Class TupleSorter
- All Implemented Interfaces:
Serializable
,SourceLocator
,Container
,Expression
,MappingFunction
,InstructionInfoProvider
- See Also:
-
Field Summary
Fields inherited from class net.sf.saxon.expr.ComputedExpression
locationId, staticProperties
Fields inherited from interface net.sf.saxon.expr.Expression
EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD
-
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionint
void
display
(int level, PrintStream out, Configuration config) Diagnostic print of expression structure.boolean
effectiveBooleanValue
(XPathContext context) Get the effective boolean value of the expression.Determine the data type of the expression, if possible.iterate
(XPathContext context) Return an Iterator to iterate over the values of a sequence.Get the immediate sub-expressions of this expression.Mapping function to map the wrapped objects returned by the SortedTupleIterator into real items.optimize
(Optimizer opt, StaticContext env, ItemType contextItemType) Perform optimisation of an expression and its subexpressions.promote
(PromotionOffer offer) Promote this expression if possibleboolean
replaceSubExpression
(Expression original, Expression replacement) Replace one subexpression by a replacement subexpressionsimplify
(StaticContext env) Simplify an expression.typeCheck
(StaticContext env, ItemType contextItemType) Perform type checking of an expression and its subexpressions.Methods inherited from class net.sf.saxon.expr.ComputedExpression
adoptChildExpression, checkPermittedContents, computeDependencies, computeSpecialProperties, computeStaticProperties, doPromotion, dynamicError, evaluateAsString, evaluateItem, getCardinality, getColumnNumber, getConstructType, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getIntrinsicDependencies, getLineNumber, getLocationId, getLocationProvider, getParentExpression, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasBadParentPointer, markTailFunctionCalls, process, resetStaticProperties, setLocationId, setParentExpression, setParentExpression, suppressValidation, typeError
-
Constructor Details
-
TupleSorter
-
-
Method Details
-
simplify
Description copied from class:ComputedExpression
Simplify an expression. This performs any static optimization (by rewriting the expression as a different expression). The default implementation does nothing.- Specified by:
simplify
in interfaceExpression
- Overrides:
simplify
in classComputedExpression
- Parameters:
env
- the static context- Returns:
- the simplified expression
- Throws:
XPathException
- if an error is discovered during expression rewriting
-
typeCheck
Description copied from interface: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 parent pointer and 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.
- Specified by:
typeCheck
in interfaceExpression
- Parameters:
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 toType.ITEM_TYPE
- Returns:
- the original expression, rewritten to perform necessary run-time type checks, and to perform other type-related optimizations
- Throws:
XPathException
-
optimize
public Expression optimize(Optimizer opt, StaticContext env, ItemType contextItemType) throws XPathException Description copied from interface:Expression
Perform optimisation of an expression and its subexpressions. This is the third and final phase of static optimization.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.
- Specified by:
optimize
in interfaceExpression
- Parameters:
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 toType.ITEM_TYPE
- Returns:
- the original expression, rewritten if appropriate to optimize execution
- Throws:
XPathException
-
getItemType
Description copied from interface: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 interfaceExpression
- Parameters:
th
-- Returns:
- a value such as Type.STRING, Type.BOOLEAN, Type.NUMBER, Type.NODE, or Type.ITEM (meaning not known at compile time)
-
computeCardinality
public int computeCardinality()- Specified by:
computeCardinality
in classComputedExpression
-
iterateSubExpressions
Description copied from class:ComputedExpression
Get the immediate sub-expressions of this expression. Default implementation returns a zero-length array, appropriate for an expression that has no sub-expressions.- Specified by:
iterateSubExpressions
in interfaceExpression
- Overrides:
iterateSubExpressions
in classComputedExpression
- Returns:
- an iterator containing the sub-expressions of this expression
-
replaceSubExpression
Replace one subexpression by a replacement subexpression- Specified by:
replaceSubExpression
in interfaceContainer
- Overrides:
replaceSubExpression
in classComputedExpression
- Parameters:
original
- the original subexpressionreplacement
- the replacement subexpression- Returns:
- true if the original subexpression is found
-
promote
Promote this expression if possible- Specified by:
promote
in interfaceExpression
- Overrides:
promote
in classComputedExpression
- Parameters:
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 expression- Returns:
- if the offer is not accepted, return this expression unchanged. Otherwise return the result of rewriting the expression to promote this subexpression
- Throws:
XPathException
- if any error is detected
-
iterate
Description copied from class:ComputedExpression
Return an Iterator to iterate over the values of a sequence. The value of every expression can be regarded as a sequence, so this method is supported for all expressions. This default implementation handles iteration for expressions that return singleton values: for non-singleton expressions, the subclass must provide its own implementation.- Specified by:
iterate
in interfaceExpression
- Overrides:
iterate
in classComputedExpression
- Parameters:
context
- supplies the context for evaluation- Returns:
- a SequenceIterator that can be used to iterate over the result of the expression
- Throws:
XPathException
- if any dynamic error occurs evaluating the expression
-
effectiveBooleanValue
Description copied from class:ComputedExpression
Get the effective boolean value of the expression. This returns false if the value is the empty sequence, a zero-length string, a number equal to zero, or the boolean false. Otherwise it returns true.- Specified by:
effectiveBooleanValue
in interfaceExpression
- Overrides:
effectiveBooleanValue
in classComputedExpression
- Parameters:
context
- The context in which the expression is to be evaluated- Returns:
- the effective boolean value
- Throws:
XPathException
- if any dynamic error occurs evaluating the expression
-
display
Description copied from interface:Expression
Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.- Specified by:
display
in interfaceExpression
- Parameters:
level
- indentation level for this expressionout
- Output destinationconfig
-
-
map
Mapping function to map the wrapped objects returned by the SortedTupleIterator into real items. This is done because each tuple may actually represent a sequence of underlying values that share the same sort key.- Specified by:
map
in interfaceMappingFunction
- Parameters:
item
- The item to be mapped.- Returns:
- one of the following: (a) a SequenceIterator over the sequence of items that the supplied input item maps to, or (b) an Item if it maps to a single item, or (c) null if it maps to an empty sequence.
- Throws:
XPathException
-