CardTab.mesa
Copyright Ó 1987, 1991 by Xerox Corporation. All rights reserved.
For Portable Cedar
Russ Atkinson (RRA) January 16, 1987 1:43:01 pm PST
Carl Hauser, January 14, 1988 4:43:00 pm PST
CardTab:
CEDAR
DEFINITIONS =
BEGIN
Ref: TYPE = REF CardTabRep;
CardTabRep: TYPE = MONITORED RECORD [impl: REF CardTabImplRep];
CardTabImplRep: TYPE;
Key: TYPE = CARD;
Val: TYPE = REF;
Create:
PROC [mod:
NAT ¬ 17]
RETURNS [Ref];
... creates new table with suggested hash size.
GetSize:
PROC [x: Ref]
RETURNS [
INT];
... returns number of key-value pairs in table (use this to properly deal with monitored data in preference to using the size field)
Fetch:
PROC [x: Ref, key: Key]
RETURNS [found:
BOOL, val: Val];
... looks up key in table, returns associated value (if any); if found = TRUE, val = value associated with given key; if found = FALSE, val = NIL
Replace:
PROC [x: Ref, key: Key, val: Val]
RETURNS [
BOOL];
... replaces value for existing key; returns TRUE if previous value overwritten; if no previous value for key, returns FALSE without inserting new pair
Store:
PROC [x: Ref, key: Key, val: Val]
RETURNS [
BOOL];
... stores new key-value pair, overwriting previous value for given key; returns TRUE if new value, FALSE if previous value overwritten
Insert:
PROC [x: Ref, key: Key, val: Val]
RETURNS [
BOOL];
... inserts new key-value pair, except if previous value for given key; returns TRUE if inserted, FALSE if previous value for key
Delete:
PROC [x: Ref, key: Key]
RETURNS [
BOOL];
... deletes key-value pair associated with given key; returns TRUE if deletion actually occurred, FALSE if no such key
Erase:
PROC [x: Ref];
... deletes all key-value pairs in the table
EachPairAction:
TYPE =
PROC [key: Key, val: Val]
RETURNS [quit:
BOOL ¬
FALSE];
Pairs:
PROC [x: Ref, action: EachPairAction]
RETURNS [
BOOL];
... enumerates pairs currently in symbol table in unspecified order; pairs inserted/deleted during enumeration may or may not be seen; applies action to each pair until action returns TRUE or no more pairs; returns TRUE if some action returns TRUE
UpdateOperation:
TYPE = {none, store, delete};
UpdateAction:
TYPE =
PROC [found:
BOOL, val: Val]
RETURNS [op: UpdateOperation ¬ none, new: Val ¬
NIL];
Update:
PROC [x: Ref, key: Key, action: UpdateAction];
... atomically performs an update action; looks up key and calls action, which returns the desired operation. If op=none, the table is not changed; if op=store, the new value is stored; if op=delete, key is removed from the table.
Copy:
PROC [x: Ref]
RETURNS [Ref];
... atomically copies the table.
END.