net.sf.saxon.instruct

Class NumberInstruction

public class NumberInstruction extends Expression

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)
Construct a NumberInstruction
Method Summary
intcomputeCardinality()
Expressioncopy()
Copy an expression.
ItemevaluateItem(XPathContext context)
voidexplain(ExpressionPresenter out)
Diagnostic print of expression structure.
intgetIntrinsicDependencies()
Determine the intrinsic dependencies of an expression, that is, those which are not derived from the dependencies of its subexpressions.
ItemTypegetItemType(TypeHierarchy th)
Iterator<Expression>iterateSubExpressions()
Get the immediate sub-expressions of this expression.
Expressionoptimize(ExpressionVisitor visitor, ItemType contextItemType)
Perform optimisation of an expression and its subexpressions.
Expressionpromote(PromotionOffer offer, Expression parent)
Offer promotion for this subexpression.
booleanreplaceSubExpression(Expression original, Expression replacement)
Replace one subexpression by a replacement subexpression
Expressionsimplify(ExpressionVisitor visitor)
ExpressiontypeCheck(ExpressionVisitor visitor, 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)
Construct a NumberInstruction

Parameters: config the Saxon configuration select the expression supplied in the select attribute level one of "single", "level", "multi" count the pattern supplied in the count attribute from the pattern supplied in the from attribute value the expression supplied in the value attribute format the expression supplied in the format attribute groupSize the expression supplied in the group-size attribute groupSeparator the expression supplied in the grouping-separator attribute letterValue the expression supplied in the letter-value attribute ordinal the expression supplied in the ordinal attribute lang the expression supplied in the lang attribute formatter A NumberFormatter to be used numberer A Numberer to be used for localization hasVariablesInPatterns true if one or more of the patterns contains variable references backwardsCompatible true if running in 1.0 compatibility mode

Method Detail

computeCardinality

public int computeCardinality()

copy

public Expression copy()
Copy an expression. This makes a deep copy.

Returns: the copy of the original expression

evaluateItem

public Item evaluateItem(XPathContext context)

explain

public void explain(ExpressionPresenter out)
Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.

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<Expression> 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

optimize

public Expression optimize(ExpressionVisitor visitor, 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: 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)

promote

public Expression promote(PromotionOffer offer, Expression parent)
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 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

replaceSubExpression

public boolean replaceSubExpression(Expression original, Expression replacement)
Replace one subexpression by a replacement subexpression

Parameters: original the original subexpression replacement the replacement subexpression

Returns: true if the original subexpression is found

simplify

public Expression simplify(ExpressionVisitor visitor)

typeCheck

public Expression typeCheck(ExpressionVisitor visitor, 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: 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)