Class TupleExpression
- All Implemented Interfaces:
Serializable
,SourceLocator
,LocationProvider
,SaxonLocator
,InstructionInfo
,Locator
- See Also:
-
Field Summary
FieldsFields inherited from class net.sf.saxon.expr.Expression
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
Constructors -
Method Summary
Modifier and TypeMethodDescriptionint
Get the cardinality of the expression.copy()
Copy an expression.evaluateItem
(XPathContext context) Evaluate an expression as a single item.void
Diagnostic print of expression structure.int
Determine the intrinsic dependencies of an expression, that is, those which are not derived from the dependencies of its subexpressions.Determine the data type of the expression, if possible.getSlots()
Get the immediate sub-expressions of this expression.boolean
replaceSubExpression
(Expression original, Expression replacement) Replace one subexpression by a replacement subexpressionvoid
setCurrentTuple
(XPathContext context, Tuple tuple) Set the local variables in the current stack frame to values corresponding to a supplied tuplevoid
typeCheck
(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) Perform type checking of an expression and its subexpressions.Methods inherited from class net.sf.saxon.expr.Expression
addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeSpecialProperties, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluatePendingUpdates, explain, getCardinality, getColumnNumber, getColumnNumber, getConstructType, getContainer, getDependencies, getEvaluationMethod, getExecutable, getExpressionName, getHostLanguage, getImplementationMethod, getIntegerBounds, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, hasLoopingSubexpression, hasVariableBinding, implementsStaticTypeCheck, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterate, iterateEvents, iterateSameFocusSubExpressions, markTailFunctionCalls, optimize, process, promote, resetLocalStaticProperties, setContainer, setEvaluationMethod, setFiltered, setFlattened, setLocationId, simplify, staticTypeCheck, suppressValidation, toString, typeError
-
Field Details
-
slots
LocalVariableReference[] slots
-
-
Constructor Details
-
TupleExpression
public TupleExpression()
-
-
Method Details
-
setVariables
-
getSlots
-
getItemType
Description copied from class:Expression
Determine the data type of the expression, if possible. All expression return sequences, in general; this method determines the type of the items within the sequence, assuming that (a) this is known in advance, and (b) it is the same for all items in the sequence.This method should always return a result, though it may be the best approximation that is available at the time.
- Specified by:
getItemType
in classExpression
- Parameters:
th
- the type hierarchy cache- Returns:
- a value such as Type.STRING, Type.BOOLEAN, Type.NUMBER, Type.NODE, or Type.ITEM (meaning not known at compile time)
-
typeCheck
public Expression typeCheck(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) throws XPathException Description copied from class:Expression
Perform type checking of an expression and its subexpressions. This is the second phase of static optimization.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.
- Overrides:
typeCheck
in classExpression
- Parameters:
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 toType.ITEM_TYPE
- Returns:
- the original expression, rewritten to perform necessary run-time type checks, and to perform other type-related optimizations
- Throws:
XPathException
- if an error is discovered during this phase (typically a type error)
-
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.- Overrides:
iterateSubExpressions
in classExpression
- Returns:
- an iterator containing the sub-expressions of this expression
-
replaceSubExpression
Replace one subexpression by a replacement subexpression- Overrides:
replaceSubExpression
in classExpression
- Parameters:
original
- the original subexpressionreplacement
- the replacement subexpression- Returns:
- true if the original subexpression is found
-
copy
Copy an expression. This makes a deep copy.- Specified by:
copy
in classExpression
- Returns:
- the copy of the original expression
-
explain
Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.- Specified by:
explain
in classExpression
- Parameters:
out
- the expression presenter used to display the structure
-
evaluateItem
Description copied from class:Expression
Evaluate an expression as a single item. This always returns either a single Item or null (denoting the empty sequence). No conversion is done. This method should not be used unless the static type of the expression is a subtype of "item" or "item?": that is, it should not be called if the expression may return a sequence. There is no guarantee that this condition will be detected.- Overrides:
evaluateItem
in classExpression
- Parameters:
context
- 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
-
setCurrentTuple
Set the local variables in the current stack frame to values corresponding to a supplied tuple- Parameters:
context
- identifies the stack frame to be modifiedtuple
- the tuple containing the current values
-
computeCardinality
public int computeCardinality()Get the cardinality of the expression. This is exactly one, in the sense that evaluating the TupleExpression returns a single tuple.- Specified by:
computeCardinality
in classExpression
- Returns:
- the static cardinality - EXACTLY_ONE
-
getIntrinsicDependencies
public int getIntrinsicDependencies()Description copied from class:Expression
Determine the intrinsic dependencies of an expression, that is, those which are not derived from the dependencies of its subexpressions. For example, position() has an intrinsic dependency on the context position, while (position()+1) does not. The default implementation of the method returns 0, indicating "no dependencies".- Overrides:
getIntrinsicDependencies
in classExpression
- Returns:
- a set of bit-significant flags identifying the "intrinsic" dependencies. The flags are documented in class net.sf.saxon.value.StaticProperty
-