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## net.sf.saxon.expr
Class GeneralComparison

    java.lang.Object
      net.sf.saxon.expr.ComputedExpression
          net.sf.saxon.expr.BinaryExpression
              net.sf.saxon.expr.GeneralComparison

All Implemented Interfaces:
  Container, Expression, InstructionInfoProvider, java.io.Serializable, javax.xml.transform.SourceLocator

Direct Known Subclasses:
  GeneralComparisonSA

public class GeneralComparison
extends BinaryExpression

GeneralComparison: a boolean expression that compares two expressions for equals, not-equals, greater-than or less-than. This implements the operators =, !=, <, >, etc. This implementation is not used when in backwards-compatible mode

See Also:
  Serialized Form

Field Summary
`protected AtomicComparer` | `comparer`
`protected int` | `singletonOperator`

Fields inherited from class net.sf.saxon.expr.BinaryExpression
`operand0, operand1, operator`

Fields inherited from class net.sf.saxon.expr.ComputedExpression
`locationId, staticProperties`

Fields inherited from interface net.sf.saxon.expr.Expression
`EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD`

Constructor Summary
`GeneralComparison(Expression p0, int op, Expression p1)` Create a relational expression identifying the two operands and the operator

Method Summary
`protected static boolean` | `compare(AtomicValue a1, int operator, AtomicValue a2, AtomicComparer comparer, XPathContext context)` Compare two atomic values
`int` | `computeCardinality()` Determine the static cardinality.
`protected java.lang.String` | `displayOperator()`
`boolean` | `effectiveBooleanValue(XPathContext context)` Evaluate the expression in a boolean context
`Item` | `evaluateItem(XPathContext context)` Evaluate the expression in a given context
`protected GeneralComparison` | `getInverseComparison()`
`ItemType` | `getItemType(TypeHierarchy th)` Determine the data type of the expression
`Expression` | `optimize(Optimizer opt, StaticContext env, ItemType contextItemType)` Optimize the expression
`Expression` | `typeCheck(StaticContext env, ItemType contextItemType)` Type-check the expression

Methods inherited from class net.sf.saxon.expr.BinaryExpression
`computeSpecialProperties, display, equals, getOperands, getOperator, hashCode, isAssociative, isCommutative, isInverse, iterateSubExpressions, promote, simplify`

Methods inherited from class net.sf.saxon.expr.ComputedExpression
`adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, dynamicError, evaluateAsString, getCardinality, getColumnNumber, getConstructType, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getIntrinsicDependencies, getLineNumber, getLocationId, getLocationProvider, getParentExpression, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasBadParentPointer, iterate, markTailFunctionCalls, process, resetStaticProperties, setLocationId, setParentExpression, suppressValidation, typeError, typeError`

Methods inherited from class java.lang.Object
`clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait`

Field Detail

### singletonOperator

    protected int singletonOperator

### comparer

    protected AtomicComparer comparer

Constructor Detail

### 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 Detail

### computeCardinality

    public int computeCardinality()

  Determine the static cardinality. Returns [1..1]

  Overrides:
    `computeCardinality` in class `BinaryExpression`

### typeCheck

    public Expression typeCheck(StaticContext env,
                                ItemType contextItemType)
                         throws XPathException

  Type-check the expression

  Specified by:
    `typeCheck` in interface `Expression`
  Overrides:
    `typeCheck` in class `BinaryExpression`
  Returns:
    the checked expression
  Throws:
    `XPathException`

### optimize

    public Expression optimize(Optimizer opt,
                               StaticContext env,
                               ItemType contextItemType)
                        throws XPathException

  Optimize the expression

  Specified by:
    `optimize` in interface `Expression`
  Overrides:
    `optimize` in class `BinaryExpression`
  Parameters:
    `opt` - the optimizer in use. This provides access to supporting functions; it also allows different optimization strategies to be used in different circumstances.
    `env` - the static context of the expression
    `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`

### evaluateItem

    public Item evaluateItem(XPathContext context)
                      throws XPathException

  Evaluate the expression in a given context

  Specified by:
    `evaluateItem` in interface `Expression`
  Overrides:
    `evaluateItem` in class `ComputedExpression`
  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

  Specified by:
    `effectiveBooleanValue` in interface `Expression`
  Overrides:
    `effectiveBooleanValue` in class `ComputedExpression`
  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

  Throws:
    `XPathException`

### getItemType

    public ItemType getItemType(TypeHierarchy th)

  Determine the data type of the expression

  Parameters:
    `th` -
  Returns:
    Type.BOOLEAN

### getInverseComparison

    protected GeneralComparison getInverseComparison()

### displayOperator

    protected java.lang.String displayOperator()

  Overrides:
    `displayOperator` in class `BinaryExpression`

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