Card2Tab:
CEDAR
DEFINITIONS =
BEGIN
Ref: TYPE = REF Card2TabRep;
Card2TabRep: TYPE = MONITORED RECORD [impl: REF Card2TabImplRep];
Card2TabImplRep: TYPE;
Key: TYPE = ARRAY [0 .. 1] OF CARD;
Val: TYPE = REF;
EqualProc: TYPE = PROC [key1, key2: Key] RETURNS [BOOL];
HashProc: TYPE = PROC [key: Key] RETURNS [CARDINAL];
Create:
PROC [mod:
NAT ¬ 17, equal: EqualProc ¬
NIL, hash: HashProc ¬
NIL]
RETURNS [Ref];
... creates new table with suggested hash size.
When equal=NIL, the keys are compared with `key1=key2'.
When hash=NIL, some reasonable hash function is used.
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.