From da566c16c0c03f56caa8bd6bfd9452b73ad1a456 Mon Sep 17 00:00:00 2001
From: unknown <igor@rurik.mysql.com>
Date: Wed, 26 Nov 2003 17:23:52 -0800
Subject: This ChangeSet Introdices Item_equal. The objects of this class
 represent multiple conjunctive equalities in where conditions: =(f1,f2,...fn)
 <=> f1=f2 and f2= ... and =fn. The objects are used to generate new possibale
 paths to access the tables when executing a query. They are also used to
 optimize the execution plan chosen by the optimizer for the query.

sql/item.cc:
  Introduced Item_equal
sql/item.h:
  Introduced Item_equal.
  Added traverse method.
sql/item_cmpfunc.cc:
  Introduced Item_equal.
  Added traverse mehtod.
sql/item_cmpfunc.h:
  Itroduced Item_equal and Item_equal_iterator.
sql/item_func.cc:
  Added traverse method.
  Introduced Item_equal.
sql/item_func.h:
  Introduced Item_equal.
  Added traverse method.
sql/item_row.cc:
  Added traverse method.
sql/item_row.h:
  Added traverse method.
sql/item_strfunc.h:
  Added traverse method.
sql/opt_range.cc:
  Used Item_equal in range analysis.
sql/opt_sum.cc:
  Introduced Item_equal.
sql/sql_list.h:
  Added concat and disjoin methods to lists.
  Fixed remove method for lists.
sql/sql_select.cc:
  Introdiced Item_equal:
    created Item_equal;
    used Item_equal objects to generate new paths to access tables.
    used Item_equal objects to optimize the execution plan chosen by optimizer.
sql/sql_select.h:
  Introduced Item_equal.
---
 sql/sql_list.h | 34 ++++++++++++++++++++++++++++++++--
 1 file changed, 32 insertions(+), 2 deletions(-)

(limited to 'sql/sql_list.h')

diff --git a/sql/sql_list.h b/sql/sql_list.h
index 7200046e6c5..d7a62b7fd7d 100644
--- a/sql/sql_list.h
+++ b/sql/sql_list.h
@@ -121,10 +121,12 @@ public:
   void remove(list_node **prev)
   {
     list_node *node=(*prev)->next;
-    delete *prev;
-    *prev=node;
     if (!--elements)
       last= &first;
+    else if (last == &(*prev)->next)
+      last= prev;
+    delete *prev;
+    *prev=node;
   }
   inline void *pop(void)
   {
@@ -135,6 +137,30 @@ public:
       last= &first;
     return tmp->info;
   }
+  inline void concat(base_list *list)
+  {
+    if (!list->is_empty())
+    {
+      *last= list->first;
+      last= list->last;
+      elements+= list->elements;
+    }
+  }
+  inline void disjoin(base_list *list)
+  {
+    list_node **prev= &first;
+    list_node *node= first;
+    list_node *list_first= list->first;
+    elements=0;
+    while (node && node != list_first)
+    {
+      prev= &node->next;
+      node= node->next;
+      elements++;
+    }
+    *prev= *last;
+    last= prev;
+  }
   inline list_node* last_node() { return *last; }
   inline list_node* first_node() { return first;}
   inline void *head() { return first->info; }
@@ -245,6 +271,8 @@ public:
   inline T* head() {return (T*) base_list::head(); }
   inline T** head_ref() {return (T**) base_list::head_ref(); }
   inline T* pop()  {return (T*) base_list::pop(); }
+  inline void concat(List<T> *list) { return base_list::concat(list); }
+  inline void disjoin(List<T> *list) { return base_list::disjoin(list); }
   void delete_elements(void)
   {
     list_node *element,*next;
@@ -265,6 +293,8 @@ public:
   inline T* operator++(int) { return (T*) base_list_iterator::next(); }
   inline T *replace(T *a)   { return (T*) base_list_iterator::replace(a); }
   inline T *replace(List<T> &a) { return (T*) base_list_iterator::replace(a); }
+  inline void rewind(void)  { base_list_iterator::rewind(); }
+  inline void remove()      { base_list_iterator::remove(); }
   inline void after(T *a)   { base_list_iterator::after(a); }
   inline T** ref(void)	    { return (T**) base_list_iterator::ref(); }
 };
-- 
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