item_strfunc.h 22.6 KB
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856
/* Copyright (C) 2000-2003 MySQL AB

   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; version 2 of the License.

   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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */


/* This file defines all string functions */

#ifdef USE_PRAGMA_INTERFACE
#pragma interface			/* gcc class implementation */
#endif

class Item_str_func :public Item_func
{
public:
  Item_str_func() :Item_func() { decimals=NOT_FIXED_DEC; }
  Item_str_func(Item *a) :Item_func(a) {decimals=NOT_FIXED_DEC; }
  Item_str_func(Item *a,Item *b) :Item_func(a,b) { decimals=NOT_FIXED_DEC; }
  Item_str_func(Item *a,Item *b,Item *c) :Item_func(a,b,c) { decimals=NOT_FIXED_DEC; }
  Item_str_func(Item *a,Item *b,Item *c,Item *d) :Item_func(a,b,c,d) {decimals=NOT_FIXED_DEC; }
  Item_str_func(Item *a,Item *b,Item *c,Item *d, Item* e) :Item_func(a,b,c,d,e) {decimals=NOT_FIXED_DEC; }
  Item_str_func(List<Item> &list) :Item_func(list) {decimals=NOT_FIXED_DEC; }
  longlong val_int();
  double val_real();
  my_decimal *val_decimal(my_decimal *);
  enum Item_result result_type () const { return STRING_RESULT; }
  void left_right_max_length();
  String *check_well_formed_result(String *str);
  bool fix_fields(THD *thd, Item **ref);
};

class Item_func_md5 :public Item_str_func
{
  String tmp_value;
public:
  Item_func_md5(Item *a) :Item_str_func(a)
  {
    collation.set(&my_charset_bin);
  }
  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "md5"; }
};


class Item_func_sha :public Item_str_func
{
public:
  Item_func_sha(Item *a) :Item_str_func(a)
  {
    collation.set(&my_charset_bin);
  }
  String *val_str(String *);    
  void fix_length_and_dec();      
  const char *func_name() const { return "sha"; }	
};

class Item_func_aes_encrypt :public Item_str_func
{
public:
  Item_func_aes_encrypt(Item *a, Item *b) :Item_str_func(a,b) {}
  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "aes_encrypt"; }
};

class Item_func_aes_decrypt :public Item_str_func	
{
public:
  Item_func_aes_decrypt(Item *a, Item *b) :Item_str_func(a,b) {}
  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "aes_decrypt"; }
};


class Item_func_concat :public Item_str_func
{
  String tmp_value;
public:
  Item_func_concat(List<Item> &list) :Item_str_func(list) {}
  Item_func_concat(Item *a,Item *b) :Item_str_func(a,b) {}
  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "concat"; }
};

class Item_func_concat_ws :public Item_str_func
{
  String tmp_value;
public:
  Item_func_concat_ws(List<Item> &list) :Item_str_func(list) {}
  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "concat_ws"; }
  table_map not_null_tables() const { return 0; }
};

class Item_func_reverse :public Item_str_func
{
  String tmp_value;
public:
  Item_func_reverse(Item *a) :Item_str_func(a) {}
  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "reverse"; }
};


class Item_func_replace :public Item_str_func
{
  String tmp_value,tmp_value2;
public:
  Item_func_replace(Item *org,Item *find,Item *replace)
    :Item_str_func(org,find,replace) {}
  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "replace"; }
};


class Item_func_insert :public Item_str_func
{
  String tmp_value;
public:
  Item_func_insert(Item *org,Item *start,Item *length,Item *new_str)
    :Item_str_func(org,start,length,new_str) {}
  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "insert"; }
};


class Item_str_conv :public Item_str_func
{
protected:
  uint multiply;
  uint (*converter)(CHARSET_INFO *cs, char *src, uint srclen,
                                      char *dst, uint dstlen);
  String tmp_value;
public:
  Item_str_conv(Item *item) :Item_str_func(item) {}
  String *val_str(String *);
};


class Item_func_lcase :public Item_str_conv
{
public:
  Item_func_lcase(Item *item) :Item_str_conv(item) {}
  const char *func_name() const { return "lcase"; }
  void fix_length_and_dec()
  {
    collation.set(args[0]->collation);
    multiply= collation.collation->casedn_multiply;
    converter= collation.collation->cset->casedn;
    max_length= args[0]->max_length * multiply;
  }
};

class Item_func_ucase :public Item_str_conv
{
public:
  Item_func_ucase(Item *item) :Item_str_conv(item) {}
  const char *func_name() const { return "ucase"; }
  void fix_length_and_dec()
  {
    collation.set(args[0]->collation);
    multiply= collation.collation->caseup_multiply;
    converter= collation.collation->cset->caseup;
    max_length= args[0]->max_length * multiply;
  }
};


class Item_func_left :public Item_str_func
{
  String tmp_value;
public:
  Item_func_left(Item *a,Item *b) :Item_str_func(a,b) {}
  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "left"; }
};


class Item_func_right :public Item_str_func
{
  String tmp_value;
public:
  Item_func_right(Item *a,Item *b) :Item_str_func(a,b) {}
  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "right"; }
};


class Item_func_substr :public Item_str_func
{
  String tmp_value;
public:
  Item_func_substr(Item *a,Item *b) :Item_str_func(a,b) {}
  Item_func_substr(Item *a,Item *b,Item *c) :Item_str_func(a,b,c) {}
  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "substr"; }
};


class Item_func_substr_index :public Item_str_func
{
  String tmp_value;
public:
  Item_func_substr_index(Item *a,Item *b,Item *c) :Item_str_func(a,b,c) {}
  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "substring_index"; }
};


class Item_func_trim :public Item_str_func
{
protected:
  String tmp_value;
  String remove;
public:
  Item_func_trim(Item *a,Item *b) :Item_str_func(a,b) {}
  Item_func_trim(Item *a) :Item_str_func(a) {}
  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "trim"; }
  void print(String *str);
  virtual const char *mode_name() const { return "both"; }
};


class Item_func_ltrim :public Item_func_trim
{
public:
  Item_func_ltrim(Item *a,Item *b) :Item_func_trim(a,b) {}
  Item_func_ltrim(Item *a) :Item_func_trim(a) {}
  String *val_str(String *);
  const char *func_name() const { return "ltrim"; }
  const char *mode_name() const { return "leading"; }
};


class Item_func_rtrim :public Item_func_trim
{
public:
  Item_func_rtrim(Item *a,Item *b) :Item_func_trim(a,b) {}
  Item_func_rtrim(Item *a) :Item_func_trim(a) {}
  String *val_str(String *);
  const char *func_name() const { return "rtrim"; }
  const char *mode_name() const { return "trailing"; }
};


/*
  Item_func_password -- new (4.1.1) PASSWORD() function implementation.
  Returns strcat('*', octet2hex(sha1(sha1(password)))). '*' stands for new
  password format, sha1(sha1(password) is so-called hash_stage2 value.
  Length of returned string is always 41 byte. To find out how entire
  authentication procedure works, see comments in password.c.
*/

class Item_func_password :public Item_str_func
{
  char tmp_value[SCRAMBLED_PASSWORD_CHAR_LENGTH+1]; 
public:
  Item_func_password(Item *a) :Item_str_func(a) {}
  String *val_str(String *str);
  void fix_length_and_dec() { max_length= SCRAMBLED_PASSWORD_CHAR_LENGTH; }
  const char *func_name() const { return "password"; }
  static char *alloc(THD *thd, const char *password);
};


/*
  Item_func_old_password -- PASSWORD() implementation used in MySQL 3.21 - 4.0
  compatibility mode. This item is created in sql_yacc.yy when
  'old_passwords' session variable is set, and to handle OLD_PASSWORD()
  function.
*/

class Item_func_old_password :public Item_str_func
{
  char tmp_value[SCRAMBLED_PASSWORD_CHAR_LENGTH_323+1];
public:
  Item_func_old_password(Item *a) :Item_str_func(a) {}
  String *val_str(String *str);
  void fix_length_and_dec() { max_length= SCRAMBLED_PASSWORD_CHAR_LENGTH_323; } 
  const char *func_name() const { return "old_password"; }
  static char *alloc(THD *thd, const char *password);
};


class Item_func_des_encrypt :public Item_str_func
{
  String tmp_value;
public:
  Item_func_des_encrypt(Item *a) :Item_str_func(a) {}
  Item_func_des_encrypt(Item *a, Item *b): Item_str_func(a,b) {}
  String *val_str(String *);
  void fix_length_and_dec()
  { maybe_null=1; max_length = args[0]->max_length+8; }
  const char *func_name() const { return "des_encrypt"; }
};

class Item_func_des_decrypt :public Item_str_func
{
  String tmp_value;
public:
  Item_func_des_decrypt(Item *a) :Item_str_func(a) {}
  Item_func_des_decrypt(Item *a, Item *b): Item_str_func(a,b) {}
  String *val_str(String *);
  void fix_length_and_dec() { maybe_null=1; max_length = args[0]->max_length; }
  const char *func_name() const { return "des_decrypt"; }
};

class Item_func_encrypt :public Item_str_func
{
  String tmp_value;

  /* Encapsulate common constructor actions */
  void constructor_helper()
  {
    collation.set(&my_charset_bin);
  }
public:
  Item_func_encrypt(Item *a) :Item_str_func(a)
  {
    constructor_helper();
  }
  Item_func_encrypt(Item *a, Item *b): Item_str_func(a,b)
  {
    constructor_helper();
  }
  String *val_str(String *);
  void fix_length_and_dec() { maybe_null=1; max_length = 13; }
  const char *func_name() const { return "encrypt"; }
};

#include "sql_crypt.h"


class Item_func_encode :public Item_str_func
{
 protected:
  SQL_CRYPT sql_crypt;
  String seed;
public:
  Item_func_encode(Item *a, char *seed_arg):
    Item_str_func(a), sql_crypt(seed_arg)
    {
      seed.copy(seed_arg, strlen(seed_arg), default_charset_info);
    }
  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "encode"; }
  void print(String *str);
};


class Item_func_decode :public Item_func_encode
{
public:
  Item_func_decode(Item *a, char *seed_arg): Item_func_encode(a, seed_arg) {}
  String *val_str(String *);
  const char *func_name() const { return "decode"; }
};


class Item_func_sysconst :public Item_str_func
{
public:
  Item_func_sysconst()
  { collation.set(system_charset_info,DERIVATION_SYSCONST); }
  Item *safe_charset_converter(CHARSET_INFO *tocs);
  /*
    Used to create correct Item name in new converted item in
    safe_charset_converter, return string representation of this function
    call
  */
  virtual const char *fully_qualified_func_name() const = 0;
};


class Item_func_database :public Item_func_sysconst
{
public:
  Item_func_database() :Item_func_sysconst() {}
  String *val_str(String *);
  void fix_length_and_dec()
  {
    max_length= MAX_FIELD_NAME * system_charset_info->mbmaxlen;
    maybe_null=1;
  }
  const char *func_name() const { return "database"; }
  const char *fully_qualified_func_name() const { return "database()"; }
};


class Item_func_user :public Item_func_sysconst
{
protected:
  bool init (const char *user, const char *host);

public:
  Item_func_user()
  {
    str_value.set("", 0, system_charset_info);
  }
  String *val_str(String *)
  {
    DBUG_ASSERT(fixed == 1);
    return (null_value ? 0 : &str_value);
  }
  bool fix_fields(THD *thd, Item **ref);
  void fix_length_and_dec()
  {
    max_length= ((USERNAME_LENGTH + HOSTNAME_LENGTH + 1) *
                 system_charset_info->mbmaxlen);
  }
  const char *func_name() const { return "user"; }
  const char *fully_qualified_func_name() const { return "user()"; }
  int save_in_field(Field *field, bool no_conversions)
  {
    return save_str_value_in_field(field, &str_value);
  }
};


class Item_func_current_user :public Item_func_user
{
  Name_resolution_context *context;

public:
  Item_func_current_user(Name_resolution_context *context_arg)
    : context(context_arg) {}
  bool fix_fields(THD *thd, Item **ref);
  const char *func_name() const { return "current_user"; }
  const char *fully_qualified_func_name() const { return "current_user()"; }
};


class Item_func_soundex :public Item_str_func
{
  String tmp_value;
public:
  Item_func_soundex(Item *a) :Item_str_func(a) {}
  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "soundex"; }
};


class Item_func_elt :public Item_str_func
{
public:
  Item_func_elt(List<Item> &list) :Item_str_func(list) {}
  double val_real();
  longlong val_int();
  String *val_str(String *str);
  void fix_length_and_dec();
  const char *func_name() const { return "elt"; }
};


class Item_func_make_set :public Item_str_func
{
  Item *item;
  String tmp_str;

public:
  Item_func_make_set(Item *a,List<Item> &list) :Item_str_func(list),item(a) {}
  String *val_str(String *str);
  bool fix_fields(THD *thd, Item **ref)
  {
    DBUG_ASSERT(fixed == 0);
    return ((!item->fixed && item->fix_fields(thd, &item)) ||
	    item->check_cols(1) ||
	    Item_func::fix_fields(thd, ref));
  }
  void split_sum_func(THD *thd, Item **ref_pointer_array, List<Item> &fields);
  void fix_length_and_dec();
  void update_used_tables();
  const char *func_name() const { return "make_set"; }

  bool walk(Item_processor processor, byte *arg)
  {
    return item->walk(processor, arg) ||
      Item_str_func::walk(processor, arg);
  }
  Item *transform(Item_transformer transformer, byte *arg);
  void print(String *str);
};


class Item_func_format :public Item_str_func
{
  String tmp_str;
public:
  Item_func_format(Item *org,int dec);
  String *val_str(String *);
  void fix_length_and_dec()
  {
    collation.set(default_charset());
    uint char_length= args[0]->max_length/args[0]->collation.collation->mbmaxlen;
    max_length= ((char_length + (char_length-args[0]->decimals)/3) *
                 collation.collation->mbmaxlen);
  }
  const char *func_name() const { return "format"; }
  void print(String *);
};


class Item_func_char :public Item_str_func
{
public:
  Item_func_char(List<Item> &list) :Item_str_func(list)
  { collation.set(&my_charset_bin); }
  Item_func_char(List<Item> &list, CHARSET_INFO *cs) :Item_str_func(list)
  { collation.set(cs); }  
  String *val_str(String *);
  void fix_length_and_dec() 
  {
    max_length= arg_count * collation.collation->mbmaxlen;
  }
  const char *func_name() const { return "char"; }
};


class Item_func_repeat :public Item_str_func
{
  String tmp_value;
public:
  Item_func_repeat(Item *arg1,Item *arg2) :Item_str_func(arg1,arg2) {}
  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "repeat"; }
};


class Item_func_rpad :public Item_str_func
{
  String tmp_value, rpad_str;
public:
  Item_func_rpad(Item *arg1,Item *arg2,Item *arg3)
    :Item_str_func(arg1,arg2,arg3) {}
  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "rpad"; }
};


class Item_func_lpad :public Item_str_func
{
  String tmp_value, lpad_str;
public:
  Item_func_lpad(Item *arg1,Item *arg2,Item *arg3)
    :Item_str_func(arg1,arg2,arg3) {}
  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "lpad"; }
};


class Item_func_conv :public Item_str_func
{
public:
  Item_func_conv(Item *a,Item *b,Item *c) :Item_str_func(a,b,c) {}
  const char *func_name() const { return "conv"; }
  String *val_str(String *);
  void fix_length_and_dec()
  {
    collation.set(default_charset());
    max_length= 64;
  }
};


class Item_func_hex :public Item_str_func
{
  String tmp_value;
public:
  Item_func_hex(Item *a) :Item_str_func(a) {}
  const char *func_name() const { return "hex"; }
  String *val_str(String *);
  void fix_length_and_dec()
  {
    collation.set(default_charset());
    decimals=0;
    max_length=args[0]->max_length*2*collation.collation->mbmaxlen;
  }
};

class Item_func_unhex :public Item_str_func
{
  String tmp_value;
public:
  Item_func_unhex(Item *a) :Item_str_func(a) 
  { 
    /* there can be bad hex strings */
    maybe_null= 1; 
  }
  const char *func_name() const { return "unhex"; }
  String *val_str(String *);
  void fix_length_and_dec()
  {
    collation.set(&my_charset_bin);
    decimals=0;
    max_length=(1+args[0]->max_length)/2;
  }
};


class Item_func_binary :public Item_str_func
{
public:
  Item_func_binary(Item *a) :Item_str_func(a) {}
  String *val_str(String *a)
  {
    DBUG_ASSERT(fixed == 1);
    String *tmp=args[0]->val_str(a);
    null_value=args[0]->null_value;
    if (tmp)
      tmp->set_charset(&my_charset_bin);
    return tmp;
  }
  void fix_length_and_dec()
  {
    collation.set(&my_charset_bin);
    max_length=args[0]->max_length;
  }
  void print(String *str);
  const char *func_name() const { return "cast_as_binary"; }
};


class Item_load_file :public Item_str_func
{
  String tmp_value;
public:
  Item_load_file(Item *a) :Item_str_func(a) {}
  String *val_str(String *);
  const char *func_name() const { return "load_file"; }
  void fix_length_and_dec()
  {
    collation.set(&my_charset_bin, DERIVATION_COERCIBLE);
    maybe_null=1;
    max_length=MAX_BLOB_WIDTH;
  }
};


class Item_func_export_set: public Item_str_func
{
 public:
  Item_func_export_set(Item *a,Item *b,Item* c) :Item_str_func(a,b,c) {}
  Item_func_export_set(Item *a,Item *b,Item* c,Item* d) :Item_str_func(a,b,c,d) {}
  Item_func_export_set(Item *a,Item *b,Item* c,Item* d,Item* e) :Item_str_func(a,b,c,d,e) {}
  String  *val_str(String *str);
  void fix_length_and_dec();
  const char *func_name() const { return "export_set"; }
};

class Item_func_inet_ntoa : public Item_str_func
{
public:
  Item_func_inet_ntoa(Item *a) :Item_str_func(a)
    {
    }
  String* val_str(String* str);
  const char *func_name() const { return "inet_ntoa"; }
  void fix_length_and_dec() { decimals = 0; max_length=3*8+7; }
};

class Item_func_quote :public Item_str_func
{
  String tmp_value;
public:
  Item_func_quote(Item *a) :Item_str_func(a) {}
  const char *func_name() const { return "quote"; }
  String *val_str(String *);
  void fix_length_and_dec()
  {
    collation.set(args[0]->collation);
    max_length= args[0]->max_length * 2 + 2;
  }
};

class Item_func_conv_charset :public Item_str_func
{
  bool use_cached_value;
public:
  bool safe;
  CHARSET_INFO *conv_charset; // keep it public
  Item_func_conv_charset(Item *a, CHARSET_INFO *cs) :Item_str_func(a) 
  { conv_charset= cs; use_cached_value= 0; safe= 0; }
  Item_func_conv_charset(Item *a, CHARSET_INFO *cs, bool cache_if_const) 
    :Item_str_func(a) 
  {
    DBUG_ASSERT(args[0]->fixed);
    conv_charset= cs;
    if (cache_if_const && args[0]->const_item())
    {
      uint errors= 0;
      String tmp, *str= args[0]->val_str(&tmp);
      if (!str || str_value.copy(str->ptr(), str->length(),
                                 str->charset(), conv_charset, &errors))
        null_value= 1;
      use_cached_value= 1;
      str_value.mark_as_const();
      safe= (errors == 0);
    }
    else
    {
      use_cached_value= 0;
      /*
        Conversion from and to "binary" is safe.
        Conversion to Unicode is safe.
        Other kind of conversions are potentially lossy.
      */
      safe= (args[0]->collation.collation == &my_charset_bin ||
             cs == &my_charset_bin ||
             (cs->state & MY_CS_UNICODE));
    }
  }
  String *val_str(String *);
  void fix_length_and_dec();
  const char *func_name() const { return "convert"; }
  void print(String *str);
};

class Item_func_set_collation :public Item_str_func
{
public:
  Item_func_set_collation(Item *a, Item *b) :Item_str_func(a,b) {};
  String *val_str(String *);
  void fix_length_and_dec();
  bool eq(const Item *item, bool binary_cmp) const;
  const char *func_name() const { return "collate"; }
  enum Functype functype() const { return COLLATE_FUNC; }
  void print(String *str);
  Item_field *filed_for_view_update()
  {
    /* this function is transparent for view updating */
    return args[0]->filed_for_view_update();
  }
};

class Item_func_charset :public Item_str_func
{
public:
  Item_func_charset(Item *a) :Item_str_func(a) {}
  String *val_str(String *);
  const char *func_name() const { return "charset"; }
  void fix_length_and_dec()
  {
     collation.set(system_charset_info);
     max_length= 64 * collation.collation->mbmaxlen; // should be enough
     maybe_null= 0;
  };
  table_map not_null_tables() const { return 0; }
};

class Item_func_collation :public Item_str_func
{
public:
  Item_func_collation(Item *a) :Item_str_func(a) {}
  String *val_str(String *);
  const char *func_name() const { return "collation"; }
  void fix_length_and_dec()
  {
     collation.set(system_charset_info);
     max_length= 64 * collation.collation->mbmaxlen; // should be enough
     maybe_null= 0;
  };
  table_map not_null_tables() const { return 0; }
};

class Item_func_crc32 :public Item_int_func
{
  String value;
public:
  Item_func_crc32(Item *a) :Item_int_func(a) { unsigned_flag= 1; }
  const char *func_name() const { return "crc32"; }
  void fix_length_and_dec() { max_length=10; }
  longlong val_int();
};

class Item_func_uncompressed_length : public Item_int_func
{
  String value;
public:
  Item_func_uncompressed_length(Item *a):Item_int_func(a){}
  const char *func_name() const{return "uncompressed_length";}
  void fix_length_and_dec() { max_length=10; }
  longlong val_int();
};

#ifdef HAVE_COMPRESS
#define ZLIB_DEPENDED_FUNCTION ;
#else
#define ZLIB_DEPENDED_FUNCTION { null_value=1; return 0; }
#endif

class Item_func_compress: public Item_str_func
{
  String buffer;
public:
  Item_func_compress(Item *a):Item_str_func(a){}
  void fix_length_and_dec(){max_length= (args[0]->max_length*120)/100+12;}
  const char *func_name() const{return "compress";}
  String *val_str(String *) ZLIB_DEPENDED_FUNCTION
};

class Item_func_uncompress: public Item_str_func
{
  String buffer;
public:
  Item_func_uncompress(Item *a): Item_str_func(a){}
  void fix_length_and_dec(){ maybe_null= 1; max_length= MAX_BLOB_WIDTH; }
  const char *func_name() const{return "uncompress";}
  String *val_str(String *) ZLIB_DEPENDED_FUNCTION
};

#define UUID_LENGTH (8+1+4+1+4+1+4+1+12)
class Item_func_uuid: public Item_str_func
{
public:
  Item_func_uuid(): Item_str_func() {}
  void fix_length_and_dec() {
    collation.set(system_charset_info);
    /*
       NOTE! uuid() should be changed to use 'ascii'
       charset when hex(), format(), md5(), etc, and implicit
       number-to-string conversion will use 'ascii'
    */
    max_length= UUID_LENGTH * system_charset_info->mbmaxlen;
  }
  const char *func_name() const{ return "uuid"; }
  String *val_str(String *);
};