/**
* Parses an expression. Returns a object of type Node, does not catch errors. Does not set the
* topNode variable of the JEP instance. This method should generally be used with the {@link
* #evaluate evaluate} method rather than getValueAsObject.
*
* @param expression represented as a string.
* @return The top node of a tree representing the parsed expression.
* @throws ParseException
* @since 2.3.0 alpha
* @since 2.3.0 beta - will raise exception if errorList non empty
*/
public Node parse(String expression) throws ParseException {
java.io.StringReader sr = new java.io.StringReader(expression);
errorList.removeAllElements();
Node node = parser.parseStream(sr, this);
if (this.hasError()) throw new ParseException(getErrorInfo());
return node;
}
/**
* Parses the expression. If there are errors in the expression, they are added to the <code>
* errorList</code> member. Errors can be obtained through <code>getErrorInfo()</code>.
*
* @param expression_in The input expression string
* @return the top node of the expression tree if the parse was successful, <code>null</code>
* otherwise
*/
public Node parseExpression(String expression_in) {
Reader reader = new StringReader(expression_in);
try {
// try parsing
errorList.removeAllElements();
topNode = parser.parseStream(reader, this);
// if there is an error in the list, the parse failed
// so set topNode to null
if (hasError()) topNode = null;
} catch (Throwable e) {
// an exception was thrown, so there is no parse tree
topNode = null;
// check the type of error
if (e instanceof ParseException) {
// the ParseException object contains additional error
// information
errorList.addElement(((ParseException) e).getMessage());
// getErrorInfo());
} else {
// if the exception was not a ParseException, it was most
// likely a syntax error
if (debug) {
System.out.println(e.getMessage());
e.printStackTrace();
}
errorList.addElement("Syntax error");
}
}
// If traversing is enabled, print a dump of the tree to
// standard output
if (traverse && !hasError()) {
ParserVisitor v = new ParserDumpVisitor();
try {
topNode.jjtAccept(v, null);
} catch (ParseException e) {
errorList.addElement(e.getMessage());
}
}
return topNode;
}