**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle INSERT statements in SQLite.
**
** $Id: insert.c,v 1.29 2001/12/22 21:48:30 drh Exp $
*/
#include "sqliteInt.h"

/*
** This routine is call to handle SQL of the following forms:
**
**    insert into TABLE (IDLIST) values(EXPRLIST)
................................................................................
    pParse->nErr++;
    goto insert_cleanup;
  }

  /* If the INSERT statement included an IDLIST term, then make sure
  ** all elements of the IDLIST really are columns of the table and 
  ** remember the column indices.







  */
  if( pColumn ){
    for(i=0; i<pColumn->nId; i++){
      pColumn->a[i].idx = -1;
    }
    for(i=0; i<pColumn->nId; i++){
      for(j=0; j<pTab->nCol; j++){
................................................................................
        pParse->nErr++;
        goto insert_cleanup;
      }
    }
  }

  /* If there is not IDLIST term but the table has an integer primary
  ** key, the set the keyColumn variable to the primary key column.

  */
  if( pColumn==0 ){
    keyColumn = pTab->iPKey;
  }

  /* Open cursors into the table that is received the new data and
  ** all indices of that table.
................................................................................
      sqliteExprCode(pParse, pList->a[keyColumn].pExpr);
    }
    sqliteVdbeAddOp(v, OP_MustBeInt, 0, 0);
  }else{
    sqliteVdbeAddOp(v, OP_NewRecno, base, 0);
  }

  /* If there are indices, we'll need this record number again, so make
  ** a copy.
  */
  if( pTab->pIndex ){
    sqliteVdbeAddOp(v, OP_Dup, 0, 0);
  }

  /* Push onto the stack data for all columns of the new entry, beginning
  ** with the first column.
  */
  for(i=0; i<pTab->nCol; i++){
    if( i==pTab->iPKey ){
      /* The value of the INTEGER PRIMARY KEY column is always a NULL.
      ** Whenever this column is used, the record number will be substituted
      ** in its place, so there is no point it it taking up space in
      ** the data record. */
      sqliteVdbeAddOp(v, OP_String, 0, 0);
      continue;
    }
    if( pColumn==0 ){
      j = i;
    }else{

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle INSERT statements in SQLite.
**
** $Id: insert.c,v 1.30 2001/12/31 02:48:51 drh Exp $
*/
#include "sqliteInt.h"

/*
** This routine is call to handle SQL of the following forms:
**
**    insert into TABLE (IDLIST) values(EXPRLIST)
................................................................................
    pParse->nErr++;
    goto insert_cleanup;
  }

  /* If the INSERT statement included an IDLIST term, then make sure
  ** all elements of the IDLIST really are columns of the table and 
  ** remember the column indices.
  **
  ** If the table has an INTEGER PRIMARY KEY column and that column
  ** is named in the IDLIST, then record in the keyColumn variable
  ** the index into IDLIST of the primary key column.  keyColumn is
  ** the index of the primary key as it appears in IDLIST, not as
  ** is appears in the original table.  (The index of the primary
  ** key in the original table is pTab->iPKey.)
  */
  if( pColumn ){
    for(i=0; i<pColumn->nId; i++){
      pColumn->a[i].idx = -1;
    }
    for(i=0; i<pColumn->nId; i++){
      for(j=0; j<pTab->nCol; j++){
................................................................................
        pParse->nErr++;
        goto insert_cleanup;
      }
    }
  }

  /* If there is not IDLIST term but the table has an integer primary
  ** key, the set the keyColumn variable to the primary key column index
  ** in the original table definition.
  */
  if( pColumn==0 ){
    keyColumn = pTab->iPKey;
  }

  /* Open cursors into the table that is received the new data and
  ** all indices of that table.
................................................................................
      sqliteExprCode(pParse, pList->a[keyColumn].pExpr);
    }
    sqliteVdbeAddOp(v, OP_MustBeInt, 0, 0);
  }else{
    sqliteVdbeAddOp(v, OP_NewRecno, base, 0);
  }

  /* If there are indices, we'll need the new record number again, so make
  ** a copy.
  */
  if( pTab->pIndex ){
    sqliteVdbeAddOp(v, OP_Dup, 0, 0);
  }

  /* Push onto the stack data for all columns of the new entry, beginning
  ** with the first column.
  */
  for(i=0; i<pTab->nCol; i++){
    if( i==pTab->iPKey ){
      /* The value of the INTEGER PRIMARY KEY column is always a NULL.
      ** Whenever this column is used, the record number will be substituted
      ** in its place, so there is no point in it taking up space in
      ** the data record. */
      sqliteVdbeAddOp(v, OP_String, 0, 0);
      continue;
    }
    if( pColumn==0 ){
      j = i;
    }else{

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle SELECT statements in SQLite.
**
** $Id: select.c,v 1.51 2001/12/22 14:49:25 drh Exp $
*/
#include "sqliteInt.h"

/*
** Allocate a new Select structure and return a pointer to that
** structure.
*/
................................................................................
    int lbl = sqliteVdbeMakeLabel(v);
    sqliteVdbeAddOp(v, OP_MakeKey, pEList->nExpr, 1);
    sqliteVdbeAddOp(v, OP_Distinct, distinct, lbl);
    sqliteVdbeAddOp(v, OP_Pop, pEList->nExpr+1, 0);
    sqliteVdbeAddOp(v, OP_Goto, 0, iContinue);
    sqliteVdbeResolveLabel(v, lbl);
    sqliteVdbeAddOp(v, OP_String, 0, 0);
    sqliteVdbeChangeP3(v, -1, "", P3_STATIC);
    sqliteVdbeAddOp(v, OP_Put, distinct, 0);
  }

  /* If there is an ORDER BY clause, then store the results
  ** in a sorter.
  */
  if( pOrderBy ){
................................................................................

  /* In this mode, write each query result to the key of the temporary
  ** table iParm.
  */
  if( eDest==SRT_Union ){
    sqliteVdbeAddOp(v, OP_MakeRecord, nColumn, 0);
    sqliteVdbeAddOp(v, OP_String, iParm, 0);
    sqliteVdbeChangeP3(v, -1, "", P3_STATIC);
    sqliteVdbeAddOp(v, OP_Put, iParm, 0);
  }else 

  /* Store the result as data using a unique key.
  */
  if( eDest==SRT_Table ){
    sqliteVdbeAddOp(v, OP_MakeRecord, nColumn, 0);
................................................................................
  /* If we are creating a set for an "expr IN (SELECT ...)" construct,
  ** then there should be a single item on the stack.  Write this
  ** item into the set table with bogus data.
  */
  if( eDest==SRT_Set ){
    assert( nColumn==1 );
    sqliteVdbeAddOp(v, OP_String, 0, 0);
    sqliteVdbeChangeP3(v, -1, "", P3_STATIC);
    sqliteVdbeAddOp(v, OP_Put, iParm, 0);
  }else 


  /* If this is a scalar select that is part of an expression, then
  ** store the results in the appropriate memory cell and break out
  ** of the scan loop.
................................................................................

  /* Reset the aggregator
  */
  if( isAgg ){
    sqliteVdbeAddOp(v, OP_AggReset, 0, pParse->nAgg);
    if( pGroupBy==0 ){
      sqliteVdbeAddOp(v, OP_String, 0, 0);
      sqliteVdbeChangeP3(v, -1, "", P3_STATIC);
      sqliteVdbeAddOp(v, OP_AggFocus, 0, 0);
      for(i=0; i<pParse->nAgg; i++){
        Expr *pE;
        if( !pParse->aAgg[i].isAgg ) continue;
        pE = pParse->aAgg[i].pExpr;
        assert( pE==0 || pE->op==TK_AGG_FUNCTION );
        assert( pE==0 || (pE->pList!=0 && pE->pList->nExpr==1) );

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle SELECT statements in SQLite.
**
** $Id: select.c,v 1.52 2001/12/31 02:48:51 drh Exp $
*/
#include "sqliteInt.h"

/*
** Allocate a new Select structure and return a pointer to that
** structure.
*/
................................................................................
    int lbl = sqliteVdbeMakeLabel(v);
    sqliteVdbeAddOp(v, OP_MakeKey, pEList->nExpr, 1);
    sqliteVdbeAddOp(v, OP_Distinct, distinct, lbl);
    sqliteVdbeAddOp(v, OP_Pop, pEList->nExpr+1, 0);
    sqliteVdbeAddOp(v, OP_Goto, 0, iContinue);
    sqliteVdbeResolveLabel(v, lbl);
    sqliteVdbeAddOp(v, OP_String, 0, 0);

    sqliteVdbeAddOp(v, OP_Put, distinct, 0);
  }

  /* If there is an ORDER BY clause, then store the results
  ** in a sorter.
  */
  if( pOrderBy ){
................................................................................

  /* In this mode, write each query result to the key of the temporary
  ** table iParm.
  */
  if( eDest==SRT_Union ){
    sqliteVdbeAddOp(v, OP_MakeRecord, nColumn, 0);
    sqliteVdbeAddOp(v, OP_String, iParm, 0);

    sqliteVdbeAddOp(v, OP_Put, iParm, 0);
  }else 

  /* Store the result as data using a unique key.
  */
  if( eDest==SRT_Table ){
    sqliteVdbeAddOp(v, OP_MakeRecord, nColumn, 0);
................................................................................
  /* If we are creating a set for an "expr IN (SELECT ...)" construct,
  ** then there should be a single item on the stack.  Write this
  ** item into the set table with bogus data.
  */
  if( eDest==SRT_Set ){
    assert( nColumn==1 );
    sqliteVdbeAddOp(v, OP_String, 0, 0);

    sqliteVdbeAddOp(v, OP_Put, iParm, 0);
  }else 


  /* If this is a scalar select that is part of an expression, then
  ** store the results in the appropriate memory cell and break out
  ** of the scan loop.
................................................................................

  /* Reset the aggregator
  */
  if( isAgg ){
    sqliteVdbeAddOp(v, OP_AggReset, 0, pParse->nAgg);
    if( pGroupBy==0 ){
      sqliteVdbeAddOp(v, OP_String, 0, 0);

      sqliteVdbeAddOp(v, OP_AggFocus, 0, 0);
      for(i=0; i<pParse->nAgg; i++){
        Expr *pE;
        if( !pParse->aAgg[i].isAgg ) continue;
        pE = pParse->aAgg[i].pExpr;
        assert( pE==0 || pE->op==TK_AGG_FUNCTION );
        assert( pE==0 || (pE->pList!=0 && pE->pList->nExpr==1) );

**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** Internal interface definitions for SQLite.
**
** @(#) $Id: sqliteInt.h,v 1.73 2001/12/21 14:30:43 drh Exp $
*/
#include "sqlite.h"
#include "hash.h"
#include "vdbe.h"
#include "parse.h"
#include "btree.h"
#include <stdio.h>
................................................................................
** Each SQL table is represented in memory by
** an instance of the following structure.
*/
struct Table {
  char *zName;     /* Name of the table */
  int nCol;        /* Number of columns in this table */
  Column *aCol;    /* Information about each column */
  int iPKey;       /* Use this column as the record-number for each row */
  Index *pIndex;   /* List of SQL indexes on this table. */
  int tnum;        /* Page containing root for this table */
  u8 readOnly;     /* True if this table should not be written by the user */
  u8 isCommit;     /* True if creation of this table has been committed */
  u8 isDelete;     /* True if this table is being deleted */
  u8 isTemp;       /* True if stored in db->pBeTemp instead of db->pBe */
  u8 hasPrimKey;   /* True if there exists a primary key */

**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** Internal interface definitions for SQLite.
**
** @(#) $Id: sqliteInt.h,v 1.74 2001/12/31 02:48:51 drh Exp $
*/
#include "sqlite.h"
#include "hash.h"
#include "vdbe.h"
#include "parse.h"
#include "btree.h"
#include <stdio.h>
................................................................................
** Each SQL table is represented in memory by
** an instance of the following structure.
*/
struct Table {
  char *zName;     /* Name of the table */
  int nCol;        /* Number of columns in this table */
  Column *aCol;    /* Information about each column */
  int iPKey;       /* If not less then 0, use aCol[iPKey] as the primary key */
  Index *pIndex;   /* List of SQL indexes on this table. */
  int tnum;        /* Page containing root for this table */
  u8 readOnly;     /* True if this table should not be written by the user */
  u8 isCommit;     /* True if creation of this table has been committed */
  u8 isDelete;     /* True if this table is being deleted */
  u8 isTemp;       /* True if stored in db->pBeTemp instead of db->pBe */
  u8 hasPrimKey;   /* True if there exists a primary key */

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle UPDATE statements.
**
** $Id: update.c,v 1.24 2001/12/22 14:49:25 drh Exp $
*/
#include "sqliteInt.h"

/*
** Process an UPDATE statement.
*/
void sqliteUpdate(
................................................................................

  if( pParse->nErr || sqlite_malloc_failed ) goto update_cleanup;
  db = pParse->db;

  /* Locate the table which we want to update.  This table has to be
  ** put in an IdList structure because some of the subroutines we
  ** will be calling are designed to work with multiple tables and expect
  ** an IdList* parameter instead of just a Table* parameger.
  */
  pTabList = sqliteIdListAppend(0, pTableName);
  if( pTabList==0 ) goto update_cleanup;
  for(i=0; i<pTabList->nId; i++){
    pTabList->a[i].pTab = sqliteFindTable(db, pTabList->a[i].zName);
    if( pTabList->a[i].pTab==0 ){
      sqliteSetString(&pParse->zErrMsg, "no such table: ", 
................................................................................
      pParse->nErr++;
      goto update_cleanup;
    }
  }

  /* Allocate memory for the array apIdx[] and fill it with pointers to every
  ** index that needs to be updated.  Indices only need updating if their
  ** key includes one of the columns named in pChanges.

  */
  for(nIdx=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
    if( chngRecno ){
      i = 0;
    }else {
      for(i=0; i<pIdx->nColumn; i++){
        if( aXRef[pIdx->aiColumn[i]]>=0 ) break;
................................................................................

  /* Delete the old indices for the current record.
  */
  for(i=0; i<nIdx; i++){
    sqliteVdbeAddOp(v, OP_Dup, 0, 0);
    pIdx = apIdx[i];
    for(j=0; j<pIdx->nColumn; j++){




      sqliteVdbeAddOp(v, OP_Column, base, pIdx->aiColumn[j]);

    }
    sqliteVdbeAddOp(v, OP_MakeIdxKey, pIdx->nColumn, 0);
    sqliteVdbeAddOp(v, OP_IdxDelete, base+i+1, 0);
  }

  /* If changing the record number, remove the old record number
  ** from the top of the stack and replace it with the new one.
................................................................................
    if( j<0 ){
      sqliteVdbeAddOp(v, OP_Column, base, i);
    }else{
      sqliteExprCode(pParse, pChanges->a[j].pExpr);
    }
  }

  /* If changing the record number, delete the hold record.
  */
  if( chngRecno ){
    sqliteVdbeAddOp(v, OP_Delete, 0, 0);
  }

  /* Insert new index entries that correspond to the new data
  */

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle UPDATE statements.
**
** $Id: update.c,v 1.25 2001/12/31 02:48:51 drh Exp $
*/
#include "sqliteInt.h"

/*
** Process an UPDATE statement.
*/
void sqliteUpdate(
................................................................................

  if( pParse->nErr || sqlite_malloc_failed ) goto update_cleanup;
  db = pParse->db;

  /* Locate the table which we want to update.  This table has to be
  ** put in an IdList structure because some of the subroutines we
  ** will be calling are designed to work with multiple tables and expect
  ** an IdList* parameter instead of just a Table* parameter.
  */
  pTabList = sqliteIdListAppend(0, pTableName);
  if( pTabList==0 ) goto update_cleanup;
  for(i=0; i<pTabList->nId; i++){
    pTabList->a[i].pTab = sqliteFindTable(db, pTabList->a[i].zName);
    if( pTabList->a[i].pTab==0 ){
      sqliteSetString(&pParse->zErrMsg, "no such table: ", 
................................................................................
      pParse->nErr++;
      goto update_cleanup;
    }
  }

  /* Allocate memory for the array apIdx[] and fill it with pointers to every
  ** index that needs to be updated.  Indices only need updating if their
  ** key includes one of the columns named in pChanges or if the record
  ** number of the original table entry is changing.
  */
  for(nIdx=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
    if( chngRecno ){
      i = 0;
    }else {
      for(i=0; i<pIdx->nColumn; i++){
        if( aXRef[pIdx->aiColumn[i]]>=0 ) break;
................................................................................

  /* Delete the old indices for the current record.
  */
  for(i=0; i<nIdx; i++){
    sqliteVdbeAddOp(v, OP_Dup, 0, 0);
    pIdx = apIdx[i];
    for(j=0; j<pIdx->nColumn; j++){
      int x = pIdx->aiColumn[j];
      if( x==pTab->iPKey ){
        sqliteVdbeAddOp(v, OP_Dup, j, 0);
      }else{
        sqliteVdbeAddOp(v, OP_Column, base, x);
      }
    }
    sqliteVdbeAddOp(v, OP_MakeIdxKey, pIdx->nColumn, 0);
    sqliteVdbeAddOp(v, OP_IdxDelete, base+i+1, 0);
  }

  /* If changing the record number, remove the old record number
  ** from the top of the stack and replace it with the new one.
................................................................................
    if( j<0 ){
      sqliteVdbeAddOp(v, OP_Column, base, i);
    }else{
      sqliteExprCode(pParse, pChanges->a[j].pExpr);
    }
  }

  /* If changing the record number, delete the old record.
  */
  if( chngRecno ){
    sqliteVdbeAddOp(v, OP_Delete, 0, 0);
  }

  /* Insert new index entries that correspond to the new data
  */

** type to the other occurs as necessary.
** 
** Most of the code in this file is taken up by the sqliteVdbeExec()
** function which does the work of interpreting a VDBE program.
** But other routines are also provided to help in building up
** a program instruction by instruction.
**
** $Id: vdbe.c,v 1.102 2001/12/22 14:49:25 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** The following global variable is incremented every time a cursor
** moves, either by the OP_MoveTo or the OP_Next opcode.  The test
................................................................................

/*
** Boolean values
*/
typedef unsigned char Bool;

/*
** A cursor is a pointer into a database file.  The database file
** can represent either an SQL table or an SQL index.  Each file is
** a bag of key/data pairs.  The cursor can loop over all key/data
** pairs (in an arbitrary order) or it can retrieve a particular
** key/data pair given a copy of the key.
** 
** Every cursor that the virtual machine has open is represented by an
** instance of the following structure.
*/
struct Cursor {
  BtCursor *pCursor;    /* The cursor structure of the backend */
  int lastRecno;        /* Last recno from a Next or NextIdx operation */
................................................................................
#define NSORT 30

/*
** Number of bytes of string storage space available to each stack
** layer without having to malloc.  NBFS is short for Number of Bytes
** For Strings.
*/
#define NBFS 30

/*
** A single level of the stack is an instance of the following
** structure.  Except, string values are stored on a separate
** list of of pointers to character.  The reason for storing
** strings separately is so that they can be easily passed
** to the callback function.
................................................................................
typedef struct Set Set;
struct Set {
  Hash hash;             /* A set is just a hash table */
};

/*
** A Keylist is a bunch of keys into a table.  The keylist can
** grow without bound.  The keylist stores the keys of database
** records that need to be deleted.
*/
typedef struct Keylist Keylist;
struct Keylist {
  int nKey;         /* Number of slots in aKey[] */
  int nUsed;        /* Next unwritten slot in aKey[] */
  int nRead;        /* Next unread slot in aKey[] */
  Keylist *pNext;   /* Next block of keys */
................................................................................
**
** 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 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;
  if( p==0 || p->aOp==0 ) return;
................................................................................
case OP_String: {
  int i = ++p->tos;
  char *z;
  VERIFY( if( NeedStack(p, p->tos) ) goto no_mem; )
  z = pOp->p3;
  if( z==0 ){
    zStack[i] = 0;

    aStack[i].flags = STK_Null;
  }else{
    zStack[i] = z;
    aStack[i].n = strlen(z) + 1;
    aStack[i].flags = STK_Str | STK_Static;
  }
  break;

** type to the other occurs as necessary.
** 
** Most of the code in this file is taken up by the sqliteVdbeExec()
** function which does the work of interpreting a VDBE program.
** But other routines are also provided to help in building up
** a program instruction by instruction.
**
** $Id: vdbe.c,v 1.103 2001/12/31 02:48:51 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** The following global variable is incremented every time a cursor
** moves, either by the OP_MoveTo or the OP_Next opcode.  The test
................................................................................

/*
** Boolean values
*/
typedef unsigned char Bool;

/*
** A cursor is a pointer into a single BTree within a database file.
** The cursor can seek to a BTree entry with a particular key, or
** loop over all entries of the Btree.  You can also insert new BTree
** entries or retrieve the key or data from the entry that the cursor
** is currently pointing to.
** 
** Every cursor that the virtual machine has open is represented by an
** instance of the following structure.
*/
struct Cursor {
  BtCursor *pCursor;    /* The cursor structure of the backend */
  int lastRecno;        /* Last recno from a Next or NextIdx operation */
................................................................................
#define NSORT 30

/*
** Number of bytes of string storage space available to each stack
** layer without having to malloc.  NBFS is short for Number of Bytes
** For Strings.
*/
#define NBFS 32

/*
** A single level of the stack is an instance of the following
** structure.  Except, string values are stored on a separate
** list of of pointers to character.  The reason for storing
** strings separately is so that they can be easily passed
** to the callback function.
................................................................................
typedef struct Set Set;
struct Set {
  Hash hash;             /* A set is just a hash table */
};

/*
** A Keylist is a bunch of keys into a table.  The keylist can
** grow without bound.  The keylist stores the ROWIDs of database
** records that need to be deleted or updated.
*/
typedef struct Keylist Keylist;
struct Keylist {
  int nKey;         /* Number of slots in aKey[] */
  int nUsed;        /* Next unwritten slot in aKey[] */
  int nRead;        /* Next unread slot in aKey[] */
  Keylist *pNext;   /* Next block of keys */
................................................................................
**
** 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;
  if( p==0 || p->aOp==0 ) return;
................................................................................
case OP_String: {
  int i = ++p->tos;
  char *z;
  VERIFY( if( NeedStack(p, p->tos) ) goto no_mem; )
  z = pOp->p3;
  if( z==0 ){
    zStack[i] = 0;
    aStack[i].n = 0;
    aStack[i].flags = STK_Null;
  }else{
    zStack[i] = z;
    aStack[i].n = strlen(z) + 1;
    aStack[i].flags = STK_Str | STK_Static;
  }
  break;