public class Choose extends Instruction implements ConditionalInstruction
Modifier and Type  Field and Description 

static OperandRole 
CHOICE_ACTION 
EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, MAX_COST, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, UPDATE_METHOD, WATCH_METHOD
Constructor and Description 

Choose(Expression[] conditions,
Expression[] actions)
Construct an xsl:choose instruction

Modifier and Type  Method and Description 

java.lang.Iterable<Operand> 
actions() 
PathMap.PathMapNodeSet 
addToPathMap(PathMap pathMap,
PathMap.PathMapNodeSet pathMapNodeSet)
Add a representation of this expression to a PathMap.

boolean 
allowExtractingCommonSubexpressions()
Ask whether common subexpressions found in the operands of this expression can
be extracted and evaluated outside the expression itself.

void 
atomizeActions()
Atomize all the action expressions

void 
checkForUpdatingSubexpressions()
Check to ensure that this expression does not contain any updating subexpressions.

void 
checkPermittedContents(SchemaType parentType,
boolean whole)
Check that any elements and attributes constructed or returned by this expression are acceptable
in the content model of a given complex type.

int 
computeCardinality()
Compute the cardinality of the sequence returned by evaluating this instruction

int 
computeSpecialProperties()
Get the static properties of this expression (other than its type).

java.lang.Iterable<Operand> 
conditions() 
Expression 
copy(RebindingMap rebindings)
Copy an expression.

Item 
evaluateItem(XPathContext context)
Evaluate an expression as a single item.

void 
evaluatePendingUpdates(XPathContext context,
PendingUpdateList pul)
Evaluate an updating expression, adding the results to a Pending Update List.

void 
export(ExpressionPresenter out)
Diagnostic print of expression structure.

Expression 
getAction(int i)
Get i'th action to be performed

Operand 
getActionOperand(int i)
Get i'th action operand

Expression 
getCondition(int i) 
java.lang.String 
getExpressionName()
Get a name identifying the kind of expression, in terms meaningful to a user.

int 
getImplementationMethod()
An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process().

int 
getInstructionNameCode()
Get the name of this instruction for diagnostic and tracing purposes
We assume that if there was
only one condition then it was an xsl:if; this is not necessarily so, but
it's adequate for tracing purposes.

ItemType 
getItemType()
Get the item type of the items returned by evaluating this instruction

int 
getNumberOfConditions() 
UType 
getStaticUType(UType contextItemType)
Get the static type of the expression as a UType, following precisely the type
inference rules defined in the XSLT 3.0 specification.

java.lang.String 
getStreamerName()
Get the (partial) name of a class that supports streaming of this kind of expression

boolean 
implementsStaticTypeCheck()
Determine whether this expression implements its own method for static type checking

boolean 
isInstruction()
Ask whether this expression is an instruction.

static boolean 
isSingleBranchChoice(Expression exp)
Test whether an expression is a singlebranch choose, that is, an expression of the form
if (condition) then exp else ()

boolean 
isUpdatingExpression()
Determine whether this is an updating expression as defined in the XQuery update specification

boolean 
isVacuousExpression()
Determine whether this is a vacuous expression as defined in the XQuery update specification

SequenceIterator<?> 
iterate(XPathContext context)
Return an Iterator to iterate over the values of a sequence.

static Expression 
makeConditional(Expression condition,
Expression thenExp)
Make a simple conditional expression (if (condition) then (thenExp) else ()

static Expression 
makeConditional(Expression condition,
Expression thenExp,
Expression elseExp)
Make a simple conditional expression (if (condition) then (thenExp) else (elseExp)

int 
markTailFunctionCalls(StructuredQName qName,
int arity)
Mark tailrecursive calls on functions.

boolean 
mayCreateNewNodes()
Determine whether this instruction creates new nodes.

java.lang.Iterable<Operand> 
operands()
Get the immediate subexpressions of this expression, with information about the relationship
of each expression to its parent expression.

Expression 
optimize(ExpressionVisitor visitor,
ContextItemStaticInfo contextItemType)
Perform optimisation of an expression and its subexpressions.

TailCall 
processLeavingTail(XPathContext context)
Process this instruction, that is, choose an xsl:when or xsl:otherwise child
and process it.

void 
setAction(int i,
Expression action) 
void 
setCondition(int i,
Expression condition) 
void 
setInstruction(boolean inst)
Say whether this choose expression originates as an XSLT instruction

Expression 
simplify()
Simplify an expression.

int 
size() 
Expression 
staticTypeCheck(SequenceType req,
boolean backwardsCompatible,
RoleDiagnostic role,
ExpressionVisitor visitor)
Static type checking for conditional expressions is delegated to the expression itself,
and is performed separately on each branch of the conditional, so that dynamic checks are
added only on those branches where the check is actually required.

java.lang.String 
toShortString()
Produce a short string identifying the expression for use in error messages

java.lang.String 
toString()
The toString() method for an expression attempts to give a representation of the expression
in an XPathlike form, but there is no guarantee that the syntax will actually be true XPath.

Expression 
typeCheck(ExpressionVisitor visitor,
ContextItemStaticInfo contextInfo)
Perform type checking of an expression and its subexpressions.

Expression 
unordered(boolean retainAllNodes,
boolean forStreaming)
Replace this expression by a simpler expression that delivers the results without regard
to order.

alwaysCreatesNewNodes, assembleParams, assembleTunnelParams, dynamicError, evaluateAsString, getConstructType, getNetCost, getSourceLocator, isXSLT, process, someOperandCreatesNewNodes
adoptChildExpression, checkedOperands, computeDependencies, computeHashCode, computeStaticProperties, dynamicError, effectiveBooleanValue, equals, explain, getCardinality, getConfiguration, getCost, getDependencies, getEvaluationMethod, getExtraProperty, getIntegerBounds, getInterpretedExpression, getIntrinsicDependencies, getLocalRetainedStaticContext, getLocation, getObjectName, getPackageData, getParentExpression, getProperties, getProperty, getRetainedStaticContext, getScopingExpression, getSlotsUsed, getSpecialProperties, getStaticBaseURI, getStaticBaseURIString, getStaticType, hasCompatibleStaticContext, hashCode, hasSpecialProperty, hasVariableBinding, identityHashCode, isCallOn, isEqual, isIdentical, isLiftable, isMultiThreaded, isStaticPropertiesKnown, isSubtreeExpression, operandList, operandSparseList, optimizeChildren, prepareForStreaming, resetLocalStaticProperties, restoreParentPointers, setEvaluationMethod, setExtraProperty, setFiltered, setFlattened, setLocation, setParentExpression, setRetainedStaticContext, setRetainedStaticContextLocally, setRetainedStaticContextThoroughly, setStaticProperty, simplifyChildren, suppressValidation, toPattern, typeCheckChildren, typeError, verifyParentPointers
public static final OperandRole CHOICE_ACTION
public Choose(Expression[] conditions, Expression[] actions)
conditions
 the conditions to be tested, in orderactions
 the actions to be taken when the corresponding condition is truepublic static Expression makeConditional(Expression condition, Expression thenExp, Expression elseExp)
condition
 the condition to be testedthenExp
 the expression to be evaluated if the condition is trueelseExp
 the expression to be evaluated if the condition is falsepublic static Expression makeConditional(Expression condition, Expression thenExp)
condition
 the condition to be testedthenExp
 the expression to be evaluated if the condition is truepublic void setInstruction(boolean inst)
inst
 true if this is an xsl:choose or xsl:if instructionpublic boolean isInstruction()
isInstruction
in class Instruction
public int size()
public static boolean isSingleBranchChoice(Expression exp)
exp
 the expression to be testedpublic int getNumberOfConditions()
public Expression getCondition(int i)
public void setCondition(int i, Expression condition)
public java.lang.Iterable<Operand> conditions()
public Operand getActionOperand(int i)
i
 the action numberpublic Expression getAction(int i)
i
 the action numberpublic void setAction(int i, Expression action)
public java.lang.Iterable<Operand> actions()
public java.lang.Iterable<Operand> operands()
Expression
If the expression is a Callable, then it is required that the order of the operands returned by this function is the same as the order of arguments supplied to the corresponding call() method.
operands
in class Instruction
public boolean allowExtractingCommonSubexpressions()
allowExtractingCommonSubexpressions
in class Expression
public void atomizeActions()
public int getInstructionNameCode()
getInstructionNameCode
in class Instruction
public Expression simplify() throws XPathException
simplify
in class Expression
XPathException
 if an error is discovered during expression
rewritingpublic Expression typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) throws XPathException
Expression
This checks statically that the operands of the expression have the correct type; if necessary it generates code to do runtime type checking or type conversion. A static type error is reported only if execution cannot possibly succeed, that is, if a runtime 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.
typeCheck
in class Expression
visitor
 an expression visitorcontextInfo
 Information available statically about the context item: whether it is (possibly)
absent; its static type; its streaming posture.XPathException
 if an error is discovered during this phase
(typically a type error)public boolean implementsStaticTypeCheck()
implementsStaticTypeCheck
in class Expression
public Expression staticTypeCheck(SequenceType req, boolean backwardsCompatible, RoleDiagnostic role, ExpressionVisitor visitor) throws XPathException
staticTypeCheck
in class Expression
req
 the required typebackwardsCompatible
 true if backwards compatibility mode appliesrole
 the role of the expression in relation to the required typevisitor
 an expression visitorXPathException
 if failures occur, for example if the static type of one branch of the conditional
is incompatible with the required typepublic Expression optimize(ExpressionVisitor visitor, ContextItemStaticInfo contextItemType) throws XPathException
Expression
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.
optimize
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(RebindingMap rebindings)
copy
in class Expression
rebindings
 public void checkForUpdatingSubexpressions() throws XPathException
checkForUpdatingSubexpressions
in class Expression
XPathException
 if the expression has a nonpermitted updateing subexpressionpublic boolean isUpdatingExpression()
isUpdatingExpression
in class Expression
public boolean isVacuousExpression()
isVacuousExpression
in class Expression
public int getImplementationMethod()
getImplementationMethod
in class Instruction
Expression.ITERATE_METHOD
or Expression.EVALUATE_METHOD
or
Expression.PROCESS_METHOD
public int markTailFunctionCalls(StructuredQName qName, int arity)
markTailFunctionCalls
in class Expression
qName
 the name of the functionarity
 the arity (number of parameters) of the functionpublic ItemType getItemType()
getItemType
in class Instruction
public UType getStaticUType(UType contextItemType)
getStaticUType
in class Expression
contextItemType
 public int computeCardinality()
computeCardinality
in class Instruction
public int computeSpecialProperties()
computeSpecialProperties
in class Instruction
public final boolean mayCreateNewNodes()
mayCreateNewNodes
in class Instruction
public Expression unordered(boolean retainAllNodes, boolean forStreaming) throws XPathException
unordered
in class Expression
retainAllNodes
 set to true if the result must contain exactly the same nodes as the
original; set to false if the result can eliminate (or introduce) duplicates.forStreaming
 set to true if optimizing for streamingXPathException
 if the rewrite failspublic void checkPermittedContents(SchemaType parentType, boolean whole) throws XPathException
checkPermittedContents
in class Expression
parentType
 the "given complex type": the method is checking that the nodes returned by this
expression are acceptable members of the content model of this typewhole
 if true, we want to check that the value of this expression satisfies the content model
as a whole; if false we want to check that the value of the expression is acceptable as one part
of the contentXPathException
 if the value delivered by this expression cannot be part of the content model
of the given typepublic PathMap.PathMapNodeSet addToPathMap(PathMap pathMap, PathMap.PathMapNodeSet pathMapNodeSet)
The default implementation of this method assumes that an expression does no navigation other than the navigation done by evaluating its subexpressions, and that the subexpressions are evaluated in the same context as the containing expression. The method must be overridden for any expression where these assumptions do not hold. For example, implementations exist for AxisExpression, ParentExpression, and RootExpression (because they perform navigation), and for the doc(), document(), and collection() functions because they create a new navigation root. Implementations also exist for PathExpression and FilterExpression because they have subexpressions that are evaluated in a different context from the calling expression.
addToPathMap
in class Expression
pathMap
 the PathMap to which the expression should be addedpathMapNodeSet
 the set of PathMap nodes to which the paths from this expression should be appendedpublic java.lang.String toString()
toString
in class Expression
public java.lang.String toShortString()
Expression
toShortString
in class Expression
public void export(ExpressionPresenter out) throws XPathException
export
in interface ExportAgent
export
in class Expression
out
 the expression presenter used to display the structureXPathException
 if the export fails, for example if an expression is found that won't work
in the target environment.public TailCall processLeavingTail(XPathContext context) throws XPathException
processLeavingTail
in interface TailCallReturner
processLeavingTail
in class Instruction
context
 the dynamic context of this transformationXPathException
 if any nonrecoverable dynamic error occurspublic Item evaluateItem(XPathContext context) throws XPathException
evaluateItem
in class Instruction
context
 The context in which the expression is to be evaluatedXPathException
 if any dynamic error occurs evaluating the
expressionpublic SequenceIterator<?> iterate(XPathContext context) throws XPathException
In principle instructions should implement a pipelined iterate() method that avoids the overhead of intermediate storage.
iterate
in class Instruction
context
 supplies the context for evaluationXPathException
 if any dynamic error occurs evaluating the
expressionpublic void evaluatePendingUpdates(XPathContext context, PendingUpdateList pul) throws XPathException
evaluatePendingUpdates
in class Expression
context
 the XPath dynamic evaluation contextpul
 the pending update list to which the results should be writtenXPathException
 if evaluation failspublic java.lang.String getExpressionName()
getExpressionName
in class Instruction
public java.lang.String getStreamerName()
Expression
getStreamerName
in class Expression
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