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 1.156 2007/05/15 01:13:47 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>
/* #include <math.h> */
#include <stdlib.h>
#include <assert.h>
#include "vdbeInt.h"

      sqlite3_result_double(context, rVal);
      break;
    }
  }
}

/*
** Implementation of the substr() function.
**
** substr(x,p1,p2)  returns p2 characters of x[] beginning with p1.
** p1 is 1-indexed.  So substr(x,1,1) returns the first character
** of x.  If x is text, then we actually count UTF-8 characters.
** If x is a blob, then we count bytes.
**
** If p1 is negative, then we begin abs(p1) from the end of x[].
*/
static void substrFunc(
  sqlite3_context *context,
  int argc,
  sqlite3_value **argv
){
  const unsigned char *z;
  const unsigned char *z2;
  int i;
  int len;
  int p0type;
  i64 p1, p2;

  assert( argc==3 );
  p0type = sqlite3_value_type(argv[0]);
  if( p0type==SQLITE_BLOB ){
    len = sqlite3_value_bytes(argv[0]);
    z = sqlite3_value_blob(argv[0]);
    if( z==0 ) return;
  }else{
    z = sqlite3_value_text(argv[0]);
    if( z==0 ) return;
    for(len=0, z2=z; *z2; z2++){ if( (0xc0&*z2)!=0x80 ) len++; }
  }
  p1 = sqlite3_value_int(argv[1]);
  p2 = sqlite3_value_int(argv[2]);

  if( p1<0 ){
    p1 += len;
    if( p1<0 ){
      p2 += p1;
      p1 = 0;
    }
  }else if( p1>0 ){
    p1--;
  }
  if( p1+p2>len ){
    p2 = len-p1;
  }
  if( p0type!=SQLITE_BLOB ){
    for(i=0; i<p1 && z[i]; i++){
      if( (z[i]&0xc0)==0x80 ) p1++;
    }
    while( z[i] && (z[i]&0xc0)==0x80 ){ i++; p1++; }
    for(; i<p1+p2 && z[i]; i++){
      if( (z[i]&0xc0)==0x80 ) p2++;
    }
    while( z[i] && (z[i]&0xc0)==0x80 ){ i++; p2++; }
    if( p2<0 ) p2 = 0;
    sqlite3_result_text(context, (char*)&z[p1], p2, SQLITE_TRANSIENT);
  }else{
    if( p2<0 ) p2 = 0;
    sqlite3_result_blob(context, (char*)&z[p1], p2, SQLITE_TRANSIENT);
  }
}

/*
** Implementation of the round() function
*/
static void roundFunc(sqlite3_context *context, int argc, sqlite3_value **argv){
  int n = 0;

# 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 1.1 2007/05/15 01:13:47 drh Exp $

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

# Create a table to work with.
#
execsql { 
  CREATE TABLE t1(t text, b blob)
}
proc substr-test {id string i1 i2 result} {
  db eval {
    DELETE FROM t1;
    INSERT INTO t1(t) VALUES($string)
  }
  do_test substr-$id.1 [subst {
    execsql {
      SELECT substr(t, $i1, $i2) FROM t1
    }
  }] [list $result]
  set qstr '[string map {' ''} $string]'
  do_test substr-$id.2 [subst {
    execsql {
      SELECT substr($qstr, $i1, $i2)
    }
  }] [list $result]
}
proc subblob-test {id hex i1 i2 hexresult} {
  db eval "
    DELETE FROM t1;
    INSERT INTO t1(b) VALUES(x'$hex')
  "
  do_test substr-$id.1 [subst {
    execsql {
      SELECT hex(substr(b, $i1, $i2)) FROM t1
    }
  }] [list $hexresult]
  do_test substr-$id.2 [subst {
    execsql {
      SELECT hex(substr(x'$hex', $i1, $i2))
    }
  }] [list $hexresult]
}

# 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 1 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

# Make sure everything works with long unicode characters
#
substr-test 2.1 \u1234\u2345\u3456 1 1 \u1234
substr-test 2.2 \u1234\u2345\u3456 2 1 \u2345
substr-test 2.3 \u1234\u2345\u3456 1 2 \u1234\u2345
substr-test 2.4 \u1234\u2345\u3456 -1 1 \u3456
substr-test 2.5 a\u1234b\u2345c\u3456c -5 3 b\u2345c

# 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 1 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
# characters.  But since they are blobs, the substr indices refer
# to bytes.
#
subblob-test 4.1 61E188B462E28D8563E3919663 1 1 61
subblob-test 4.2 61E188B462E28D8563E3919663 2 1 E1
subblob-test 4.3 61E188B462E28D8563E3919663 1 2 61E1
subblob-test 4.4 61E188B462E28D8563E3919663 -2 1 96
subblob-test 4.5 61E188B462E28D8563E3919663 -5 4 63E39196
subblob-test 4.6 61E188B462E28D8563E3919663 -100 98 61E188B462E28D8563E391 

finish_test

#
# Run this Tcl script to generate the lang-*.html files.
#
set rcsid {$Id: lang.tcl,v 1.129 2007/05/15 01:13:47 drh Exp $}
source common.tcl

if {[llength $argv]>0} {
  set outputdir [lindex $argv 0]
} else {
  set outputdir ""
}

<tr>
<td valign="top" align="right">substr(<i>X</i>,<i>Y</i>,<i>Z</i>)</td>
<td valign="top">Return a substring of input string <i>X</i> that begins
with the <i>Y</i>-th character and which is <i>Z</i> characters long.
The left-most character of <i>X</i> is number 1.  If <i>Y</i> is negative
the the first character of the substring is found by counting from the
right rather than the left.  If <i>X</i> is string
then characters indices refer to actual UTF-8 characters.  If
<i>X</i> is a BLOB then the indices refer to bytes.</td>
</tr>

<tr>
<td valign="top" align="right">
<a name="trimFunc">
trim(<i>X</i>)<br>trim(<i>X</i>,<i>Y</i>)</td>
<td valign="top">Return a string formed by removing any and all