266 lines
8.3 KiB
C
266 lines
8.3 KiB
C
/*
|
||
* list.h --
|
||
*
|
||
* Structures, macros, and routines exported by the List module.
|
||
*
|
||
* Copyright (C) 1985 Regents of the University of California
|
||
* All rights reserved.
|
||
*
|
||
* Header: list.h,v 2.0 87/08/11 09:32:18 brent Exp $ SPRITE (Berkeley)"
|
||
*/
|
||
|
||
#ifndef _LIST
|
||
#define _LIST
|
||
|
||
#include "sprite.h"
|
||
#include <unistd.h>
|
||
#include <stdlib.h>
|
||
#include <bstring.h>
|
||
#include <stdio.h>
|
||
|
||
/*
|
||
* 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, itype) \
|
||
for ((itemPtr) = (itype)List_First(headerPtr); \
|
||
!List_IsAtEnd((headerPtr),(List_Links *)(itemPtr)); \
|
||
(itemPtr) = (itype)List_Next((List_Links *)(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
|