net.sf.saxon.instruct
Class NumberInstruction

java.lang.Object
  net.sf.saxon.expr.ComputedExpression
      net.sf.saxon.instruct.NumberInstruction

All Implemented Interfaces:

Container, Expression, InstructionInfoProvider, java.io.Serializable, javax.xml.transform.SourceLocator

public class NumberInstruction

extends ComputedExpression

An xsl:number element in the stylesheet. Although this is an XSLT instruction, it is compiled into an expression, evaluated using xsl:value-of to create the resulting text node.

See Also:

Serialized Form

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

NumberInstruction(Configuration config, Expression select, int level, Pattern count, Pattern from, Expression value, Expression format, Expression groupSize, Expression groupSeparator, Expression letterValue, Expression ordinal, Expression lang, NumberFormatter formatter, Numberer numberer, boolean hasVariablesInPatterns, boolean backwardsCompatible)

Method Summary

int	computeCardinality()
void	display(int level, NamePool pool, java.io.PrintStream out) Diagnostic print of expression structure.
Item	evaluateItem(XPathContext context) Evaluate an expression as a single item.
int	getIntrinsicDependencies() Determine the intrinsic dependencies of an expression, that is, those which are not derived from the dependencies of its subexpressions.
ItemType	getItemType(TypeHierarchy th) Determine the data type of the expression, if possible.
java.util.Iterator	iterateSubExpressions() Get the immediate sub-expressions of this expression.
static Numberer	makeNumberer(java.lang.String language, java.lang.String country, XPathContext context) Load a Numberer class for a given language and check it is OK.
Expression	optimize(Optimizer opt, StaticContext env, ItemType contextItemType) Perform optimisation of an expression and its subexpressions.
Expression	promote(PromotionOffer offer) Offer promotion for this subexpression.
Expression	simplify(StaticContext env) Simplify an expression.
Expression	typeCheck(StaticContext env, ItemType contextItemType) Perform static analysis of an expression and its subexpressions.

Methods inherited from class net.sf.saxon.expr.ComputedExpression

adoptChildExpression, checkPermittedContents, computeDependencies, computeSpecialProperties, computeStaticProperties, doPromotion, dynamicError, dynamicError, effectiveBooleanValue, evaluateAsString, getCardinality, getColumnNumber, getConstructType, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getLineNumber, getLocationId, getLocationProvider, getParentExpression, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasBadParentPointer, iterate, markTailFunctionCalls, process, resetStaticProperties, setLocationId, setParentExpression, suppressValidation, typeError, typeError

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

NumberInstruction

public NumberInstruction(Configuration config,
                         Expression select,
                         int level,
                         Pattern count,
                         Pattern from,
                         Expression value,
                         Expression format,
                         Expression groupSize,
                         Expression groupSeparator,
                         Expression letterValue,
                         Expression ordinal,
                         Expression lang,
                         NumberFormatter formatter,
                         Numberer numberer,
                         boolean hasVariablesInPatterns,
                         boolean backwardsCompatible)

Method Detail

simplify

public Expression simplify(StaticContext env)
                    throws XPathException

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 interface Expression

Overrides:

simplify in class ComputedExpression

Returns:

the simplified expression

Throws:

XPathException - if an error is discovered during expression rewriting

typeCheck

public Expression typeCheck(StaticContext env,
                            ItemType contextItemType)
                     throws XPathException

Perform static analysis of an expression and its subexpressions.

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 will only be accurately known if they have been explicitly declared.

Parameters:

env - the static context of the expression

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 Type.ITEM_TYPE

Returns:

the original expression, rewritten to perform necessary run-time type checks, and to perform other type-related optimizations

Throws:

StaticError - if an error is discovered during this phase (typically a type error)

XPathException

optimize

public Expression optimize(Optimizer opt,
                           StaticContext env,
                           ItemType contextItemType)
                    throws XPathException

Perform optimisation of an expression and its subexpressions.

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:

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 expression

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 Type.ITEM_TYPE

Returns:

the original expression, rewritten if appropriate to optimize execution

Throws:

StaticError - if an error is discovered during this phase (typically a type error)

XPathException

iterateSubExpressions

public java.util.Iterator 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.

Specified by:

iterateSubExpressions in interface Expression

Overrides:

iterateSubExpressions in class ComputedExpression

Returns:

an iterator containing the sub-expressions of this expression

getIntrinsicDependencies

public int getIntrinsicDependencies()

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 class ComputedExpression

Returns:

a set of bit-significant flags identifying the "intrinsic" dependencies. The flags are documented in class net.sf.saxon.value.StaticProperty

getItemType

public ItemType getItemType(TypeHierarchy th)

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.

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 class ComputedExpression

promote

public Expression promote(PromotionOffer offer)
                   throws XPathException

Offer promotion for this subexpression. The offer will be accepted if the subexpression is not dependent on the factors (e.g. the context item) identified in the PromotionOffer. By default the offer is not accepted - this is appropriate in the case of simple expressions such as constant values and variable references where promotion would give no performance advantage. This method is always called at compile time.

Specified by:

promote in interface Expression

Overrides:

promote in class ComputedExpression

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

evaluateItem

public Item evaluateItem(XPathContext context)
                  throws XPathException

Description copied from class: ComputedExpression

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.

Specified by:

evaluateItem in interface Expression

Overrides:

evaluateItem in class ComputedExpression

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

makeNumberer

public static Numberer makeNumberer(java.lang.String language,
                                    java.lang.String country,
                                    XPathContext context)

Load a Numberer class for a given language and check it is OK.

Parameters:

language - the language for which a Numberer is required

Returns:

a suitable numberer. If no specific numberer is available for the language, the default (English) numberer is used.

display

public void display(int level,
                    NamePool pool,
                    java.io.PrintStream out)

Diagnostic print of expression structure. The expression is written to the System.err output stream

Parameters:

level - indentation level for this expression

out -

pool - NamePool used to expand any names appearing in the expression