java.lang.Object
- net.sf.saxon.expr.Expression
- - net.sf.saxon.expr.BinaryExpression
  - - net.sf.saxon.expr.BooleanExpression

All Implemented Interfaces:

ExportAgent, Locatable, Negatable, IdentityComparable, Traceable

Direct Known Subclasses:

AndExpression, OrExpression
```
public abstract class BooleanExpression
extends BinaryExpression
implements Negatable
```
Boolean expression: two truth values combined using AND or OR.

Field Summary
- Fields inherited from class net.sf.saxon.expr.BinaryExpression
  operator
- Fields inherited from class net.sf.saxon.expr.Expression
  EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, MAX_COST, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, UPDATE_METHOD, WATCH_METHOD

Constructor Summary

Constructors
Constructor Description

BooleanExpression(Expression p1, int operator, Expression p2)
Construct a boolean expression

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method	Description
`protected int`	`computeCardinality()`	Determine the static cardinality.
`abstract boolean`	`effectiveBooleanValue(XPathContext c)`	Evaluate as a boolean.
`BooleanValue`	`evaluateItem(XPathContext context)`	Evaluate the expression
`protected Expression`	`forceToBoolean(Expression in)`
`java.lang.String`	`getExpressionName()`	Get a name identifying the kind of expression, in terms meaningful to a user.
`ItemType`	`getItemType()`	Determine the data type of the expression
`protected OperandRole`	`getOperandRole(int arg)`	Get the operand role
`UType`	`getStaticUType(UType contextItemType)`	Get the static type of the expression as a UType, following precisely the type inference rules defined in the XSLT 3.0 specification.
`boolean`	`isNegatable(TypeHierarchy th)`	Check whether this specific instance of the expression is negatable
`static void`	`listAndComponents(Expression exp, java.util.List<Expression> list)`	Construct a list containing the "anded" subexpressions of an expression: if the expression is (A and B and C), this returns (A, B, C).
`abstract Expression`	`negate()`	Return the negation of this boolean expression, that is, an expression that returns true when this expression returns false, and vice versa
`Expression`	`optimize(ExpressionVisitor visitor, ContextItemStaticInfo contextItemType)`	Perform optimisation of an expression and its subexpressions.
`protected abstract Expression`	`preEvaluate()`	Evaluate the expression statically if either or both operands are literals.
`Expression`	`typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo)`	Type-check the expression.

Methods inherited from class net.sf.saxon.expr.BinaryExpression
computeHashCode, computeSpecialProperties, displayOperator, equals, explainExtraAttributes, export, getImplementationMethod, getLhs, getLhsExpression, getOperator, getRhs, getRhsExpression, isAssociative, isCommutative, isInverse, operands, setFlattened, setLhsExpression, setRhsExpression, tag, toShortString, toString

Methods inherited from class net.sf.saxon.expr.Expression
addToPathMap, adoptChildExpression, allowExtractingCommonSubexpressions, checkedOperands, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, copy, dynamicError, evaluateAsString, evaluatePendingUpdates, explain, getCardinality, getConfiguration, getCost, getDependencies, getEvaluationMethod, getExtraProperty, getIntegerBounds, getInterpretedExpression, getIntrinsicDependencies, getLocalRetainedStaticContext, getLocation, getNetCost, getObjectName, getPackageData, getParentExpression, getProperties, getProperty, getRetainedStaticContext, getScopingExpression, getSlotsUsed, getSpecialProperties, getStaticBaseURI, getStaticBaseURIString, getStaticType, getStreamerName, getTracingTag, hasCompatibleStaticContext, hashCode, hasSpecialProperty, hasVariableBinding, identityHashCode, implementsStaticTypeCheck, isCallOn, isEqual, isIdentical, isInstruction, isLiftable, isMultiThreaded, isStaticPropertiesKnown, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterate, markTailFunctionCalls, operandList, operandSparseList, optimizeChildren, prepareForStreaming, process, resetLocalStaticProperties, restoreParentPointers, setEvaluationMethod, setExtraProperty, setFiltered, setLocation, setParentExpression, setRetainedStaticContext, setRetainedStaticContextLocally, setRetainedStaticContextThoroughly, setStaticProperty, simplify, simplifyChildren, staticTypeCheck, suppressValidation, toPattern, typeCheckChildren, typeError, unordered, verifyParentPointers

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

Methods inherited from interface net.sf.saxon.trace.Traceable
gatherProperties

- Constructor Detail
  - BooleanExpression
```
public BooleanExpression(Expression p1,
                         int operator,
                         Expression p2)
```
    Construct a boolean expression
    
    Parameters:
    
    p1 - the first operand
    
    operator - one of Token.AND or Token.OR
    
    p2 - the second operand
- Method Detail
  - getExpressionName
```
public java.lang.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 explain() output displaying the expression.
  - typeCheck
```
public Expression typeCheck(ExpressionVisitor visitor,
                            ContextItemStaticInfo contextInfo)
                     throws XPathException
```
    Description copied from class: BinaryExpression
    
    Type-check the expression. Default implementation for binary operators that accept any kind of operand
    
    Overrides:
    
    typeCheck in class BinaryExpression
    
    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)
  - computeCardinality
```
protected 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. May also return StaticProperty.ALLOWS_ZERO if the result is known to be an empty sequence, or StaticProperty.ALLOWS_MANY if if is known to return a sequence of length two or more.
  - optimize
```
public Expression optimize(ExpressionVisitor visitor,
                           ContextItemStaticInfo contextItemType)
                    throws XPathException
```
    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 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 original expression, rewritten if appropriate to optimize execution
    
    Throws:
    
    XPathException - if an error is discovered during this phase (typically a type error)
  - preEvaluate
```
protected abstract Expression preEvaluate()
```
    Evaluate the expression statically if either or both operands are literals. For example, (true() or X) returns true().
    
    Returns:
    
    a boolean literal if the expression can be evaluated now, or the original expression otherwise.
  - forceToBoolean
```
protected Expression forceToBoolean(Expression in)
```
  - isNegatable
```
public boolean isNegatable(TypeHierarchy th)
```
    Check whether this specific instance of the expression is negatable
    
    Specified by:
    
    isNegatable in interface Negatable
    
    Parameters:
    
    th - the type hierarchy, if needed
    
    Returns:
    
    true if it is
  - negate
```
public abstract Expression negate()
```
    Return the negation of this boolean expression, that is, an expression that returns true when this expression returns false, and vice versa
    
    Specified by:
    
    negate in interface Negatable
    
    Returns:
    
    the negation of this expression
  - evaluateItem
```
public BooleanValue evaluateItem(XPathContext context)
                          throws XPathException
```
    Evaluate the expression
    
    Overrides:
    
    evaluateItem in class Expression
    
    Parameters:
    
    context - The context in which the expression is to be evaluated
    
    Returns:
    
    the node or atomic value that results from evaluating the expression; or null to indicate that the result is an empty sequence
    
    Throws:
    
    XPathException - if any dynamic error occurs evaluating the expression
  - effectiveBooleanValue
```
public abstract boolean effectiveBooleanValue(XPathContext c)
                                       throws XPathException
```
    Evaluate as a boolean.
    
    Overrides:
    
    effectiveBooleanValue in class Expression
    
    Parameters:
    
    c - The context in which the expression is to be evaluated
    
    Returns:
    
    the effective boolean value
    
    Throws:
    
    XPathException - if any dynamic error occurs evaluating the expression
  - getItemType
```
public ItemType getItemType()
```
    Determine the data type of the expression
    
    Specified by:
    
    getItemType in class Expression
    
    Returns:
    
    BuiltInAtomicType.BOOLEAN
  - getStaticUType
```
public UType getStaticUType(UType contextItemType)
```
    Get the static type of the expression as a UType, following precisely the type inference rules defined in the XSLT 3.0 specification.
    
    Overrides:
    
    getStaticUType in class Expression
    
    Parameters:
    
    contextItemType - static information about the context item
    
    Returns:
    
    the static item type of the expression according to the XSLT 3.0 defined rules
  - listAndComponents
```
public static void listAndComponents(Expression exp,
                                     java.util.List<Expression> list)
```
    Construct a list containing the "anded" subexpressions of an expression: if the expression is (A and B and C), this returns (A, B, C).
    
    Parameters:
    
    exp - the expression to be decomposed
    
    list - the list to which the subexpressions are to be added.
  - getOperandRole
```
protected OperandRole getOperandRole(int arg)
```
    Description copied from class: BinaryExpression
    
    Get the operand role
    
    Overrides:
    
    getOperandRole in class BinaryExpression
    
    Parameters:
    
    arg - which argument: 0 for the lhs, 1 for the rhs
    
    Returns:
    
    the operand role

Class BooleanExpression

Field Summary

Fields inherited from class net.sf.saxon.expr.BinaryExpression

Fields inherited from class net.sf.saxon.expr.Expression

Constructor Summary

Method Summary

Methods inherited from class net.sf.saxon.expr.BinaryExpression

Methods inherited from class net.sf.saxon.expr.Expression

Methods inherited from class java.lang.Object

Methods inherited from interface net.sf.saxon.trace.Traceable

Constructor Detail

BooleanExpression

Method Detail

getExpressionName

typeCheck

computeCardinality

optimize

preEvaluate

forceToBoolean

isNegatable

negate

evaluateItem

effectiveBooleanValue

getItemType

getStaticUType

listAndComponents

getOperandRole