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SQLite training in Houston TX on 2019-11-05 (details)
Part of the 2019 Tcl Conference

Artifact 56b7de7af5800fbbf79fd953da95ee61c379a387:


/*
** 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 implement APIs that are part of the
** VDBE.
*/
#include "sqliteInt.h"
#include "vdbeInt.h"

/**************************** sqlite3_value_  *******************************
** The following routines extract information from a Mem or sqlite3_value
** structure.
*/
const void *sqlite3_value_blob(sqlite3_value *pVal){
  Mem *p = (Mem*)pVal;
  if( p->flags & (MEM_Blob|MEM_Str) ){
    return p->z;
  }else{
    return sqlite3_value_text(pVal);
  }
}
int sqlite3_value_bytes(sqlite3_value *pVal){
  Mem *p = (Mem*)pVal;
  if( (p->flags & MEM_Blob)!=0 || sqlite3_value_text(pVal) ){
    return p->n;
  }
  return 0;
}
int sqlite3_value_bytes16(sqlite3_value *pVal){
  Mem *p = (Mem*)pVal;
  if( (p->flags & MEM_Blob)!=0 || sqlite3_value_text16(pVal) ){
    return ((Mem *)pVal)->n;
  }
  return 0;
}
double sqlite3_value_double(sqlite3_value *pVal){
  Mem *pMem = (Mem *)pVal;
  Realify(pMem, flagsToEnc(pMem->flags));
  return pMem->r;
}
int sqlite3_value_int(sqlite3_value *pVal){
  Mem *pMem = (Mem *)pVal;
  Integerify(pMem, flagsToEnc(pMem->flags));
  return (int)pVal->i;
}
long long int sqlite3_value_int64(sqlite3_value *pVal){
  Mem *pMem = (Mem *)pVal;
  Integerify(pMem, flagsToEnc(pMem->flags));
  return pVal->i;
}
const unsigned char *sqlite3_value_text(sqlite3_value *pVal){
  if( pVal->flags&MEM_Null ){
    /* For a NULL return a NULL Pointer */
    return 0;
  }

  if( pVal->flags&MEM_Str ){
    /* If there is already a string representation, make sure it is in
    ** encoded in UTF-8.
    */
    SetEncoding(pVal, MEM_Utf8|MEM_Term);
  }else if( !(pVal->flags&MEM_Blob) ){
    /* Otherwise, unless this is a blob, convert it to a UTF-8 string */
    Stringify(pVal, TEXT_Utf8);
  }

  return pVal->z;
}
const void *sqlite3_value_text16(sqlite3_value* pVal){
  if( pVal->flags&MEM_Null ){
    /* For a NULL return a NULL Pointer */
    return 0;
  }

  if( pVal->flags&MEM_Str ){
    /* If there is already a string representation, make sure it is in
    ** encoded in UTF-16 machine byte order.
    */
    SetEncoding(pVal, encToFlags(TEXT_Utf16)|MEM_Term);
  }else if( !(pVal->flags&MEM_Blob) ){
    /* Otherwise, unless this is a blob, convert it to a UTF-16 string */
    Stringify(pVal, TEXT_Utf16);
  }

  return (const void *)(pVal->z);
}
int sqlite3_value_type(sqlite3_value* pVal){
  int f = ((Mem *)pVal)->flags;
  if( f&MEM_Null ){
    return SQLITE3_NULL;
  }
  if( f&MEM_Int ){
    return SQLITE3_INTEGER;
  }
  if( f&MEM_Real ){
    return SQLITE3_FLOAT;
  }
  if( f&MEM_Str ){
    return SQLITE3_TEXT;
  }
  if( f&MEM_Blob ){
    return SQLITE3_BLOB;
  }
  assert(0);
}

/**************************** sqlite3_result_  *******************************
** The following routines are used by user-defined functions to specify
** the function result.
*/
void sqlite3_result_blob(
  sqlite3_context *pCtx, 
  const void *z, 
  int n, 
  int eCopy
){
  assert( n>0 );
  MemSetStr(&pCtx->s, z, n, 0, eCopy);
}
void sqlite3_result_double(sqlite3_context *pCtx, double rVal){
  sqlite3VdbeMemSetDouble(&pCtx->s, rVal);
}
void sqlite3_result_error(sqlite3_context *pCtx, const char *z, int n){
  pCtx->isError = 1;
  sqlite3VdbeMemSetStr(&pCtx->s, z, n, TEXT_Utf8, 1);
}
void sqlite3_result_error16(sqlite3_context *pCtx, const void *z, int n){
  pCtx->isError = 1;
  sqlite3VdbeMemSetStr(&pCtx->s, z, n, TEXT_Utf16, 1);
}
void sqlite3_result_int32(sqlite3_context *pCtx, int iVal){
  sqlite3VdbeMemSetInt64(&pCtx->s, (i64)iVal);
}
void sqlite3_result_int64(sqlite3_context *pCtx, i64 iVal){
  sqlite3VdbeMemSetInt64(&pCtx->s, iVal);
}
void sqlite3_result_null(sqlite3_context *pCtx){
  sqilte3VdbeMemSetNull(&pCtx->s);
}
void sqlite3_result_text(
  sqlite3_context *pCtx, 
  const char *z, 
  int n,
  int eCopy
){
  MemSetStr(&pCtx->s, z, n, TEXT_Utf8, eCopy);
}
void sqlite3_result_text16(
  sqlite3_context *pCtx, 
  const void *z, 
  int n, 
  int eCopy
){
  MemSetStr(&pCtx->s, z, n, TEXT_Utf16, eCopy);
}
void sqlite3_result_value(sqlite3_context *pCtx, sqlite3_value *pValue){
  sqlite3VdbeMemCopy(&pCtx->s, pValue);
}


/*
** Execute the statement pStmt, either until a row of data is ready, the
** statement is completely executed or an error occurs.
*/
int sqlite3_step(sqlite3_stmt *pStmt){
  Vdbe *p = (Vdbe*)pStmt;
  sqlite *db;
  int rc;

  if( p->magic!=VDBE_MAGIC_RUN ){
    return SQLITE_MISUSE;
  }
  db = p->db;
  if( sqlite3SafetyOn(db) ){
    p->rc = SQLITE_MISUSE;
    return SQLITE_MISUSE;
  }
  if( p->explain ){
    rc = sqlite3VdbeList(p);
  }else{
    rc = sqlite3VdbeExec(p);
  }

  if( sqlite3SafetyOff(db) ){
    rc = SQLITE_MISUSE;
  }

  sqlite3Error(p->db, rc, p->zErrMsg);
  return rc;
}

/*
** Extract the user data from a sqlite3_context structure and return a
** pointer to it.
*/
void *sqlite3_user_data(sqlite3_context *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 sqlite3_context structure which is only defined in
** this source file.
*/
void *sqlite3_aggregate_context(sqlite3_context *p, int nByte){
  assert( p && p->pFunc && p->pFunc->xStep );
  if( p->pAgg==0 ){
    if( nByte<=NBFS ){
      p->pAgg = (void*)p->s.z;
      memset(p->pAgg, 0, nByte);
    }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 sqlite3_context structure which is only defined in
** this source file.
*/
int sqlite3_aggregate_count(sqlite3_context *p){
  assert( p && p->pFunc && p->pFunc->xStep );
  return p->cnt;
}

/*
** Return the number of columns in the result set for the statement pStmt.
*/
int sqlite3_column_count(sqlite3_stmt *pStmt){
  Vdbe *pVm = (Vdbe *)pStmt;
  return pVm->nResColumn;
}

/*
** Return the number of values available from the current row of the
** currently executing statement pStmt.
*/
int sqlite3_data_count(sqlite3_stmt *pStmt){
  Vdbe *pVm = (Vdbe *)pStmt;
  if( !pVm->resOnStack ) return 0;
  return pVm->nResColumn;
}


/*
** Check to see if column iCol of the given statement is valid.  If
** it is, return a pointer to the Mem for the value of that column.
** If iCol is not valid, return a pointer to a Mem which has a value
** of NULL.
*/
static Mem *columnMem(sqlite3_stmt *pStmt, int i){
  Vdbe *pVm = (Vdbe *)pStmt;
  int vals = sqlite3_data_count(pStmt);
  if( i>=vals || i<0 ){
    static Mem nullMem;
    if( nullMem.flags==0 ){ nullMem.flags = MEM_Null; }
    sqlite3Error(pVm->db, SQLITE_RANGE, 0);
    return &nullMem;
  }
  return &pVm->pTos[(1-vals)+i];
}

/**************************** sqlite3_column_  *******************************
** The following routines are used to access elements of the current row
** in the result set.
*/
int sqlite3_column_bytes(sqlite3_stmt *pStmt, int i){
  return sqlite3_value_bytes( columnMem(pStmt,i) );
}
int sqlite3_column_bytes16(sqlite3_stmt *pStmt, int i){
  return sqlite3_value_bytes16( columnMem(pStmt,i) );
}
double sqlite3_column_double(sqlite3_stmt *pStmt, int i){
  return sqlite3_value_double( columnMem(pStmt,i) );
}
int sqlite3_column_int(sqlite3_stmt *pStmt, int i){
  return sqlite3_value_int( columnMem(pStmt,i) );
}
long long int sqlite3_column_int64(sqlite3_stmt *pStmt, int i){
  return sqlite3_value_int64( columnMem(pStmt,i) );
}
const unsigned char *sqlite3_column_text(sqlite3_stmt *pStmt, int i){
  return sqlite3_value_text( columnMem(pStmt,i) );
}
const void *sqlite3_column_text16(sqlite3_stmt *pStmt, int i){
  return sqlite3_value_text16( columnMem(pStmt,i) );
}
int sqlite3_column_type(sqlite3_stmt *pStmt, int i){
  return sqlite3_value_type( columnMem(pStmt,i) );
}


/*
** Return the name of the Nth column of the result set returned by SQL
** statement pStmt.
*/
const char *sqlite3_column_name(sqlite3_stmt *pStmt, int N){
  Vdbe *p = (Vdbe *)pStmt;
  Mem *pColName;

  if( N>=sqlite3_column_count(pStmt) || N<0 ){
    sqlite3Error(p->db, SQLITE_RANGE, 0);
    return 0;
  }

  pColName = &(p->aColName[N]);
  return sqlite3_value_text(pColName);
}

/*
** Return the name of the 'i'th column of the result set of SQL statement
** pStmt, encoded as UTF-16.
*/
const void *sqlite3_column_name16(sqlite3_stmt *pStmt, int N){
  Vdbe *p = (Vdbe *)pStmt;
  Mem *pColName;

  if( N>=sqlite3_column_count(pStmt) || N<0 ){
    sqlite3Error(p->db, SQLITE_RANGE, 0);
    return 0;
  }

  pColName = &(p->aColName[N]);
  return sqlite3_value_text16(pColName);
}


/*
** This routine returns either the column name, or declaration type (see
** sqlite3_column_decltype16() ) of the 'i'th column of the result set of
** SQL statement pStmt. The returned string is UTF-16 encoded.
**
** The declaration type is returned if 'decltype' is true, otherwise
** the column name.
*/
static const void *columnName16(sqlite3_stmt *pStmt, int i, int decltype){
  Vdbe *p = (Vdbe *)pStmt;

  if( i>=sqlite3_column_count(pStmt) || i<0 ){
    sqlite3Error(p->db, SQLITE_RANGE, 0);
    return 0;
  }

  if( decltype ){
    i += p->nResColumn;
  }

  if( !p->azColName16 ){
    p->azColName16 = (void **)sqliteMalloc(sizeof(void *)*p->nResColumn*2);
    if( !p->azColName16 ){
      sqlite3Error(p->db, SQLITE_NOMEM, 0);
      return 0;
    }
  }
  if( !p->azColName16[i] ){
    if( SQLITE3_BIGENDIAN ){
      p->azColName16[i] = sqlite3utf8to16be(p->azColName[i], -1);
    }
    if( !p->azColName16[i] ){
      sqlite3Error(p->db, SQLITE_NOMEM, 0);
      return 0;
    }
  }
  return p->azColName16[i];
}

/*
** Return the column declaration type (if applicable) of the 'i'th column
** of the result set of SQL statement pStmt, encoded as UTF-8.
*/
const char *sqlite3_column_decltype(sqlite3_stmt *pStmt, int i){
  Vdbe *p = (Vdbe *)pStmt;

  if( i>=sqlite3_column_count(pStmt) || i<0 ){
    sqlite3Error(p->db, SQLITE_RANGE, 0);
    return 0;
  }

  return p->azColName[i+p->nResColumn];
}

/*
** Return the column declaration type (if applicable) of the 'i'th column
** of the result set of SQL statement pStmt, encoded as UTF-16.
*/
const void *sqlite3_column_decltype16(sqlite3_stmt *pStmt, int i){
  return columnName16(pStmt, i, 1);
}

/******************************* sqlite3_bind_  ***************************
** 
** Routines used to attach values to wildcards in a compiled SQL statement.
*/
/*
** Unbind the value bound to variable i in virtual machine p. This is the 
** the same as binding a NULL value to the column. If the "i" parameter is
** out of range, then SQLITE_RANGE is returned. Othewise SQLITE_OK.
**
** The error code stored in database p->db is overwritten with the return
** value in any case.
*/
static int vdbeUnbind(Vdbe *p, int i){
  Mem *pVar;
  if( p->magic!=VDBE_MAGIC_RUN || p->pc!=0 ){
    sqlite3Error(p->db, SQLITE_MISUSE, 0);
    return SQLITE_MISUSE;
  }
  if( i<1 || i>p->nVar ){
    sqlite3Error(p->db, SQLITE_RANGE, 0);
    return SQLITE_RANGE;
  }
  i--;
  pVar = &p->apVar[i];
  if( pVar->flags&MEM_Dyn ){
    sqliteFree(pVar->z);
  }
  pVar->flags = MEM_Null;
  sqlite3Error(p->db, SQLITE_OK, 0);
  return SQLITE_OK;
}

/*
** Bind a blob value to an SQL statement variable.
*/
int sqlite3_bind_blob(
  sqlite3_stmt *p, 
  int i, 
  const void *zData, 
  int nData, 
  int eCopy
){
  Vdbe *p = (Vdbe *)pStmt;
  Mem *pVar;
  int rc;

  rc = vdbeUnbind(p, i);
  if( rc ){
    return rc;
  }
  pVar = &p->apVar[i-1];
  rc = sqlite3VdbeMemSetStr(pVar, zData, nData, 0, eCopy);
  return rc;
}
int sqlite3_bind_double(sqlite3_stmt *pStmt, int i, double rValue){
  int rc;
  Vdbe *p = (Vdbe *)pStmt;
  Mem *pVar;
  rc = vdbeUnbind(p, i);
  if( rc==SQLITE_OK ){
    sqlite3VdbeMemSetReal(&p->apVar[i-1], rValue);
  }
  return SQLITE_OK;
}
int sqlite3_bind_int(sqlite3_stmt *p, int i, int iValue){
  return sqlite3_bind_int64(p, i, (long long int)iValue);
}
int sqlite3_bind_int64(sqlite3_stmt *pStmt, int i, long long int iValue){
  int rc;
  Vdbe *p = (Vdbe *)pStmt;
  rc = vdbeUnbind(p, i);
  if( rc==SQLITE_OK ){
    sqlite3VdbeMemSetInt(&p->apVar[i-1], iValue);
  }
  return rc;
}
int sqlite3_bind_null(sqlite3_stmt* p, int i){
  return vdbeUnbind((Vdbe *)p, i);
}
int sqlite3_bind_text( 
  sqlite3_stmt *pStmt, 
  int i, 
  const char *zData, 
  int nData, 
  int eCopy
){
  Vdbe *p = (Vdbe *)pStmt;
  Mem *pVar;
  int rc;

  rc = vdbeUnbind(p, i);
  if( rc ){
    return rc;
  }
  pVar = &p->apVar[i-1];
  rc = sqlite3VdbeMemSetStr(pVar, zData, nData, TEXT_Utf8, eCopy);
  if( rc ){
    return rc;
  }
  rc = sqlite3VdbeSetEncoding(pVar, p->db->enc);
  return rc;
}
int sqlite3_bind_text16(
  sqlite3_stmt *pStmt, 
  int i, 
  const void *zData, 
  int nData, 
  int eCopy
){
  Vdbe *p = (Vdbe *)pStmt;
  Mem *pVar;
  int rc;

  rc = vdbeUnbind(p, i);
  if( rc ){
    return rc;
  }
  Mem *pVar = &p->apVar[i-1];

  /* There may or may not be a byte order mark at the start of the UTF-16.
  ** Either way set 'txt_enc' to the TEXT_Utf16* value indicating the 
  ** actual byte order used by this string. If the string does happen
  ** to contain a BOM, then move zData so that it points to the first
  ** byte after the BOM.
  */
  txt_enc = sqlite3UtfReadBom(zData, nData);
  if( txt_enc ){
    zData = (void *)(((u8 *)zData) + 2);
    nData -= 2;
  }else{
    txt_enc = SQLITE3_BIGENDIAN?TEXT_Utf16be:TEXT_Utf16le;
  }
  rc = sqlite3VdbeMemSetStr(pVar, zData, nData, txt_enc, eCopy);
  if( rc ){
    return rc;
  }
  rc = sqlite3VdbeSetEncoding(pVar, p->db->enc);
  return rc;
}