Package net.sf.saxon.expr

Class GeneralComparison

java.lang.Object
net.sf.saxon.expr.Expression
net.sf.saxon.expr.BinaryExpression
net.sf.saxon.expr.GeneralComparison
All Implemented Interfaces:
Serializable, SourceLocator, LocationProvider, SaxonLocator, ComparisonExpression, EvaluableItem, SequenceIterable, InstructionInfo, Locator
public class GeneralComparison extends BinaryExpression implements ComparisonExpression
GeneralComparison: a boolean expression that compares two expressions for equals, not-equals, greater-than or less-than. This implements the operators =, !=, invalid input: '<', >, etc. This implementation is not used when in backwards-compatible mode
See Also:

  • Field Details

    • singletonOperator

      protected int singletonOperator

    • comparer

      protected AtomicComparer comparer

  • Constructor Details

    • GeneralComparison

      public GeneralComparison(Expression p0, int op, Expression p1)
      Create a relational expression identifying the two operands and the operator
      Parameters:
      p0 - the left-hand operand
      op - the operator, as a token returned by the Tokenizer (e.g. Token.LT)
      p1 - the right-hand operand

  • Method Details

    • getAtomicComparer

      public AtomicComparer getAtomicComparer()
      Get the AtomicComparer used to compare atomic values. This encapsulates any collation that is used
      Specified by:
      getAtomicComparer in interface ComparisonExpression

    • getSingletonOperator

      public int getSingletonOperator()
      Get the primitive (singleton) operator used: one of Token.FEQ, Token.FNE, Token.FLT, Token.FGT, Token.FLE, Token.FGE
      Specified by:
      getSingletonOperator in interface ComparisonExpression

    • convertsUntypedToOther

      public boolean convertsUntypedToOther()
      Determine whether untyped atomic values should be converted to the type of the other operand
      Specified by:
      convertsUntypedToOther in interface ComparisonExpression
      Returns:
      true if untyped values should be converted to the type of the other operand, false if they should be converted to strings.

    • computeCardinality

      public int computeCardinality()
      Determine the static cardinality. Returns [1..1]
      Overrides:
      computeCardinality in class BinaryExpression
      Returns:
      the computed cardinality, as one of the values StaticProperty.ALLOWS_ZERO_OR_ONE, StaticProperty.EXACTLY_ONE, StaticProperty.ALLOWS_ONE_OR_MORE, StaticProperty.ALLOWS_ZERO_OR_MORE

    • typeCheck

      public Expression typeCheck(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException
      Type-check the expression
      Overrides:
      typeCheck in class BinaryExpression
      Parameters:
      visitor - an expression visitor
      contextItemType - 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 checked expression
      Throws:
      XPathException - if an error is discovered during this phase (typically a type error)

    • optimize

      public Expression optimize(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException
      Optimize the expression
      Overrides:
      optimize in class BinaryExpression
      Parameters:
      visitor - an expression visitor
      contextItemType - 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 checked expression
      Throws:
      XPathException - if an error is discovered during this phase (typically a type error)

    • copy

      public Expression copy()
      Copy an expression. This makes a deep copy.
      Specified by:
      copy in class Expression
      Returns:
      the copy of the original expression

    • evaluateItem

      public Item evaluateItem(XPathContext context) throws XPathException
      Evaluate the expression in a given context
      Specified by:
      evaluateItem in interface EvaluableItem
      Overrides:
      evaluateItem in class Expression
      Parameters:
      context - the given context for evaluation
      Returns:
      a BooleanValue representing the result of the numeric comparison of the two operands
      Throws:
      XPathException - if any dynamic error occurs evaluating the expression

    • effectiveBooleanValue

      public boolean effectiveBooleanValue(XPathContext context) throws XPathException
      Evaluate the expression in a boolean context
      Overrides:
      effectiveBooleanValue in class Expression
      Parameters:
      context - the given context for evaluation
      Returns:
      a boolean representing the result of the numeric comparison of the two operands
      Throws:
      XPathException - if any dynamic error occurs evaluating the expression

    • compare

      protected static boolean compare(AtomicValue a1, int operator, AtomicValue a2, AtomicComparer comparer, XPathContext context) throws XPathException
      Compare two atomic values
      Parameters:
      a1 - the first value
      operator - the operator, for example Token.EQUALS
      a2 - the second value
      comparer - the comparer to be used to perform the comparison
      context - the XPath evaluation context
      Returns:
      true if the comparison succeeds
      Throws:
      XPathException

    • getItemType

      public ItemType getItemType(TypeHierarchy th)
      Determine the data type of the expression
      Specified by:
      getItemType in class Expression
      Parameters:
      th - the type hierarchy cache
      Returns:
      the value BuiltInAtomicType.BOOLEAN

    • getInverseComparison

      protected GeneralComparison getInverseComparison()

    • displayOperator

      protected String displayOperator()
      Overrides:
      displayOperator in class BinaryExpression