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+/*
+ Copyright (c) 2000, 2010, Oracle and/or its affiliates.
+
+ 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 02110-1335 USA */
+
+
+/**
+ @file
+
+ @brief
+ Buffers to save and compare item values
+*/
+
+#include "mariadb.h"
+#include "sql_priv.h"
+/*
+ It is necessary to include set_var.h instead of item.h because there
+ are dependencies on include order for set_var.h and item.h. This
+ will be resolved later.
+*/
+#include "sql_class.h" // THD
+#include "set_var.h" // Cached_item, Cached_item_field, ...
+
+/**
+ Create right type of Cached_item for an item.
+*/
+
+Cached_item *new_Cached_item(THD *thd, Item *item, bool pass_through_ref)
+{
+ if (pass_through_ref && item->real_item()->type() == Item::FIELD_ITEM &&
+ !(((Item_field *) (item->real_item()))->field->flags & BLOB_FLAG))
+ {
+ Item_field *real_item= (Item_field *) item->real_item();
+ Field *cached_field= real_item->field;
+ return new (thd->mem_root) Cached_item_field(thd, cached_field);
+ }
+ switch (item->result_type()) {
+ case STRING_RESULT:
+ return new Cached_item_str(thd, item);
+ case INT_RESULT:
+ return new Cached_item_int(item);
+ case REAL_RESULT:
+ return new Cached_item_real(item);
+ case DECIMAL_RESULT:
+ return new Cached_item_decimal(item);
+ case ROW_RESULT:
+ default:
+ DBUG_ASSERT(0);
+ return 0;
+ }
+}
+
+Cached_item::~Cached_item() {}
+
+/**
+ Compare with old value and replace value with new value.
+
+ @return
+ Return true if values have changed
+*/
+
+Cached_item_str::Cached_item_str(THD *thd, Item *arg)
+ :Cached_item_item(arg),
+ value_max_length(MY_MIN(arg->max_length, thd->variables.max_sort_length)),
+ value(value_max_length)
+{}
+
+bool Cached_item_str::cmp(void)
+{
+ String *res;
+ bool tmp;
+
+ if ((res=item->val_str(&tmp_value)))
+ res->length(MY_MIN(res->length(), value_max_length));
+ if (null_value != item->null_value)
+ {
+ if ((null_value= item->null_value))
+ return TRUE; // New value was null
+ tmp=TRUE;
+ }
+ else if (null_value)
+ return 0; // new and old value was null
+ else
+ tmp= sortcmp(&value,res,item->collation.collation) != 0;
+ if (tmp)
+ value.copy(*res); // Remember for next cmp
+ return tmp;
+}
+
+
+int Cached_item_str::cmp_read_only()
+{
+ String *res= item->val_str(&tmp_value);
+
+ if (null_value)
+ {
+ if (item->null_value)
+ return 0;
+ else
+ return -1;
+ }
+ if (item->null_value)
+ return 1;
+
+ return sortcmp(&value, res, item->collation.collation);
+}
+
+
+Cached_item_str::~Cached_item_str()
+{
+ item=0; // Safety
+}
+
+bool Cached_item_real::cmp(void)
+{
+ double nr= item->val_real();
+ if (null_value != item->null_value || nr != value)
+ {
+ null_value= item->null_value;
+ value=nr;
+ return TRUE;
+ }
+ return FALSE;
+}
+
+
+int Cached_item_real::cmp_read_only()
+{
+ double nr= item->val_real();
+ if (null_value)
+ {
+ if (item->null_value)
+ return 0;
+ else
+ return -1;
+ }
+ if (item->null_value)
+ return 1;
+ return (nr == value)? 0 : ((nr < value)? 1: -1);
+}
+
+
+bool Cached_item_int::cmp(void)
+{
+ longlong nr=item->val_int();
+ if (null_value != item->null_value || nr != value)
+ {
+ null_value= item->null_value;
+ value=nr;
+ return TRUE;
+ }
+ return FALSE;
+}
+
+
+int Cached_item_int::cmp_read_only()
+{
+ longlong nr= item->val_int();
+ if (null_value)
+ {
+ if (item->null_value)
+ return 0;
+ else
+ return -1;
+ }
+ if (item->null_value)
+ return 1;
+ return (nr == value)? 0 : ((nr < value)? 1: -1);
+}
+
+
+bool Cached_item_field::cmp(void)
+{
+ bool tmp= FALSE; // Value is identical
+ /* Note that field can't be a blob here ! */
+ if (null_value != field->is_null())
+ {
+ null_value= !null_value;
+ tmp= TRUE; // Value has changed
+ }
+
+ /*
+ If value is not null and value changed (from null to not null or
+ because of value change), then copy the new value to buffer.
+ */
+ if (! null_value && (tmp || (tmp= (field->cmp(buff) != 0))))
+ field->get_image(buff,length,field->charset());
+ return tmp;
+}
+
+
+int Cached_item_field::cmp_read_only()
+{
+ if (null_value)
+ {
+ if (field->is_null())
+ return 0;
+ else
+ return -1;
+ }
+ if (field->is_null())
+ return 1;
+
+ return field->cmp(buff);
+}
+
+
+Cached_item_decimal::Cached_item_decimal(Item *it)
+ :Cached_item_item(it)
+{
+ my_decimal_set_zero(&value);
+}
+
+
+bool Cached_item_decimal::cmp()
+{
+ VDec tmp(item);
+ if (null_value != tmp.is_null() ||
+ (!tmp.is_null() && tmp.cmp(&value)))
+ {
+ null_value= tmp.is_null();
+ /* Save only not null values */
+ if (!null_value)
+ {
+ my_decimal2decimal(tmp.ptr(), &value);
+ return TRUE;
+ }
+ return FALSE;
+ }
+ return FALSE;
+}
+
+
+int Cached_item_decimal::cmp_read_only()
+{
+ VDec tmp(item);
+ if (null_value)
+ return tmp.is_null() ? 0 : -1;
+ return tmp.is_null() ? 1 : value.cmp(tmp.ptr());
+}
+