SQLite

** This file contains the C functions that implement various SQL
** functions of SQLite.  
**
** There is only one exported symbol in this file - the function
** sqliteRegisterBuildinFunctions() found at the bottom of the file.
** All other code has file scope.
**
** $Id: func.c,v 1.216 2009/02/02 16:32:55 drh Exp $
*/
#include "sqliteInt.h"
#include <stdlib.h>
#include <assert.h>
#include "vdbeInt.h"

/*

  sqlite3_value **argv
){
  int i;
  int mask;    /* 0 for min() or 0xffffffff for max() */
  int iBest;
  CollSeq *pColl;

  assert( argc>1 );
  mask = sqlite3_user_data(context)==0 ? 0 : -1;
  pColl = sqlite3GetFuncCollSeq(context);
  assert( pColl );
  assert( mask==-1 || mask==0 );
  iBest = 0;
  if( sqlite3_value_type(argv[0])==SQLITE_NULL ) return;
  for(i=1; i<argc; i++){
    if( sqlite3_value_type(argv[i])==SQLITE_NULL ) return;
    if( (sqlite3MemCompare(argv[iBest], argv[i], pColl)^mask)>=0 ){
      testcase( mask==0 );
      iBest = i;
    }
  }
  sqlite3_result_value(context, argv[iBest]);
}

/*
** Return the type of the argument.
*/
static void typeofFunc(
  sqlite3_context *context,
  int NotUsed,
  sqlite3_value **argv
){
  const char *z = 0;
  UNUSED_PARAMETER(NotUsed);
  switch( sqlite3_value_type(argv[0]) ){

    case SQLITE_INTEGER: z = "integer"; break;
    case SQLITE_TEXT:    z = "text";    break;
    case SQLITE_FLOAT:   z = "real";    break;
    case SQLITE_BLOB:    z = "blob";    break;
    default:             z = "null";    break;
  }
  sqlite3_result_text(context, z, -1, SQLITE_STATIC);
}


/*
** Implementation of the length() function

  sqlite3_value **argv
){
  const unsigned char *z;
  const unsigned char *z2;
  int len;
  int p0type;
  i64 p1, p2;
  int negP2 = 0;

  assert( argc==3 || argc==2 );
  if( sqlite3_value_type(argv[1])==SQLITE_NULL
   || (argc==3 && sqlite3_value_type(argv[2])==SQLITE_NULL)
  ){
    return;
  }

    for(z2=z; *z2; len++){
      SQLITE_SKIP_UTF8(z2);
    }
  }
  p1 = sqlite3_value_int(argv[1]);
  if( argc==3 ){
    p2 = sqlite3_value_int(argv[2]);
    if( p2<0 ){
      p2 = -p2;
      negP2 = 1;
    }
  }else{
    p2 = sqlite3_context_db_handle(context)->aLimit[SQLITE_LIMIT_LENGTH];
  }
  if( p1<0 ){
    p1 += len;
    if( p1<0 ){
      p2 += p1;
      if( p2<0 ) p2 = 0;
      p1 = 0;
    }
  }else if( p1>0 ){
    p1--;
  }else if( p2>0 ){
    p2--;
  }
  if( negP2 ){
    p1 -= p2;

    if( p1<0 ){
      p2 += p1;
      p1 = 0;
    }
  }
  assert( p1>=0 && p2>=0 );
  if( p1+p2>len ){
    p2 = len-p1;
  }
  if( p0type!=SQLITE_BLOB ){
    while( *z && p1 ){
      SQLITE_SKIP_UTF8(z);
      p1--;
    }
    for(z2=z; *z2 && p2; p2--){
      SQLITE_SKIP_UTF8(z2);
    }
    sqlite3_result_text(context, (char*)z, (int)(z2-z), SQLITE_TRANSIENT);
  }else{

    sqlite3_result_blob(context, (char*)&z[p1], (int)p2, SQLITE_TRANSIENT);
  }
}

/*
** Implementation of the round() function
*/

# 2007 May 14
#
# 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 implements regression tests for SQLite library.  The
# focus of this file is testing the built-in SUBSTR() functions.
#
# $Id: substr.test,v 1.6 2009/02/02 16:32:55 drh Exp $

set testdir [file dirname $argv0]
source $testdir/tester.tcl

ifcapable !tclvar {
  finish_test
  return

# Basic SUBSTR functionality
#
substr-test 1.1 abcdefg 1 1 a
substr-test 1.2 abcdefg 2 1 b
substr-test 1.3 abcdefg 1 2 ab
substr-test 1.4 abcdefg 1 100 abcdefg
substr-test 1.5 abcdefg 0 2 a
substr-test 1.6 abcdefg -1 1 g
substr-test 1.7 abcdefg -1 10 g
substr-test 1.8 abcdefg -5 3 cde
substr-test 1.9 abcdefg -7 3 abc
substr-test 1.10 abcdefg -100 98 abcde
substr-test 1.11 abcdefg 5 -1 d
substr-test 1.12 abcdefg 5 -4 abcd

# Basic functionality for BLOBs
#
subblob-test 3.1 61626364656667 1 1 61
subblob-test 3.2 61626364656667 2 1 62
subblob-test 3.3 61626364656667 1 2 6162
subblob-test 3.4 61626364656667 1 100 61626364656667
subblob-test 3.5 61626364656667 0 2 61
subblob-test 3.6 61626364656667 -1 1 67
subblob-test 3.7 61626364656667 -1 10 67
subblob-test 3.8 61626364656667 -5 3 636465
subblob-test 3.9 61626364656667 -7 3 616263
subblob-test 3.10 61626364656667 -100 98 6162636465

# If these blobs were strings, then they would contain multi-byte