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authorrgrimes <rgrimes@FreeBSD.org>1994-05-27 12:33:43 +0000
committerrgrimes <rgrimes@FreeBSD.org>1994-05-27 12:33:43 +0000
commit95bef729766af92a2bde4dcc8eff56c2924b0d9f (patch)
treebb6c42bb4fd7743bbac30e6c4f0b874b6d5ec9b9 /usr.bin/make/list.h
downloadFreeBSD-src-95bef729766af92a2bde4dcc8eff56c2924b0d9f.zip
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+/*
+ * 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 */
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