SymTab.mesa - definitions for symbol table abstraction
Copyright © 1985 by Xerox Corporation. All rights reserved.
Russ Atkinson, February 5, 1985 2:03:26 pm PST
DIRECTORY
Rope USING [ROPE];
SymTab: CEDAR DEFINITIONS = BEGIN
Ref: TYPE = REF SymTabRep;
SymTabRep: TYPE = MONITORED RECORD [
mod: CARDINAL, size: INT, case: BOOL, data: REF Seq];
Seq: TYPE = RECORD[nodes: SEQUENCE max: CARDINAL OF Node];
SeqIndex: TYPE = CARDINAL[0..4000);
NodeRep: TYPE = RECORD [key: Key, val: Val, next: Node];
Node: TYPE = REF NodeRep;
Key: TYPE = Rope.ROPE;
TextKey: TYPE = REF READONLY TEXT;
Val: TYPE = REF;
EachPairAction: TYPE = PROC [key: Key, val: Val] RETURNS [quit: BOOL];
The type of procedure called for each pair in Pairs
Create: PROC [mod: SeqIndex ← 17, case: BOOLTRUE] 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 [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
FetchText: PROC [x: Ref, key: TextKey] 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; the key MUST NOT BE ALTERED during a call of this procedure
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.