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
,CallableExpression
,ComparisonExpression
,InstructionInfo
,org.xml.sax.Locator
- Direct Known Subclasses:
GeneralComparison20
public class GeneralComparison extends BinaryExpression implements ComparisonExpression, CallableExpression
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
comparisonCardinality
static int
MANY_TO_MANY
static int
MANY_TO_ONE
protected boolean
needsRuntimeCheck
static int
ONE_TO_ONE
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
EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, EVENT_FEED_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, PUSH_SELECTION, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, WATCH_METHOD
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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 SequenceIterator
call(SequenceIterator[] arguments, XPathContext context)
Evaluate the expressionstatic boolean
compare(AtomicValue a0, int operator, AtomicValue a1, AtomicComparer comparer, boolean checkTypes, 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.boolean
effectiveBooleanValue(XPathContext context)
Evaluate the expression in a boolean contextItem
evaluateItem(XPathContext context)
Evaluate the expression in a given contextboolean
evaluateManyToMany(SequenceIterator iter0, SequenceIterator iter1, XPathContext context)
Evaluate a (zero-or-one)-to-(zero-or-one) comparisonprotected void
explainExtraAttributes(ExpressionPresenter out)
Add subclass-specific attributes to the expression tree explanation.AtomicComparer
getAtomicComparer()
Get the AtomicComparer used to compare atomic values.int
getComparisonCardinality()
Ask whether the comparison is known to be many-to-one, one-to-one, or many-to-many.static int
getCorrespondingSingletonOperator(int op)
Return the singleton form of the comparison operator, e.g.java.lang.String
getExpressionName()
Get a name identifying the kind of expression, in terms meaningful to a user.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.FGEboolean
needsRuntimeCheck()
Ask whether a runtime check of the types of the operands is neededExpression
optimize(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType)
Optimize the expressionvoid
setAtomicComparer(AtomicComparer comparer)
Set the comparer to be usedvoid
setComparisonCardinality(int card)
Say whether the comparison is known to be many-to-one, one-to-one, or many-to-many.void
setNeedsRuntimeCheck(boolean needsCheck)
Say whether a runtime check of the types of the operands is neededExpression
simplify(ExpressionVisitor visitor)
Simplify an expressionExpression
typeCheck(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType)
Type-check the expression-
Methods inherited from class net.sf.saxon.expr.BinaryExpression
computeSpecialProperties, displayOperator, equals, explain, getArguments, getOperands, getOperator, hashCode, isAssociative, isCommutative, isInverse, iterateSubExpressions, promote, replaceSubExpression, setFlattened, toString
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Methods inherited from class net.sf.saxon.expr.Expression
addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, evaluateAsString, evaluatePendingUpdates, explain, getCardinality, getColumnNumber, getColumnNumber, getConstructType, getContainer, getDependencies, getEvaluationMethod, getExecutable, getHostLanguage, getImplementationMethod, getIntegerBounds, getIntrinsicDependencies, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, hasLoopingSubexpression, hasVariableBinding, implementsStaticTypeCheck, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterate, iterateEvents, iterateSameFocusSubExpressions, markTailFunctionCalls, process, resetLocalStaticProperties, setContainer, setEvaluationMethod, 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.CallableExpression
getArguments
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Methods inherited from interface net.sf.saxon.expr.ComparisonExpression
getOperands
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Field Detail
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ONE_TO_ONE
public static final int ONE_TO_ONE
- See Also:
- Constant Field Values
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MANY_TO_ONE
public static final int MANY_TO_ONE
- See Also:
- Constant Field Values
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MANY_TO_MANY
public static final int MANY_TO_MANY
- See Also:
- Constant Field Values
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singletonOperator
protected int singletonOperator
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comparer
protected AtomicComparer comparer
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needsRuntimeCheck
protected boolean needsRuntimeCheck
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comparisonCardinality
protected int comparisonCardinality
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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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needsRuntimeCheck
public boolean needsRuntimeCheck()
Ask whether a runtime check of the types of the operands is needed
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setNeedsRuntimeCheck
public void setNeedsRuntimeCheck(boolean needsCheck)
Say whether a runtime check of the types of the operands is needed
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getComparisonCardinality
public int getComparisonCardinality()
Ask whether the comparison is known to be many-to-one, one-to-one, or many-to-many. (Note, an expression that is one-to-many will be converted to one that is many-to-one).
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setComparisonCardinality
public void setComparisonCardinality(int card)
Say whether the comparison is known to be many-to-one, one-to-one, or many-to-many.
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setAtomicComparer
public void setAtomicComparer(AtomicComparer comparer)
Set the comparer to be used- Parameters:
comparer
- the comparer to be used
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simplify
public Expression simplify(ExpressionVisitor visitor) throws XPathException
Description copied from class:BinaryExpression
Simplify an expression- Overrides:
simplify
in classBinaryExpression
- Parameters:
visitor
- an expression visitor- Returns:
- the simplified expression
- Throws:
XPathException
- if an error is discovered during expression rewriting
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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:
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 explain() output displaying the expression.
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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, ExpressionVisitor.ContextItemType 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, ExpressionVisitor.ContextItemType 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- 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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call
public SequenceIterator call(SequenceIterator[] arguments, XPathContext context) throws XPathException
Evaluate the expression- Specified by:
call
in interfaceCallableExpression
- Parameters:
arguments
- the values of the arguments, supplied as SequenceIteratorscontext
- the dynamic evaluation context- Returns:
- the result of the evaluation, in the form of a SequenceIterator
- Throws:
XPathException
- if a dynamic error occurs during the evaluation of 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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evaluateManyToMany
public boolean evaluateManyToMany(SequenceIterator iter0, SequenceIterator iter1, XPathContext context) throws XPathException
Evaluate a (zero-or-one)-to-(zero-or-one) comparison- Parameters:
iter0
- iterator over the first valueiter1
- iterator the second valuecontext
- dynamic evaluation context- Returns:
- the comparison result
- Throws:
XPathException
- if a dynamic error occurs
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compare
public static boolean compare(AtomicValue a0, int operator, AtomicValue a1, AtomicComparer comparer, boolean checkTypes, XPathContext context) throws XPathException
Compare two atomic values- Parameters:
a0
- the first valueoperator
- the operator, for exampleToken.EQUALS
a1
- the second valuecomparer
- the comparer to be used to perform the comparisoncheckTypes
- set to true if the operand types need to be checked for comparability at runtimecontext
- the XPath evaluation context @return 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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getCorrespondingSingletonOperator
public static int getCorrespondingSingletonOperator(int op)
Return the singleton form of the comparison operator, e.g. FEQ for EQUALS, FGT for GT
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getInverseComparison
protected GeneralComparison getInverseComparison()
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explainExtraAttributes
protected void explainExtraAttributes(ExpressionPresenter out)
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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