/*

** 2004 May 26

**

** 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 use to manipulate "Mem" structure.  A "Mem"

** stores a single value in the VDBE.  Mem is an opaque structure visible

** only within the VDBE.  Interface routines refer to a Mem using the

** name sqlite_value

**

** $Id: vdbemem.c,v 1.123 2008/09/16 12:06:08 danielk1977 Exp $

*/

#include "sqliteInt.h"

#include <ctype.h>

#include "vdbeInt.h"

/*

** Call sqlite3VdbeMemExpandBlob() on the supplied value (type Mem*)

** P if required.

*/

#define expandBlob(P) (((P)->flags&MEM_Zero)?sqlite3VdbeMemExpandBlob(P):0)

/*

** If pMem is an object with a valid string representation, this routine

** ensures the internal encoding for the string representation is

** 'desiredEnc', one of SQLITE_UTF8, SQLITE_UTF16LE or SQLITE_UTF16BE.

**

** If pMem is not a string object, or the encoding of the string

** representation is already stored using the requested encoding, then this

** routine is a no-op.

**

** SQLITE_OK is returned if the conversion is successful (or not required).

** SQLITE_NOMEM may be returned if a malloc() fails during conversion

** between formats.

*/

int sqlite3VdbeChangeEncoding(Mem *pMem, int desiredEnc){

  int rc;

  if( !(pMem->flags&MEM_Str) || pMem->enc==desiredEnc ){

    return SQLITE_OK;

  }

  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );

#ifdef SQLITE_OMIT_UTF16

  return SQLITE_ERROR;

#else

  /* MemTranslate() may return SQLITE_OK or SQLITE_NOMEM. If NOMEM is returned,

  ** then the encoding of the value may not have changed.

  */

  rc = sqlite3VdbeMemTranslate(pMem, desiredEnc);

  assert(rc==SQLITE_OK    || rc==SQLITE_NOMEM);

  assert(rc==SQLITE_OK    || pMem->enc!=desiredEnc);

  assert(rc==SQLITE_NOMEM || pMem->enc==desiredEnc);

  return rc;

#endif

}

/*

** Make sure pMem->z points to a writable allocation of at least 

** n bytes.

**

** If the memory cell currently contains string or blob data

** and the third argument passed to this function is true, the 

** current content of the cell is preserved. Otherwise, it may

** be discarded.  

**

** This function sets the MEM_Dyn flag and clears any xDel callback.

** It also clears MEM_Ephem and MEM_Static. If the preserve flag is 

** not set, Mem.n is zeroed.

*/

int sqlite3VdbeMemGrow(Mem *pMem, int n, int preserve){

  assert( 1 >=

    ((pMem->zMalloc && pMem->zMalloc==pMem->z) ? 1 : 0) +

    (((pMem->flags&MEM_Dyn)&&pMem->xDel) ? 1 : 0) + 

    ((pMem->flags&MEM_Ephem) ? 1 : 0) + 

    ((pMem->flags&MEM_Static) ? 1 : 0)

  );

  if( n<32 ) n = 32;

  if( sqlite3DbMallocSize(pMem->db, pMem->zMalloc)<n ){

    if( preserve && pMem->z==pMem->zMalloc ){

      pMem->z = pMem->zMalloc = sqlite3DbReallocOrFree(pMem->db, pMem->z, n);

      if( !pMem->z ){

        pMem->flags = MEM_Null;

      }

      preserve = 0;

    }else{

      sqlite3DbFree(pMem->db, pMem->zMalloc);

      pMem->zMalloc = sqlite3DbMallocRaw(pMem->db, n);

    }

  }

  if( preserve && pMem->z && pMem->zMalloc && pMem->z!=pMem->zMalloc ){

    memcpy(pMem->zMalloc, pMem->z, pMem->n);

  }

  if( pMem->flags&MEM_Dyn && pMem->xDel ){

    pMem->xDel((void *)(pMem->z));

  }

  pMem->z = pMem->zMalloc;

  pMem->flags &= ~(MEM_Ephem|MEM_Static);

  pMem->xDel = 0;

  return (pMem->z ? SQLITE_OK : SQLITE_NOMEM);

}

/*

** Make the given Mem object MEM_Dyn.  In other words, make it so

** that any TEXT or BLOB content is stored in memory obtained from

** malloc().  In this way, we know that the memory is safe to be

** overwritten or altered.

**

** Return SQLITE_OK on success or SQLITE_NOMEM if malloc fails.

*/

int sqlite3VdbeMemMakeWriteable(Mem *pMem){

  int f;

  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );

  expandBlob(pMem);

  f = pMem->flags;

  if( (f&(MEM_Str|MEM_Blob)) && pMem->z!=pMem->zMalloc ){

    if( sqlite3VdbeMemGrow(pMem, pMem->n + 2, 1) ){

      return SQLITE_NOMEM;

    }

    pMem->z[pMem->n] = 0;

    pMem->z[pMem->n+1] = 0;

    pMem->flags |= MEM_Term;

  }

  return SQLITE_OK;

}

/*

** If the given Mem* has a zero-filled tail, turn it into an ordinary

** blob stored in dynamically allocated space.

*/

#ifndef SQLITE_OMIT_INCRBLOB

int sqlite3VdbeMemExpandBlob(Mem *pMem){

  if( pMem->flags & MEM_Zero ){

    int nByte;

    assert( pMem->flags&MEM_Blob );

    assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );

    /* Set nByte to the number of bytes required to store the expanded blob. */

    nByte = pMem->n + pMem->u.i;

    if( nByte<=0 ){

      nByte = 1;

    }

    if( sqlite3VdbeMemGrow(pMem, nByte, 1) ){

      return SQLITE_NOMEM;

    }

    memset(&pMem->z[pMem->n], 0, pMem->u.i);

    pMem->n += pMem->u.i;

    pMem->flags &= ~(MEM_Zero|MEM_Term);

  }

  return SQLITE_OK;

}

#endif

/*

** Make sure the given Mem is \u0000 terminated.

*/

int sqlite3VdbeMemNulTerminate(Mem *pMem){

  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );

  if( (pMem->flags & MEM_Term)!=0 || (pMem->flags & MEM_Str)==0 ){

    return SQLITE_OK;   /* Nothing to do */

  }

  if( sqlite3VdbeMemGrow(pMem, pMem->n+2, 1) ){

    return SQLITE_NOMEM;

  }

  pMem->z[pMem->n] = 0;

  pMem->z[pMem->n+1] = 0;

  pMem->flags |= MEM_Term;

  return SQLITE_OK;

}

/*

** Add MEM_Str to the set of representations for the given Mem.  Numbers

** are converted using sqlite3_snprintf().  Converting a BLOB to a string

** is a no-op.

**

** Existing representations MEM_Int and MEM_Real are *not* invalidated.

**

** A MEM_Null value will never be passed to this function. This function is

** used for converting values to text for returning to the user (i.e. via

** sqlite3_value_text()), or for ensuring that values to be used as btree

** keys are strings. In the former case a NULL pointer is returned the

** user and the later is an internal programming error.

*/

int sqlite3VdbeMemStringify(Mem *pMem, int enc){

  int rc = SQLITE_OK;

  int fg = pMem->flags;

  const int nByte = 32;

  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );

  assert( !(fg&MEM_Zero) );

  assert( !(fg&(MEM_Str|MEM_Blob)) );

  assert( fg&(MEM_Int|MEM_Real) );

  if( sqlite3VdbeMemGrow(pMem, nByte, 0) ){

    return SQLITE_NOMEM;

  }

  /* For a Real or Integer, use sqlite3_mprintf() to produce the UTF-8

  ** string representation of the value. Then, if the required encoding

  ** is UTF-16le or UTF-16be do a translation.

  ** 

  ** FIX ME: It would be better if sqlite3_snprintf() could do UTF-16.

  */

  if( fg & MEM_Int ){

    sqlite3_snprintf(nByte, pMem->z, "%lld", pMem->u.i);

  }else{

    assert( fg & MEM_Real );

    sqlite3_snprintf(nByte, pMem->z, "%!.15g", pMem->r);

  }

  pMem->n = strlen(pMem->z);

  pMem->enc = SQLITE_UTF8;

  pMem->flags |= MEM_Str|MEM_Term;

  sqlite3VdbeChangeEncoding(pMem, enc);

  return rc;

}

/*

** Memory cell pMem contains the context of an aggregate function.

** This routine calls the finalize method for that function.  The

** result of the aggregate is stored back into pMem.

**

** Return SQLITE_ERROR if the finalizer reports an error.  SQLITE_OK

** otherwise.

*/

int sqlite3VdbeMemFinalize(Mem *pMem, FuncDef *pFunc){

  int rc = SQLITE_OK;

  if( pFunc && pFunc->xFinalize ){

    sqlite3_context ctx;

    assert( (pMem->flags & MEM_Null)!=0 || pFunc==pMem->u.pDef );

    assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );

    memset(&ctx, 0, sizeof(ctx));

    ctx.s.flags = MEM_Null;

    ctx.s.db = pMem->db;

    ctx.pMem = pMem;

    ctx.pFunc = pFunc;

    pFunc->xFinalize(&ctx);

    assert( 0==(pMem->flags&MEM_Dyn) && !pMem->xDel );

    sqlite3DbFree(pMem->db, pMem->zMalloc);

    *pMem = ctx.s;

    rc = (ctx.isError?SQLITE_ERROR:SQLITE_OK);

  }

  return rc;

}

/*

** If the memory cell contains a string value that must be freed by

** invoking an external callback, free it now. Calling this function

** does not free any Mem.zMalloc buffer.

*/

void sqlite3VdbeMemReleaseExternal(Mem *p){

  assert( p->db==0 || sqlite3_mutex_held(p->db->mutex) );

  if( p->flags&MEM_Agg ){

    sqlite3VdbeMemFinalize(p, p->u.pDef);

    assert( (p->flags & MEM_Agg)==0 );

    sqlite3VdbeMemRelease(p);

  }else if( p->flags&MEM_Dyn && p->xDel ){

    p->xDel((void *)p->z);

    p->xDel = 0;

  }

}

/*

** Release any memory held by the Mem. This may leave the Mem in an

** inconsistent state, for example with (Mem.z==0) and

** (Mem.type==SQLITE_TEXT).

*/

void sqlite3VdbeMemRelease(Mem *p){

  sqlite3VdbeMemReleaseExternal(p);

  sqlite3DbFree(p->db, p->zMalloc);

  p->z = 0;

  p->zMalloc = 0;

  p->xDel = 0;

}

/*

** Convert a 64-bit IEEE double into a 64-bit signed integer.

** If the double is too large, return 0x8000000000000000.

**

** Most systems appear to do this simply by assigning

** variables and without the extra range tests.  But

** there are reports that windows throws an expection

** if the floating point value is out of range. (See ticket #2880.)

** Because we do not completely understand the problem, we will

** take the conservative approach and always do range tests

** before attempting the conversion.

*/

static i64 doubleToInt64(double r){

  /*

  ** Many compilers we encounter do not define constants for the

  ** minimum and maximum 64-bit integers, or they define them

  ** inconsistently.  And many do not understand the "LL" notation.

  ** So we define our own static constants here using nothing

  ** larger than a 32-bit integer constant.

  */

  static const i64 maxInt = LARGEST_INT64;

  static const i64 minInt = SMALLEST_INT64;

  if( r<(double)minInt ){

    return minInt;

  }else if( r>(double)maxInt ){

    return minInt;

  }else{

    return (i64)r;

  }

}

/*

** Return some kind of integer value which is the best we can do

** at representing the value that *pMem describes as an integer.

** If pMem is an integer, then the value is exact.  If pMem is

** a floating-point then the value returned is the integer part.

** If pMem is a string or blob, then we make an attempt to convert

** it into a integer and return that.  If pMem is NULL, return 0.

**

** If pMem is a string, its encoding might be changed.

*/

i64 sqlite3VdbeIntValue(Mem *pMem){

  int flags;

  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );

  flags = pMem->flags;

  if( flags & MEM_Int ){

    return pMem->u.i;

  }else if( flags & MEM_Real ){

    return doubleToInt64(pMem->r);

  }else if( flags & (MEM_Str|MEM_Blob) ){

    i64 value;

    pMem->flags |= MEM_Str;

    if( sqlite3VdbeChangeEncoding(pMem, SQLITE_UTF8)

       || sqlite3VdbeMemNulTerminate(pMem) ){

      return 0;

    }

    assert( pMem->z );

    sqlite3Atoi64(pMem->z, &value);

    return value;

  }else{

    return 0;

  }

}

/*

** Return the best representation of pMem that we can get into a

** double.  If pMem is already a double or an integer, return its

** value.  If it is a string or blob, try to convert it to a double.

** If it is a NULL, return 0.0.

*/

double sqlite3VdbeRealValue(Mem *pMem){

  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );

  if( pMem->flags & MEM_Real ){

    return pMem->r;

  }else if( pMem->flags & MEM_Int ){

    return (double)pMem->u.i;

  }else if( pMem->flags & (MEM_Str|MEM_Blob) ){

    double val = 0.0;

    pMem->flags |= MEM_Str;

    if( sqlite3VdbeChangeEncoding(pMem, SQLITE_UTF8)

       || sqlite3VdbeMemNulTerminate(pMem) ){

      return 0.0;

    }

    assert( pMem->z );

    sqlite3AtoF(pMem->z, &val);

    return val;

  }else{

    return 0.0;

  }

}

/*

** The MEM structure is already a MEM_Real.  Try to also make it a

** MEM_Int if we can.

*/

void sqlite3VdbeIntegerAffinity(Mem *pMem){

  assert( pMem->flags & MEM_Real );

  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );

  pMem->u.i = doubleToInt64(pMem->r);

  if( pMem->r==(double)pMem->u.i ){

    pMem->flags |= MEM_Int;

  }

}

static void setTypeFlag(Mem *pMem, int f){

  MemSetTypeFlag(pMem, f);

}

/*

** Convert pMem to type integer.  Invalidate any prior representations.

*/

int sqlite3VdbeMemIntegerify(Mem *pMem){

  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );

  pMem->u.i = sqlite3VdbeIntValue(pMem);

  setTypeFlag(pMem, MEM_Int);

  return SQLITE_OK;

}

/*

** Convert pMem so that it is of type MEM_Real.

** Invalidate any prior representations.

*/

int sqlite3VdbeMemRealify(Mem *pMem){

  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );

  pMem->r = sqlite3VdbeRealValue(pMem);

  setTypeFlag(pMem, MEM_Real);

  return SQLITE_OK;

}

/*

** Convert pMem so that it has types MEM_Real or MEM_Int or both.

** Invalidate any prior representations.

*/

int sqlite3VdbeMemNumerify(Mem *pMem){

  double r1, r2;

  i64 i;

  assert( (pMem->flags & (MEM_Int|MEM_Real|MEM_Null))==0 );

  assert( (pMem->flags & (MEM_Blob|MEM_Str))!=0 );

  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );

  r1 = sqlite3VdbeRealValue(pMem);

  i = doubleToInt64(r1);

  r2 = (double)i;

  if( r1==r2 ){

    sqlite3VdbeMemIntegerify(pMem);

  }else{

    pMem->r = r1;

    setTypeFlag(pMem, MEM_Real);

  }

  return SQLITE_OK;

}

/*

** Delete any previous value and set the value stored in *pMem to NULL.

*/

void sqlite3VdbeMemSetNull(Mem *pMem){

  setTypeFlag(pMem, MEM_Null);

  pMem->type = SQLITE_NULL;

}

/*

** Delete any previous value and set the value to be a BLOB of length

** n containing all zeros.

*/

void sqlite3VdbeMemSetZeroBlob(Mem *pMem, int n){

  sqlite3VdbeMemRelease(pMem);

  setTypeFlag(pMem, MEM_Blob);

  pMem->flags = MEM_Blob|MEM_Zero;

  pMem->type = SQLITE_BLOB;

  pMem->n = 0;

  if( n<0 ) n = 0;

  pMem->u.i = n;

  pMem->enc = SQLITE_UTF8;

}

/*

** Delete any previous value and set the value stored in *pMem to val,

** manifest type INTEGER.

*/

void sqlite3VdbeMemSetInt64(Mem *pMem, i64 val){

  sqlite3VdbeMemRelease(pMem);

  pMem->u.i = val;

  pMem->flags = MEM_Int;

  pMem->type = SQLITE_INTEGER;

}

/*

** Delete any previous value and set the value stored in *pMem to val,

** manifest type REAL.

*/

void sqlite3VdbeMemSetDouble(Mem *pMem, double val){

  if( sqlite3IsNaN(val) ){

    sqlite3VdbeMemSetNull(pMem);

  }else{

    sqlite3VdbeMemRelease(pMem);

    pMem->r = val;

    pMem->flags = MEM_Real;

    pMem->type = SQLITE_FLOAT;

  }

}

/*

** Return true if the Mem object contains a TEXT or BLOB that is

** too large - whose size exceeds SQLITE_MAX_LENGTH.

*/

int sqlite3VdbeMemTooBig(Mem *p){

  assert( p->db!=0 );

  if( p->flags & (MEM_Str|MEM_Blob) ){

    int n = p->n;

    if( p->flags & MEM_Zero ){

      n += p->u.i;

    }

    return n>p->db->aLimit[SQLITE_LIMIT_LENGTH];

  }

  return 0; 

}

/*

** Size of struct Mem not including the Mem.zMalloc member.

*/

#define MEMCELLSIZE (size_t)(&(((Mem *)0)->zMalloc))

/*

** Make an shallow copy of pFrom into pTo.  Prior contents of

** pTo are freed.  The pFrom->z field is not duplicated.  If

** pFrom->z is used, then pTo->z points to the same thing as pFrom->z

** and flags gets srcType (either MEM_Ephem or MEM_Static).

*/

void sqlite3VdbeMemShallowCopy(Mem *pTo, const Mem *pFrom, int srcType){

  sqlite3VdbeMemReleaseExternal(pTo);

  memcpy(pTo, pFrom, MEMCELLSIZE);

  pTo->xDel = 0;

  if( (pFrom->flags&MEM_Dyn)!=0 || pFrom->z==pFrom->zMalloc ){

    pTo->flags &= ~(MEM_Dyn|MEM_Static|MEM_Ephem);

    assert( srcType==MEM_Ephem || srcType==MEM_Static );

    pTo->flags |= srcType;

  }

}

/*

** Make a full copy of pFrom into pTo.  Prior contents of pTo are

** freed before the copy is made.