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1 | (* Copyright (C) 1999-2006 Henry Cejtin, Matthew Fluet, Suresh |
2 | * Jagannathan, and Stephen Weeks. | |
3 | * | |
4 | * MLton is released under a BSD-style license. | |
5 | * See the file MLton-LICENSE for details. | |
6 | *) | |
7 | ||
8 | functor DoublyLinked(S: DOUBLY_LINKED_STRUCTS): DOUBLY_LINKED = | |
9 | struct | |
10 | ||
11 | open S | |
12 | ||
13 | fun prevp d = #1(destruct d) | |
14 | fun prev d = Pointer.!(prevp d) | |
15 | fun setPrev(d,d') = Pointer.:=(prevp d,d') | |
16 | fun value d = #2(destruct d) | |
17 | fun nextp d = #3(destruct d) | |
18 | fun next d = Pointer.!(nextp d) | |
19 | fun setNext(d,d') = Pointer.:=(nextp d,d') | |
20 | ||
21 | fun link(d, d') = | |
22 | (setNext(d, d') | |
23 | ; setPrev(d',d)) | |
24 | ||
25 | fun insertL(d, d') = | |
26 | (if Pointer.isNull(prevp d') then () else link(prev d',d) | |
27 | ; link(d,d')) | |
28 | ||
29 | fun insertR(d, d') = | |
30 | (if Pointer.isNull(nextp d) then () else link(d',next d) | |
31 | ; link(d, d')) | |
32 | ||
33 | fun unlink d = | |
34 | (link(prev d,next d) | |
35 | ; Pointer.clear(prevp d) | |
36 | ; Pointer.clear(nextp d)) | |
37 | ||
38 | fun isLinked d = | |
39 | not(Pointer.isNull(prevp d) orelse Pointer.isNull(nextp d)) | |
40 | ||
41 | fun eqPrev(d, d') = Pointer.eq(prevp d, prevp d') | |
42 | ||
43 | end |