116
thelist,selectingonlyinformationcontainedinaninsertionthatispartoftheactivever-
sionandnotpartofadeletionintheactiveversion.
Comparisonoftwoversionsisquitesimple,sincetextalwaysappearsinthesameorderin
bothversions,althoughanyparticularsubstringmayappearineitherorbothversions,or
neitherone.Theresultsofacomparisoncanbesummarizedasanorderedsequenceofpairs
ofrangesinthetwoversions,withazerolengthsequenceinacorrespondenceindicatinga
deletedregion.Thisresultisaccumulatedbytraversingthestructure,enumeratingthecon-
tentsofbothversionstobecompared.Eachpointwillbecontainedbyone,both,orneither
ofthetwoversions.Thecomparisonresultcanbeaccumulatedbysimplystartinganewcor-
respondencepairanytimetheinclusionstatechangesineitherversion.Suchanindexis
sufficienttoallowparallelscrollingandhighlightingintwoversions(SeeFigure6.3).
F F F F iii ig g g gu u u ur r r re e e e 6666....3333:::: VVVVTTTTMMMMLLLL eeeeddddiiiittttoooorrrr ddddiiiiffffffff wwwwiiiinnnnddddoooowwww,,,, wwwwiiiitttthhhh ccccoooorrrrrrrreeeessssppppoooonnnnddddiiiinnnngggg ppppoooorrrrttttiiiioooonnnnssss hhhhiiiigggghhhhlllliiiigggghhhhtttteeeedddd
thelist,selectingonlyinformationcontainedinaninsertionthatispartoftheactivever-
sionandnotpartofadeletionintheactiveversion.
Comparisonoftwoversionsisquitesimple,sincetextalwaysappearsinthesameorderin
bothversions,althoughanyparticularsubstringmayappearineitherorbothversions,or
neitherone.Theresultsofacomparisoncanbesummarizedasanorderedsequenceofpairs
ofrangesinthetwoversions,withazerolengthsequenceinacorrespondenceindicatinga
deletedregion.Thisresultisaccumulatedbytraversingthestructure,enumeratingthecon-
tentsofbothversionstobecompared.Eachpointwillbecontainedbyone,both,orneither
ofthetwoversions.Thecomparisonresultcanbeaccumulatedbysimplystartinganewcor-
respondencepairanytimetheinclusionstatechangesineitherversion.Suchanindexis
sufficienttoallowparallelscrollingandhighlightingintwoversions(SeeFigure6.3).
F F F F iii ig g g gu u u ur r r re e e e 6666....3333:::: VVVVTTTTMMMMLLLL eeeeddddiiiittttoooorrrr ddddiiiiffffffff wwwwiiiinnnnddddoooowwww,,,, wwwwiiiitttthhhh ccccoooorrrrrrrreeeessssppppoooonnnnddddiiiinnnngggg ppppoooorrrrttttiiiioooonnnnssss hhhhiiiigggghhhhlllliiiigggghhhhtttteeeedddd