lookupLine method
Returns LineNode located at specified character offset
.
Implementation
LookupResult lookupLine(int offset) {
// TODO: prevent user from moving caret after last line-break.
var result = _root.lookup(offset, inclusive: true);
if (result.node is LineNode) return result;
BlockNode block = result.node as BlockNode;
return block.lookup(result.offset, inclusive: true);
}