Package net.sf.saxon.expr
Class PositionRange
java.lang.Object
net.sf.saxon.expr.ComputedExpression
net.sf.saxon.expr.PositionRange
- All Implemented Interfaces:
Serializable
,SourceLocator
,Container
,Expression
,InstructionInfoProvider
PositionRange: a boolean expression that tests whether the position() is
within a certain range. This expression can occur in any context but it is
optimized when it appears as a predicate (see FilterIterator)
- See Also:
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Field Summary
FieldsFields inherited from class net.sf.saxon.expr.ComputedExpression
locationId, staticProperties
Fields inherited from interface net.sf.saxon.expr.Expression
EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD
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Constructor Summary
ConstructorsConstructorDescriptionPositionRange
(int min, int max) Create a constant position rangePositionRange
(Expression pos) Create a position "range" for an exact positionPositionRange
(Expression min, Expression max) Create a position range -
Method Summary
Modifier and TypeMethodDescriptionint
Determine the static cardinalityint
Determine the special properties of this expressionvoid
display
(int level, PrintStream out, Configuration config) Diagnostic print of expression structureEvaluate the expressionint
Get the dependenciesDetermine the data type of the expressionboolean
Test whether the range is focus-dependent.boolean
Test if the first and last position are both constant 1Get the immediate sub-expressions of this expression.Make an iterator over a range of a sequence determined by this position rangemakeTailExpression
(Expression start) If this is an open-ended range with a constant start position, make a TailExpression.boolean
Test if the position range matches at most one itemoptimize
(Optimizer opt, StaticContext env, ItemType contextItemType) Perform optimisation of an expression and its subexpressions.boolean
replaceSubExpression
(Expression original, Expression replacement) Replace one subexpression by a replacement subexpressionsimplify
(StaticContext env) Simplify an expressiontypeCheck
(StaticContext env, ItemType contextItemType) Type-check the expressionMethods inherited from class net.sf.saxon.expr.ComputedExpression
adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, getCardinality, getColumnNumber, getConstructType, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getLineNumber, getLocationId, getLocationProvider, getParentExpression, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasBadParentPointer, iterate, markTailFunctionCalls, process, promote, resetStaticProperties, setLocationId, setParentExpression, setParentExpression, suppressValidation, typeError
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Field Details
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maxSameAsMin
boolean maxSameAsMin
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Constructor Details
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PositionRange
Create a position range -
PositionRange
Create a position "range" for an exact position -
PositionRange
public PositionRange(int min, int max) Create a constant position range
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Method Details
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simplify
Simplify an expression- Specified by:
simplify
in interfaceExpression
- Overrides:
simplify
in classComputedExpression
- Parameters:
env
- the static context- Returns:
- the simplified expression
- Throws:
XPathException
- if an error is discovered during expression rewriting
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typeCheck
Type-check the expression- Parameters:
env
- the static context of the expressioncontextItemType
- 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 to perform necessary run-time type checks, and to perform other type-related optimizations
- Throws:
XPathException
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optimize
public Expression optimize(Optimizer opt, StaticContext env, ItemType 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.
- Parameters:
opt
- the optimizer in use. This provides access to supporting functions; it also allows different optimization strategies to be used in different circumstances.env
- the static context of the expressioncontextItemType
- 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:
StaticError
- if an error is discovered during this phase (typically a type error)XPathException
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computeSpecialProperties
public int computeSpecialProperties()Determine the special properties of this expression- Overrides:
computeSpecialProperties
in classComputedExpression
- Returns:
StaticProperty.NON_CREATIVE
.
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evaluateItem
Evaluate the expression- Specified by:
evaluateItem
in interfaceExpression
- Overrides:
evaluateItem
in classComputedExpression
- Parameters:
c
- 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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makePositionIterator
public SequenceIterator makePositionIterator(SequenceIterator base, XPathContext c) throws XPathException Make an iterator over a range of a sequence determined by this position range- Throws:
XPathException
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getItemType
Determine the data type of the expression- Parameters:
th
-- Returns:
- Type.BOOLEAN
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computeCardinality
public int computeCardinality()Determine the static cardinality- Specified by:
computeCardinality
in classComputedExpression
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getIntrinsicDependencies
public int getIntrinsicDependencies()Get the dependencies- Overrides:
getIntrinsicDependencies
in classComputedExpression
- Returns:
- a set of bit-significant flags identifying the "intrinsic" dependencies. The flags are documented in class net.sf.saxon.value.StaticProperty
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iterateSubExpressions
Get the immediate sub-expressions of this expression. Default implementation returns a zero-length array, appropriate for an expression that has no sub-expressions.- Specified by:
iterateSubExpressions
in interfaceExpression
- Overrides:
iterateSubExpressions
in classComputedExpression
- Returns:
- an iterator containing the sub-expressions of this expression
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replaceSubExpression
Replace one subexpression by a replacement subexpression- Specified by:
replaceSubExpression
in interfaceContainer
- Overrides:
replaceSubExpression
in classComputedExpression
- Parameters:
original
- the original subexpressionreplacement
- the replacement subexpression- Returns:
- true if the original subexpression is found
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isFirstPositionOnly
public boolean isFirstPositionOnly()Test if the first and last position are both constant 1 -
hasFocusDependentRange
public boolean hasFocusDependentRange()Test whether the range is focus-dependent. An example of a focus-dependent range is (1 to position()). We could treat last() specially but we don't. -
matchesAtMostOneItem
public boolean matchesAtMostOneItem()Test if the position range matches at most one item -
makeTailExpression
If this is an open-ended range with a constant start position, make a TailExpression. Otherwise return null -
display
Diagnostic print of expression structure- Parameters:
level
- indentation level for this expressionout
- Output destinationconfig
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