Package org.apache.xpath.compiler

Class Compiler

  • public class Compiler
extends OpMap
    An instance of this class compiles an XPath string expression into a Expression object. This class compiles the string into a sequence of operation codes (op map) and then builds from that into an Expression tree.

    • Constructor Detail

      • Compiler

        public Compiler​(javax.xml.transform.ErrorListener errorHandler,
                javax.xml.transform.SourceLocator locator,
                FunctionTable fTable)
        Construct a Compiler object with a specific ErrorListener and SourceLocator where the expression is located.
        Parameters:
        errorHandler - Error listener where messages will be sent, or null if messages should be sent to System err.
        locator - The location object where the expression lives, which may be null, but which, if not null, must be valid over the long haul, in other words, it will not be cloned.
        fTable - The FunctionTable object where the xpath build-in functions are stored.

      • Compiler

        public Compiler()
        Construct a Compiler instance that has a null error listener and a null source locator.

    • Method Detail

      • compile

        public Expression compile​(int opPos)
                   throws javax.xml.transform.TransformerException
        Execute the XPath object from a given opcode position.
        Parameters:
        opPos - The current position in the xpath.m_opMap array.
        Returns:
        The result of the XPath.
        Throws:
        javax.xml.transform.TransformerException - if there is a syntax or other error.

      • getLocationPathDepth

        public int getLocationPathDepth()
        Get the level of the location path or union being constructed.
        Returns:
        0 if it is a top-level path.

      • locationPath

        public Expression locationPath​(int opPos)
                        throws javax.xml.transform.TransformerException
        Compile a location path. The LocPathIterator itself may create AxesWalker children.
        Parameters:
        opPos - The current position in the m_opMap array.
        Returns:
        reference to LocPathIterator instance.
        Throws:
        javax.xml.transform.TransformerException - if a error occurs creating the Expression.

      • predicate

        public Expression predicate​(int opPos)
                     throws javax.xml.transform.TransformerException
        Compile a location step predicate expression.
        Parameters:
        opPos - The current position in the m_opMap array.
        Returns:
        the contained predicate expression.
        Throws:
        javax.xml.transform.TransformerException - if a error occurs creating the Expression.

      • locationPathPattern

        public Expression locationPathPattern​(int opPos)
                               throws javax.xml.transform.TransformerException
        Compile a location match pattern unit expression.
        Parameters:
        opPos - The current position in the m_opMap array.
        Returns:
        reference to StepPattern instance.
        Throws:
        javax.xml.transform.TransformerException - if a error occurs creating the Expression.

      • getWhatToShow

        public int getWhatToShow​(int opPos)
        Get a NodeFilter bit set that tells what to show for a given node test.
        Parameters:
        opPos - the op map position for the location step.
        Returns:
        NodeFilter bit set that tells what to show for a given node test.

      • getCompiledPredicates

        public Expression[] getCompiledPredicates​(int opPos)
                                   throws javax.xml.transform.TransformerException
        Compile a zero or more predicates for a given match pattern.
        Parameters:
        opPos - The position of the first predicate the m_opMap array.
        Returns:
        reference to array of Expression instances.
        Throws:
        javax.xml.transform.TransformerException - if a error occurs creating the Expression.

      • countPredicates

        public int countPredicates​(int opPos)
                    throws javax.xml.transform.TransformerException
        Count the number of predicates in the step.
        Parameters:
        opPos - The position of the first predicate the m_opMap array.
        Returns:
        The number of predicates for this step.
        Throws:
        javax.xml.transform.TransformerException - if a error occurs creating the Expression.

      • warn

        public void warn​(java.lang.String msg,
                 java.lang.Object[] args)
          throws javax.xml.transform.TransformerException
        Warn the user of an problem.
        Parameters:
        msg - An error msgkey that corresponds to one of the constants found in XPATHErrorResources, which is a key for a format string.
        args - An array of arguments represented in the format string, which may be null.
        Throws:
        javax.xml.transform.TransformerException - if the current ErrorListoner determines to throw an exception.

      • assertion

        public void assertion​(boolean b,
                      java.lang.String msg)
        Tell the user of an assertion error, and probably throw an exception.
        Parameters:
        b - If false, a runtime exception will be thrown.
        msg - The assertion message, which should be informative.
        Throws:
        java.lang.RuntimeException - if the b argument is false.

      • error

        public void error​(java.lang.String msg,
                  java.lang.Object[] args)
           throws javax.xml.transform.TransformerException
        Tell the user of an error, and probably throw an exception.
        Overrides:
        error in class OpMap
        Parameters:
        msg - An error msgkey that corresponds to one of the constants found in XPATHErrorResources, which is a key for a format string.
        args - An array of arguments represented in the format string, which may be null.
        Throws:
        javax.xml.transform.TransformerException - if the current ErrorListoner determines to throw an exception.

      • getNamespaceContext

        public PrefixResolver getNamespaceContext()
        Get the current namespace context for the xpath.
        Returns:
        The current prefix resolver, *may* be null, though hopefully not.

      • setNamespaceContext

        public void setNamespaceContext​(PrefixResolver pr)
        Set the current namespace context for the xpath.
        Parameters:
        pr - The resolver for prefixes in the XPath expression.