Package net.sf.saxon.pattern

Class BooleanExpressionPattern

java.lang.Object
net.sf.saxon.expr.Expression
net.sf.saxon.expr.PseudoExpression
net.sf.saxon.pattern.Pattern
net.sf.saxon.pattern.BooleanExpressionPattern
All Implemented Interfaces:
ExportAgent, Locatable, IdentityComparable, PatternWithPredicate, Traceable
public class BooleanExpressionPattern extends Pattern implements PatternWithPredicate
A BooleanExpressionPattern is a pattern of the form .[ Expr ] introduced in XSLT 3.0. It matches an item if the expression has an effective boolean value of true() when evaluated with that item as the singleton focus.

  • Constructor Details

    • BooleanExpressionPattern

      public BooleanExpressionPattern(Expression expression)
      Create a BooleanExpressionPattern
      Parameters:
      expression - the expression to be evaluated (the expression in the predicate)

  • Method Details

    • getPredicate

      public Expression getPredicate()
      Specified by:
      getPredicate in interface PatternWithPredicate

    • operands

      public Iterable<Operand> operands()
      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

    • getUType

      public UType getUType()
      Get a UType indicating which kinds of items this Pattern can match.
      Specified by:
      getUType in class Pattern
      Returns:
      a UType indicating all the primitive types of item that the pattern can match.

    • allocateSlots

      public int allocateSlots(SlotManager slotManager, int nextFree)
      Allocate slots to any variables used within the pattern
      Overrides:
      allocateSlots in class Pattern
      Parameters:
      slotManager - holds details of the allocated slots
      nextFree - the next slot that is free to be allocated @return the next slot that is free to be allocated
      Returns:
      the next slot that is free to be allocated

    • typeCheck

      public Pattern typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextItemType) throws XPathException
      Type-check the pattern.
      Overrides:
      typeCheck in class Pattern
      Parameters:
      visitor - the expression visitor
      contextItemType - the type of the context item at the point where the pattern is defined. Set to null if it is known that the context item is undefined.
      Returns:
      the optimised Pattern
      Throws:
      XPathException - if an error is discovered during this phase (typically a type error)

    • optimize

      public Pattern optimize(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) throws XPathException
      Description copied from class: Pattern
      Perform optimisation of an expression and its subexpressions. This is the third and final phase of static optimization.

      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 Pattern
      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)

    • isMotionless

      public boolean isMotionless()
      Description copied from class: Pattern
      Test whether a pattern is motionless, that is, whether it can be evaluated against a node without repositioning the input stream. This is a necessary condition for patterns used as the match pattern of a streamed template rule.
      Overrides:
      isMotionless in class Pattern
      Returns:
      true if the pattern is motionless, that is, if it can be evaluated against a streamed node without changing the position in the streamed input file

    • matches

      public boolean matches(Item item, XPathContext context)
      Determine whether this Pattern matches the given item. This is the main external interface for matching patterns: it sets current() to the node being tested
      Specified by:
      matches in class Pattern
      Parameters:
      item - The item to be tested against the Pattern
      context - The context in which the match is to take place. Only relevant if the pattern uses variables, or contains calls on functions such as document() or key().
      Returns:
      true if the item matches the Pattern, false otherwise

    • getItemType

      public ItemType getItemType()
      Get an Itemtype that all the items matching this pattern must satisfy
      Specified by:
      getItemType in class Pattern
      Returns:
      an ItemType, as specific as possible, which all the matching items satisfy

    • getFingerprint

      public int getFingerprint()
      Determine the name fingerprint of nodes to which this pattern applies. Used for optimisation.
      Overrides:
      getFingerprint in class Pattern
      Returns:
      A fingerprint that the nodes must match, or -1 if it can match multiple fingerprints

    • reconstruct

      public String reconstruct()
      Display the pattern for diagnostics
      Overrides:
      reconstruct in class Pattern

    • equals

      public boolean equals(Object other)
      Determine whether this pattern is the same as another pattern
      Overrides:
      equals in class Expression
      Parameters:
      other - the other object
      Returns:
      true if the other operand is an expression and if it can be determined that the two expressions are equivalent, in the sense that they will always return the same result.

    • computeHashCode

      protected int computeHashCode()
      Hashcode supporting equals()
      Overrides:
      computeHashCode in class Expression
      Returns:
      a computed hash code

    • copy

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

    • export

      public void export(ExpressionPresenter presenter) 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 Pattern
      Parameters:
      presenter - 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.