Package net.sf.saxon.expr.sort

Class 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 Detail

      • sortKey

        protected Operand sortKey

      • dataTypeExpression

        protected Operand dataTypeExpression

      • caseOrder

        protected Operand caseOrder

      • language

        protected Operand language

      • collationName

        protected Operand collationName

      • baseURI

        protected java.lang.String baseURI

      • emptyLeast

        protected boolean emptyLeast

      • backwardsCompatible

        protected boolean backwardsCompatible

      • setContextForSortKey

        protected boolean setContextForSortKey

    • Constructor Detail

      • SortKeyDefinition

        public SortKeyDefinition()

    • Method Detail

      • 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​(java.lang.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 java.lang.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 java.lang.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. Default implementation works off the results of iterateSubExpressions()

        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

      • 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

      • equals

        public boolean equals​(java.lang.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.