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Diffstat (limited to 'sql/item_buff.cc')
| -rw-r--r-- | sql/item_buff.cc | 252 |
1 files changed, 252 insertions, 0 deletions
diff --git a/sql/item_buff.cc b/sql/item_buff.cc new file mode 100644 index 00000000..05cef687 --- /dev/null +++ b/sql/item_buff.cc @@ -0,0 +1,252 @@ +/* + 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()); +} + |