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java.lang.Object net.sf.saxon.expr.Expression com.saxonica.expr.SwitchExpression
public class SwitchExpression
An optimized Choose expression in which all the branches are tests of the same expression for equality with some value.
Field Summary |
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Fields inherited from class net.sf.saxon.expr.Expression |
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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 |
Constructor Summary | |
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SwitchExpression(Expression subject,
Map<Object,Expression> map,
Expression defaultAction,
StringCollator collation)
Create a switch expression |
Method Summary | |
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protected int |
computeCardinality()
Compute the static cardinality of this expression |
Expression |
copy()
Copy an expression. |
Item |
evaluateItem(XPathContext context)
Evaluate an expression as a single item. |
void |
explain(ExpressionPresenter out)
Diagnostic print of expression structure. |
Map<Object,Expression> |
getCaseMap()
Get the map from XPathComparable objects representing the values to the expressions to be executed for each of these values |
StringCollator |
getCollation()
Get the collation used |
ItemType |
getItemType(TypeHierarchy th)
Determine the data type of the expression, if possible. |
Expression |
getOtherwiseExpression()
Get the default ("otherwise") expression |
Expression |
getSubjectExpression()
Get the subject expression (the expression that computes the switch value) |
SequenceIterator |
iterate(XPathContext context)
Return an Iterator to iterate over the values of a sequence. |
Iterator<Expression> |
iterateSubExpressions()
Get the immediate sub-expressions of this expression. |
void |
process(XPathContext context)
Process the instruction, without returning any tail calls |
Expression |
promote(PromotionOffer offer,
Expression parent)
Offer promotion for this subexpression. |
boolean |
replaceSubExpression(Expression original,
Expression replacement)
Replace one subexpression by a replacement subexpression |
Expression |
typeCheck(ExpressionVisitor visitor,
ExpressionVisitor.ContextItemType contextItemType)
Perform type checking of an expression and its subexpressions. |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait |
Constructor Detail |
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public SwitchExpression(Expression subject, Map<Object,Expression> map, Expression defaultAction, StringCollator collation)
subject
- the value to be testedmap
- a map from possible values to the action to be performed on eachdefaultAction
- the expression to be evaluated if the value is not found in the mapcollation
- the collation to be used for comparing stringsMethod Detail |
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public Expression getSubjectExpression()
public Map<Object,Expression> getCaseMap()
public Expression getOtherwiseExpression()
public StringCollator getCollation()
protected int computeCardinality()
computeCardinality
in class Expression
StaticProperty.ALLOWS_ZERO_OR_ONE
,
StaticProperty.EXACTLY_ONE
, StaticProperty.ALLOWS_ONE_OR_MORE
,
StaticProperty.ALLOWS_ZERO_OR_MORE
public Expression typeCheck(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) throws XPathException
Expression
This checks statically that the operands of the expression have the correct type; if necessary it generates code to do run-time type checking or type conversion. A static type error is reported only if execution cannot possibly succeed, that is, if a run-time type error is inevitable. The call may return a modified form of the expression.
This method is called after all references to functions and variables have been resolved to the declaration of the function or variable. However, the types of such functions and variables may not be accurately known if they have not been explicitly declared.
If the implementation returns a value other than "this", then it is required to ensure that the location information in the returned expression have been set up correctly. It should not rely on the caller to do this, although for historical reasons many callers do so.
typeCheck
in class Expression
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 to
Type.ITEM_TYPE
XPathException
- if an error is discovered during this phase
(typically a type error)public Expression copy()
copy
in class Expression
public void explain(ExpressionPresenter out)
explain
in class Expression
out
- the expression presenter used to display the structurepublic ItemType getItemType(TypeHierarchy th)
This method should always return a result, though it may be the best approximation that is available at the time.
getItemType
in class Expression
th
- the type hierarchy cache
public Expression promote(PromotionOffer offer, Expression parent) throws XPathException
promote
in class Expression
offer
- details of the offer, for example the offer to move
expressions that don't depend on the context to an outer level in
the containing expressionparent
-
XPathException
- if any error is detectedpublic Item evaluateItem(XPathContext context) throws XPathException
evaluateItem
in class Expression
context
- The context in which the expression is to be evaluated
XPathException
- if any dynamic error occurs evaluating the
expressionpublic Iterator<Expression> iterateSubExpressions()
iterateSubExpressions
in class Expression
public boolean replaceSubExpression(Expression original, Expression replacement)
replaceSubExpression
in class Expression
original
- the original subexpressionreplacement
- the replacement subexpression
public SequenceIterator iterate(XPathContext context) throws XPathException
iterate
in class Expression
context
- supplies the context for evaluation
XPathException
- if any dynamic error occurs evaluating the
expressionpublic void process(XPathContext context) throws XPathException
process
in class Expression
context
- The dynamic context, giving access to the current node,
the current variables, etc.
XPathException
- if a dynamic error occurs
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