## net.sf.saxon.sort
Class SortKeyDefinition

    java.lang.Object
      |
      +--net.sf.saxon.sort.SortKeyDefinition

All Implemented Interfaces:
  java.io.Serializable

Direct Known Subclasses:
  FixedSortKeyDefinition

public class SortKeyDefinition
extends java.lang.Object
implements java.io.Serializable

A SortKeyDefinition defines one component of a sort key.
Note that most attributes defining the sort key can be attribute value templates, and can therefore vary from one invocation to another. We hold them as expressions. As soon as they are all known (which in general is only at run-time), the SortKeyDefinition is replaced by a FixedSortKeyDefinition in which all these values are fixed.

See Also:
  Serialized Form

Field Summary
`protected Expression` `caseOrder`
`protected java.util.Comparator` `collation`
`protected Expression` `dataTypeExpression`
`protected boolean` `emptyFirst`
`protected Expression` `language`
`protected Expression` `order`
`protected Expression` `sortKey`

Constructor Summary
`SortKeyDefinition()`

Method Summary
`Expression` `getCaseOrder()`
`java.util.Comparator` `getCollation()`
`Expression` `getDataTypeExpression()`
`boolean` `getEmptyFirst()`
`Expression` `getLanguage()`
`Expression` `getOrder()`
`Expression` `getSortKey()` Get the expression used as the sort key
`FixedSortKeyDefinition` `reduce(XPathContext context)` Evaluate any aspects of the sort definition that were specified as AVTs, for example ascending/descending, language, case-order, data-type.
`void` `setCaseOrder(Expression exp)` Set the case order.
`void` `setCollation(java.util.Comparator collation)` Set the collation.
`void` `setDataTypeExpression(Expression exp)` Set the data type.
`void` `setEmptyFirst(boolean emptyFirst)` Set whether empty sequence comes before other values or after them
`void` `setLanguage(Expression exp)` Set the language.
`void` `setOrder(Expression exp)` Set the order.
`void` `setSortKey(Expression exp)` Set the expression used as the sort key
`SortKeyDefinition` `simplify()`

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

Field Detail

### sortKey

    protected Expression sortKey

### order

    protected Expression order

### dataTypeExpression

    protected Expression dataTypeExpression

### caseOrder

    protected Expression caseOrder

### language

    protected Expression language

### collation

    protected java.util.Comparator collation

### emptyFirst

    protected boolean emptyFirst

Constructor Detail

### SortKeyDefinition

    public SortKeyDefinition()

Method Detail

### setSortKey

    public void setSortKey(Expression exp)

  Set the expression used as the sort key

### getSortKey

    public Expression getSortKey()

  Get the expression used as the sort key

### setOrder

    public void setOrder(Expression exp)

  Set the order. This is supplied as an expression which must evaluate to "ascending" or "descending". If the order is fixed, supply e.g. new StringValue("ascending"). Default is "ascending".

### getOrder

    public Expression getOrder()

### setDataTypeExpression

    public void setDataTypeExpression(Expression exp)

  Set the data type. This is supplied as an expression which must evaluate to "text", "number", or a QName. If the data type is fixed, the valus should be supplied using setDataType() and not via this method.

### getDataTypeExpression

    public Expression getDataTypeExpression()

### setCaseOrder

    public void setCaseOrder(Expression exp)

  Set the case order. This is supplied as an expression which must evaluate to "upper-first" or "lower-first" or "#default". If the order is fixed, supply e.g. new StringValue("lower-first"). Default is "#default".

### getCaseOrder

    public Expression getCaseOrder()

### setLanguage

    public void setLanguage(Expression exp)

  Set the language. This is supplied as an expression which evaluates to the language name. If the order is fixed, supply e.g. new StringValue("de").

### getLanguage

    public Expression getLanguage()

### setCollation

    public void setCollation(java.util.Comparator collation)

  Set the collation.

### getCollation

    public java.util.Comparator getCollation()

### setEmptyFirst

    public void setEmptyFirst(boolean emptyFirst)

  Set whether empty sequence comes before other values or after them

  Parameters:
    `emptyFirst` - true if () is considered lower than any other value

### getEmptyFirst

    public boolean getEmptyFirst()

### simplify

    public SortKeyDefinition simplify()
                               throws XPathException

    `XPathException`

### reduce

    public FixedSortKeyDefinition reduce(XPathContext context)
                                  throws XPathException

  Evaluate any aspects of the sort definition that were specified as AVTs, for example ascending/descending, language, case-order, data-type. This is done at the start of each sort. A FixedSortKeyDefinition is a SortKeyDefinition in which these properties are all known values.

    `XPathException`