SQLite

/*
** Construct a trigger step that implements a DELETE statement and return
** a pointer to that trigger step.  The parser calls this routine when it
** sees a DELETE statement inside the body of a CREATE TRIGGER.
*/
TriggerStep *sqlite3TriggerDeleteStep(Token *pTableName, Expr *pWhere){
  TriggerStep *pTriggerStep = sqliteMalloc(sizeof(TriggerStep));
  if( pTriggerStep==0 ){
    sqlite3ExprDelete(pWhere);
    return 0;
  }

  pTriggerStep->op = TK_DELETE;
  pTriggerStep->target  = *pTableName;
  pTriggerStep->pWhere = pWhere;
  pTriggerStep->orconf = OE_Default;
  sqlitePersistTriggerStep(pTriggerStep);

** This module contains C code that generates VDBE code used to process
** the WHERE clause of SQL statements.  This module is reponsible for
** generating the code that loops through a table looking for applicable
** rows.  Indices are selected and used to speed the search when doing
** so is applicable.  Because this module is responsible for selecting
** indices, you might also think of this module as the "query optimizer".
**
** $Id: where.c,v 1.245 2007/03/31 01:34:45 drh Exp $
*/
#include "sqliteInt.h"

/*
** The number of bits in a Bitmask.  "BMS" means "BitMask Size".
*/
#define BMS  (sizeof(Bitmask)*8)

  }
}

/*
** Add a new entries to the WhereClause structure.  Increase the allocated
** space as necessary.
**
** If the flags argument includes TERM_DYNAMIC, then responsibility
** for freeing the expression p is assumed by the WhereClause object.
**
** WARNING:  This routine might reallocate the space used to store
** WhereTerms.  All pointers to WhereTerms should be invalided after
** calling this routine.  Such pointers may be reinitialized by referencing
** the pWC->a[] array.
*/
static int whereClauseInsert(WhereClause *pWC, Expr *p, int flags){
  WhereTerm *pTerm;
  int idx;
  if( pWC->nTerm>=pWC->nSlot ){
    WhereTerm *pOld = pWC->a;
    pWC->a = sqliteMalloc( sizeof(pWC->a[0])*pWC->nSlot*2 );
    if( pWC->a==0 ){
      if( flags & TERM_DYNAMIC ){
        sqlite3ExprDelete(p);
      }
      return 0;
    }
    memcpy(pWC->a, pOld, sizeof(pWC->a[0])*pWC->nTerm);
    if( pOld!=pWC->aStatic ){
      sqliteFree(pOld);
    }
    pWC->nSlot *= 2;
  }
  pTerm = &pWC->a[idx = pWC->nTerm];

    if( pRight && pRight->op==TK_COLUMN ){
      WhereTerm *pNew;
      Expr *pDup;
      if( pTerm->leftCursor>=0 ){
        int idxNew;
        pDup = sqlite3ExprDup(pExpr);
        if( sqlite3MallocFailed() ){
          sqlite3ExprDelete(pDup);
          return;
        }
        idxNew = whereClauseInsert(pWC, pDup, TERM_VIRTUAL|TERM_DYNAMIC);
        if( idxNew==0 ) return;
        pNew = &pWC->a[idxNew];
        pNew->iParent = idxTerm;
        pTerm = &pWC->a[idxTerm];