Package net.sf.saxon.expr
Class EquivalenceComparison
java.lang.Object
net.sf.saxon.expr.Expression
net.sf.saxon.expr.BinaryExpression
net.sf.saxon.expr.EquivalenceComparison
- All Implemented Interfaces:
ComparisonExpression
,ExportAgent
,Locatable
,IdentityComparable
,Traceable
Class to handle equivalence comparisons of singletons. This only handles equality comparison.
It follows the rules used for grouping and for XQuery 3.0 switch expressions:
- each operand must be zero or one atomic values
- untypedAtomic is treated as string
- non-comparable values are not equal (no type errors)
- two empty sequences are equal to each other
- two NaN values are equal to each other
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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
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Constructor Summary
ConstructorsConstructorDescriptionEquivalenceComparison
(Expression p1, int operator, Expression p2) Create a singleton comparison - that is, a comparison between two singleton (0:1) sequences using the general comparison semantics -
Method Summary
Modifier and TypeMethodDescriptionint
Determine the static cardinality.boolean
Determine whether untyped atomic values should be converted to the type of the other operandcopy
(RebindingMap rebindings) Copy an expression.boolean
effectiveBooleanValue
(XPathContext context) Evaluate the expression in a boolean contextevaluateItem
(XPathContext context) Evaluate the expression in a given contextprotected void
Add subclass-specific attributes to the expression tree explanation.Get the AtomicComparer used to compare atomic values.Get a name identifying the kind of expression, in terms meaningful to a user.Determine the data type of the expressionint
Get the primitive (singleton) operator used: one of Token.FEQ, Token.FNE, Token.FLT, Token.FGT, Token.FLE, Token.FGEboolean
typeCheck
(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) Type-check the expression.Methods inherited from class net.sf.saxon.expr.BinaryExpression
computeHashCode, computeSpecialProperties, displayOperator, equals, export, getImplementationMethod, getLhs, getLhsExpression, getOperandRole, getOperator, getRhs, getRhsExpression, isAssociative, isCommutative, isInverse, operands, optimize, setFlattened, setLhsExpression, setRhsExpression, tag, toShortString, toString
Methods inherited from class net.sf.saxon.expr.Expression
addToPathMap, adoptChildExpression, allowExtractingCommonSubexpressions, checkedOperands, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, 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, getStaticUType, 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.expr.ComparisonExpression
getLhs, getLhsExpression, getRhs, getRhsExpression
Methods inherited from interface net.sf.saxon.trace.Traceable
gatherProperties
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Constructor Details
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EquivalenceComparison
Create a singleton comparison - that is, a comparison between two singleton (0:1) sequences using the general comparison semantics- Parameters:
p1
- the first operandoperator
- the operatorp2
- the second operand
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Method Details
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typeCheck
public Expression typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) throws XPathException Type-check the expression. Default implementation for binary operators that accept any kind of operand- Overrides:
typeCheck
in 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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getAtomicComparer
Description copied from interface:ComparisonExpression
Get the AtomicComparer used to compare atomic values. This encapsulates any collation that is used- Specified by:
getAtomicComparer
in interfaceComparisonExpression
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getSingletonOperator
public int getSingletonOperator()Description copied from interface:ComparisonExpression
Get the primitive (singleton) operator used: one of Token.FEQ, Token.FNE, Token.FLT, Token.FGT, Token.FLE, Token.FGE- Specified by:
getSingletonOperator
in interfaceComparisonExpression
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convertsUntypedToOther
public boolean convertsUntypedToOther()Determine whether untyped atomic values should be converted to the type of the other operand- Specified by:
convertsUntypedToOther
in interfaceComparisonExpression
- Returns:
- true if untyped values should be converted to the type of the other operand, false if they should be converted to strings.
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computeCardinality
public int computeCardinality()Determine the static cardinality. Returns [1..1]- Overrides:
computeCardinality
in 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_ZERO
if the result is known to be an empty sequence, orStaticProperty.ALLOWS_MANY
if if is known to return a sequence of length two or more.
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getItemType
Determine the data type of the expression- Specified by:
getItemType
in classExpression
- Returns:
- Type.BOOLEAN
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isKnownToBeComparable
public boolean isKnownToBeComparable() -
getComparer
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copy
Copy an expression. This makes a deep copy.- Specified by:
copy
in classExpression
- Parameters:
rebindings
-- Returns:
- the copy of the original expression
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evaluateItem
Evaluate the expression in a given context- Overrides:
evaluateItem
in classExpression
- 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
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effectiveBooleanValue
Evaluate the expression in a boolean context- Overrides:
effectiveBooleanValue
in classExpression
- 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
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getExpressionName
Get a name identifying the kind of expression, in terms meaningful to a user.- Overrides:
getExpressionName
in 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 export() output displaying the expression.
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explainExtraAttributes
Description copied from class:BinaryExpression
Add subclass-specific attributes to the expression tree explanation. Default implementation does nothing; this is provided for subclasses to override.- Overrides:
explainExtraAttributes
in classBinaryExpression
- Parameters:
out
- the output destination for the displayed expression tree
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