It isn’t easy to do with regular expressions, but how about a macro like this (JavaScript):
// Create an array
a = new Array();
// Fill the array a with all lines (with returns) in the document.
document.selection.StartOfDocument();
for( ; ; ){
y = document.selection.GetActivePointY( eePosLogical );
document.selection.SelectLine();
sLine = document.selection.Text;
if( sLine == "" ) { // Reached the end of document, escape from the loop
break;
}
a.push( sLine );
document.selection.Collapse();
if( document.selection.GetActivePointY( eePosLogical ) == y ) {
// Reached the end of document (the last line without return), escape from the loop
break;
}
}
// Delete duplicate elements.
for( i = 0; i < a.length; i++ ){
sLine = a[i];
for( j = i + 1; j < a.length; j++ ){
if( sLine == a[j] ){
a.splice( j, 1 );
j--;
}
}
}
// Replace the entire document with new elements
document.selection.SelectAll();
document.selection.Text = a.join( "" );
Please let me know if you have questions. :-)