Drizzled Public API Documentation

substr_functions.cc
1 /* -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-
2  * vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
3  *
4  * Copyright (C) 2008 Sun Microsystems, Inc.
5  * Copyright (C) 2010 Stewart Smith
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License as published by
9  * the Free Software Foundation; version 2 of the License.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with this program; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #include <config.h>
22 
23 #include <algorithm>
24 
25 #include <drizzled/charset.h>
26 #include <drizzled/function/str/strfunc.h>
27 #include <drizzled/plugin/function.h>
28 
29 using namespace std;
30 using namespace drizzled;
31 
33 {
34  String tmp_value;
35 public:
37 
38  String *val_str(String *);
39  void fix_length_and_dec();
40  const char *func_name() const { return "substr"; }
41 
42  bool check_argument_count(int n) { return n == 2 || n == 3; }
43 };
44 
45 
47 {
48  String tmp_value;
49 public:
51 
52  String *val_str(String *);
53  void fix_length_and_dec();
54  const char *func_name() const { return "substring_index"; }
55 
56  bool check_argument_count(int n) { return n == 3; }
57 };
58 
60 {
61  assert(fixed == 1);
62  String *res = args[0]->val_str(str);
63  /* must be int64_t to avoid truncation */
64  int64_t start= args[1]->val_int();
65  /* Assumes that the maximum length of a String is < INT32_MAX. */
66  /* Limit so that code sees out-of-bound value properly. */
67  int64_t length= arg_count == 3 ? args[2]->val_int() : INT32_MAX;
68  int64_t tmp_length;
69 
70  if ((null_value=(args[0]->null_value || args[1]->null_value ||
71  (arg_count == 3 && args[2]->null_value))))
72  return 0;
73 
74  /* Negative or zero length, will return empty string. */
75  if ((arg_count == 3) && (length <= 0) &&
76  (length == 0 || !args[2]->unsigned_flag))
77  return &my_empty_string;
78 
79  /* Assumes that the maximum length of a String is < INT32_MAX. */
80  /* Set here so that rest of code sees out-of-bound value as such. */
81  if ((length <= 0) || (length > INT32_MAX))
82  length= INT32_MAX;
83 
84  /* if "unsigned_flag" is set, we have a *huge* positive number. */
85  /* Assumes that the maximum length of a String is < INT32_MAX. */
86  if ((!args[1]->unsigned_flag && (start < INT32_MIN || start > INT32_MAX)) ||
87  (args[1]->unsigned_flag && ((uint64_t) start > INT32_MAX)))
88  return &my_empty_string;
89 
90  start= ((start < 0) ?
91  static_cast<int64_t>(res->numchars() + start)
92  : start - 1);
93  start= res->charpos((int) start);
94  if ((start < 0) || ((uint) start + 1 > res->length()))
95  return &my_empty_string;
96 
97  length= res->charpos((int) length, (uint32_t) start);
98  tmp_length= res->length() - start;
99  length= min(length, tmp_length);
100 
101  if (!start && (int64_t) res->length() == length)
102  return res;
103  tmp_value.set(*res, (uint32_t) start, (uint32_t) length);
104  return &tmp_value;
105 }
106 
107 void SubstrFunction::fix_length_and_dec()
108 {
109  max_length=args[0]->max_length;
110 
111  collation.set(args[0]->collation);
112  if (args[1]->const_item())
113  {
114  int32_t start= (int32_t) args[1]->val_int();
115  if (start < 0)
116  max_length= ((uint)(-start) > max_length) ? 0 : (uint)(-start);
117  else
118  max_length-= min((uint)(start - 1), max_length);
119  }
120  if (arg_count == 3 && args[2]->const_item())
121  {
122  int32_t length= (int32_t) args[2]->val_int();
123  if (length <= 0)
124  max_length=0;
125  else
126  set_if_smaller(max_length,(uint) length);
127  }
128  max_length*= collation.collation->mbmaxlen;
129 }
130 
131 
132 void SubstrIndexFunction::fix_length_and_dec()
133 {
134  max_length= args[0]->max_length;
135 
136  if (agg_arg_charsets(collation, args, 2, MY_COLL_CMP_CONV, 1))
137  return;
138 }
139 
140 
142 {
143  assert(fixed == 1);
144  String *res= args[0]->val_str(str);
145  String *delimiter= args[1]->val_str(&tmp_value);
146  int32_t count= (int32_t) args[2]->val_int();
147  uint32_t offset;
148 
149  if (args[0]->null_value || args[1]->null_value || args[2]->null_value)
150  { // string and/or delim are null
151  null_value=1;
152  return 0;
153  }
154  null_value=0;
155  uint32_t delimiter_length= delimiter->length();
156  if (!res->length() || !delimiter_length || !count)
157  return &my_empty_string; // Wrong parameters
158 
159  res->set_charset(collation.collation);
160 
161  if (use_mb(res->charset()))
162  {
163  const char *ptr= res->ptr();
164  const char *strend= ptr+res->length();
165  const char *end= strend-delimiter_length+1;
166  const char *search= delimiter->ptr();
167  const char *search_end= search+delimiter_length;
168  int32_t n=0,c=count,pass;
169  register uint32_t l;
170  for (pass=(count>0);pass<2;++pass)
171  {
172  while (ptr < end)
173  {
174  if (*ptr == *search)
175  {
176  register char *i,*j;
177  i=(char*) ptr+1; j=(char*) search+1;
178  while (j != search_end)
179  if (*i++ != *j++) goto skip;
180  if (pass==0) ++n;
181  else if (!--c) break;
182  ptr+= delimiter_length;
183  continue;
184  }
185  skip:
186  if ((l=my_ismbchar(res->charset(), ptr,strend))) ptr+=l;
187  else ++ptr;
188  } /* either not found or got total number when count<0 */
189  if (pass == 0) /* count<0 */
190  {
191  c+=n+1;
192  if (c<=0) return res; /* not found, return original string */
193  ptr=res->ptr();
194  }
195  else
196  {
197  if (c) return res; /* Not found, return original string */
198  if (count>0) /* return left part */
199  {
200  tmp_value.set(*res,0,(ulong) (ptr-res->ptr()));
201  }
202  else /* return right part */
203  {
204  ptr+= delimiter_length;
205  tmp_value.set(*res,(ulong) (ptr-res->ptr()), (ulong) (strend-ptr));
206  }
207  }
208  }
209  }
210  else
211  {
212  if (count > 0)
213  { // start counting from the beginning
214  for (offset=0; ; offset+= delimiter_length)
215  {
216  if ((int) (offset= res->strstr(*delimiter, offset)) < 0)
217  return res; // Didn't find, return org string
218  if (!--count)
219  {
220  tmp_value.set(*res,0,offset);
221  break;
222  }
223  }
224  }
225  else
226  {
227  /*
228  Negative index, start counting at the end
229  */
230  for (offset=res->length(); offset ;)
231  {
232  /*
233  this call will result in finding the position pointing to one
234  address space less than where the found substring is located
235  in res
236  */
237  if ((int) (offset= res->strrstr(*delimiter, offset)) < 0)
238  return res; // Didn't find, return org string
239  /*
240  At this point, we've searched for the substring
241  the number of times as supplied by the index value
242  */
243  if (!++count)
244  {
245  offset+= delimiter_length;
246  tmp_value.set(*res,offset,res->length()- offset);
247  break;
248  }
249  }
250  }
251  }
252  /*
253  We always mark tmp_value as const so that if val_str() is called again
254  on this object, we don't disrupt the contents of tmp_value when it was
255  derived from another String.
256  */
257  tmp_value.mark_as_const();
258  return (&tmp_value);
259 }
260 
261 plugin::Create_function<SubstrFunction> *substr_function= NULL;
262 plugin::Create_function<SubstrIndexFunction> *substr_index_function= NULL;
263 
264 static int initialize(drizzled::module::Context &context)
265 {
266  substr_function= new plugin::Create_function<SubstrFunction>("substr");
267  substr_index_function= new plugin::Create_function<SubstrIndexFunction>("substring_index");
268  context.add(substr_function);
269  context.add(substr_index_function);
270  return 0;
271 }
272 
273 DRIZZLE_DECLARE_PLUGIN
274 {
275  DRIZZLE_VERSION_ID,
276  "substr_functions",
277  "1.0",
278  "Stewart Smith",
279  N_("SUBSTR and SUBSTR functions"),
280  PLUGIN_LICENSE_GPL,
281  initialize,
282  NULL,
283  NULL
284 }
285 DRIZZLE_DECLARE_PLUGIN_END;
TODO: Rename this file - func.h is stupid.
String * val_str(String *)
bool check_argument_count(int n)
String * val_str(String *)
bool check_argument_count(int n)