/*

** 2003 September 6

**

** The author disclaims copyright to this source code.  In place of

** a legal notice, here is a blessing:

**

**    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.

**

*************************************************************************

** This file contains code used for creating, destroying, and populating

** a VDBE (or an "sqlite3_stmt" as it is known to the outside world.)  Prior

** to version 2.8.7, all this code was combined into the vdbe.c source file.

** But that file was getting too big so this subroutines were split out.

*/

#include "sqliteInt.h"

#include <ctype.h>

#include "vdbeInt.h"

/*

** When debugging the code generator in a symbolic debugger, one can

** set the sqlite3_vdbe_addop_trace to 1 and all opcodes will be printed

** as they are added to the instruction stream.

*/

#ifdef SQLITE_DEBUG

int sqlite3_vdbe_addop_trace = 0;

#endif

/*

** Create a new virtual database engine.

*/

Vdbe *sqlite3VdbeCreate(sqlite3 *db){

  Vdbe *p;

  p = (Vdbe*)sqlite3DbMallocZero(db, sizeof(Vdbe) );

  if( p==0 ) return 0;

  p->db = db;

  if( db->pVdbe ){

    db->pVdbe->pPrev = p;

  }

  p->pNext = db->pVdbe;

  p->pPrev = 0;

  db->pVdbe = p;

  p->magic = VDBE_MAGIC_INIT;

  return p;

}

/*

** Remember the SQL string for a prepared statement.

*/

void sqlite3VdbeSetSql(Vdbe *p, const char *z, int n){

  if( p==0 ) return;

  assert( p->zSql==0 );

  p->zSql = sqlite3DbStrNDup(p->db, z, n);

}

/*

** Return the SQL associated with a prepared statement

*/

EXPORT_C const char *sqlite3_sql(sqlite3_stmt *pStmt){

  return ((Vdbe *)pStmt)->zSql;

}

/*

** Swap all content between two VDBE structures.

*/

void sqlite3VdbeSwap(Vdbe *pA, Vdbe *pB){

  Vdbe tmp, *pTmp;

  char *zTmp;

  int nTmp;

  tmp = *pA;

  *pA = *pB;

  *pB = tmp;

  pTmp = pA->pNext;

  pA->pNext = pB->pNext;

  pB->pNext = pTmp;

  pTmp = pA->pPrev;

  pA->pPrev = pB->pPrev;

  pB->pPrev = pTmp;

  zTmp = pA->zSql;

  pA->zSql = pB->zSql;

  pB->zSql = zTmp;

  nTmp = pA->nSql;

  pA->nSql = pB->nSql;

  pB->nSql = nTmp;

}

#ifdef SQLITE_DEBUG

/*

** Turn tracing on or off

*/

void sqlite3VdbeTrace(Vdbe *p, FILE *trace){

  p->trace = trace;

}

#endif

/*

** Resize the Vdbe.aOp array so that it contains at least N

** elements.

**

** If an out-of-memory error occurs while resizing the array,

** Vdbe.aOp and Vdbe.nOpAlloc remain unchanged (this is so that

** any opcodes already allocated can be correctly deallocated

** along with the rest of the Vdbe).

*/

static void resizeOpArray(Vdbe *p, int N){

  VdbeOp *pNew;

  int oldSize = p->nOpAlloc;

  pNew = (VdbeOp*)sqlite3DbRealloc(p->db, p->aOp, N*sizeof(Op));

  if( pNew ){

    p->nOpAlloc = N;

    p->aOp = pNew;

    if( N>oldSize ){

      memset(&p->aOp[oldSize], 0, (N-oldSize)*sizeof(Op));

    }

  }

}

/*

** Add a new instruction to the list of instructions current in the

** VDBE.  Return the address of the new instruction.

**

** Parameters:

**

**    p               Pointer to the VDBE

**

**    op              The opcode for this instruction

**

**    p1, p2          First two of the three possible operands.

**

** Use the sqlite3VdbeResolveLabel() function to fix an address and

** the sqlite3VdbeChangeP3() function to change the value of the P3

** operand.

*/

int sqlite3VdbeAddOp(Vdbe *p, int op, int p1, int p2){

  int i;

  VdbeOp *pOp;

  i = p->nOp;

  assert( p->magic==VDBE_MAGIC_INIT );

  if( p->nOpAlloc<=i ){

    resizeOpArray(p, p->nOpAlloc*2 + 100);

    if( p->db->mallocFailed ){

      return 0;

    }

  }

  p->nOp++;

  pOp = &p->aOp[i];

  pOp->opcode = op;

  pOp->p1 = p1;

  pOp->p2 = p2;

  pOp->p3 = 0;

  pOp->p3type = P3_NOTUSED;

  p->expired = 0;

#ifdef SQLITE_DEBUG

  if( sqlite3_vdbe_addop_trace ) sqlite3VdbePrintOp(0, i, &p->aOp[i]);

#endif

  return i;

}

/*

** Add an opcode that includes the p3 value.

*/

int sqlite3VdbeOp3(Vdbe *p, int op, int p1, int p2, const char *zP3,int p3type){

  int addr = sqlite3VdbeAddOp(p, op, p1, p2);

  sqlite3VdbeChangeP3(p, addr, zP3, p3type);

  return addr;

}

/*

** Create a new symbolic label for an instruction that has yet to be

** coded.  The symbolic label is really just a negative number.  The

** label can be used as the P2 value of an operation.  Later, when

** the label is resolved to a specific address, the VDBE will scan

** through its operation list and change all values of P2 which match

** the label into the resolved address.

**

** The VDBE knows that a P2 value is a label because labels are

** always negative and P2 values are suppose to be non-negative.

** Hence, a negative P2 value is a label that has yet to be resolved.

**

** Zero is returned if a malloc() fails.

*/

int sqlite3VdbeMakeLabel(Vdbe *p){

  int i;

  i = p->nLabel++;

  assert( p->magic==VDBE_MAGIC_INIT );

  if( i>=p->nLabelAlloc ){

    p->nLabelAlloc = p->nLabelAlloc*2 + 10;

    p->aLabel = (int*)sqlite3DbReallocOrFree(p->db, p->aLabel,

                                    p->nLabelAlloc*sizeof(p->aLabel[0]));

  }

  if( p->aLabel ){

    p->aLabel[i] = -1;

  }

  return -1-i;

}

/*

** Resolve label "x" to be the address of the next instruction to

** be inserted.  The parameter "x" must have been obtained from

** a prior call to sqlite3VdbeMakeLabel().

*/

void sqlite3VdbeResolveLabel(Vdbe *p, int x){

  int j = -1-x;

  assert( p->magic==VDBE_MAGIC_INIT );

  assert( j>=0 && j<p->nLabel );

  if( p->aLabel ){

    p->aLabel[j] = p->nOp;

  }

}

/*

** Return non-zero if opcode 'op' is guarenteed not to push more values

** onto the VDBE stack than it pops off.

*/

static int opcodeNoPush(u8 op){

  /* The 10 NOPUSH_MASK_n constants are defined in the automatically

  ** generated header file opcodes.h. Each is a 16-bit bitmask, one

  ** bit corresponding to each opcode implemented by the virtual

  ** machine in vdbe.c. The bit is true if the word "no-push" appears

  ** in a comment on the same line as the "case OP_XXX:" in 

  ** sqlite3VdbeExec() in vdbe.c.

  **

  ** If the bit is true, then the corresponding opcode is guarenteed not

  ** to grow the stack when it is executed. Otherwise, it may grow the

  ** stack by at most one entry.

  **

  ** NOPUSH_MASK_0 corresponds to opcodes 0 to 15. NOPUSH_MASK_1 contains

  ** one bit for opcodes 16 to 31, and so on.

  **

  ** 16-bit bitmasks (rather than 32-bit) are specified in opcodes.h 

  ** because the file is generated by an awk program. Awk manipulates

  ** all numbers as floating-point and we don't want to risk a rounding

  ** error if someone builds with an awk that uses (for example) 32-bit 

  ** IEEE floats.

  */ 

  static const u32 masks[5] = {

    NOPUSH_MASK_0 + (((unsigned)NOPUSH_MASK_1)<<16),

    NOPUSH_MASK_2 + (((unsigned)NOPUSH_MASK_3)<<16),

    NOPUSH_MASK_4 + (((unsigned)NOPUSH_MASK_5)<<16),

    NOPUSH_MASK_6 + (((unsigned)NOPUSH_MASK_7)<<16),

    NOPUSH_MASK_8 + (((unsigned)NOPUSH_MASK_9)<<16)

  };

  assert( op<32*5 );

  return (masks[op>>5] & (1<<(op&0x1F)));

}

#ifndef NDEBUG

int sqlite3VdbeOpcodeNoPush(u8 op){

  return opcodeNoPush(op);

}

#endif

/*

** Loop through the program looking for P2 values that are negative.

** Each such value is a label.  Resolve the label by setting the P2

** value to its correct non-zero value.

**

** This routine is called once after all opcodes have been inserted.

**

** Variable *pMaxFuncArgs is set to the maximum value of any P2 argument 

** to an OP_Function, OP_AggStep or OP_VFilter opcode. This is used by 

** sqlite3VdbeMakeReady() to size the Vdbe.apArg[] array.

**

** The integer *pMaxStack is set to the maximum number of vdbe stack

** entries that static analysis reveals this program might need.

**

** This routine also does the following optimization:  It scans for

** instructions that might cause a statement rollback.  Such instructions

** are:

**

**   *  OP_Halt with P1=SQLITE_CONSTRAINT and P2=OE_Abort.

**   *  OP_Destroy

**   *  OP_VUpdate

**   *  OP_VRename

**

** If no such instruction is found, then every Statement instruction 

** is changed to a Noop.  In this way, we avoid creating the statement 

** journal file unnecessarily.

*/

static void resolveP2Values(Vdbe *p, int *pMaxFuncArgs, int *pMaxStack){

  int i;

  int nMaxArgs = 0;

  int nMaxStack = p->nOp;

  Op *pOp;

  int *aLabel = p->aLabel;

  int doesStatementRollback = 0;

  int hasStatementBegin = 0;

  for(pOp=p->aOp, i=p->nOp-1; i>=0; i--, pOp++){

    u8 opcode = pOp->opcode;

    if( opcode==OP_Function || opcode==OP_AggStep 

#ifndef SQLITE_OMIT_VIRTUALTABLE

        || opcode==OP_VUpdate

#endif

    ){

      if( pOp->p2>nMaxArgs ) nMaxArgs = pOp->p2;

    }

    if( opcode==OP_Halt ){

      if( pOp->p1==SQLITE_CONSTRAINT && pOp->p2==OE_Abort ){

        doesStatementRollback = 1;

      }

    }else if( opcode==OP_Statement ){

      hasStatementBegin = 1;

    }else if( opcode==OP_Destroy ){

      doesStatementRollback = 1;

#ifndef SQLITE_OMIT_VIRTUALTABLE

    }else if( opcode==OP_VUpdate || opcode==OP_VRename ){

      doesStatementRollback = 1;

    }else if( opcode==OP_VFilter ){

      int n;

      assert( p->nOp - i >= 3 );

      assert( pOp[-2].opcode==OP_Integer );

      n = pOp[-2].p1;

      if( n>nMaxArgs ) nMaxArgs = n;

#endif

    }

    if( opcodeNoPush(opcode) ){

      nMaxStack--;

    }

    if( pOp->p2>=0 ) continue;

    assert( -1-pOp->p2<p->nLabel );

    pOp->p2 = aLabel[-1-pOp->p2];

  }

  sqlite3_free(p->aLabel);

  p->aLabel = 0;

  *pMaxFuncArgs = nMaxArgs;

  *pMaxStack = nMaxStack;

  /* If we never rollback a statement transaction, then statement

  ** transactions are not needed.  So change every OP_Statement

  ** opcode into an OP_Noop.  This avoid a call to sqlite3OsOpenExclusive()

  ** which can be expensive on some platforms.

  */

  if( hasStatementBegin && !doesStatementRollback ){

    for(pOp=p->aOp, i=p->nOp-1; i>=0; i--, pOp++){

      if( pOp->opcode==OP_Statement ){

        pOp->opcode = OP_Noop;

      }

    }

  }

}

/*

** Return the address of the next instruction to be inserted.

*/

int sqlite3VdbeCurrentAddr(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 sqlite3VdbeAddOpList(Vdbe *p, int nOp, VdbeOpList const *aOp){

  int addr;

  assert( p->magic==VDBE_MAGIC_INIT );

  if( p->nOp + nOp > p->nOpAlloc ){

    resizeOpArray(p, p->nOp*2 + nOp);

  }

  if( p->db->mallocFailed ){

    return 0;

  }

  addr = p->nOp;

  if( nOp>0 ){

    int i;

    VdbeOpList const *pIn = aOp;

    for(i=0; i<nOp; i++, pIn++){

      int p2 = pIn->p2;

      VdbeOp *pOut = &p->aOp[i+addr];

      pOut->opcode = pIn->opcode;

      pOut->p1 = pIn->p1;

      pOut->p2 = p2<0 ? addr + ADDR(p2) : p2;

      pOut->p3 = pIn->p3;

      pOut->p3type = pIn->p3 ? P3_STATIC : P3_NOTUSED;

#ifdef SQLITE_DEBUG

      if( sqlite3_vdbe_addop_trace ){

        sqlite3VdbePrintOp(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 sqlite3VdbeAddOpList but we want to make a

** few minor changes to the program.

*/

void sqlite3VdbeChangeP1(Vdbe *p, int addr, int val){

  assert( p==0 || 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 sqlite3VdbeChangeP2(Vdbe *p, int addr, int val){

  assert( val>=0 );

  assert( p==0 || p->magic==VDBE_MAGIC_INIT );

  if( p && addr>=0 && p->nOp>addr && p->aOp ){

    p->aOp[addr].p2 = val;

  }

}

/*

** Change the P2 operand of instruction addr so that it points to

** the address of the next instruction to be coded.

*/

void sqlite3VdbeJumpHere(Vdbe *p, int addr){

  sqlite3VdbeChangeP2(p, addr, p->nOp);

}

/*

** If the input FuncDef structure is ephemeral, then free it.  If

** the FuncDef is not ephermal, then do nothing.

*/

static void freeEphemeralFunction(FuncDef *pDef){

  if( pDef && (pDef->flags & SQLITE_FUNC_EPHEM)!=0 ){

    sqlite3_free(pDef);

  }

}

/*

** Delete a P3 value if necessary.

*/

static void freeP3(int p3type, void *p3){

  if( p3 ){

    switch( p3type ){

      case P3_REAL:

      case P3_INT64:

      case P3_MPRINTF:

      case P3_DYNAMIC:

      case P3_KEYINFO:

      case P3_KEYINFO_HANDOFF: {

        sqlite3_free(p3);

        break;

      }

      case P3_VDBEFUNC: {

        VdbeFunc *pVdbeFunc = (VdbeFunc *)p3;

        freeEphemeralFunction(pVdbeFunc->pFunc);

        sqlite3VdbeDeleteAuxData(pVdbeFunc, 0);

        sqlite3_free(pVdbeFunc);

        break;

      }

      case P3_FUNCDEF: {

        freeEphemeralFunction((FuncDef*)p3);

        break;

      }

      case P3_MEM: {

        sqlite3ValueFree((sqlite3_value*)p3);

        break;

      }

    }

  }

}

/*

** Change N opcodes starting at addr to No-ops.

*/

void sqlite3VdbeChangeToNoop(Vdbe *p, int addr, int N){

  if( p && p->aOp ){

    VdbeOp *pOp = &p->aOp[addr];

    while( N-- ){

      freeP3(pOp->p3type, pOp->p3);

      memset(pOp, 0, sizeof(pOp[0]));

      pOp->opcode = OP_Noop;

      pOp++;

    }

  }

}

/*

** 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 sqlite3VdbeAddOpList 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 sqlite3_malloc().

** 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_KEYINFO it means that zP3 is a pointer to a KeyInfo structure.

** A copy is made of the KeyInfo structure into memory obtained from

** sqlite3_malloc, to be freed when the Vdbe is finalized.

** n==P3_KEYINFO_HANDOFF indicates that zP3 points to a KeyInfo structure

** stored in memory that the caller has obtained from sqlite3_malloc. The 

** caller should not free the allocation, it will be freed when the Vdbe is

** finalized.

** 

** Other values of n (P3_STATIC, P3_COLLSEQ etc.) indicate that zP3 points

** to a string or structure that is guaranteed to exist for the lifetime of

** the Vdbe. In these cases we can just copy the pointer.

**

** If addr<0 then change P3 on the most recently inserted instruction.

*/

void sqlite3VdbeChangeP3(Vdbe *p, int addr, const char *zP3, int n){

  Op *pOp;

  assert( p==0 || p->magic==VDBE_MAGIC_INIT );

  if( p==0 || p->aOp==0 || p->db->mallocFailed ){

    if (n != P3_KEYINFO) {

      freeP3(n, (void*)*(char**)&zP3);

    }

    return;

  }

  if( addr<0 || addr>=p->nOp ){

    addr = p->nOp - 1;

    if( addr<0 ) return;

  }

  pOp = &p->aOp[addr];

  freeP3(pOp->p3type, pOp->p3);

  pOp->p3 = 0;