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