~drizzle-trunk/drizzle/development

/* - mode: c; c-basic-offset: 2; indent-tabs-mode: nil; -*-
 *  vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
 *
 *  Copyright (C) 2008 MySQL
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

#ifdef USE_PRAGMA_IMPLEMENTATION
#pragma implementation				// gcc: Class implementation
#endif

#include <drizzled/field/varstring.h>

/****************************************************************************
  VARCHAR type
  Data in field->ptr is stored as:
    1 or 2 bytes length-prefix-header  (from Field_varstring::length_bytes)
    data

  NOTE:
  When VARCHAR is stored in a key (for handler::index_read() etc) it's always
  stored with a 2 byte prefix. (Just like blob keys).

  Normally length_bytes is calculated as (field_length < 256 : 1 ? 2)
  The exception is if there is a prefix key field that is part of a long
  VARCHAR, in which case field_length for this may be 1 but the length_bytes
  is 2.
****************************************************************************/

const uint Field_varstring::MAX_SIZE= UINT16_MAX;

/**
   Save the field metadata for varstring fields.

   Saves the field length in the first byte. Note: may consume
   2 bytes. Caller must ensure second byte is contiguous with
   first byte (e.g. array index 0,1).

   @param   metadata_ptr   First byte of field metadata

   @returns number of bytes written to metadata_ptr
*/
int Field_varstring::do_save_field_metadata(uchar *metadata_ptr)
{
  char *ptr= (char *)metadata_ptr;
  assert(field_length <= 65535);
  int2store(ptr, field_length);
  return 2;
}

int Field_varstring::store(const char *from,uint length,CHARSET_INFO *cs)
{
  uint copy_length;
  const char *well_formed_error_pos;
  const char *cannot_convert_error_pos;
  const char *from_end_pos;

  copy_length= well_formed_copy_nchars(field_charset,
                                       (char*) ptr + length_bytes,
                                       field_length,
                                       cs, from, length,
                                       field_length / field_charset->mbmaxlen,
                                       &well_formed_error_pos,
                                       &cannot_convert_error_pos,
                                       &from_end_pos);

  if (length_bytes == 1)
    *ptr= (uchar) copy_length;
  else
    int2store(ptr, copy_length);

  if (check_string_copy_error(this, well_formed_error_pos,
                              cannot_convert_error_pos, from + length, cs))
    return 2;

  return report_if_important_data(from_end_pos, from + length);
}


int Field_varstring::store(int64_t nr, bool unsigned_val)
{
  char buff[64];
  uint  length;
  length= (uint) (field_charset->cset->int64_t10_to_str)(field_charset,
                                                          buff,
                                                          sizeof(buff),
                                                          (unsigned_val ? 10:
                                                           -10),
                                                           nr);
  return Field_varstring::store(buff, length, field_charset);
}


double Field_varstring::val_real(void)
{
  int not_used;
  char *end_not_used;
  uint length= length_bytes == 1 ? (uint) *ptr : uint2korr(ptr);
  return my_strntod(field_charset, (char*) ptr+length_bytes, length,
                    &end_not_used, &not_used);
}


int64_t Field_varstring::val_int(void)
{
  int not_used;
  char *end_not_used;
  uint length= length_bytes == 1 ? (uint) *ptr : uint2korr(ptr);
  return my_strntoll(field_charset, (char*) ptr+length_bytes, length, 10,
                     &end_not_used, &not_used);
}

String *Field_varstring::val_str(String *val_buffer __attribute__((unused)),
				 String *val_ptr)
{
  uint length=  length_bytes == 1 ? (uint) *ptr : uint2korr(ptr);
  val_ptr->set((const char*) ptr+length_bytes, length, field_charset);
  return val_ptr;
}


my_decimal *Field_varstring::val_decimal(my_decimal *decimal_value)
{
  uint length= length_bytes == 1 ? (uint) *ptr : uint2korr(ptr);
  str2my_decimal(E_DEC_FATAL_ERROR, (char*) ptr+length_bytes, length,
                 charset(), decimal_value);
  return decimal_value;
}


int Field_varstring::cmp_max(const uchar *a_ptr, const uchar *b_ptr,
                             uint max_len)
{
  uint a_length, b_length;
  int diff;

  if (length_bytes == 1)
  {
    a_length= (uint) *a_ptr;
    b_length= (uint) *b_ptr;
  }
  else
  {
    a_length= uint2korr(a_ptr);
    b_length= uint2korr(b_ptr);
  }
  set_if_smaller(a_length, max_len);
  set_if_smaller(b_length, max_len);
  diff= field_charset->coll->strnncollsp(field_charset,
                                         a_ptr+
                                         length_bytes,
                                         a_length,
                                         b_ptr+
                                         length_bytes,
                                         b_length,0);
  return diff;
}


/**
  @note
    varstring and blob keys are ALWAYS stored with a 2 byte length prefix
*/

int Field_varstring::key_cmp(const uchar *key_ptr, uint max_key_length)
{
  uint length=  length_bytes == 1 ? (uint) *ptr : uint2korr(ptr);
  uint local_char_length= max_key_length / field_charset->mbmaxlen;

  local_char_length= my_charpos(field_charset, ptr + length_bytes,
                          ptr + length_bytes + length, local_char_length);
  set_if_smaller(length, local_char_length);
  return field_charset->coll->strnncollsp(field_charset, 
                                          ptr + length_bytes,
                                          length,
                                          key_ptr+
                                          HA_KEY_BLOB_LENGTH,
                                          uint2korr(key_ptr), 0);
}


/**
  Compare to key segments (always 2 byte length prefix).

  @note
    This is used only to compare key segments created for index_read().
    (keys are created and compared in key.cc)
*/

int Field_varstring::key_cmp(const uchar *a,const uchar *b)
{
  return field_charset->coll->strnncollsp(field_charset,
                                          a + HA_KEY_BLOB_LENGTH,
                                          uint2korr(a),
                                          b + HA_KEY_BLOB_LENGTH,
                                          uint2korr(b),
                                          0);
}


void Field_varstring::sort_string(uchar *to,uint length)
{
  uint tot_length=  length_bytes == 1 ? (uint) *ptr : uint2korr(ptr);

  if (field_charset == &my_charset_bin)
  {
    /* Store length last in high-byte order to sort longer strings first */
    if (length_bytes == 1)
      to[length-1]= tot_length;
    else
      mi_int2store(to+length-2, tot_length);
    length-= length_bytes;
  }
 
  tot_length= my_strnxfrm(field_charset,
			  to, length, ptr + length_bytes,
			  tot_length);
  assert(tot_length == length);
}


enum ha_base_keytype Field_varstring::key_type() const
{
  enum ha_base_keytype res;

  if (binary())
    res= length_bytes == 1 ? HA_KEYTYPE_VARBINARY1 : HA_KEYTYPE_VARBINARY2;
  else
    res= length_bytes == 1 ? HA_KEYTYPE_VARTEXT1 : HA_KEYTYPE_VARTEXT2;
  return res;
}


void Field_varstring::sql_type(String &res) const
{
  THD *thd= table->in_use;
  CHARSET_INFO *cs=res.charset();
  ulong length;

  length= cs->cset->snprintf(cs,(char*) res.ptr(),
                             res.alloced_length(), "%s(%d)",
                              (has_charset() ? "varchar" : "varbinary"),
                             (int) field_length / charset()->mbmaxlen);
  res.length(length);
  if ((thd->variables.sql_mode & (MODE_MYSQL323 | MODE_MYSQL40)) &&
      has_charset() && (charset()->state & MY_CS_BINSORT))
    res.append(STRING_WITH_LEN(" binary"));
}


uint32_t Field_varstring::data_length()
{
  return length_bytes == 1 ? (uint32_t) *ptr : uint2korr(ptr);
}

uint32_t Field_varstring::used_length()
{
  return length_bytes == 1 ? 1 + (uint32_t) (uchar) *ptr : 2 + uint2korr(ptr);
}

/*
  Functions to create a packed row.
  Here the number of length bytes are depending on the given max_length
*/

uchar *Field_varstring::pack(uchar *to, const uchar *from,
                             uint max_length,
                             bool low_byte_first __attribute__((unused)))
{
  uint length= length_bytes == 1 ? (uint) *from : uint2korr(from);
  set_if_smaller(max_length, field_length);
  if (length > max_length)
    length=max_length;

  /* Length always stored little-endian */
  *to++= length & 0xFF;
  if (max_length > 255)
    *to++= (length >> 8) & 0xFF;

  /* Store bytes of string */
  if (length > 0)
    memcpy(to, from+length_bytes, length);
  return to+length;
}


uchar *
Field_varstring::pack_key(uchar *to, const uchar *key, uint max_length,
                          bool low_byte_first __attribute__((unused)))
{
  uint length=  length_bytes == 1 ? (uint) *key : uint2korr(key);
  uint local_char_length= ((field_charset->mbmaxlen > 1) ?
                     max_length/field_charset->mbmaxlen : max_length);
  key+= length_bytes;
  if (length > local_char_length)
  {
    local_char_length= my_charpos(field_charset, key, key+length,
                                  local_char_length);
    set_if_smaller(length, local_char_length);
  }
  *to++= (char) (length & 255);
  if (max_length > 255)
    *to++= (char) (length >> 8);
  if (length)
    memcpy(to, key, length);
  return to+length;
}


/**
  Unpack a key into a record buffer.

  A VARCHAR key has a maximum size of 64K-1.
  In its packed form, the length field is one or two bytes long,
  depending on 'max_length'.

  @param to                          Pointer into the record buffer.
  @param key                         Pointer to the packed key.
  @param max_length                  Key length limit from key description.

  @return
    Pointer to end of 'key' (To the next key part if multi-segment key)
*/

const uchar *
Field_varstring::unpack_key(uchar *to __attribute__((unused)),
                            const uchar *key, uint max_length,
                            bool low_byte_first __attribute__((unused)))
{
  /* get length of the blob key */
  uint32_t length= *key++;
  if (max_length > 255)
    length+= (*key++) << 8;

  /* put the length into the record buffer */
  if (length_bytes == 1)
    *ptr= (uchar) length;
  else
    int2store(ptr, length);
  memcpy(ptr + length_bytes, key, length);
  return key + length;
}

/**
  Create a packed key that will be used for storage in the index tree.

  @param to		Store packed key segment here
  @param from		Key segment (as given to index_read())
  @param max_length  	Max length of key

  @return
    end of key storage
*/

uchar *
Field_varstring::pack_key_from_key_image(uchar *to, const uchar *from, uint max_length,
                                         bool low_byte_first __attribute__((unused)))
{
  /* Key length is always stored as 2 bytes */
  uint length= uint2korr(from);
  if (length > max_length)
    length= max_length;
  *to++= (char) (length & 255);
  if (max_length > 255)
    *to++= (char) (length >> 8);
  if (length)
    memcpy(to, from+HA_KEY_BLOB_LENGTH, length);
  return to+length;
}


/**
   Unpack a varstring field from row data.

   This method is used to unpack a varstring field from a master
   whose size of the field is less than that of the slave.

   @note
   The string length is always packed little-endian.
  
   @param   to         Destination of the data
   @param   from       Source of the data
   @param   param_data Length bytes from the master's field data

   @return  New pointer into memory based on from + length of the data
*/
const uchar *
Field_varstring::unpack(uchar *to, const uchar *from,
                        uint param_data,
                        bool low_byte_first __attribute__((unused)))
{
  uint length;
  uint l_bytes= (param_data && (param_data < field_length)) ? 
                (param_data <= 255) ? 1 : 2 : length_bytes;
  if (l_bytes == 1)
  {
    to[0]= *from++;
    length= to[0];
    if (length_bytes == 2)
      to[1]= 0;
  }
  else /* l_bytes == 2 */
  {
    length= uint2korr(from);
    to[0]= *from++;
    to[1]= *from++;
  }
  if (length)
    memcpy(to+ length_bytes, from, length);
  return from+length;
}


int Field_varstring::pack_cmp(const uchar *a, const uchar *b,
                              uint key_length_arg,
                              my_bool insert_or_update)
{
  uint a_length, b_length;
  if (key_length_arg > 255)
  {
    a_length=uint2korr(a); a+= 2;
    b_length=uint2korr(b); b+= 2;
  }
  else
  {
    a_length= (uint) *a++;
    b_length= (uint) *b++;
  }
  return field_charset->coll->strnncollsp(field_charset,
                                          a, a_length,
                                          b, b_length,
                                          insert_or_update);
}


int Field_varstring::pack_cmp(const uchar *b, uint key_length_arg,
                              my_bool insert_or_update)
{
  uchar *a= ptr+ length_bytes;
  uint a_length=  length_bytes == 1 ? (uint) *ptr : uint2korr(ptr);
  uint b_length;
  uint local_char_length= ((field_charset->mbmaxlen > 1) ?
                           key_length_arg / field_charset->mbmaxlen :
                           key_length_arg);

  if (key_length_arg > 255)
  {
    b_length=uint2korr(b); b+= HA_KEY_BLOB_LENGTH;
  }
  else
    b_length= (uint) *b++;

  if (a_length > local_char_length)
  {
    local_char_length= my_charpos(field_charset, a, a+a_length,
                                  local_char_length);
    set_if_smaller(a_length, local_char_length);
  }

  return field_charset->coll->strnncollsp(field_charset,
                                          a, a_length,
                                          b, b_length,
                                          insert_or_update);
}


uint Field_varstring::packed_col_length(const uchar *data_ptr, uint length)
{
  if (length > 255)
    return uint2korr(data_ptr)+2;
  return (uint) *data_ptr + 1;
}


uint Field_varstring::max_packed_col_length(uint max_length)
{
  return (max_length > 255 ? 2 : 1)+max_length;
}

uint Field_varstring::get_key_image(uchar *buff,
                                    uint length,
                                    imagetype type __attribute__((unused)))
{
  uint f_length=  length_bytes == 1 ? (uint) *ptr : uint2korr(ptr);
  uint local_char_length= length / field_charset->mbmaxlen;
  uchar *pos= ptr+length_bytes;
  local_char_length= my_charpos(field_charset, pos, pos + f_length,
                                local_char_length);
  set_if_smaller(f_length, local_char_length);
  /* Key is always stored with 2 bytes */
  int2store(buff,f_length);
  memcpy(buff+HA_KEY_BLOB_LENGTH, pos, f_length);
  if (f_length < length)
  {
    /*
      Must clear this as we do a memcmp in opt_range.cc to detect
      identical keys
    */
    memset(buff+HA_KEY_BLOB_LENGTH+f_length, 0, (length-f_length));
  }
  return HA_KEY_BLOB_LENGTH+f_length;
}


void Field_varstring::set_key_image(const uchar *buff,uint length)
{
  length= uint2korr(buff);			// Real length is here
  (void) Field_varstring::store((const char*) buff+HA_KEY_BLOB_LENGTH, length,
                                field_charset);
}


int Field_varstring::cmp_binary(const uchar *a_ptr, const uchar *b_ptr,
                                uint32_t max_length)
{
  uint32_t a_length,b_length;

  if (length_bytes == 1)
  {
    a_length= (uint) *a_ptr;
    b_length= (uint) *b_ptr;
  }
  else
  {
    a_length= uint2korr(a_ptr);
    b_length= uint2korr(b_ptr);
  }
  set_if_smaller(a_length, max_length);
  set_if_smaller(b_length, max_length);
  if (a_length != b_length)
    return 1;
  return memcmp(a_ptr+length_bytes, b_ptr+length_bytes, a_length);
}


Field *Field_varstring::new_field(MEM_ROOT *root, struct st_table *new_table,
                                  bool keep_type)
{
  Field_varstring *res= (Field_varstring*) Field::new_field(root, new_table,
                                                            keep_type);
  if (res)
    res->length_bytes= length_bytes;
  return res;
}


Field *Field_varstring::new_key_field(MEM_ROOT *root,
                                      struct st_table *new_table,
                                      uchar *new_ptr, uchar *new_null_ptr,
                                      uint new_null_bit)
{
  Field_varstring *res;
  if ((res= (Field_varstring*) Field::new_key_field(root,
                                                    new_table,
                                                    new_ptr,
                                                    new_null_ptr,
                                                    new_null_bit)))
  {
    /* Keys length prefixes are always packed with 2 bytes */
    res->length_bytes= 2;
  }
  return res;
}


uint Field_varstring::is_equal(Create_field *new_field)
{
  if (new_field->sql_type == real_type() &&
      new_field->charset == field_charset)
  {
    if (new_field->length == max_display_length())
      return IS_EQUAL_YES;
    if (new_field->length > max_display_length() &&
	((new_field->length <= 255 && max_display_length() <= 255) ||
	 (new_field->length > 255 && max_display_length() > 255)))
      return IS_EQUAL_PACK_LENGTH; // VARCHAR, longer variable length
  }
  return IS_EQUAL_NO;
}


void Field_varstring::hash(ulong *nr, ulong *nr2)
{
  if (is_null())
  {
    *nr^= (*nr << 1) | 1;
  }
  else
  {
    uint len=  length_bytes == 1 ? (uint) *ptr : uint2korr(ptr);
    CHARSET_INFO *cs= charset();
    cs->coll->hash_sort(cs, ptr + length_bytes, len, nr, nr2);
  }
}