Class Path

java.lang.Object
org.apache.commons.jxpath.ri.compiler.Expression
org.apache.commons.jxpath.ri.compiler.Path
Direct Known Subclasses:
ExpressionPath, LocationPath
public abstract class Path extends Expression
Version:
$Revision: 681111 $ $Date: 2008-07-30 11:30:29 -0500 (Wed, 30 Jul 2008) $
Author:
Dmitri Plotnikov

  • Field Details

    • steps

      private Step[] steps

    • basicKnown

      private boolean basicKnown

    • basic

      private boolean basic

  • Constructor Details

    • Path

      public Path(Step[] steps)
      Create a new Path.
      Parameters:
      steps - that compose the Path

  • Method Details

    • getSteps

      public Step[] getSteps()
      Get the steps.
      Returns:
      Step[]

    • computeContextDependent

      public boolean computeContextDependent()
      Description copied from class: Expression
      Implemented by subclasses and result is cached by isContextDependent()
      Specified by:
      computeContextDependent in class Expression
      Returns:
      calculated context-dependentness as boolean

    • isSimplePath

      public boolean isSimplePath()
      Recognizes paths formatted as foo/bar[3]/baz[@name = 'biz']. The evaluation of such "simple" paths is optimized and streamlined.
      Returns:
      true if this path is simple

    • isSimpleStep

      protected boolean isSimpleStep(Step step)
      A Step is "simple" if it takes one of these forms: ".", "/foo", "@bar", "/foo[3]". If there are predicates, they should be context independent for the step to still be considered simple.
      Parameters:
      step - the step to check
      Returns:
      boolean

    • areBasicPredicates

      protected boolean areBasicPredicates(Expression[] predicates)
      Learn whether the elements of the specified array are "basic" predicates.
      Parameters:
      predicates - the Expression[] to check
      Returns:
      boolean

    • getSingleNodePointerForSteps

      protected Pointer getSingleNodePointerForSteps(EvalContext context)
      Given a root context, walks a path therefrom and finds the pointer to the first element matching the path.
      Parameters:
      context - evaluation context
      Returns:
      Pointer

    • searchForPath

      protected Pointer searchForPath(EvalContext context)
      The idea here is to return a NullPointer rather than null if that's at all possible. Take for example this path: "//map/key". Let's say, "map" is an existing node, but "key" is not there. We will create a NullPointer that can be used to set/create the "key" property.

      However, a path like "//key" would still produce null, because we have no way of knowing where "key" would be if it existed.

      To accomplish this, we first try the path itself. If it does not find anything, we chop off last step of the path, as long as it is a simple one like child:: or attribute:: and try to evaluate the truncated path. If it finds exactly one node - create a NullPointer and return. If it fails, chop off another step and repeat. If it finds more than one location - return null.

      Parameters:
      context - evaluation context
      Returns:
      Pointer

    • evalSteps

      protected EvalContext evalSteps(EvalContext context)
      Given a root context, walks a path therefrom and builds a context that contains all nodes matching the path.
      Parameters:
      context - evaluation context
      Returns:
      EvaluationContext

    • buildContextChain

      protected EvalContext buildContextChain(EvalContext context, int stepCount, boolean createInitialContext)
      Build a context from a chain of contexts.
      Parameters:
      context - evaluation context
      stepCount - number of steps to descend
      createInitialContext - whether to create the initial context
      Returns:
      created context

    • createContextForStep

      protected EvalContext createContextForStep(EvalContext context, int axis, NodeTest nodeTest)
      Different axes are serviced by different contexts. This method allocates the right context for the supplied step.
      Parameters:
      context - evaluation context
      axis - code
      nodeTest - node test
      Returns:
      EvalContext