ErrorExpression
Date: 2016-07-03

com.icl.saxon.expr

## Class ErrorExpression

- java.lang.Object
- - com.icl.saxon.expr.Expression
  - - com.icl.saxon.expr.ErrorExpression

-     public class ErrorExpression
      extends Expression

  Error expression: this expression is generated when the supplied expression cannot be parsed, and the containing element enables forwards-compatible processing. It defers the generation of an error message until an attempt is made to evaluate the expression

- - ### Field Summary

    - ### Fields inherited from class com.icl.saxon.expr.Expression

      `staticContext`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `ErrorExpression(XPathException exception)` Constructor

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `display(int level)` Diagnostic print of expression structure
    `Value` | `evaluate(Context c)` Evaluate this expression.
    `int` | `getDataType()` Determine the data type of the expression, if possible
    `int` | `getDependencies()` Determine which aspects of the context the expression depends on.
    `Expression` | `reduce(int dependencies, Context context)` Perform a partial evaluation of the expression, by eliminating specified dependencies on the context.

    - ### Methods inherited from class com.icl.saxon.expr.Expression

      `containsReferences, enumerate, evaluateAsBoolean, evaluateAsNodeSet, evaluateAsNumber, evaluateAsString, getStaticContext, indent, isContextDocumentNodeSet, make, outputStringValue, setStaticContext, simplify, usesCurrent`

    - ### Methods inherited from class java.lang.Object

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

- - ### Constructor Detail

    - #### ErrorExpression

          public ErrorExpression(XPathException exception)

      Constructor
      Parameters:
        `exception` - the error found when parsing this expression

  - ### Method Detail

    - #### evaluate

          public Value evaluate(Context c)
                         throws XPathException

      Evaluate this expression. This always throws the exception registered when the expression was first parsed.
      Specified by:
        `evaluate` in class `Expression`
      Parameters:
        `c` - The context in which the expression is to be evaluated
      Returns:
        the value of the expression, evaluated in the current context
      Throws:
        `XPathException`

    - #### getDataType

          public int getDataType()

      Determine the data type of the expression, if possible
      Specified by:
        `getDataType` in class `Expression`
      Returns:
        Value.ANY (meaning not known in advance)

    - #### getDependencies

          public int getDependencies()

      Determine which aspects of the context the expression depends on. The result is a bitwise-or'ed value composed from constants such as Context.VARIABLES and Context.CURRENT_NODE
      Specified by:
        `getDependencies` in class `Expression`

    - #### reduce

          public Expression reduce(int dependencies,
                          Context context)
                            throws XPathException

      Perform a partial evaluation of the expression, by eliminating specified dependencies on the context.
      Specified by:
        `reduce` in class `Expression`
      Parameters:
        `dependencies` - The dependencies to be removed
        `context` - The context to be used for the partial evaluation
      Returns:
        a new expression that does not have any of the specified dependencies
      Throws:
        `XPathException`

    - #### display

          public void display(int level)

      Diagnostic print of expression structure
      Specified by:
        `display` in class `Expression`