Add yet-another linked list type

The use of macros to access existing linked list type makes it
unsuitable for its current use as a base class.  Since this type and
the accompanying macros are used all over the place in Mesa, we can't
really change them.

diff --git a/list.h b/list.h
new file mode 100644 (file)
index 0000000..d122369
--- /dev/null
+++ b/list.h
@@ -0,0 +1,298 @@
+/*
+ * Copyright © 2008, 2010 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+/**
+ * \file list.h
+ * \brief Doubly-linked list abstract container type.
+ *
+ * Each doubly-linked list has a sentinal head and tail node.  These nodes
+ * contain no data.  The head sentinal can be identified by its \c prev
+ * pointer being \c NULL.  The tail sentinal can be identified by its
+ * \c next pointer being \c NULL.
+ *
+ * A list is empty if either the head sentinal's \c next pointer points to the
+ * tail sentinal or the tail sentinal's \c prev poiner points to the head
+ * sentinal.
+ *
+ * Instead of tracking two separate \c node structures and a \c list structure
+ * that points to them, the sentinal nodes are in a single structure.  Noting
+ * that each sentinal node always has one \c NULL pointer, the \c NULL
+ * pointers occupy the same memory location.  In the \c list structure
+ * contains a the following:
+ *
+ *   - A \c head pointer that represents the \c next pointer of the
+ *     head sentinal node.
+ *   - A \c tail pointer that represents the \c prev pointer of the head
+ *     sentinal node and the \c next pointer of the tail sentinal node.  This
+ *     pointer is \b always \c NULL.
+ *   - A \c tail_prev pointer that represents the \c prev pointer of the
+ *     tail sentinal node.
+ *
+ * Therefore, if \c head->next is \c NULL or \c tail_prev->prev is \c NULL,
+ * the list is empty.
+ *
+ * To anyone familiar with "exec lists" on the Amiga, this structure should
+ * be immediately recognizable.  See the following link for the original Amiga
+ * operating system documentation on the subject.
+ *
+ * http://www.natami.net/dev/Libraries_Manual_guide/node02D7.html
+ *
+ * \author Ian Romanick <ian.d.romanick@intel.com>
+ */
+
+#pragma once
+#ifndef LIST_CONTAINER_H
+#define LIST_CONTAINER_H
+
+#include <assert.h>
+
+struct exec_node {
+   struct exec_node *next;
+   struct exec_node *prev;
+
+#ifdef __cplusplus
+   exec_node() : next(NULL), prev(NULL)
+   {
+      /* empty */
+   }
+
+   const exec_node *get_next() const
+   {
+      return next;
+   }
+
+   exec_node *get_next()
+   {
+      return next;
+   }
+
+   const exec_node *get_prev() const
+   {
+      return prev;
+   }
+
+   exec_node *get_prev()
+   {
+      return prev;
+   }
+
+   void remove()
+   {
+      next->prev = prev;
+      prev->next = next;
+      next = NULL;
+      prev = NULL;
+   }
+
+   /**
+    * Link a node with itself
+    *
+    * This creates a sort of degenerate list that is occasionally useful.
+    */
+   void self_link()
+   {
+      next = this;
+      prev = this;
+   }
+
+   /**
+    * Insert a node in the list after the current node
+    */
+   void insert_after(exec_node *after)
+   {
+      after->next = this->next;
+      after->prev = this;
+
+      this->next->prev = after;
+      this->next = after;
+   }
+#endif
+};
+
+#ifdef __cplusplus
+struct exec_node;
+
+class iterator {
+public:
+   void next()
+   {
+   }
+
+   void *get()
+   {
+      return NULL;
+   }
+
+   bool has_next() const
+   {
+      return false;
+   }
+};
+
+class exec_list_iterator : public iterator {
+public:
+   exec_list_iterator(exec_node *n) : node(n), _next(n->next)
+   {
+      /* empty */
+   }
+
+   void next()
+   {
+      node = _next;
+      _next = node->next;
+   }
+
+   void remove()
+   {
+      node->remove();
+   }
+
+   exec_node *get()
+   {
+      return node;
+   }
+
+   bool has_next() const
+   {
+      return _next != NULL;
+   }
+
+private:
+   exec_node *node;
+   exec_node *_next;
+};
+
+#define foreach_iter(iter_type, iter, container) \
+   for (iter_type iter = container . iterator(); iter.has_next(); iter.next())
+#endif
+
+
+struct exec_list {
+   struct exec_node *head;
+   struct exec_node *tail;
+   struct exec_node *tail_pred;
+
+#ifdef __cplusplus
+   exec_list()
+   {
+      make_empty();
+   }
+
+   void make_empty()
+   {
+      head = (exec_node *) & tail;
+      tail = NULL;
+      tail_pred = (exec_node *) & head;
+   }
+
+   bool is_empty() const
+   {
+      /* There are three ways to test whether a list is empty or not.
+       *
+       * - Check to see if the \c head points to the \c tail.
+       * - Check to see if the \c tail_pred points to the \c head.
+       * - Check to see if the \c head is the sentinal node by test whether its
+       *   \c next pointer is \c NULL.
+       *
+       * The first two methods tend to generate better code on modern systems
+       * because they save a pointer dereference.
+       */
+      return head == (exec_node *) &tail;
+   }
+
+   const exec_node *get_head() const
+   {
+      return !is_empty() ? head : NULL;
+   }
+
+   exec_node *get_head()
+   {
+      return !is_empty() ? head : NULL;
+   }
+
+   const exec_node *get_tail() const
+   {
+      return !is_empty() ? tail_pred : NULL;
+   }
+
+   exec_node *get_tail()
+   {
+      return !is_empty() ? tail_pred : NULL;
+   }
+
+   void push_head(exec_node *n)
+   {
+      n->next = head;
+      n->prev = (exec_node *) &head;
+
+      n->next->prev = n;
+      head = n;
+   }
+
+   void push_tail(exec_node *n)
+   {
+      n->next = (exec_node *) &tail;
+      n->prev = tail_pred;
+
+      n->prev->next = n;
+      tail_pred = n;
+   }
+
+   void push_degenerate_list_at_head(exec_node *n)
+   {
+      assert(n->prev->next == n);
+
+      n->prev->next = head;
+      head->prev = n->prev;
+      n->prev = (exec_node *) &head;
+      head = n;
+   }
+
+   /**
+    * Move all of the nodes from this list to the target list
+    */
+   void move_nodes_to(exec_list *target)
+   {
+      target->head = head;
+      target->tail = NULL;
+      target->tail_pred = tail_pred;
+
+      target->head->prev = (exec_node *) &target->head;
+      target->tail_pred->next = (exec_node *) &target->tail;
+
+      make_empty();
+   }
+
+   exec_list_iterator iterator()
+   {
+      return exec_list_iterator(head);
+   }
+
+   exec_list_iterator iterator() const
+   {
+      return exec_list_iterator((exec_node *) head);
+   }
+#endif
+};
+
+#endif /* LIST_CONTAINER_H */