Package net.sf.saxon.expr
Class GeneralComparison
- 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.GeneralComparison
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- All Implemented Interfaces:
java.io.Serializable
,javax.xml.transform.SourceLocator
,LocationProvider
,SaxonLocator
,ComparisonExpression
,EvaluableItem
,SequenceIterable
,InstructionInfo
,org.xml.sax.Locator
public class GeneralComparison extends BinaryExpression implements ComparisonExpression
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
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Field Summary
Fields Modifier and Type Field Description protected AtomicComparer
comparer
protected int
singletonOperator
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Fields inherited from class net.sf.saxon.expr.BinaryExpression
operand0, operand1, operator
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Fields inherited from class net.sf.saxon.expr.Expression
EVALUATE_METHOD, ITERATE_METHOD, locationId, PROCESS_METHOD, staticProperties
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Constructor Summary
Constructors Constructor Description GeneralComparison(Expression p0, int op, Expression p1)
Create a relational expression identifying the two operands and the operator
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description protected static boolean
compare(AtomicValue a1, int operator, AtomicValue a2, AtomicComparer comparer, XPathContext context)
Compare two atomic valuesint
computeCardinality()
Determine the static cardinality.boolean
convertsUntypedToOther()
Determine whether untyped atomic values should be converted to the type of the other operandExpression
copy()
Copy an expression.protected java.lang.String
displayOperator()
boolean
effectiveBooleanValue(XPathContext context)
Evaluate the expression in a boolean contextItem
evaluateItem(XPathContext context)
Evaluate the expression in a given contextAtomicComparer
getAtomicComparer()
Get the AtomicComparer used to compare atomic values.protected GeneralComparison
getInverseComparison()
ItemType
getItemType(TypeHierarchy th)
Determine the data type of the expressionint
getSingletonOperator()
Get the primitive (singleton) operator used: one of Token.FEQ, Token.FNE, Token.FLT, Token.FGT, Token.FLE, Token.FGEExpression
optimize(ExpressionVisitor visitor, ItemType contextItemType)
Optimize the expressionExpression
typeCheck(ExpressionVisitor visitor, ItemType contextItemType)
Type-check the expression-
Methods inherited from class net.sf.saxon.expr.BinaryExpression
computeSpecialProperties, equals, explain, getOperands, getOperator, hashCode, isAssociative, isCommutative, isInverse, iterateSubExpressions, promote, replaceSubExpression, setFlattened, simplify, toString
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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
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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.expr.ComparisonExpression
getOperands
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Field Detail
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singletonOperator
protected int singletonOperator
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comparer
protected AtomicComparer comparer
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Constructor Detail
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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 operandop
- the operator, as a token returned by the Tokenizer (e.g. Token.LT)p1
- the right-hand operand
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Method Detail
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getAtomicComparer
public AtomicComparer 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
public Expression 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
public Item evaluateItem(XPathContext context) throws XPathException
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
public boolean effectiveBooleanValue(XPathContext context) throws XPathException
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
public ItemType getItemType(TypeHierarchy th)
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
protected GeneralComparison getInverseComparison()
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displayOperator
protected java.lang.String displayOperator()
- Overrides:
displayOperator
in classBinaryExpression
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