Hermes: A Tutorial and Reference Manual - Researcher - IBM
Hermes: A Tutorial and Reference Manual - Researcher - IBM
Hermes: A Tutorial and Reference Manual - Researcher - IBM
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11011.6.TableOperations ashorth<strong>and</strong>forwhere('true').Ifthemappinglisthasasingleexpression, <strong>and</strong>thetableisordered,thenexpressionisassumedtobeaposition<strong>and</strong>the selectedelementistheelementatthatposition.Thust[n]isshorth<strong>and</strong>for eintwhere(positionofe=n).Iftheaboveruledoesnotapply,<strong>and</strong><br />
toselectasingleelement;thepurposeofothersistoselectanentireset. elementsdependsupontheoperation.Thepurposeofsomeoperationsis illegal. =x<strong>and</strong>e.address=y).Ifnoneoftheserulesapply,orifmorethanone keyhasthecorrectnumberofvariables,theuseofthemappingselectoris themappinglisthaskexpressions,<strong>and</strong>onekeyhaskvariables,thekexpressionsareassumedtobecomparisonvaluesforthosekeys.Thusifthas<br />
typepersontable,thent[x,y]isshorth<strong>and</strong>foreintwhere(e.name<br />
anarbitrarychoiceismade. Whenthepurposeistoselectasingleelement,<strong>and</strong>noelementisselected, tableisordered,theearliestelementischosen.Ifthetableisunordered, exceptionNotFoundisraised.Ifmorethanoneelementisselected,<strong>and</strong>the Theresultisacopyofthechosenselectedelement,orelseNotFoundis Aselectorbyitselfinanexpressionistheoperationcalledtheelement. Selectorsappearaspartofseveraloperations.Theuseoftheselected<br />
raised.Theresulthastheelementtype<strong>and</strong>elementtypestate.Theelement Every typemustbecopyable. Theeveryoperationreturnsatablecontainingacopyofalltheselected elements.Iftheoriginaltablewasordered,thecopiedelementsareinthe sameorder.Theresultofeverywillbeanemptytableifnoelementsare Exists,Forall selected.Theelementtypemustbecopyable. secondary::=everyofselector<br />
selected;elseitreturnsfalse.Theforalloperationreturnsatrueboolean Theexistsoperationreturnsatruebooleanvalueifatleastoneelementis valueifallelementsareselected;elseitreturnsfalse. Insert,Insert-at secondary::=existsofselector<br />
simple{statement ::=forallofselector ::=insertelement{expressionintotable{variable [atposition{expression]
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