net.sf.saxon.pattern
public class PatternSponsor extends Expression
This class implements the Expression interface, so that an Expression can have a PatternSponsor as a subexpression; it wraps a Pattern.
A Pattern is treated as a boolean expression that returns true if the pattern matches the context node. It is evaluated in that way only when obtained through the s9api compilePattern method.
Constructor Summary | |
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PatternSponsor(Pattern pattern)
Create a sponsor expression for a pattern |
Method Summary | |
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void | checkPermittedContents(SchemaType parentType, StaticContext env, boolean whole)
Check statically that the results of the expression are capable of constructing the content
of a given schema type.
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protected int | computeCardinality() |
Expression | copy()
Copy an expression. |
boolean | effectiveBooleanValue(XPathContext context)
Get the effective boolean value of the expression. |
CharSequence | evaluateAsString(XPathContext context)
Evaluate an expression as a String. |
Item | evaluateItem(XPathContext context)
Evaluate an expression as a single item. |
void | explain(ExpressionPresenter out)
Diagnostic print of expression structure. |
int | getCardinality() Determine the static cardinality of the expression. |
Container | getContainer()
Get the container that immediately contains this expression. |
int | getDependencies()
Determine which aspects of the context the expression depends on. |
int | getImplementationMethod()
An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process().
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ItemType | getItemType(TypeHierarchy th)
Determine the data type of the expression, if possible. |
Pattern | getPattern()
Get the wrapped pattern |
boolean | hasLoopingSubexpression(Expression child)
Treat all subexpressions as being evaluated repeatedly |
SequenceIterator | iterate(XPathContext context)
Return an Iterator to iterate over the values of a sequence. |
Iterator<Expression> | iterateSubExpressions()
Get the immediate sub-expressions of this expression. |
Expression | optimize(ExpressionVisitor visitor, ItemType contextItemType)
Perform optimisation of an expression and its subexpressions.
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void | process(XPathContext context)
Process the instruction, without returning any tail calls
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Expression | promote(PromotionOffer offer, Expression parent)
Offer promotion for this subexpression. |
boolean | replaceSubExpression(Expression original, Expression replacement)
Replace one subexpression by a replacement subexpression |
Expression | simplify(ExpressionVisitor visitor)
Simplify an expression. |
Expression | typeCheck(ExpressionVisitor visitor, ItemType contextItemType)
Perform type checking of an expression and its subexpressions.
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Parameters: pattern the pattern being wrapped
Parameters: parentType The schema type env the static context whole true if this expression is expected to make the whole content of the type, false if it is expected to make up only a part
Throws: net.sf.saxon.trans.XPathException if the expression doesn't match the required content type
Returns: the copy of the original expression
Parameters: context The context in which the expression is to be evaluated
Returns: the effective boolean value
Throws: net.sf.saxon.trans.XPathException if any dynamic error occurs evaluating the expression
Parameters: context The context in which the expression is to be evaluated
Returns: the value of the expression, evaluated in the current context. The expression must return a string or (); if the value of the expression is (), this method returns "".
Throws: net.sf.saxon.trans.XPathException if any dynamic error occurs evaluating the expression ClassCastException if the result type of the expression is not xs:string?
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: net.sf.saxon.trans.XPathException if any dynamic error occurs evaluating the expression
Determine the static cardinality of the expression. This establishes how many items there will be in the result of the expression, at compile time (i.e., without actually evaluating the result.
This method should always return a result, though it may be the best approximation that is available at the time.
Returns: one of the values ALLOWS_ONE, ALLOWS_ZERO_OR_MORE, ALLOWS_ZERO_OR_ONE, ALLOWS_ONE_OR_MORE, EMPTY.
Returns: the expression that contains this expression, if known; return null if there is no containing expression or if the containing expression is unknown.
Returns: a set of bit-significant flags identifying the dependencies of the expression
This method should always return a result, though it may be the best approximation that is available at the time.
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)
Returns: the wrapped pattern
Parameters: child
Returns:
Parameters: context supplies the context for evaluation
Returns: a SequenceIterator that can be used to iterate over the result of the expression
Throws: net.sf.saxon.trans.XPathException if any dynamic error occurs evaluating the expression
Returns: an iterator containing the sub-expressions of this 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.
Parameters: visitor an expression visitor contextItemType 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 ITEM_TYPE
Returns: the original expression, rewritten if appropriate to optimize execution
Throws: XPathException if an error is discovered during this phase (typically a type error)
Parameters: context The dynamic context, giving access to the current node, the current variables, etc.
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 parent
Returns: if the offer is not accepted, return this expression unchanged. Otherwise return the result of rewriting the expression to promote this subexpression
Throws: net.sf.saxon.trans.XPathException if any error is detected
Parameters: original the original subexpression replacement the replacement subexpression
Returns: true if the original subexpression is found
Parameters: visitor an expression visitor
Returns: the simplified expression
Throws: XPathException if an error is discovered during expression rewriting
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.
Parameters: visitor an expression visitor contextItemType 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 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)