Package com.saxonica.ee.optim

Class QuickXPathParser

java.lang.Object

com.saxonica.ee.optim.QuickXPathParser

All Implemented Interfaces:

XPathParser.Accelerator

public class QuickXPathParser
extends Object
implements XPathParser.Accelerator

This class performs a quick parse of commonly encountered XPath expressions that conform to common syntactic patterns. Instead of using the full recursive-descent parser, the expression is tokenized, and the sequence of tokens is tested against a table of known common sequences. If the XPath expression supplied cannot be parsed (either because it is too complicated or because it is invalid), the quick parser simply returns null and leaves the work to the regular parser.

Constructor Summary

Constructors

Constructor	Description
QuickXPathParser()

Method Summary

Modifier and Type	Method	Description
Expression	parse(Tokenizer t, StaticContext env, String expression, int start, int terminator)	Attempt to parse an expression, provided it is very simple.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

QuickXPathParser

public QuickXPathParser()

Method Details

parse

public Expression parse(Tokenizer t,
 StaticContext env,
 String expression,
 int start,
 int terminator)

Attempt to parse an expression, provided it is very simple.

Specified by:

parse in interface XPathParser.Accelerator

Parameters:

t - the tokenizer

env - the static context

expression - the string containing expression to be parsed

start - start position within the input string

terminator - either EOF or RCURLY, indicating how parsing should end

Returns:

either the parsed expression, or null if it is erroneous or too complex to parse.