net.sf.saxon.instruct
public class Choose extends Instruction
Constructor Summary | |
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Choose(Expression[] conditions, Expression[] actions)
Construct an xsl:choose instruction |
Method Summary | |
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PathMap.PathMapNodeSet | addToPathMap(PathMap pathMap, PathMap.PathMapNodeSet pathMapNodeSet)
Add a representation of this expression to a PathMap. |
void | checkForUpdatingSubexpressions()
Check to ensure that this expression does not contain any updating subexpressions.
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void | checkPermittedContents(SchemaType parentType, StaticContext env, 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). |
Expression | copy()
Copy an expression. |
boolean | createsNewNodes()
Determine whether this instruction creates new nodes.
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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.
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void | explain(ExpressionPresenter out)
Diagnostic print of expression structure. |
Expression[] | getActions()
Get the array of actions to be performed |
Expression[] | getConditions()
Get the array of conditions to be tested |
int | getImplementationMethod()
An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process().
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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(TypeHierarchy th)
Get the item type of the items returned by evaluating this instruction |
boolean | implementsStaticTypeCheck()
Determine whether this expression implements its own method for static type checking
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static boolean | isSingleBranchChoice(Expression exp)
Test whether an expression is a single-branch 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
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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. |
EventIterator | iterateEvents(XPathContext context)
Deliver the result of the expression as a sequence of events.
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Iterator<Expression> | iterateSubExpressions()
Get all the XPath expressions associated with this instruction
(in XSLT terms, the expression present on attributes of the instruction,
as distinct from the child instructions in a sequence construction) |
static Expression | makeConditional(Expression condition, Expression thenExp, Expression elseExp)
Make a simple conditional expression (if (condition) then (thenExp) else (elseExp) |
static Expression | makeConditional(Expression condition, Expression thenExp)
Make a simple conditional expression (if (condition) then (thenExp) else () |
int | markTailFunctionCalls(StructuredQName qName, int arity)
Mark tail-recursive calls on functions. |
Expression | optimize(ExpressionVisitor visitor, ItemType contextItemType) |
TailCall | processLeavingTail(XPathContext context)
Process this instruction, that is, choose an xsl:when or xsl:otherwise child
and process it. |
protected void | promoteInst(PromotionOffer offer)
Handle promotion offers, that is, non-local tree rewrites. |
boolean | replaceSubExpression(Expression original, Expression replacement)
Replace one subexpression by a replacement subexpression |
Expression | simplify(ExpressionVisitor visitor)
Simplify an expression. |
Expression | staticTypeCheck(SequenceType req, boolean backwardsCompatible, RoleLocator 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. |
String | toString()
The toString() method for an expression attempts to give a representation of the expression
in an XPath-like form, but there is no guarantee that the syntax will actually be true XPath.
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Expression | typeCheck(ExpressionVisitor visitor, ItemType contextItemType) |
Parameters: conditions the conditions to be tested, in order actions the actions to be taken when the corresponding condition is true
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.
Parameters: pathMap the PathMap to which the expression should be added pathMapNodeSet the set of PathMap nodes to which the paths from this expression should be appended
Returns: the pathMapNode representing the focus established by this expression, in the case where this expression is the first operand of a path expression or filter expression. For an expression that does navigation, it represents the end of the arc in the path map that describes the navigation route. For other expressions, it is the same as the input pathMapNode.
Throws: net.sf.saxon.trans.XPathException if the expression has a non-permitted updateing subexpression
Returns: the static cardinality
Returns: a set of flags indicating static properties of this expression
Returns: the copy of the original expression
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
Parameters: context the XPath dynamic evaluation context pul the pending update list to which the results should be written
Returns: the array of expressions to be evaluated when the corresponding condition is true
Returns: the array of condition expressions
Parameters: th Type hierarchy cache
Returns: the static item type of the instruction
Returns: true - this expression has a non-trivial implementation of the staticTypeCheck() method
Parameters: exp the expression to be tested
Returns: true if the expression is a choose expression and there is only one condition, so that the expression returns () if this condition is false
Returns: true if this is an updating expression
Returns: true if this expression is vacuous
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
The events (of class PullEvent) are either complete items, or one of startElement, endElement, startDocument, or endDocument, known as semi-nodes. The stream of events may also include a nested EventIterator. If a start-end pair exists in the sequence, then the events between this pair represent the content of the document or element. The content sequence will have been processed to the extent that any attribute and namespace nodes in the content sequence will have been merged into the startElement event. Namespace fixup will have been performed: that is, unique prefixes will have been allocated to element and attribute nodes, and all namespaces will be declared by means of a namespace node in the startElement event or in an outer startElement forming part of the sequence. However, duplicate namespaces may appear in the sequence.
The content of an element or document may include adjacent or zero-length text nodes, atomic values, and nodes represented as nodes rather than broken down into events.
Parameters: context The dynamic evaluation context
Returns: the result of the expression as an iterator over a sequence of PullEvent objects
Throws: net.sf.saxon.trans.XPathException if a dynamic error occurs during expression evaluation
Parameters: condition the condition to be tested thenExp the expression to be evaluated if the condition is true elseExp the expression to be evaluated if the condition is false
Returns: the expression
Parameters: condition the condition to be tested thenExp the expression to be evaluated if the condition is true
Returns: the expression
Returns: 0 if no tail call was found; 1 if a tail call on a different function was found; 2 if a tail recursive call was found and if this call accounts for the whole of the value.
Parameters: context the dynamic context of this transformation
Returns: a TailCall, if the chosen branch ends with a call of call-template or apply-templates. It is the caller's responsibility to execute such a TailCall. If there is no TailCall, returns null.
Throws: XPathException if any non-recoverable dynamic error occurs
Parameters: offer The type of rewrite being offered
Throws: XPathException
Parameters: original the original subexpression replacement the replacement subexpression
Returns: true if the original subexpression is found
Parameters: visitor expression visitor object
Returns: the simplified expression
Throws: XPathException if an error is discovered during expression rewriting
Parameters: req the required type backwardsCompatible true if backwards compatibility mode applies role the role of the expression in relation to the required type visitor an expression visitor
Returns: the expression after type checking (perhaps augmented with dynamic type checking code)
Throws: XPathException if failures occur, for example if the static type of one branch of the conditional is incompatible with the required type
Returns: a representation of the expression as a string