Class StringLength

All Implemented Interfaces:
Serializable, SourceLocator, Container, Expression, InstructionInfoProvider

public class StringLength extends SystemFunction
Implement the XPath string-length() function
See Also:
  • Constructor Details

    • StringLength

      public StringLength()
  • Method Details

    • simplify

      public Expression simplify(StaticContext env) throws XPathException
      Simplify and validate. This is a pure function so it can be simplified in advance if the arguments are known
      Specified by:
      simplify in interface Expression
      Overrides:
      simplify in class FunctionCall
      Parameters:
      env - the static context
      Returns:
      the simplified expression
      Throws:
      XPathException - if an error is discovered during expression rewriting
    • getIntrinsicDependencies

      public int getIntrinsicDependencies()
      Determine the intrinsic dependencies of an expression, that is, those which are not derived from the dependencies of its subexpressions. For example, position() has an intrinsic dependency on the context position, while (position()+1) does not. The default implementation of the method returns 0, indicating "no dependencies".
      Overrides:
      getIntrinsicDependencies in class ComputedExpression
      Returns:
      a set of bit-significant flags identifying the "intrinsic" dependencies. The flags are documented in class net.sf.saxon.value.StaticProperty
    • preEvaluate

      public Expression preEvaluate(StaticContext env) throws XPathException
      Pre-evaluate a function at compile time. Functions that do not allow pre-evaluation, or that need access to context information, can override this method.
      Overrides:
      preEvaluate in class FunctionCall
      Throws:
      XPathException
    • setShortcut

      public void setShortcut()
      setShortCut() - used by optimizer when we only need to know if the length is non-zero
    • evaluateItem

      public Item evaluateItem(XPathContext c) throws XPathException
      Evaluate in a general context
      Specified by:
      evaluateItem in interface Expression
      Overrides:
      evaluateItem in class ComputedExpression
      Parameters:
      c - The context in which the expression is to be evaluated
      Returns:
      the node or atomic value that results from evaluating the expression; or null to indicate that the result is an empty sequence
      Throws:
      XPathException - if any dynamic error occurs evaluating the expression