net.sf.saxon.instruct

Class NumberInstruction

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.
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
intcomputeCardinality()
voiddisplay(int level, NamePool pool, PrintStream out)
Diagnostic print of expression structure.
ItemevaluateItem(XPathContext context)
intgetIntrinsicDependencies()
Determine the intrinsic dependencies of an expression, that is, those which are not derived from the dependencies of its subexpressions.
ItemTypegetItemType(TypeHierarchy th)
IteratoriterateSubExpressions()
Get the immediate sub-expressions of this expression.
static NumberermakeNumberer(String language, String country, XPathContext context)
Load a Numberer class for a given language and check it is OK.
Expressionoptimize(Optimizer opt, StaticContext env, ItemType contextItemType)
Perform optimisation of an expression and its subexpressions.
Expressionpromote(PromotionOffer offer)
Offer promotion for this subexpression.
Expressionsimplify(StaticContext env)
ExpressiontypeCheck(StaticContext env, ItemType contextItemType)
Perform static analysis of an expression and its subexpressions.

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

computeCardinality

public int computeCardinality()

display

public void display(int level, NamePool pool, 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

evaluateItem

public Item evaluateItem(XPathContext context)

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".

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)

iterateSubExpressions

public 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.

Returns: an iterator containing the sub-expressions of this expression

makeNumberer

public static Numberer makeNumberer(String language, 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.

optimize

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

Returns: the original expression, rewritten if appropriate to optimize execution

Throws: net.sf.saxon.trans.StaticError if an error is discovered during this phase (typically a type error)

promote

public Expression promote(PromotionOffer offer)
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.

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: net.sf.saxon.trans.XPathException if any error is detected

simplify

public Expression simplify(StaticContext env)

typeCheck

public Expression typeCheck(StaticContext env, ItemType contextItemType)
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

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

Throws: net.sf.saxon.trans.StaticError if an error is discovered during this phase (typically a type error)