public class TupleExpression extends ComputedExpression
Modifier and Type | Field and Description |
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(package private) Expression[] |
components |
locationId, staticProperties
EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD
Constructor and Description |
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TupleExpression(int width) |
Modifier and Type | Method and Description |
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int |
computeCardinality()
Get the cardinality of the expression.
|
void |
display(int level,
NamePool pool,
PrintStream out)
Diagnostic print of expression structure.
|
Item |
evaluateItem(XPathContext context)
Evaluate an expression as a single item.
|
int |
getIntrinsicDependencies()
Determine the intrinsic dependencies of an expression, that is, those which are not derived
from the dependencies of its subexpressions.
|
ItemType |
getItemType(TypeHierarchy th)
Determine the data type of the expression, if possible.
|
Iterator |
iterateSubExpressions()
Get the immediate sub-expressions of this expression.
|
Expression |
optimize(Optimizer opt,
StaticContext env,
ItemType contextItemType)
Perform optimisation of an expression and its subexpressions.
|
Expression |
promote(PromotionOffer offer)
Offer promotion for this subexpression.
|
void |
setExpression(int i,
Expression exp) |
Expression |
simplify(StaticContext env)
Simplify an expression.
|
Expression |
typeCheck(StaticContext env,
ItemType contextItemType)
Perform type checking of an expression and its subexpressions.
|
adoptChildExpression, checkPermittedContents, computeDependencies, computeSpecialProperties, computeStaticProperties, doPromotion, dynamicError, dynamicError, effectiveBooleanValue, evaluateAsString, getCardinality, getColumnNumber, getConstructType, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getLineNumber, getLocationId, getLocationProvider, getParentExpression, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasBadParentPointer, iterate, markTailFunctionCalls, process, resetStaticProperties, setLocationId, setParentExpression, suppressValidation, typeError, typeError
Expression[] components
public void setExpression(int i, Expression exp)
public Expression simplify(StaticContext env) throws XPathException
ComputedExpression
simplify
in interface Expression
simplify
in class ComputedExpression
XPathException
- if an error is discovered during expression
rewritingpublic Expression promote(PromotionOffer offer) throws XPathException
ComputedExpression
promote
in interface Expression
promote
in class ComputedExpression
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 expressionXPathException
- if any error is detectedpublic ItemType getItemType(TypeHierarchy th)
Expression
This method should always return a result, though it may be the best approximation that is available at the time.
public Expression typeCheck(StaticContext env, ItemType 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.
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 to
Type.ITEM_TYPE
StaticError
- if an error is discovered during this phase
(typically a type error)XPathException
public Expression optimize(Optimizer opt, StaticContext env, ItemType contextItemType) 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.
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 to
Type.ITEM_TYPE
StaticError
- if an error is discovered during this phase
(typically a type error)XPathException
public void display(int level, NamePool pool, PrintStream out)
Expression
level
- indentation level for this expressionpool
- NamePool used to expand any names appearing in the expressionout
- Output destinationpublic Item evaluateItem(XPathContext context) throws XPathException
ComputedExpression
evaluateItem
in interface Expression
evaluateItem
in class ComputedExpression
context
- The context in which the expression is to be evaluatedXPathException
- if any dynamic error occurs evaluating the
expressionpublic int computeCardinality()
computeCardinality
in class ComputedExpression
public int getIntrinsicDependencies()
ComputedExpression
getIntrinsicDependencies
in class ComputedExpression
public Iterator iterateSubExpressions()
ComputedExpression
iterateSubExpressions
in interface Expression
iterateSubExpressions
in class ComputedExpression