public final class Atomizer extends UnaryExpression
Modifier and Type | Field and Description |
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static UType |
STRING_KINDS
Node kinds whose typed value is always a string
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static UType |
UNTYPED_IF_UNTYPED_KINDS
Node kinds whose typed value is untypedAtomic if the configuration is untyped
|
static UType |
UNTYPED_KINDS
Node kinds whose typed value is always untypedAtomic
|
EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, UPDATE_METHOD, WATCH_METHOD
Constructor and Description |
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Atomizer(Expression sequence)
Constructor
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Modifier and Type | Method and Description |
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PathMap.PathMapNodeSet |
addToPathMap(PathMap pathMap,
PathMap.PathMapNodeSet pathMapNodeSet)
Add a representation of this expression to a PathMap.
|
int |
computeCardinality()
Determine the static cardinality of the expression
|
int |
computeSpecialProperties()
Determine the special properties of this expression
|
Expression |
copy(RebindingMap rebindings)
Copy an expression.
|
AtomicValue |
evaluateItem(XPathContext context)
Evaluate as an Item.
|
static ItemType |
getAtomizedItemType(Expression operand,
boolean alwaysUntyped,
TypeHierarchy th)
Compute the type that will result from atomizing the result of a given expression
|
static SequenceIterator |
getAtomizingIterator(SequenceIterator base,
boolean oneToOne)
Get an iterator that returns the result of atomizing the sequence delivered by the supplied
iterator
|
java.lang.String |
getExpressionName()
Diagnostic print of expression structure.
|
int |
getImplementationMethod()
An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process().
|
ItemType |
getItemType()
Determine the data type of the items returned by the expression, if possible
|
ItemType |
getOperandItemType() |
protected OperandRole |
getOperandRole()
Get the usage (in terms of streamability analysis) of the single operand
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java.lang.String |
getStreamerName()
Get the (partial) name of a class that supports streaming of this kind of expression
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boolean |
isUntyped()
Ask whether it is known that any nodes in the input will always be untyped
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SequenceIterator |
iterate(XPathContext context)
Iterate over the sequence of values
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static Expression |
makeAtomizer(Expression sequence)
Make an atomizer with a given operand
|
Expression |
optimize(ExpressionVisitor visitor,
ContextItemStaticInfo contextInfo)
Perform optimisation of an expression and its subexpressions.
|
void |
resetLocalStaticProperties()
Reset the static properties of the expression to -1, so that they have to be recomputed
next time they are used.
|
Expression |
simplify()
Simplify an expression
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java.lang.String |
toShortString()
Produce a short string identifying the expression for use in error messages
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java.lang.String |
toString()
The toString() method for an expression attempts to give a representation of the expression
in an XPath-like form, but there is no guarantee that the syntax will actually be true XPath.
|
Expression |
typeCheck(ExpressionVisitor visitor,
ContextItemStaticInfo contextInfo)
Type-check the expression
|
computeHashCode, displayOperator, equals, export, getBaseExpression, getOperand, operands, setBaseExpression
adoptChildExpression, allowExtractingCommonSubexpressions, checkedOperands, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, dynamicError, effectiveBooleanValue, evaluateAsString, evaluatePendingUpdates, explain, getCardinality, getConfiguration, getConstructType, getCost, getDependencies, getEvaluationMethod, getExtraProperty, getIntegerBounds, getInterpretedExpression, getIntrinsicDependencies, getLocalRetainedStaticContext, getLocation, getNetCost, getObjectName, getPackageData, getParentExpression, getProperties, getProperty, getRetainedStaticContext, getScopingExpression, getSlotsUsed, getSpecialProperties, getStaticBaseURI, getStaticBaseURIString, getStaticType, getStaticUType, hasCompatibleStaticContext, hashCode, hasVariableBinding, identityHashCode, implementsStaticTypeCheck, isCallOn, isCallOnSystemFunction, isIdentical, isInstruction, isLiftable, isMultiThreaded, isSameExpression, isStaticPropertiesKnown, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, markTailFunctionCalls, operandList, operandSparseList, optimizeChildren, process, restoreParentPointers, setEvaluationMethod, setExtraProperty, setFiltered, setFlattened, setLocation, setParentExpression, setRetainedStaticContext, setRetainedStaticContextLocally, setRetainedStaticContextThoroughly, setStaticProperty, simplifyChildren, staticTypeCheck, suppressValidation, toPattern, typeCheckChildren, typeError, unordered, verifyParentPointers, verifyParentPointers
public static final UType STRING_KINDS
public static final UType UNTYPED_KINDS
public static final UType UNTYPED_IF_UNTYPED_KINDS
public Atomizer(Expression sequence)
sequence
- the sequence to be atomizedpublic static Expression makeAtomizer(Expression sequence)
sequence
- the operandprotected OperandRole getOperandRole()
UnaryExpression
getOperandRole
in class UnaryExpression
public int getImplementationMethod()
getImplementationMethod
in class Expression
Expression.ITERATE_METHOD
or Expression.EVALUATE_METHOD
or
Expression.PROCESS_METHOD
public ItemType getOperandItemType()
public Expression simplify() throws XPathException
simplify
in class Expression
XPathException
- if an error is discovered during expression
rewritingpublic Expression typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) throws XPathException
typeCheck
in class UnaryExpression
visitor
- an expression visitorcontextInfo
- Information available statically about the context item: whether it is (possibly)
absent; its static type; its streaming posture.XPathException
- if an error is discovered during this phase
(typically a type error)public Expression optimize(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) throws XPathException
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.
optimize
in class UnaryExpression
visitor
- an expression visitorcontextInfo
- 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 to
Type.ITEM_TYPE
XPathException
- if an error is discovered during this phase
(typically a type error)public boolean isUntyped()
public int computeSpecialProperties()
computeSpecialProperties
in class UnaryExpression
StaticProperty.NON_CREATIVE
.public void resetLocalStaticProperties()
resetLocalStaticProperties
in class Expression
public Expression copy(RebindingMap rebindings)
copy
in class Expression
rebindings
- public java.lang.String getStreamerName()
Expression
getStreamerName
in class Expression
public SequenceIterator iterate(XPathContext context) throws XPathException
iterate
in class Expression
context
- supplies the context for evaluationXPathException
- if any dynamic error occurs evaluating the
expressionpublic AtomicValue evaluateItem(XPathContext context) throws XPathException
evaluateItem
in class Expression
context
- The context in which the expression is to be evaluatedXPathException
- if any dynamic error occurs evaluating the
expressionpublic ItemType getItemType()
getItemType
in class UnaryExpression
public static ItemType getAtomizedItemType(Expression operand, boolean alwaysUntyped, TypeHierarchy th)
operand
- the given expressionalwaysUntyped
- true if it is known that nodes will always be untypedth
- the type hierarchy cachepublic int computeCardinality()
computeCardinality
in class UnaryExpression
StaticProperty.ALLOWS_ZERO_OR_ONE
,
StaticProperty.EXACTLY_ONE
, StaticProperty.ALLOWS_ONE_OR_MORE
,
StaticProperty.ALLOWS_ZERO_OR_MORE
public PathMap.PathMapNodeSet addToPathMap(PathMap pathMap, PathMap.PathMapNodeSet pathMapNodeSet)
The default implementation of this method assumes that an expression does no navigation other than the navigation done by evaluating its subexpressions, and that the subexpressions are evaluated in the same context as the containing expression. The method must be overridden for any expression where these assumptions do not hold. For example, implementations exist for AxisExpression, ParentExpression, and RootExpression (because they perform navigation), and for the doc(), document(), and collection() functions because they create a new navigation root. Implementations also exist for PathExpression and FilterExpression because they have subexpressions that are evaluated in a different context from the calling expression.
addToPathMap
in class Expression
pathMap
- the PathMap to which the expression should be addedpathMapNodeSet
- the PathMapNodeSet to which the paths embodied in this expression should be addedpublic static SequenceIterator getAtomizingIterator(SequenceIterator base, boolean oneToOne) throws XPathException
base
- the supplied iterator, the input to atomizationoneToOne
- this can safely be set to true if it is known that all nodes in the base sequence will
be untyped and that there will be no arrays in the base sequence; but it is always OK
to set it to false.XPathException
- if a dynamic evaluation error occurspublic java.lang.String getExpressionName()
getExpressionName
in class Expression
public java.lang.String toString()
toString
in class UnaryExpression
public java.lang.String toShortString()
Expression
toShortString
in class UnaryExpression
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