Fixed bug #17526: incorrect print method

for class Item_func_trim. 
For 4.1 it caused wrong output for EXPLAIN EXTENDED commands
if expressions with the TRIM function of two arguments were used.
For 5.0 it caused an error message when trying to select
from a view with the TRIM function of two arguments.
This unexpected error message was due to the fact that the
print method for the class Item_func_trim was inherited from
the class Item_func. Yet the TRIM function does not take a list
of its arguments. Rather it takes the arguments in the form:
  [{BOTH | LEADING | TRAILING} [remstr] FROM] str) |
  [remstr FROM] str


mysql-test/r/func_str.result:
  Added a test case for bug #17526: uncorrect print method
  for class Item_func_trim.
mysql-test/t/func_str.test:
  Added a test case for bug #17526: incorrect print method
  for class Item_func_trim.
sql/item_strfunc.cc:
  Fixed bug #17526: incorrect print method
  for class Item_func_trim.
      
  Added an implementation for the virtual function print
  in the class Item_func_trim.
  The implementation takes into account the fact the TRIM
  function takes the arguments in the following forms:
    [{BOTH | LEADING | TRAILING} [remstr] FROM] str) |
    [remstr FROM] str
sql/item_strfunc.h:
  Fixed bug #17526: incorrect print method
  for class Item_func_trim.
      
  Added an implementation for the virtual function print
  in the class Item_func_trim.
  Declared a virtual method to return the mode of the TRIM 
  function: LEADING, TRAILING or BOTH.
  Added implementations of this method for Item_func_trim and
  its descendants Item_func_ltrim and Item_func_rtrim.

mysql-test/r/func_str.result

@@ -1036,4 +1036,32 @@ a	c
 abc	abc abc
 xyz	xyz xyz
 DROP TABLE t1;
+CREATE TABLE t1 (s varchar(10));
+INSERT INTO t1 VALUES ('yadda'), ('yaddy');
+EXPLAIN EXTENDED SELECT s FROM t1 WHERE TRIM(s) > 'ab';
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	Using where
+Warnings:
+Note	1003	select test.t1.s AS `s` from test.t1 where (trim(test.t1.s) > _latin1'ab')
+EXPLAIN EXTENDED SELECT s FROM t1 WHERE TRIM('y' FROM s) > 'ab';
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	Using where
+Warnings:
+Note	1003	select test.t1.s AS `s` from test.t1 where (trim(both _latin1'y' from test.t1.s) > _latin1'ab')
+EXPLAIN EXTENDED SELECT s FROM t1 WHERE TRIM(LEADING 'y' FROM s) > 'ab';
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	Using where
+Warnings:
+Note	1003	select test.t1.s AS `s` from test.t1 where (trim(leading _latin1'y' from test.t1.s) > _latin1'ab')
+EXPLAIN EXTENDED SELECT s FROM t1 WHERE TRIM(TRAILING 'y' FROM s) > 'ab';
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	Using where
+Warnings:
+Note	1003	select test.t1.s AS `s` from test.t1 where (trim(trailing _latin1'y' from test.t1.s) > _latin1'ab')
+EXPLAIN EXTENDED SELECT s FROM t1 WHERE TRIM(BOTH 'y' FROM s) > 'ab';
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	Using where
+Warnings:
+Note	1003	select test.t1.s AS `s` from test.t1 where (trim(both _latin1'y' from test.t1.s) > _latin1'ab')
+DROP TABLE t1;
 End of 4.1 tests

mysql-test/t/func_str.test

@@ -698,4 +698,19 @@ SELECT a, CONCAT(a,' ',a) AS c FROM t1
 
 DROP TABLE t1;
 
+#
+# Bug#17526: WRONG PRINT for TRIM FUNCTION with two arguments
+#
+
+CREATE TABLE t1 (s varchar(10));
+INSERT INTO t1 VALUES ('yadda'), ('yaddy');
+
+EXPLAIN EXTENDED SELECT s FROM t1 WHERE TRIM(s) > 'ab';
+EXPLAIN EXTENDED SELECT s FROM t1 WHERE TRIM('y' FROM s) > 'ab';
+EXPLAIN EXTENDED SELECT s FROM t1 WHERE TRIM(LEADING 'y' FROM s) > 'ab';
+EXPLAIN EXTENDED SELECT s FROM t1 WHERE TRIM(TRAILING 'y' FROM s) > 'ab';
+EXPLAIN EXTENDED SELECT s FROM t1 WHERE TRIM(BOTH 'y' FROM s) > 'ab';
+
+DROP TABLE t1;
+ 
 --echo End of 4.1 tests

sql/item_strfunc.cc

@@ -1444,6 +1444,23 @@ void Item_func_trim::fix_length_and_dec()
   }
 }
 
+void Item_func_trim::print(String *str)
+{
+  if (arg_count == 1)
+  {
+    Item_func::print(str);
+    return;
+  }
+  str->append(Item_func_trim::func_name());
+  str->append('(');
+  str->append(mode_name());
+  str->append(' ');
+  args[1]->print(str);
+  str->append(" from ",6);
+  args[0]->print(str);
+  str->append(')');
+}
+
 
 /* Item_func_password */
 

sql/item_strfunc.h

@@ -218,6 +218,8 @@ class Item_func_trim :public Item_str_func
   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"; }
 };
 
 
@@ -228,6 +230,7 @@ class Item_func_ltrim :public Item_func_trim
   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"; }
 };
 
 
@@ -238,6 +241,7 @@ class Item_func_rtrim :public Item_func_trim
   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"; }
 };