sqlite_func structure and return a
** pointer to it.
**
** This routine is defined here in vdbe.c because it depends on knowing
** the internals of the sqlite_func structure which is only defined in 
** this source file.
*/
void *sqlite_user_data(sqlite_func *p){
  assert( p && p->pFunc );
  return p->pFunc->pUserData;
}

/*
** Allocate or return the aggregate context for a user function.  A new
** context is allocated on the first call.  Subsequent calls return the
** same context that was returned on prior calls.
**
** This routine is defined here in vdbe.c because it depends on knowing
** the internals of the sqlite_func structure which is only defined in
** this source file.
*/
void *sqlite_aggregate_context(sqlite_func *p, int nByte){
  assert( p && p->pFunc && p->pFunc->xStep );
  if( p->pAgg==0 ){
    if( nByte<=NBFS ){
      p->pAgg = (void*)p->z;
    }else{
      p->pAgg = sqliteMalloc( nByte );
    }
  }
  return p->pAgg;
}

/*
** Return the number of times the Step function of a aggregate has been 
** called.
**
** This routine is defined here in vdbe.c because it depends on knowing
** the internals of the sqlite_func structure which is only defined in
** this source file.
*/
int sqlite_aggregate_count(sqlite_func *p){
  assert( p && p->pFunc && p->pFunc->xStep );
  return p->cnt;
}

/*
** Advance the virtual machine to the next output row.
**
** The return vale will be either SQLITE_BUSY, SQLITE_DONE, 
** SQLITE_ROW, SQLITE_ERROR, or SQLITE_MISUSE.
**
** SQLITE_BUSY means that the virtual machine attempted to open
** a locked database and there is no busy callback registered.
** Call sqlite_step() again to retry the open.  *pN is set to 0
** and *pazColName and *pazValue are both set to NULL.
**
** SQLITE_DONE means that the virtual machine has finished
** executing.  sqlite_step() should not be called again on this
** virtual machine.  *pN and *pazColName are set appropriately
** but *pazValue is set to NULL.
**
** SQLITE_ROW means that the virtual machine has generated another
** row of the result set.  *pN is set to the number of columns in
** the row.  *pazColName is set to the names of the columns followed
** by the column datatypes.  *pazValue is set to the values of each
** column in the row.  The value of the i-th column is (*pazValue)[i].
** The name of the i-th column is (*pazColName)[i] and the datatype
** of the i-th column is (*pazColName)[i+*pN].
**
** SQLITE_ERROR means that a run-time error (such as a constraint
** violation) has occurred.  The details of the error will be returned
** by the next call to sqlite_finalize().  sqlite_step() should not
** be called again on the VM.
**
** SQLITE_MISUSE means that the this routine was called inappropriately.
** Perhaps it was called on a virtual machine that had already been
** finalized or on one that had previously returned SQLITE_ERROR or
** SQLITE_DONE.  Or it could be the case the the same database connection
** is being used simulataneously by two or more threads.
*/
int sqlite_step(
  sqlite_vm *pVm,              /* The virtual machine to execute */
  int *pN,                     /* OUT: Number of columns in result */
  const char ***pazValue,      /* OUT: Column data */
  const char ***pazColName     /* OUT: Column names and datatypes */
){
  Vdbe *p = (Vdbe*)pVm;
  sqlite *db;
  int rc;

  if( p->magic!=VDBE_MAGIC_RUN ){
    return SQLITE_MISUSE;
  }
  db = p->db;
  if( sqliteSafetyOn(db) ){
    return SQLITE_MISUSE;
  }
  if( p->explain ){
    rc = sqliteVdbeList(p);
  }else{
    rc = sqliteVdbeExec(p);
  }
  if( rc==SQLITE_DONE || rc==SQLITE_ROW ){
    if( pazColName ) *pazColName = (const char**)p->azColName;
    if( pN ) *pN = p->nResColumn;
  }else{
    if( pazColName) *pazColName = 0;
    if( pN ) *pN = 0;
  }
  if( pazValue ){
    if( rc==SQLITE_ROW ){
      *pazValue = (const char**)p->azResColumn;
    }else{
      *pazValue = 0;
    }
  }
  if( sqliteSafetyOff(db) ){
    return SQLITE_MISUSE;
  }
  return rc;
}

/*
** Reset an Agg structure.  Delete all its contents. 
**
** For installable aggregate functions, if the step function has been
** called, make sure the finalizer function has also been called.  The
** finalizer might need to free memory that was allocated as part of its
** private context.  If the finalizer has not been called yet, call it
** now.
*/
static void AggReset(Agg *pAgg){
  int i;
  HashElem *p;
  for(p = sqliteHashFirst(&pAgg->hash); p; p = sqliteHashNext(p)){
    AggElem *pElem = sqliteHashData(p);
    assert( pAgg->apFunc!=0 );
    for(i=0; i<pAgg->nMem; i++){
      Mem *pMem = &pElem->aMem[i];
      if( pAgg->apFunc[i] && (pMem->s.flags & STK_AggCtx)!=0 ){
        sqlite_func ctx;
        ctx.pFunc = pAgg->apFunc[i];
        ctx.s.flags = STK_Null;
        ctx.z = 0;
        ctx.pAgg = pMem->z;
        ctx.cnt = pMem->s.i;
        ctx.isStep = 0;
        ctx.isError = 0;
        (*pAgg->apFunc[i]->xFinalize)(&ctx);
        if( pMem->z!=0 && pMem->z!=pMem->s.z ){
          sqliteFree(pMem->z);
        }
      }else if( pMem->s.flags & STK_Dyn ){
        sqliteFree(pMem->z);
      }
    }
    sqliteFree(pElem);
  }
  sqliteHashClear(&pAgg->hash);