4.4BSD/usr/src/usr.bin/make/list.h
/*
* Copyright (c) 1988, 1989, 1990, 1993
* The Regents of the University of California. All rights reserved.
* Copyright (c) 1989 by Berkeley Softworks
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Adam de Boor.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)list.h 8.1 (Berkeley) 6/6/93
*/
/*
* list.h --
*
* Structures, macros, and routines exported by the List module.
*/
#ifndef _LIST
#define _LIST
#ifndef _SPRITE
#include "sprite.h"
#endif _SPRITE
/*
* This module defines the list abstraction, which enables one to link
* together arbitrary data structures. Lists are doubly-linked and
* circular. A list contains a header followed by its real members, if
* any. (An empty list therefore consists of a single element, the
* header, whose nextPtr and prevPtr fields point to itself). To refer
* to a list as a whole, the user keeps a pointer to the header; that
* header is initialized by a call to List_Init(), which creates an empty
* list given a pointer to a List_Links structure (described below).
*
* The links are contained in a two-element structure called List_Links.
* A list joins List_Links records (that is, each List_Links structure
* points to other List_Links structures), but if the List_Links is the
* first field within a larger structure, then the larger structures are
* effectively linked together as follows:
*
* header
* (List_Links) first elt. second elt.
* ----------------- ----------------- -----------------
* ..-> | nextPtr | ----> | List_Links | ----> | List_Links |----..
* | - - - - - - - | | | | |
* ..-- | prevPtr | <---- | | <---- | |<---..
* ----------------- - --- --- --- - - --- --- --- -
* | rest of | | rest of |
* | structure | | structure |
* | | | |
* | ... | | ... |
* ----------------- -----------------
*
* It is possible to link structures through List_Links fields that are
* not at the beginning of the larger structure, but it is then necessary
* to perform pointer arithmetic to find the beginning of the larger
* structure, given a pointer to some point within it.
*
* A typical structure might be something like:
*
* typedef struct {
* List_Links links;
* char ch;
* integer flags;
* } EditChar;
*
* Before an element is inserted in a list for the first time, it must
* be initialized by calling the macro List_InitElement().
*/
/*
* data structure for lists
*/
typedef struct List_Links {
struct List_Links *prevPtr;
struct List_Links *nextPtr;
} List_Links;
/*
* procedures
*/
void List_Init(); /* initialize a header to a list */
void List_Insert(); /* insert an element into a list */
void List_Remove(); /* remove an element from a list */
void List_Move(); /* move an element elsewhere in a list */
/*
* ----------------------------------------------------------------------------
*
* List_InitElement --
*
* Initialize a list element. Must be called before an element is first
* inserted into a list.
*
* ----------------------------------------------------------------------------
*/
#define List_InitElement(elementPtr) \
(elementPtr)->prevPtr = (List_Links *) NIL; \
(elementPtr)->nextPtr = (List_Links *) NIL;
/*
* Macros for stepping through or selecting parts of lists
*/
/*
* ----------------------------------------------------------------------------
*
* LIST_FORALL --
*
* Macro to loop through a list and perform an operation on each member.
*
* Usage: LIST_FORALL(headerPtr, itemPtr) {
* / *
* * operation on itemPtr, which points to successive members
* * of the list
* *
* * It may be appropriate to first assign
* * foobarPtr = (Foobar *) itemPtr;
* * to refer to the entire Foobar structure.
* * /
* }
*
* Note: itemPtr must be a List_Links pointer variable, and headerPtr
* must evaluate to a pointer to a List_Links structure.
*
* ----------------------------------------------------------------------------
*/
#define LIST_FORALL(headerPtr, itemPtr) \
for (itemPtr = List_First(headerPtr); \
!List_IsAtEnd((headerPtr),itemPtr); \
itemPtr = List_Next(itemPtr))
/*
* ----------------------------------------------------------------------------
*
* List_IsEmpty --
*
* Macro: Boolean value, TRUE if the given list does not contain any
* members.
*
* Usage: if (List_IsEmpty(headerPtr)) ...
*
* ----------------------------------------------------------------------------
*/
#define List_IsEmpty(headerPtr) \
((headerPtr) == (headerPtr)->nextPtr)
/*
* ----------------------------------------------------------------------------
*
* List_IsAtEnd --
*
* Macro: Boolean value, TRUE if itemPtr is after the end of headerPtr
* (i.e., itemPtr is the header of the list).
*
* Usage: if (List_IsAtEnd(headerPtr, itemPtr)) ...
*
* ----------------------------------------------------------------------------
*/
#define List_IsAtEnd(headerPtr, itemPtr) \
((itemPtr) == (headerPtr))
/*
* ----------------------------------------------------------------------------
*
* List_First --
*
* Macro to return the first member in a list, which is the header if
* the list is empty.
*
* Usage: firstPtr = List_First(headerPtr);
*
* ----------------------------------------------------------------------------
*/
#define List_First(headerPtr) ((headerPtr)->nextPtr)
/*
* ----------------------------------------------------------------------------
*
* List_Last --
*
* Macro to return the last member in a list, which is the header if
* the list is empty.
*
* Usage: lastPtr = List_Last(headerPtr);
*
* ----------------------------------------------------------------------------
*/
#define List_Last(headerPtr) ((headerPtr)->prevPtr)
/*
* ----------------------------------------------------------------------------
*
* List_Prev --
*
* Macro to return the member preceding the given member in its list.
* If the given list member is the first element in the list, List_Prev
* returns the list header.
*
* Usage: prevPtr = List_Prev(itemPtr);
*
* ----------------------------------------------------------------------------
*/
#define List_Prev(itemPtr) ((itemPtr)->prevPtr)
/*
* ----------------------------------------------------------------------------
*
* List_Next --
*
* Macro to return the member following the given member in its list.
* If the given list member is the last element in the list, List_Next
* returns the list header.
*
* Usage: nextPtr = List_Next(itemPtr);
*
* ----------------------------------------------------------------------------
*/
#define List_Next(itemPtr) ((itemPtr)->nextPtr)
/*
* ----------------------------------------------------------------------------
* The List_Insert procedure takes two arguments. The first argument
* is a pointer to the structure to be inserted into a list, and
* the second argument is a pointer to the list member after which
* the new element is to be inserted. Macros are used to determine
* which existing member will precede the new one.
*
* The List_Move procedure takes a destination argument with the same
* semantics as List_Insert.
*
* The following macros define where to insert the new element
* in the list:
*
* LIST_AFTER(itemPtr) -- insert after itemPtr
* LIST_BEFORE(itemPtr) -- insert before itemPtr
* LIST_ATFRONT(headerPtr) -- insert at front of list
* LIST_ATREAR(headerPtr) -- insert at end of list
*
* For example,
*
* List_Insert(itemPtr, LIST_AFTER(otherPtr));
*
* will insert itemPtr following otherPtr in the list containing otherPtr.
* ----------------------------------------------------------------------------
*/
#define LIST_AFTER(itemPtr) ((List_Links *) itemPtr)
#define LIST_BEFORE(itemPtr) (((List_Links *) itemPtr)->prevPtr)
#define LIST_ATFRONT(headerPtr) ((List_Links *) headerPtr)
#define LIST_ATREAR(headerPtr) (((List_Links *) headerPtr)->prevPtr)
#endif /* _LIST */