GrammarBasic USING[Grammar, Symbol];

BEGIN OPEN GrammarBasic;

TerminalSeq: TYPE = REF TerminalSeqBody;

TerminalSeqBody: TYPE;

TerminalSeqSet: TYPE = REF TerminalSeqSetBody;

TerminalSeqSetBody: TYPE;

CreateEmptyTerminalSeqSet: PROC[Grammar] RETURNS[TerminalSeqSet];

TestIfTerminalSeqInSet: PROC[TerminalSeqSet, TerminalSeq] RETURNS[BOOLEAN];

InsertTerminalSeqInSet: PROC[TerminalSeqSet, TerminalSeq] RETURNS[notPreviouslyPresent: BOOLEAN];

RemoveTerminalSeqFromSet: PROC[TerminalSeqSet, TerminalSeq];

TestIfTerminalSeqSetEmpty: PROC[TerminalSeqSet] RETURNS[BOOLEAN];

GenTerminalSeqsFromSet: PROC[TerminalSeqSet, PROC[TerminalSeq]];

FreezeTerminalSeqSet: PROC[TerminalSeqSet] RETURNS[TerminalSeqSet, --hash code-- CARDINAL];

TestIfEmptySeqInSet: PROC[TerminalSeqSet] RETURNS[BOOLEAN];

GetOneSymbolTerminalSeq: PROC[Symbol] RETURNS[TerminalSeq];

GetEmptyTerminalSeq: PROC[Grammar] RETURNS[TerminalSeq];

GetSymbolFromTerminalSeq: PROC[TerminalSeq] RETURNS[Symbol]; -- NIL if empty seq

GenFirstNonEmptyTerminalSeqs: PROC[Symbol, PROC[TerminalSeq]];

GetSetOfExactlyTheEmptyTermSeq: PROC[Grammar] RETURNS[TerminalSeqSet];

GetWithEmptyTerminalSeqRemoved: PROC[TerminalSeqSet] RETURNS[TerminalSeqSet];

CompareTwoTerminalSeqSets: PROC[TerminalSeqSet, TerminalSeqSet] RETURNS[BOOLEAN];

-- following support working with sets of terminal sequences as a whole

InsertTermSeqSetInSet: PROC[add: TerminalSeqSet, to: TerminalSeqSet] RETURNS[--some new ones-- BOOLEAN];

CompareTermSeqSetWithSet: PROC[testThese: TerminalSeqSet, with: TerminalSeqSet] RETURNS[--diff--TerminalSeqSet]; --diff are those elements in "test these" and not in "with", NIL if empty

TestNonEmptyIntersection: PROC[a, b: TerminalSeqSet] RETURNS[--nonEmpty-- BOOLEAN];

END..