Package net.sf.saxon.expr
Class BooleanExpression
- java.lang.Object
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- net.sf.saxon.expr.Expression
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- net.sf.saxon.expr.BinaryExpression
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- net.sf.saxon.expr.BooleanExpression
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- 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.
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Field Summary
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Fields inherited from class net.sf.saxon.expr.BinaryExpression
operator
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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
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Constructor Summary
Constructors Constructor Description BooleanExpression(Expression p1, int operator, Expression p2)Construct a boolean expression
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Method Summary
All Methods Static Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description intcomputeCardinality()Determine the static cardinality.abstract booleaneffectiveBooleanValue(XPathContext c)Evaluate as a boolean.BooleanValueevaluateItem(XPathContext context)Evaluate the expressionprotected ExpressionforceToBoolean(Expression in)java.lang.StringgetExpressionName()Get a name identifying the kind of expression, in terms meaningful to a user.ItemTypegetItemType()Determine the data type of the expressionprotected OperandRolegetOperandRole(int arg)Get the operand roleUTypegetStaticUType(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.booleanisNegatable(TypeHierarchy th)Check whether this specific instance of the expression is negatablestatic voidlistAndComponents(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 Expressionnegate()Return the negation of this boolean expression, that is, an expression that returns true when this expression returns false, and vice versaExpressionoptimize(ExpressionVisitor visitor, ContextItemStaticInfo contextItemType)Perform optimisation of an expression and its subexpressions.protected abstract ExpressionpreEvaluate()Evaluate the expression statically if either or both operands are literals.ExpressiontypeCheck(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
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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
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Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
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Methods inherited from interface net.sf.saxon.trace.Traceable
gatherProperties
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Constructor Detail
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BooleanExpression
public BooleanExpression(Expression p1, int operator, Expression p2)
Construct a boolean expression
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Method Detail
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getExpressionName
public java.lang.String getExpressionName()
Get a name identifying the kind of expression, in terms meaningful to a user.- Overrides:
getExpressionNamein classExpression- 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.
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typeCheck
public Expression typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) throws XPathException
Description copied from class:BinaryExpressionType-check the expression. Default implementation for binary operators that accept any kind of operand- Overrides:
typeCheckin classBinaryExpression- Parameters:
visitor- an expression visitorcontextInfo- 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)
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computeCardinality
public int computeCardinality()
Determine the static cardinality. Returns [1..1]- Overrides:
computeCardinalityin classBinaryExpression- 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 returnStaticProperty.ALLOWS_ZEROif the result is known to be an empty sequence, orStaticProperty.ALLOWS_MANYif if is known to return a sequence of length two or more.
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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:
optimizein classBinaryExpression- Parameters:
visitor- an expression visitorcontextItemType- 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 toType.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)
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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.
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forceToBoolean
protected Expression forceToBoolean(Expression in)
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isNegatable
public boolean isNegatable(TypeHierarchy th)
Check whether this specific instance of the expression is negatable- Specified by:
isNegatablein interfaceNegatable- Parameters:
th- the type hierarchy, if needed- Returns:
- true if it is
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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
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evaluateItem
public BooleanValue evaluateItem(XPathContext context) throws XPathException
Evaluate the expression- Overrides:
evaluateItemin classExpression- 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
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effectiveBooleanValue
public abstract boolean effectiveBooleanValue(XPathContext c) throws XPathException
Evaluate as a boolean.- Overrides:
effectiveBooleanValuein classExpression- 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
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getItemType
public ItemType getItemType()
Determine the data type of the expression- Specified by:
getItemTypein classExpression- Returns:
- BuiltInAtomicType.BOOLEAN
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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:
getStaticUTypein classExpression- Parameters:
contextItemType- static information about the context item- Returns:
- the static item type of the expression according to the XSLT 3.0 defined rules
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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 decomposedlist- the list to which the subexpressions are to be added.
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getOperandRole
protected OperandRole getOperandRole(int arg)
Description copied from class:BinaryExpressionGet the operand role- Overrides:
getOperandRolein classBinaryExpression- Parameters:
arg- which argument: 0 for the lhs, 1 for the rhs- Returns:
- the operand role
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