public STATE state; /* compare state for section */
#endregion Fields
#region Constructors
public Section( Line firstParam, Line lastParam )
{
first = firstParam;
last = lastParam;
link = null;
correspond = null;
state = STATE.NONE;
leftbase = 1;
rightbase = 1;
}
public void compare( ListAnchor secsComposite, ListAnchor linesLeft, ListAnchor linesRight, bool isIgnoreBlanks )
{
Section wholeLeft, wholeRight;
ListAnchor secsLeft = new ListAnchor();
ListAnchor secsRight = new ListAnchor();
bool bChanges;
do {
bChanges = false; /* we have made no changes so far this time round the loop */
/* make a section covering the whole file */
wholeLeft = new Section( (Line)linesLeft. GetHead(), (Line)linesLeft.GetTail() );
wholeRight = new Section( (Line)linesRight.GetHead(), (Line)linesRight.GetTail() );
/* link up matching unique lines between these sections */
if( wholeLeft.Match( wholeRight, isIgnoreBlanks ) ) bChanges = true;
/* discard previous section lists if made */
secsLeft. RemoveAll();
secsRight.RemoveAll();
/* build new section lists for both files */
Section.MakeList( secsLeft, linesLeft, true ,isIgnoreBlanks);
Section.MakeList( secsRight, linesRight, false,isIgnoreBlanks);
/* match up sections - make links and corresponds between
* sections. Attempts to section_match corresponding
* sections that are not matched. returns true if any
* further links were made */
if( Section.MatchList( secsLeft, secsRight, isIgnoreBlanks ) ) bChanges = true;
/* repeat as long as we keep adding new links */
} while( bChanges );
/* all possible lines linked, and section lists made .
* combine the two section lists to get a view of the
* whole comparison - the composite section list. This also
* sets the state of each section in the composite list. */
Section.MakeComposite( secsComposite, secsLeft, secsRight );
}
/***************************************************************************
* Function: ExpandAnchor
* Purpose:
* Given an anchor point (two lines that we think should match),
* try to link them, and the lines above and below them for as long
* as the lines can be linked (are the same, are unlinked).
* Return true if we make any links. */
public static bool ExpandAnchor(Section sec1, Line line1, Section sec2, Line line2,bool isIgnoreBlanks)
{
/* when a line is matched we set bChanges. If we notice some
* blank lines, but do NOT link any new non-blank lines, we
* do NOT set bChanges. (If we did it would cause a closed
* loop as they would get noticed again next time. line_link
* only returns true if it is a NEW link).
* At this stage we are only interested in making links, not in
* the size of the section that results (that fun comes later).
* therefore trailing blanks at the end of a section are not
* interesting and we don't look for them. */
bool bChanges = false;
/* We handle the section limits by using a sentinel which is one
* past the end of the section. (If the section ends at the end
* of the list then the sentinel is null). */
Line leftend = (Line)sec1.last.GetNext();
Line rightend = (Line)sec2.last.GetNext();
/* null lines shall not match */
if ((line1 == null) || (line2 == null)) return false;
/* check all lines forward until fail to link (because null,
* not matching, or already linked). include the passed in anchor point since this has not
* yet been linked. If blanks are ignorable then skip over any number of whole
* blank lines. */
Line left = line1;
Line right = line2;
for(;;){
if( left.Link( right, isIgnoreBlanks ) ){
bChanges = true;
left = (Line)left.GetNext();
right = (Line)right.GetNext();
if( left == leftend || right == rightend ) break;
}
else if( isIgnoreBlanks ){
/* even though no match, maybe an ignorable blank? */
bool moved = false;
moved |= AbsorbAnyBlanks( ref left, leftend, /*bMoveToNext=*/true);
moved |= AbsorbAnyBlanks( ref right, rightend,/*bMoveToNext=*/true);
if( !moved ) break; /* it didn't match and we didn't move on */
if( left == leftend || right == rightend ) break;
}
else break;
}
/* check all matches going backwards from anchor point
but only if it was a real anchor (could have been
end-of-section/end-of-file and non-matching). */
if( line1.link == null ) return bChanges;
left = (Line)line1.GetPrev();
right = (Line)line2.GetPrev();
if( left == null || right == null ) return bChanges;
leftend = (Line)sec1.first.GetPrev();
rightend = (Line)sec2.first.GetPrev();
for(;;){
if( left.Link(right,isIgnoreBlanks) ){
bChanges = true;
left = (Line)left.GetPrev();
right = (Line)right.GetPrev();
if( left == leftend || right == rightend ) break;
}
else if( isIgnoreBlanks ){
/* even though no match, maybe an ignorable blank? */
bool moved = false;
moved |= AbsorbAnyBlanks( ref left, leftend, /*bMoveToNext=*/false);
moved |= AbsorbAnyBlanks( ref right, rightend, /*bMoveToNext=*/false);
if( !moved ) break; /* it didn't match and we didn't move on */
if( left == leftend || right == rightend ) break;
}
else break;
}
return bChanges;
}
public bool Match(Section sec,bool isIgnoreBlanks)
{
if (/*(this == null)||*/ (sec == null)) return(false);
if ((first == null) || (sec.first == null)) return(false);
/* ASSERT if first is non-null, so is last */
/* attempt to link the first line of each file, and
* if matched, expand as long as we keep matching*/
bool bLinked = false;
bLinked |= ExpandAnchor(this, first, sec, sec.first, isIgnoreBlanks );
/* attempt to link the last lines of each file and
* expand upwards */
bLinked |= ExpandAnchor(this, last, sec, sec.last, isIgnoreBlanks );
/* build a tree of lines, indexed by the line hashcode.
* a ctree will hold only the first value of any given key, but
* it will keep track of the number of items inserted on this key.
* thus we can keep count of the number of times this line
* (or at least this hashcode) appears.*/
Tree ctleft = MakeCTree(isIgnoreBlanks);
Tree ctright = sec.MakeCTree(isIgnoreBlanks);
/* for each unlinked line in one list (doesnt matter which), find if
* appears once only in each list. if so, link, and expand
* the link to link lines before and after the matching line
* as long as they continue to match.*/
for( Line line = first; line != null; line = (Line)line.GetNext() ) {
if( ( line.link == null ) &&
( ctleft .getcount( line.GetHashcode(isIgnoreBlanks) ) == 1 ) &&
( ctright.getcount( line.GetHashcode(isIgnoreBlanks) ) == 1) ){
/* line appears exactly once in each list */
Line line2 = (Line)ctright.find( line.GetHashcode(isIgnoreBlanks) ).data;
bLinked |= ExpandAnchor( this, line, sec, line2, isIgnoreBlanks );
}
if( line == last ) break;
}
return bLinked;
}
/***************************************************************************
* Function: TakeSection
* Purpose:
* Add a section to the composite list. Called from make_composites
* to copy a section, add it to the composite list and set the state,
* leftbase and rightbase. Note that the state could be STATE.SAME
* with a null section on the left. May NOT call with STATE.SAME and
* a null right section! */
public static void TakeSection(ListAnchor compo, Section left, Section right, STATE state)
{
Section sec = null;
/* select which section is being output, and change the state to indicate it has been output */
switch( state ){
case STATE.SAME:
/* both the same. we mark both as output, and
* take the right one. It is possible that the
* left one could be null (an ignorable blank section) */
if( left != null ) left.state = STATE.MARKED;
right.state = STATE.MARKED;
sec = right;
break;
case STATE.LEFTONLY:
case STATE.MOVEDLEFT:
sec = left;
left.state = STATE.MARKED;
break;
case STATE.RIGHTONLY:
case STATE.MOVEDRIGHT:
sec = right;
right.state = STATE.MARKED;
break;
}
/* create a new section on the list */
Section newsec = new Section( sec.first, sec.last );
compo.AddTail( newsec );
newsec.state = state;
if (left != null) newsec.leftbase = left.first.linenr;
else newsec.leftbase = 0;
if (right != null) newsec.rightbase = right.first.linenr;
else newsec.rightbase = 0;
}
/***************************************************************************
* Function: section_makelist
* Purpose:
* Make a list of sections by traversing a list of lines. Consecutive
* linked lines that are linked to consecutive lines are put in a single
* section. Blocks of unlinked lines are placed in a section.
* If isIgnoreBlanks is set then we first try to link them as normal.
* but if they won't link then we just skip over them and keep them
* in the same section.
* Left must be set true iff the list of lines is a left hand section.
* Returns a handle to a list of sections */
public static void MakeList(ListAnchor sections, ListAnchor linelist, bool left,bool isIgnoreBlanks)
{
/* for each line in the list */
for( Line line1 = (Line)linelist.GetHead(); line1 != null; line1 = (Line)line1.GetNext() ){
/* is it linked ? */
bool matched;
Line line2;
if( line1.link != null || ( isIgnoreBlanks && line1.IsBlank() ) ){
line2 = FindEndOfMatched(line1,isIgnoreBlanks);
matched = true;
} else {
line2 = FindEndOfUnmatched(line1);
matched = false;
}
Section sect = new Section(line1, line2); /* create the section and add to list */
sections.AddTail( sect );
sect.state = (
matched ? STATE.SAME
: left ? STATE.LEFTONLY
: STATE.RIGHTONLY
);
line1 = line2; /* advance to end of section (no-op if 1 line section) */
}
}