Enabling Line Continuation
One feature of Visual Basic is that you can type a comment that spans multiple lines, if you use the underscore " _" at the end of each line. For example:
rem this is a comment _
this is still a comment _
yet more comment
In the above example, all three lines would be highlighted in green, the same as a single line comment.
Because Objective Edit has no built-in way to specify line continuation for syntax coloring, ordinarily only the first line "rem this is a comment _" would be green and the rest would look like regular text. However, you can customize your project to produce Visual Basic syntax coloring. To handle line continuation so that a remark that covers two lines would all be properly colored as a comment, modify SECEdit::GetLineColor() and check whether the previous line has a line continuation symbol (_) and is a single line comment. Take a look at this pseudocode:
If (FindSymbol && IsComment)
color the current line as comment.
if (FindSymbol && !IsComment)
check the line above previous line by repeating this step --->
Recursion
if (no Symbol)
Stop.
This means we will need a recursive helper function to determine if the current line is continued from a single line comment.
You can derive a new class from SECEdit. In the following sample implementation, GetLineColor() is derived from SECEdit::GetLineColor() and IsComment() is the recursive helper function.
// in .h file:
public:
BOOL m_bConcat;
BOOL IsComment(int nLine);
SECEditLineColor* GetLineColor(int nLine);
//in .cpp file:
SECEditLineColor* CMyEdit::GetLineColor(int nLine)
{
// If Syntax Highlighting is off, then return NULL
if(!GetSyntaxColoring())
{
return NULL;
}
if(nLine > m_LineColorArray.GetUpperBound())
{
ASSERT(FALSE);
return NULL;
}
ASSERT(nLine < GetLineCount());
// If we have no coloring for this SECEdit, return NULL;
// If we are asking to color a line that is beyond the last
// line that we have checked for ML comments, then we need to
// look ahead to nLine and make sure that we have no
// ML Comments in this range.
if(nLine >= m_nInvalidIndex)
{
SECEditLineColPair lcBlock(m_nInvalidIndex, 0, nLine, 0);
ColorMLComments(lcBlock);
}
ASSERT(nLine <= m_nInvalidIndex);
// Now, return the line color for this line
SECEditLineColor* pLineColor = m_LineColorArray.GetAt(nLine);
if(pLineColor == NULL)
{
pLineColor = SetLineColor(nLine);
}
ASSERT(pLineColor == m_LineColorArray.GetAt(nLine));
// Check whether this line is continued from a single line comment
if (IsComment(nLine))
for (int i = 0; i < GetLangPtr()->GetColorInfoCount(); i++)
{
if(GetLangPtr()->GetColorInfo(i)->
m_strDisplayName.CompareNoCase(_T("Comment"))==0)
{
SECEditTextColor tc;
tc.m_nColorInfo = i;
tc.m_nLength = GetLineVisibleLength(nLine);
pLineColor->RemoveAll();
pLineColor->Add(tc);
break;
}
}
// End Checking Continuation
// Look up if this line is Highlighted
if (this->GetItemDataFlag(nLine, ID_SECEDIT_ITEMDATA_HIGHLIGHT))
{
file://Look up the color map
for (int i = 0; i < GetLangPtr()->GetColorInfoCount(); i++)
{
if(GetLangPtr()->GetColorInfo(i)->
m_strDisplayName.CompareNoCase(_T("Highlight"))==0)
{
SECEditTextColor tc;
tc.m_nColorInfo = i;
tc.m_nLength = GetLineVisibleLength(nLine);
pLineColor->RemoveAll();
pLineColor->Add(tc);
break;
}
}
}
return pLineColor;
}
// Helper function
BOOL CMyEdit::IsComment(int nLine)
{
BOOL bIsComment = FALSE;
if (nLine > 0)
{
CString strLine;
LPCTSTR szLine;
int nLength = GetLine(nLine - 1, strLine, szLine);
if (strLine == _T(""))
strLine = szLine;
strLine = strLine.Left(nLength);
strLine.Remove('\r');
strLine.Remove('\n');
strLine.Remove(' ');
CString xstr = strLine.Right(1);
if (strLine.Right(1) == _T("_"))
{
SECEditLineCol lc;
lc.line = nLine - 1;
lc.col = nLength - 1;
if (IsLineColInSLComment(lc))
{
bIsComment = TRUE;
}
if(!bIsComment && (nLine - 1) > 0)
return IsComment(nLine - 1);
}
}
return bIsComment;
}
