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
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:
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Field Summary
FieldsFields inherited from class net.sf.saxon.expr.BinaryExpression
operand0, operand1, operator
Fields inherited from class net.sf.saxon.expr.Expression
EVALUATE_METHOD, ITERATE_METHOD, locationId, PROCESS_METHOD, staticProperties
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Constructor Summary
ConstructorsConstructorDescriptionGeneralComparison
(Expression p0, int op, Expression p1) Create a relational expression identifying the two operands and the operator -
Method Summary
Modifier and TypeMethodDescriptionprotected static boolean
compare
(AtomicValue a1, int operator, AtomicValue a2, AtomicComparer comparer, XPathContext context) Compare two atomic valuesint
Determine the static cardinality.boolean
Determine whether untyped atomic values should be converted to the type of the other operandcopy()
Copy an expression.protected String
boolean
effectiveBooleanValue
(XPathContext context) Evaluate the expression in a boolean contextevaluateItem
(XPathContext context) Evaluate the expression in a given contextGet the AtomicComparer used to compare atomic values.protected GeneralComparison
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.FGEoptimize
(ExpressionVisitor visitor, ItemType contextItemType) Optimize the expressiontypeCheck
(ExpressionVisitor visitor, ItemType contextItemType) Type-check the expressionMethods inherited from class net.sf.saxon.expr.BinaryExpression
computeSpecialProperties, equals, explain, getOperands, getOperator, hashCode, isAssociative, isCommutative, isInverse, iterateSubExpressions, promote, replaceSubExpression, setFlattened, simplify, toString
Methods inherited from class net.sf.saxon.expr.Expression
addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, display, doPromotion, dynamicError, evaluateAsString, evaluatePendingUpdates, explain, findParentOf, getCardinality, getColumnNumber, getColumnNumber, getConstructType, getContainer, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getIntrinsicDependencies, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, isUpdatingExpression, iterate, iterateEvents, markTailFunctionCalls, process, resetLocalStaticProperties, setContainer, setFiltered, setLocationId, staticTypeCheck, suppressValidation, typeError
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
Methods inherited from interface net.sf.saxon.expr.ComparisonExpression
getOperands
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Field Details
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singletonOperator
protected int singletonOperator -
comparer
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Constructor Details
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GeneralComparison
Create a relational expression identifying the two operands and the operator- Parameters:
p0
- the left-hand operandop
- the operator, as a token returned by the Tokenizer (e.g. Token.LT)p1
- the right-hand operand
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Method Details
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getAtomicComparer
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()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
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typeCheck
public Expression typeCheck(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException Type-check the expression- Overrides:
typeCheck
in 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 checked expression
- Throws:
XPathException
- if an error is discovered during this phase (typically a type error)
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optimize
public Expression optimize(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException Optimize the expression- Overrides:
optimize
in 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 checked expression
- Throws:
XPathException
- if an error is discovered during this phase (typically a type error)
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copy
Copy an expression. This makes a deep copy.- Specified by:
copy
in classExpression
- Returns:
- the copy of the original expression
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evaluateItem
Evaluate the expression in a given context- Specified by:
evaluateItem
in interfaceEvaluableItem
- 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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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 valueoperator
- the operator, for exampleToken.EQUALS
a2
- the second valuecomparer
- the comparer to be used to perform the comparisoncontext
- the XPath evaluation context- Returns:
- true if the comparison succeeds
- Throws:
XPathException
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getItemType
Determine the data type of the expression- Specified by:
getItemType
in classExpression
- Parameters:
th
- the type hierarchy cache- Returns:
- the value BuiltInAtomicType.BOOLEAN
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getInverseComparison
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displayOperator
- Overrides:
displayOperator
in classBinaryExpression
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