Package net.sf.saxon.expr

Class MultiSubscriptExpression

java.lang.Object
net.sf.saxon.expr.Expression
net.sf.saxon.expr.UnaryExpression
net.sf.saxon.expr.MultiSubscriptExpression
All Implemented Interfaces:
ExportAgent, Locatable, IdentityComparable, Traceable
public class MultiSubscriptExpression extends UnaryExpression
A MultiSubscriptExpression represents a FilterExpression of the form EXPR[n] where n is known to be of type xs:numeric* and to be independent of the focus; it does not need to be constant. Used in 4.0 which allows the filter to be a sequence of numbers.

  • Constructor Details

    • MultiSubscriptExpression

      public MultiSubscriptExpression(Expression base, Expression subscript)
      Construct a MultiSubscriptExpression
      Parameters:
      base - the expression to be filtered
      subscript - the positional subscript filter

  • Method Details

    • getOperandRole

      protected OperandRole getOperandRole()
      Description copied from class: UnaryExpression
      Get the usage (in terms of streamability analysis) of the single operand
      Specified by:
      getOperandRole in class UnaryExpression
      Returns:
      the operand usage

    • gatherProperties

      public void gatherProperties(BiConsumer<String,Object> consumer)
      Get the properties of this object to be included in trace messages, by supplying the property values to a supplied consumer function
      Parameters:
      consumer - the function to which the properties should be supplied, as (property name, value) pairs.

    • getSubscript

      public Expression getSubscript()

    • setSubscript

      public void setSubscript(Expression subscript)

    • typeCheck

      public Expression typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) throws XPathException
      Type-check the expression.
      Overrides:
      typeCheck in class UnaryExpression
      Parameters:
      visitor - an expression visitor
      contextInfo - Information available statically about the context item: whether it is (possibly) absent; its static type; its streaming posture.
      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)

    • optimize

      public Expression optimize(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) throws XPathException
      Description copied from class: UnaryExpression
      Perform optimisation of an expression and its subexpressions.

      This method is called after all references to functions and variables have been resolved to the declaration of the function or variable, and after all type checking has been done.

      Overrides:
      optimize in class UnaryExpression
      Parameters:
      visitor - an expression visitor
      contextInfo - the static type of "." at the point where this expression is invoked. The parameter is set to null if it is known statically that the context item will be undefined. If the type of the context item is not known statically, the argument is set to Type.ITEM_TYPE
      Returns:
      the original expression, rewritten if appropriate to optimize execution
      Throws:
      XPathException - if an error is discovered during this phase (typically a type error)

    • copy

      public Expression copy(RebindingMap rebindings)
      Copy an expression. This makes a deep copy.
      Specified by:
      copy in class Expression
      Parameters:
      rebindings - variables that need to be re-bound
      Returns:
      the copy of the original expression

    • 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 UnaryExpression
      Returns:
      an iterator containing the sub-expressions of this expression

    • getSubscriptExpression

      public Expression getSubscriptExpression()
      Get the subscript expression
      Returns:
      the expression used to compute the one-based start offset

    • 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.
      Specified by:
      getImplementationMethod in class Expression
      Returns:
      the implementation method, for example Expression.ITERATE_METHOD or Expression.EVALUATE_METHOD or Expression.PROCESS_METHOD

    • equals

      public boolean equals(Object other)
      Compare two expressions to see if they are equal
      Overrides:
      equals in class UnaryExpression
      Parameters:
      other - the other expression
      Returns:
      true if the expressions are equivalent

    • computeHashCode

      protected int computeHashCode()
      Description copied from class: UnaryExpression
      get HashCode for comparing two expressions. Note that this hashcode gives the same result for (A op B) and for (B op A), whether or not the operator is commutative.
      Overrides:
      computeHashCode in class UnaryExpression
      Returns:
      a computed hash code

    • getStreamerName

      public String getStreamerName()
      Get the (partial) name of a class that supports streaming of this kind of expression
      Overrides:
      getStreamerName in class Expression
      Returns:
      the partial name of a class that can be instantiated to provide streaming support in Saxon-EE, or null if there is no such class

    • iterate

      public SequenceIterator iterate(XPathContext context) throws XPathException
      Return an Iterator to iterate over the values of a sequence. The value of every expression can be regarded as a sequence, so this method is supported for all expressions. This default implementation handles iteration for expressions that return singleton values: for non-singleton expressions, the subclass must provide its own implementation.
      Overrides:
      iterate in class Expression
      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

    • getItemAt

      public static Item getItemAt(SequenceIterator iter, int index) throws XPathException
      Get the item at a specified position within a SequenceIterator
      Parameters:
      iter - the SequenceIterator (which may be consumed by this operation)
      index - the position (1-based) - must be positive
      Returns:
      the item at that position, or null if out of range
      Throws:
      XPathException - if a failure occurs evaluating the iterator

    • getExpressionName

      public String getExpressionName()
      Get a name identifying the kind of expression, in terms meaningful to a user.
      Overrides:
      getExpressionName in class Expression
      Returns:
      a name identifying the kind of expression, in terms meaningful to a user. The name will always be in the form of a lexical XML QName, and should match the name used in export() output displaying the expression.

    • export

      public void export(ExpressionPresenter destination) throws XPathException
      Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.
      Specified by:
      export in interface ExportAgent
      Overrides:
      export in class UnaryExpression
      Parameters:
      destination - 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.

    • toString

      public String toString()

      The toString() method for an expression attempts to give a representation of the expression in an XPath-like form.

      For subclasses of Expression that represent XPath expressions, the result should always be a string that parses as an XPath 3.0 expression.

      Overrides:
      toString in class UnaryExpression
      Returns:
      a representation of the expression as a string

    • toShortString

      public String toShortString()

      The toString() method for an expression attempts to give a representation of the expression in an XPath-like form.

      For subclasses of Expression that represent XPath expressions, the result should always be a string that parses as an XPath 3.0 expression.

      Overrides:
      toShortString in class UnaryExpression
      Returns:
      a representation of the expression as a string

    • getElaborator

      public Elaborator getElaborator()
      Make an elaborator for this expression
      Overrides:
      getElaborator in class Expression
      Returns:
      a suitable elaborator