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: Class RootExpression

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com.icl.saxon.expr
Class RootExpression


java.lang.Object

  |

  +--com.icl.saxon.expr.Expression

        |

        +--com.icl.saxon.expr.NodeSetExpression

              |

              +--com.icl.saxon.expr.SingletonExpression

                    |

                    +--com.icl.saxon.expr.RootExpression

public class RootExpression
extends SingletonExpression

An expression whose value is always a set of nodes containing a single node, the document root.

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

staticContext

Constructor Summary

RootExpression()


Method Summary

void display(int level)
          Diagnostic print of expression structure

boolean evaluateAsBoolean(Context context)
          Evaluate as a boolean.

java.lang.String evaluateAsString(Context context)
          Evaluate as a string

int getDependencies()
          Determine which aspects of the context the expression depends on.

NodeInfo getNode(Context context)
          Return the first element selected by this Expression

Expression reduce(int dependencies, Context context)
          Perform a partial evaluation of the expression, by eliminating specified dependencies on the context.

Expression simplify()
          Simplify an expression

Methods inherited from class com.icl.saxon.expr.SingletonExpression

enumerate, evaluateAsNodeSet, isContextDocumentNodeSet, selectFirst

Methods inherited from class com.icl.saxon.expr.NodeSetExpression

evaluate, getDataType, outputStringValue

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

containsReferences, evaluateAsNumber, getStaticContext, indent, make, setStaticContext, usesCurrent

Methods inherited from class java.lang.Object

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

Constructor Detail

RootExpression


public RootExpression()

Method Detail

simplify


public Expression simplify()
                    throws XPathException

Simplify an expression

Overrides:: simplify in class Expression

Returns:: the simplified expression

getNode


public NodeInfo getNode(Context context)
                 throws XPathException

Return the first element selected by this Expression

Overrides:: getNode in class SingletonExpression

Parameters:: context - The evaluation context
Returns:: the NodeInfo of the first selected element, or null if no element is selected

evaluateAsString


public java.lang.String evaluateAsString(Context context)
                                  throws XPathException

Evaluate as a string

Overrides:: evaluateAsString in class SingletonExpression

Parameters:: context - The context for evaluation
Returns:: The concatenation of all the character data within the document

evaluateAsBoolean


public boolean evaluateAsBoolean(Context context)
                          throws XPathException

Evaluate as a boolean.

Overrides:: evaluateAsBoolean in class SingletonExpression

Parameters:: context - The context (not used)
Returns:: true (always - because the nodeset is never empty)

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

Overrides:: 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.

Overrides:: 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

display


public void display(int level)

Diagnostic print of expression structure

Overrides:: display in class Expression