-- SymTab - definitions for symbol table abstraction
-- Russ Atkinson, September 1, 1982 6:42 pm

DIRECTORY
Rope USING [ROPE];

SymTab: CEDAR DEFINITIONS = BEGIN

Ref: TYPE = REF SymTabRep;
Key: TYPE = Rope.ROPE;
Val: TYPE = REF;
EachPairAction: TYPE = PROC [key: Key, val: Val] RETURNS [quit: BOOL];
SymTabRep: TYPE;

Create: PROC [mod: CARDINAL ← 17, case: BOOL ← TRUE] RETURNS [Ref];
-- creates new table with suggested hash size
-- if case is TRUE, keys are compared exactly
-- if case is FALSE, case is ignored in comparing keys

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

Fetch: PROC [x: Ref, key: Key] RETURNS [found: BOOL, 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

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

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

END.