PropertyListsDoc.tioga
Created by: Christian Jacobi, March 12, 1986 8:15:10 pm PST
gbb May 15, 1986 11:45:10 am PDT
Last Edited by: Jacobi June 13, 1986 10:26:22 am PDT
PROPERTIES
CEDAR 6.1 — FOR INTERNAL XEROX USE ONLY
PropertyLists
Christian Jacobi
© Copyright 1986 Xerox Corporation. All rights reserved.
Abstract: Implements property lists similar to Atom, but uses less memory.
Created by: Christian Jacobi
Maintained by: Christian Jacobi <Jacobi.pa>
Keywords: properties
XEROX Xerox Corporation
Palo Alto Research Center
3333 Coyote Hill Road
Palo Alto, California 94304
For Internal Xerox Use Only
PropertyLists
Implements property list. Uses less memory than Atom's implementation. This module has no protection against concurrent calls of PutProp. Usage is either in sequential applications or with a higher level application monitor giving protection. Other modules must not modify any PropList; a modification of a PropList while Properties is inside its monitor lock can cause failures.
PropList:
TYPE =
LIST
OF KeyVal;
KeyVal: TYPE = RECORD [key, val: REF];
GetProp:
PROC [propList: PropList, prop:
REF]
RETURNS [
REF];
--Fetches a value from a property list; NIL if not found
PutProp:
PROC [propList: PropList, prop:
REF, val:
REF
← NIL]
RETURNS [PropList];
--Puts a property key value pair on a property list; The property list must be written back.
--A nil val value removes the property
EachProp: TYPE = PROC [key, val: REF] RETURNS [quit: BOOL←FALSE];
Enumerate:
PROC [propList: PropList, proc: EachProp]
RETURNS [quit:
BOOL];
--Enumerates the list
--Changes of the list while the enumeration is in progress may or may not be seen