net.sf.saxon.sort
Class SortExpression

java.lang.Object
  net.sf.saxon.expr.ComputedExpression
      net.sf.saxon.sort.SortExpression

All Implemented Interfaces:

Serializable, Expression

public class SortExpression
extends ComputedExpression

Expression equivalent to the imaginary syntax expr sortby (sort-key)+

See Also:

Serialized Form

Field Summary

Fields inherited from class net.sf.saxon.expr.ComputedExpression

lineNumber, NO_ARGUMENTS, staticProperties

Constructor Summary

SortExpression(Expression select, SortKeyDefinition[] sortKeys)

Method Summary

Expression	analyze(StaticContext env) Type-check the expression
int	computeCardinality() Determine the static cardinality
int	computeSpecialProperties() Get the static properties of this expression (other than its type).
void	display(int level, NamePool pool) Diagnostic print of expression structure.
ItemType	getItemType() Determine the data type of the items returned by the expression, if possible
SequenceIterator	iterate(XPathContext context) Enumerate the results of the expression
Expression	simplify() Simplify an expression

Methods inherited from class net.sf.saxon.expr.ComputedExpression

computeDependencies, computeStaticProperties, dynamicError, effectiveBooleanValue, evaluateAsString, evaluateItem, getCardinality, getDependencies, getIntrinsicDependencies, getLineNumber, getSpecialProperties, getSubExpressions, markTailFunctionCalls, promote, setLineNumber, typeError

Methods inherited from class java.lang.Object

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

Constructor Detail

SortExpression

public SortExpression(Expression select,
                      SortKeyDefinition[] sortKeys)

Method Detail

simplify

public Expression simplify()
                    throws XPathException

Simplify an expression

Specified by:

simplify in interface Expression

Overrides:

simplify in class ComputedExpression

Returns:

the simplified expression

Throws:

XPathException - if an error is discovered during expression rewriting

analyze

public Expression analyze(StaticContext env)
                   throws XPathException

Type-check the expression

Parameters:

env - the static context of the expression

Returns:

the original expression, rewritten to perform necessary run-time type checks, and to perform other type-related optimizations

Throws:

XPathException - if an error is discovered during this phase (typically a type error)

computeCardinality

public int computeCardinality()

Determine the static cardinality

Specified by:

computeCardinality in class ComputedExpression

getItemType

public ItemType getItemType()

Determine the data type of the items returned by the expression, if possible

Returns:

a value such as Type.STRING, Type.BOOLEAN, Type.NUMBER, Type.NODE, or Type.ITEM (meaning not known in advance)

computeSpecialProperties

public int computeSpecialProperties()

Get the static properties of this expression (other than its type). The result is bit-significant. These properties are used for optimizations. In general, if property bit is set, it is true, but if it is unset, the value is unknown.

Overrides:

computeSpecialProperties in class ComputedExpression

iterate

public SequenceIterator iterate(XPathContext context)
                         throws XPathException

Enumerate the results of the expression

Specified by:

iterate in interface Expression

Overrides:

iterate in class ComputedExpression

Parameters:

context - supplies the context for evaluation

Returns:

a SequenceIterator that can be used to iterate over the result of the expression

Throws:

XPathException - if any dynamic error occurs evaluating the expression

display

public void display(int level,
                    NamePool pool)

Description copied from interface: Expression

Diagnostic print of expression structure. The expression is written to the System.err output stream

Parameters:

level - indentation level for this expression