Package net.sf.saxon.expr.sort

Class SortKeyDefinition

java.lang.Object
net.sf.saxon.expr.Expression
net.sf.saxon.expr.PseudoExpression
net.sf.saxon.expr.sort.SortKeyDefinition
All Implemented Interfaces:
ExportAgent, Locatable, IdentityComparable, Traceable
public class SortKeyDefinition extends PseudoExpression
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.

  • Field Details

    • sortKey

      protected Operand sortKey

    • order

      protected Operand order

    • dataTypeExpression

      protected Operand dataTypeExpression

    • caseOrder

      protected Operand caseOrder

    • language

      protected Operand language

    • collationName

      protected Operand collationName

    • stable

      protected Operand stable

    • collation

      protected StringCollator collation

    • baseURI

      protected String baseURI

    • emptyLeast

      protected boolean emptyLeast

    • backwardsCompatible

      protected boolean backwardsCompatible

    • setContextForSortKey

      protected boolean setContextForSortKey

  • Constructor Details

    • SortKeyDefinition

      public SortKeyDefinition()

  • Method Details

    • isLiftable

      public boolean isLiftable(boolean forStreaming)
      Ask whether the expression can be lifted out of a loop, assuming it has no dependencies on the controlling variable/focus of the loop
      Overrides:
      isLiftable in class Expression
      Parameters:
      forStreaming - true if we are optimizing for streamed evaluation
      Returns:
      true if the expression can be loop lifted

    • setSortKey

      public void setSortKey(Expression exp, boolean setContext)
      Set the expression used as the sort key
      Parameters:
      exp - the sort key select expression
      setContext - set to true if the sort key is to be evaluated with the item-being-sorted as the context item (as in XSLT); false if the context item is not to be set (as in XQuery)

    • getSortKey

      public Expression getSortKey()
      Get the expression used as the sort key
      Returns:
      the sort key select expression

    • getSortKeyOperand

      public Operand getSortKeyOperand()
      Get the sort key operand
      Returns:
      the operand that computes the sort key

    • isSetContextForSortKey

      public boolean isSetContextForSortKey()
      Ask whether the sortkey is to be evaluated with the item-being-sorted as the context item
      Returns:
      true if the context needs to be set for evaluating 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".
      Parameters:
      exp - the expression that determines the order (always a literal in XQuery, but can be defined by an AVT in XSLT)

    • getOrder

      public Expression getOrder()
      Get the expression that defines the order as ascending or descending
      Returns:
      the expression that determines the order (always a literal in XQuery, but can be defined by an AVT in XSLT)

    • 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.
      Parameters:
      exp - the expression that defines the data type, as used in XSLT 1.0

    • getDataTypeExpression

      public Expression getDataTypeExpression()
      Get the expression that defines the data type of the sort keys
      Returns:
      the expression that defines the data type, as used in XSLT 1.0

    • 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".
      Parameters:
      exp - the expression that defines the case order

    • getCaseOrder

      public Expression getCaseOrder()
      Get the expression that defines the case order of the sort keys.
      Returns:
      the expression that defines the case order, whose run-time value will be "upper-first", "lower-first", or "#default".

    • 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").
      Parameters:
      exp - the expression that determines the language

    • getLanguage

      public Expression getLanguage()
      Get the expression that defines the language of the sort keys
      Returns:
      exp the expression that determines the language

    • setCollationNameExpression

      public void setCollationNameExpression(Expression collationNameExpr)
      Set the collation name (specifically, an expression which when evaluated returns the collation URI).
      Parameters:
      collationNameExpr - the expression that determines the collation name

    • getCollationNameExpression

      public Expression getCollationNameExpression()
      Get the selected collation name (specifically, an expression which when evaluated returns the collation URI).
      Returns:
      the expression that determines the collation name

    • setCollation

      public void setCollation(StringCollator collation)
      Set the collation to be used
      Parameters:
      collation - A StringCollator, which encapsulates both the collation URI and the collating function

    • getCollation

      public StringCollator getCollation()
      Get the collation to be used
      Returns:
      A StringCollator, which encapsulates both the collation URI and the collating function

    • setBaseURI

      public void setBaseURI(String baseURI)
      Set the base URI of the expression. This is needed to handle the case where a collation URI evaluated at run-time turns out to be a relative URI.
      Parameters:
      baseURI - the static base URI of the expression

    • getBaseURI

      public String getBaseURI()
      Get the static base URI of the expression. This is needed to handle the case where a collation URI evaluated at run-time turns out to be a relative URI.
      Returns:
      the static base URI of the expression

    • setStable

      public void setStable(Expression stableExpr)
      Set whether this sort key definition is stable
      Parameters:
      stableExpr - the expression that determines whether the sort key definition is stable (it evaluates to the string "yes" or "no".

    • getStable

      public Expression getStable()
      Ask whether this sort key definition is stable
      Returns:
      the expression that determines whether the sort key definition is stable (it evaluates to the string "yes" or "no".

    • setBackwardsCompatible

      public void setBackwardsCompatible(boolean compatible)
      Set whether this sort key is evaluated in XSLT 1.0 backwards compatibility mode
      Parameters:
      compatible - true if backwards compatibility mode is selected

    • isBackwardsCompatible

      public boolean isBackwardsCompatible()
      Ask whether this sort key is evaluated in XSLT 1.0 backwards compatibility mode
      Returns:
      true if backwards compatibility mode was selected

    • setEmptyLeast

      public void setEmptyLeast(boolean emptyLeast)
      Set whether empty sequence comes before other values or after them
      Parameters:
      emptyLeast - true if () is considered lower than any other value

    • getEmptyLeast

      public boolean getEmptyLeast()
      Ask whether empty sequence comes before other values or after them
      Returns:
      true if () is considered lower than any other value

    • isFixed

      public boolean isFixed()
      Ask whether the sort key definition is fixed, that is, whether all the information needed to create a Comparator is known statically
      Returns:
      true if all information needed to create a Comparator is known statically

    • copy

      public SortKeyDefinition copy(RebindingMap rm)
      Copy this SortKeyDefinition
      Specified by:
      copy in class Expression
      Parameters:
      rm - a mutable list of (old binding, new binding) pairs that is used to update the bindings held in any local variable references that are copied.
      Returns:
      a copy of this SortKeyDefinition

    • typeCheck

      public SortKeyDefinition typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextItemType) throws XPathException
      Type-check this sort key definition (all properties other than the sort key select expression, when it has a different dynamic context)
      Overrides:
      typeCheck in class Expression
      Parameters:
      visitor - the expression visitor
      contextItemType - the type of the context item
      Returns:
      the original expression, rewritten to perform necessary run-time type checks, and to perform other type-related optimizations
      Throws:
      XPathException - if any failure occurs

    • operands

      public Iterable<Operand> operands()
      Description copied from class: Expression
      Get the immediate sub-expressions of this expression, with information about the relationship of each expression to its parent expression.

      If the expression is a Callable, then it is required that the order of the operands returned by this function is the same as the order of arguments supplied to the corresponding call() method.

      Overrides:
      operands in class Expression
      Returns:
      an iterator containing the sub-expressions of this expression

    • getImplementationMethod

      public int getImplementationMethod()
      An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process(). This method indicates which of these methods is provided directly. The other methods will always be available indirectly, using an implementation that relies on one of the other methods.
      Overrides:
      getImplementationMethod in class PseudoExpression
      Returns:
      the implementation method, for example Expression.ITERATE_METHOD or Expression.EVALUATE_METHOD or Expression.PROCESS_METHOD

    • makeComparator

      public AtomicComparer makeComparator(XPathContext context) throws XPathException
      Allocate an AtomicComparer to perform the comparisons described by this sort key component. The AtomicComparer takes into account not only the collation, but also parameters such as order=descending and handling of empty sequence and NaN (the result of the compare() method of the comparator is +1 if the second item is to sort after the first item). The AtomicComparer is allocated at compile time if possible (during typeCheck), otherwise at run-time.
      Parameters:
      context - the dynamic evaluation context
      Returns:
      an AtomicComparer suitable for making the sort comparisons
      Throws:
      XPathException - for example if the collation URI is invalid or unknown

    • setFinalComparator

      public void setFinalComparator(AtomicComparer comp)
      Set the comparator which is used to compare two values according to this sort key. The comparator makes the final decision whether one value sorts before or after another: this takes into account the data type, the collation, whether empty comes first or last, whether the sort order is ascending or descending.

      This method is called at compile time if all these factors are known at compile time. It must not be called at run-time, except to reconstitute a finalComparator that has been lost by virtue of serialization .

      Parameters:
      comp - the Atomic Comparer to be used

    • getFinalComparator

      public AtomicComparer getFinalComparator()
      Get the comparator which is used to compare two values according to this sort key. This method may be called either at compile time or at run-time. If no comparator has been allocated, it returns null. It is then necessary to allocate a comparator using the makeComparator(net.sf.saxon.expr.XPathContext) method.
      Returns:
      the Atomic Comparer to be used

    • fix

      public SortKeyDefinition fix(XPathContext context) throws XPathException
      Throws:
      XPathException

    • equals

      public boolean equals(Object other)
      Compare two SortKeyDefinition values for equality. This compares the sortKeys and attribute values.
      Overrides:
      equals in class Expression
      Parameters:
      other - SortKeyDefinition
      Returns:
      boolean

    • computeHashCode

      protected int computeHashCode()
      Get a hashcode to reflect the equals() method
      Overrides:
      computeHashCode in class Expression
      Returns:
      a hashcode based sortkey attribute values.

    • export

      public void export(ExpressionPresenter out) throws XPathException
      Description copied from class: Expression
      Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.
      Specified by:
      export in interface ExportAgent
      Specified by:
      export in class Expression
      Parameters:
      out - the expression presenter used to display the structure
      Throws:
      XPathException - if the export fails, for example if an expression is found that won't work in the target environment.