final XPathParser parser = new XPathParser(errorListener, locator);
final Compiler compiler = new Compiler(errorListener, locator, funcTable_);
parser.initXPath(compiler, exprString, prefixResolver);
final Expression expr = compiler.compile(0);
mainExp_ = expr;
if (locator != null && locator instanceof ExpressionNode) {
expr.exprSetParent((ExpressionNode) locator);