DIRECTORY Basics, IO, RefTab, Rope, SafeStorage; Pipal: CEDAR DEFINITIONS = BEGIN ROPE: TYPE = Rope.ROPE; Error: SIGNAL [reason: ATOM _ $Client, message: ROPE _ NIL, data: REF ANY _ NIL]; Class: TYPE = SafeStorage.Type; Method: TYPE = NAT; RegisterClass: PROC [name: ROPE, type: SafeStorage.Type] RETURNS [class: Class]; RegisterMethod: PROC [name: ROPE] RETURNS [method: Method]; ClassName: PROC [class: Class] RETURNS [name: ROPE _ NIL]; MethodName: PROC [method: Method] RETURNS [name: ROPE _ NIL]; PutClassMethod: PROC [class: Class, method: Method, data: REF]; GetClassMethod: PROC [class: Class, method: Method] RETURNS [data: REF _ NIL]; Object: TYPE = REF; Objects: TYPE = LIST OF Object; ObjectClass: PROC [object: Object] RETURNS [class: Class]; ObjectMethod: PROC [object: Object, method: Method] RETURNS [data: REF _ NIL]; overlayClass: Class; OverlayIndex: TYPE = NAT; Overlay: TYPE = REF OverlayRec; OverlayRec: TYPE = RECORD [children: SEQUENCE size: OverlayIndex OF Object]; void: READONLY Overlay; CreateOverlay: PROC [children: Objects] RETURNS [overlay: Overlay]; CreateOv: PROC [children: Objects] RETURNS [Object]; ExpandOverlay: PROC [object: Pipal.Object] RETURNS [children: Objects _ NIL]; iconClass: Class; Icon: TYPE = REF IconRec; IconRec: TYPE = RECORD [ reference: Object, -- the appearance (painted) referent: Object]; -- the guts CreateIcon: PROC [reference: Object, referent: Object] RETURNS [icon: Icon]; annotationClass: Class; Annotation: TYPE = REF AnnotationRec; AnnotationRec: TYPE = RECORD [ child: Object, key: ATOM, value: REF ]; CreateAnnotation: PROC [child: Object, key: ATOM, value: REF] RETURNS [annotation: Annotation]; nameProp: ATOM; hashMethod: Method; HashProc: TYPE = PROC [object: Object] RETURNS [hash: CARD]; Hash: HashProc; HashObjectClass: HashProc; equalMethod: Method; EqualProc: TYPE = PROC [object1, object2: Object] RETURNS [equal: BOOL _ FALSE]; Equal: EqualProc; describeMethod: Method; DescribeProc: TYPE = PROC [out: IO.STREAM, object: Object, indent: NAT _ 0, level: NAT _ 2, cr: BOOL _ TRUE]; Describe: DescribeProc; DescribeToRope: PROC [object: Object, indent: NAT _ 0, level: NAT _ 1, cr: BOOL _ FALSE] RETURNS [ROPE]; PutIndent: PROC [out: IO.STREAM, indent: NAT, cr: BOOL _ TRUE]; ObjectCache: TYPE = RefTab.Ref; CreateObjectCache: PROC RETURNS [ObjectCache]; FlushObjectCaches: PROC [object: Object]; Reverse: PROC [objects: Objects] RETURNS [Objects]; Add: PROC [objects: Objects, candidate: Object] RETURNS [Objects]; Delete: PROC [objects: Objects, candidate: Object] RETURNS [Objects]; Member: PROC [objects: Objects, candidate: Object] RETURNS [BOOL]; Length: PROC [objects: Objects] RETURNS [INT]; CompareProc: TYPE = PROC [object1, object2: Object] RETURNS [Basics.Comparison]; Sort: PROC [objects: Objects, compare: CompareProc] RETURNS [Objects]; AlwaysTrue: PROC [Object] RETURNS [BOOL]; AlwaysFalse: PROC [Object] RETURNS [BOOL]; ClassTable: TYPE = REF ClassTableRec; ClassTableRec: PRIVATE TYPE = ARRAY SafeStorage.TypeIndex OF REF; CreateClassTable: PROC RETURNS [table: ClassTable]; StoreInClassTable: PROC [table: ClassTable, class: Class, value: REF]; FetchFromClassTable: PROC [table: ClassTable, class: Class] RETURNS [value: REF _ NIL]; END. zPipal.mesa Copyright ╙ 1988 by Xerox Corporation. All rights reserved. Created at the beginning of 1988 by Bertrand, Louis & Rick Louis Monier January 14, 1988 12:54:29 pm PST Bertrand Serlet May 18, 1988 11:57:35 am PDT Barth, January 28, 1988 4:20:58 pm PST Theory Pipal is a sacred fig-tree for the Buddhists. The rest is self-explanatory. Basic Type Aliases Errors Every procedure which raises this error must document in the interface the reason atoms which it might use. Classes and Methods For efficiency reasons, the class of an object is its Cedar type. For efficiency reasons, the implementation deals with a method as an index, not as a pointer to a data structure. Clients should not assume any property of the representation of methods, except that in a single VM two methods are the same if and only if their method index's are equal. Low level definition of a new class. Type is the Cedar type of objects af class name. This restricts objects of different classes to be of different types. Double registration: - same name, same type or not: legal, but any data attached to old registration is lost; a message is issued in the terminal - different name, same type: crash Low level definition of a new method. Double registration under the same name: returns a new method index, and any data attached to old method is lost; a message is issued in the terminal Returns registration name, NIL if class has not been registered. Returns registration name, NIL if method has not been registered. Usually data is a REF PROC. Usually data is a REF PROC. Objects Uses the Cedar type of the object and the class registration table to extract the object class. Short cut for GetClassMethod[ObjectClass[object], method]. Universal Composition Classes Overlay Overlay with no element. Neutral element for various operations! It is legal for an overlay to have no child, but then it must be void. Children of an overlay are not ordered. Optimizes the creation of an overlay for the case when there is only one child. Crash and burn if the object is not an overlay. Icon Annotation The annotation class can be used for any immutable annotation (i.e. a property whose key and value will never change during a VM). It is convenient when objects are created by code, to name them without using visible properties. The annotation value must the name ROPE. Universal Methods Hash High quality hashing. No describeMethod method => HashObjectClass[object>]". Hashes the class of the object. Equal Since high quality hashing exists, efficient conservative equality is possible. Having an equality implies: - maximum sharing by avoiding creation of duplicate objects; - successive unpickling produce identical objects ... - therefore allowing for a simple saving of caches; - possibility to implement utilities such as diff. Invariant: Equal[object1, object2] => Class[object1]=Class[object2] and Hash[object1]=Hash[object2]. EqualProcs can assume that object1 and object2 are of the same class. If objects are REF-equal it is easy. If classes are different or if hashes are different, objects must be different. Then, if there is an EqualProc, it is applied; otherwise FALSE is returned. Describe The describe method is useful for debugging and (poor) user-interface. No describeMethod method => " object". Debugging feature: also knows how to describe object RefTabs, object SymTabs, and list of objects. Same as previous but returns a ROPE. Utility that puts on out a CR (iff cr) followed by indent spaces. Utilities This section regroups various utilities always useful. Object Caches Creates a new RefTab, and keeps a pointer on it in order to be able to do flushes. Flushes all object caches for object. Operations on objects Reverses! Same list is returned if candidate is already a member. Same list is returned if candidate is not a member. Searches for candidate in objects. Returns the # of elements in the list. Attention: modifies in place objects! Objects Predicates Class Tables It is often convenient to have tables keyed by Class. The implementation of Pipal itself uses such convenience. Clients should not depend on this type, as representation might change. Э╩0ШЦ "Cedar" styleЪЬЩJЪЬ<Щ