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.

Field Summary
- Fields inherited from class com.icl.saxon.expr.Expression
  staticContext

Constructor Summary

Constructors
Constructor Description

RootExpression()

Constructors
Constructor	Description
`RootExpression()`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`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.Expression
containsReferences, evaluateAsNumber, getStaticContext, indent, make, setStaticContext, usesCurrent

Methods inherited from class com.icl.saxon.expr.NodeSetExpression
evaluate, getDataType, outputStringValue

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from class com.icl.saxon.expr.SingletonExpression
enumerate, evaluateAsNodeSet, isContextDocumentNodeSet, selectFirst

- 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
    
    Throws:
    
    XPathException
  - getNode
```
public NodeInfo getNode(Context context)
                 throws XPathException
```
    Return the first element selected by this Expression
    
    Specified by:
    
    getNode in class SingletonExpression
    
    Parameters:
    
    context - The evaluation context
    
    Returns:
    
    the NodeInfo of the first selected element, or null if no element is selected
    
    Throws:
    
    XPathException
  - 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
    
    Throws:
    
    XPathException
  - 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)
    
    Throws:
    
    XPathException
  - 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

Class RootExpression

Field Summary

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

Constructor Summary

Method Summary

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

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

Methods inherited from class java.lang.Object

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

Constructor Detail

RootExpression

Method Detail

simplify

getNode

evaluateAsString

evaluateAsBoolean

getDependencies

reduce

display