~drizzle-trunk/drizzle/development

/* -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-

 *  vim:expandtab:shiftwidth=2:tabstop=2:smarttab:

 *

 *  Copyright (C) 2008 Sun Microsystems

 *  Copyright (C) 2010 Stewart Smith

 *

 *  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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

 */

#include "config.h"

#include <drizzled/plugin/function.h>

#include <algorithm>

using namespace std;

using namespace drizzled;

#include <drizzled/function/str/strfunc.h>

class SubstrFunction :public Item_str_func

{

  String tmp_value;

public:

  SubstrFunction() :Item_str_func() {}

  String *val_str(String *);

  void fix_length_and_dec();

  const char *func_name() const { return "substr"; }

  bool check_argument_count(int n) { return n == 2 || n == 3; }

};

class SubstrIndexFunction :public Item_str_func

{

  String tmp_value;

public:

  SubstrIndexFunction() :Item_str_func() {}

  String *val_str(String *);

  void fix_length_and_dec();

  const char *func_name() const { return "substring_index"; }

  bool check_argument_count(int n) { return n == 3; }

};

String *SubstrFunction::val_str(String *str)

{

  assert(fixed == 1);

  String *res  = args[0]->val_str(str);

  /* must be int64_t to avoid truncation */

  int64_t start= args[1]->val_int();

  /* Assumes that the maximum length of a String is < INT32_MAX. */

  /* Limit so that code sees out-of-bound value properly. */

  int64_t length= arg_count == 3 ? args[2]->val_int() : INT32_MAX;

  int64_t tmp_length;

  if ((null_value=(args[0]->null_value || args[1]->null_value ||

		   (arg_count == 3 && args[2]->null_value))))

    return 0;

  /* Negative or zero length, will return empty string. */

  if ((arg_count == 3) && (length <= 0) &&

      (length == 0 || !args[2]->unsigned_flag))

    return &my_empty_string;

  /* Assumes that the maximum length of a String is < INT32_MAX. */

  /* Set here so that rest of code sees out-of-bound value as such. */

  if ((length <= 0) || (length > INT32_MAX))

    length= INT32_MAX;

  /* if "unsigned_flag" is set, we have a *huge* positive number. */

  /* Assumes that the maximum length of a String is < INT32_MAX. */

  if ((!args[1]->unsigned_flag && (start < INT32_MIN || start > INT32_MAX)) ||

      (args[1]->unsigned_flag && ((uint64_t) start > INT32_MAX)))

    return &my_empty_string;

  start= ((start < 0) ? res->numchars() + start : start - 1);

  start= res->charpos((int) start);

  if ((start < 0) || ((uint) start + 1 > res->length()))

    return &my_empty_string;

  length= res->charpos((int) length, (uint32_t) start);

  tmp_length= res->length() - start;

  length= min(length, tmp_length);

  if (!start && (int64_t) res->length() == length)

    return res;

  tmp_value.set(*res, (uint32_t) start, (uint32_t) length);

  return &tmp_value;

}

void SubstrFunction::fix_length_and_dec()

{

  max_length=args[0]->max_length;

  collation.set(args[0]->collation);

  if (args[1]->const_item())

  {

    int32_t start= (int32_t) args[1]->val_int();

    if (start < 0)

      max_length= ((uint)(-start) > max_length) ? 0 : (uint)(-start);

    else

      max_length-= min((uint)(start - 1), max_length);

  }

  if (arg_count == 3 && args[2]->const_item())

  {

    int32_t length= (int32_t) args[2]->val_int();

    if (length <= 0)

      max_length=0;

    else

      set_if_smaller(max_length,(uint) length);

  }

  max_length*= collation.collation->mbmaxlen;

}

void SubstrIndexFunction::fix_length_and_dec()

{

  max_length= args[0]->max_length;

  if (agg_arg_charsets(collation, args, 2, MY_COLL_CMP_CONV, 1))

    return;

}

String *SubstrIndexFunction::val_str(String *str)

{

  assert(fixed == 1);

  String *res= args[0]->val_str(str);

  String *delimiter= args[1]->val_str(&tmp_value);

  int32_t count= (int32_t) args[2]->val_int();

  uint32_t offset;

  if (args[0]->null_value || args[1]->null_value || args[2]->null_value)

  {					// string and/or delim are null

    null_value=1;

    return 0;

  }

  null_value=0;

  uint32_t delimiter_length= delimiter->length();

  if (!res->length() || !delimiter_length || !count)

    return &my_empty_string;		// Wrong parameters

  res->set_charset(collation.collation);

  if (use_mb(res->charset()))

  {

    const char *ptr= res->ptr();

    const char *strend= ptr+res->length();

    const char *end= strend-delimiter_length+1;

    const char *search= delimiter->ptr();

    const char *search_end= search+delimiter_length;

    int32_t n=0,c=count,pass;

    register uint32_t l;

    for (pass=(count>0);pass<2;++pass)

    {

      while (ptr < end)

      {

        if (*ptr == *search)

        {

	  register char *i,*j;

	  i=(char*) ptr+1; j=(char*) search+1;

	  while (j != search_end)

	    if (*i++ != *j++) goto skip;

	  if (pass==0) ++n;

	  else if (!--c) break;

	  ptr+= delimiter_length;

	  continue;

	}

    skip:

        if ((l=my_ismbchar(res->charset(), ptr,strend))) ptr+=l;

        else ++ptr;

      } /* either not found or got total number when count<0 */

      if (pass == 0) /* count<0 */

      {

        c+=n+1;

        if (c<=0) return res; /* not found, return original string */

        ptr=res->ptr();

      }

      else

      {

        if (c) return res; /* Not found, return original string */

        if (count>0) /* return left part */

        {

	  tmp_value.set(*res,0,(ulong) (ptr-res->ptr()));

        }

        else /* return right part */

        {

	  ptr+= delimiter_length;

	  tmp_value.set(*res,(ulong) (ptr-res->ptr()), (ulong) (strend-ptr));

        }

      }

    }

  }

  else

  {

    if (count > 0)

    {					// start counting from the beginning

      for (offset=0; ; offset+= delimiter_length)

      {

        if ((int) (offset= res->strstr(*delimiter, offset)) < 0)

          return res;			// Didn't find, return org string

        if (!--count)

        {

          tmp_value.set(*res,0,offset);

          break;

        }

      }

    }

    else

    {

      /*

        Negative index, start counting at the end

      */

      for (offset=res->length(); offset ;)

      {

        /*

          this call will result in finding the position pointing to one

          address space less than where the found substring is located

          in res

        */

        if ((int) (offset= res->strrstr(*delimiter, offset)) < 0)

          return res;			// Didn't find, return org string

        /*

          At this point, we've searched for the substring

          the number of times as supplied by the index value

        */

        if (!++count)

        {

          offset+= delimiter_length;

          tmp_value.set(*res,offset,res->length()- offset);

          break;

        }

      }

    }

  }

  /*

    We always mark tmp_value as const so that if val_str() is called again

    on this object, we don't disrupt the contents of tmp_value when it was

    derived from another String.

  */

  tmp_value.mark_as_const();

  return (&tmp_value);

}

plugin::Create_function<SubstrFunction> *substr_function= NULL;

plugin::Create_function<SubstrIndexFunction> *substr_index_function= NULL;

static int initialize(drizzled::plugin::Context &context)

{

  substr_function= new plugin::Create_function<SubstrFunction>("substr");

  substr_index_function= new plugin::Create_function<SubstrIndexFunction>("substring_index");

  context.add(substr_function);

  context.add(substr_index_function);

  return 0;

}

DRIZZLE_DECLARE_PLUGIN

{

  DRIZZLE_VERSION_ID,

  "substr_functions",

  "1.0",

  "Stewart Smith",

  "SUBSTR and SUBSTR",

  PLUGIN_LICENSE_GPL,

  initialize, /* Plugin Init */

  NULL,   /* system variables */

  NULL    /* config options */

}

DRIZZLE_DECLARE_PLUGIN_END;