-- RefTab.Mesa - definitions for REF table abstraction
-- last change: Bill Paxton - August 19, 1982 9:24 am
-- last change: Warren Teitelman - August 31, 1982 2:20 pm
-- last change: Paul Rovner - May 13, 1983 10:39 am

Last Edited by: Sweet, February 4, 1985 1:03:00 pm PST

DIRECTORY

RefTab: CEDAR DEFINITIONS = BEGIN

Ref: TYPE = REF RefTabRep;
RefTabRep: TYPE;

Key: TYPE = RECORD [
link: PrincOps.ControlLink, fill: CARDINAL ← 0];
Val: TYPE = REF LONG CARDINAL;

Create: PROC [mod: CARDINAL ← 17] RETURNS [Ref];
-- creates new table with suggested hash size

GetSize: PROC [x: Ref] RETURNS [CARDINAL];
-- returns number of key-value pairs in table

Fetch: PROC [x: Ref, key: Key] RETURNS [found: BOOLEAN, val: Val];
-- looks up key in table, returns associated value (if any)
-- if found is TRUE, val is value associated with given key
-- if found is FALSE, val is NIL

Replace: PROC [x: Ref, key: Key, val: Val] RETURNS [BOOLEAN];
-- returns TRUE after overwriting old value for existing key-value pair
-- if no previous value for key, returns FALSE without inserting new pair

Store: PROC [x: Ref, key: Key, val: Val] RETURNS [BOOLEAN];
-- returns TRUE after inserting new pair
-- returns FALSE after overwriting old value for existing key-value pair

Insert: PROC [x: Ref, key: Key, val: Val] RETURNS [BOOLEAN];
-- returns TRUE after inserted new pair
-- if previous value existed for key, returns FALSE without changing value

Delete: PROC [x: Ref, key: Key] RETURNS [BOOLEAN];
-- deletes key-value pair associated with given key
-- returns TRUE if deletion actually occurred, FALSE if no such key

Pairs: PROC [x: Ref, action: EachPairAction] RETURNS [BOOLEAN];
-- 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
EachPairAction: TYPE = PROC [key: Key, val: Val] RETURNS [quit: BOOLEAN];

END.