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java.lang.Object net.sf.saxon.expr.Expression com.saxonica.expr.TryCatch
public class TryCatch
This class implements a try/catch expression. It consists of a try expression, and a sequence of Nametest/Catch expression pairs. If the try expression succeeds, its result is returned; otherwise the error code of the exception is matched against each of the Nametests in turn, and the first matching catch expression is evaluated.
Nested Class Summary | |
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static class |
TryCatch.CatchClause
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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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TryCatch(Expression tryExpr)
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Method Summary | |
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void |
addCatchExpression(QNameTest test,
Expression catchExpr)
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int |
computeCardinality()
Determine the cardinality of the function. |
Expression |
copy()
Copy an expression. |
Item |
evaluateItem(XPathContext c)
Evaluate as a singleton item |
void |
explain(ExpressionPresenter out)
Diagnostic print of expression structure. |
List<TryCatch.CatchClause> |
getCatchClauses()
Get the list of catch clauses |
ItemType |
getItemType(TypeHierarchy th)
Determine the item type of the value returned by the function |
Expression |
getTryExpr()
Get the "try" expression |
boolean |
hasLoopingSubexpression(Expression child)
Given an expression that is an immediate child of this expression, test whether the evaluation of the parent expression causes the child expression to be evaluated repeatedly |
SequenceIterator |
iterate(XPathContext c)
Iterate over the results of the function |
Iterator<Expression> |
iterateSubExpressions()
Get the immediate sub-expressions of this expression. |
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 |
simplify(ExpressionVisitor visitor)
Simplify an expression. |
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 TryCatch(Expression tryExpr)
Method Detail |
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public void addCatchExpression(QNameTest test, Expression catchExpr)
public Expression simplify(ExpressionVisitor visitor) throws XPathException
Expression
simplify
in class Expression
visitor
- an expression visitor
XPathException
- if an error is discovered during expression
rewritingpublic Expression getTryExpr()
public List<TryCatch.CatchClause> getCatchClauses()
public 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 ItemType getItemType(TypeHierarchy th)
getItemType
in class Expression
th
- the type hierarchy cache
public Expression typeCheck(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) throws XPathException
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 Iterator<Expression> iterateSubExpressions()
iterateSubExpressions
in class Expression
public boolean hasLoopingSubexpression(Expression child)
hasLoopingSubexpression
in class Expression
child
- the immediate subexpression
public Expression promote(PromotionOffer offer, Expression parent) throws XPathException
This method must be overridden for any Expression that has subexpressions.
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 boolean replaceSubExpression(Expression original, Expression replacement)
replaceSubExpression
in class Expression
original
- the original subexpressionreplacement
- the replacement subexpression
public Expression copy()
copy
in class Expression
public Item evaluateItem(XPathContext c) throws XPathException
evaluateItem
in class Expression
c
- the dynamic XPath evaluation context
XPathException
- if any dynamic error occurs evaluating the
expressionpublic SequenceIterator iterate(XPathContext c) throws XPathException
iterate
in class Expression
c
- supplies the context for evaluation
XPathException
- if any dynamic error occurs evaluating the
expressionpublic void explain(ExpressionPresenter out)
explain
in class Expression
out
- the expression presenter used to display the structure
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