net.sf.saxon.pattern

Class Pattern

public abstract class Pattern extends Object implements PatternFinder, Serializable, Container

A Pattern represents the result of parsing an XSLT pattern string.
Patterns are created by calling the static method Pattern.make(string).
The pattern is used to test a particular node by calling match().
Method Summary
intallocateSlots(StaticContext env, SlotManager slotManager, int nextFree)
Allocate slots to any variables used within the pattern
Patternanalyze(ExpressionVisitor visitor, ItemType contextItemType)
Type-check the pattern.
intgetColumnNumber()
Get the column number (always -1)
intgetContainerGranularity()
Get the granularity of the container.
doublegetDefaultPriority()
Determine the default priority to use if this pattern appears as a match pattern for a template with no explicit priority attribute.
intgetDependencies()
Get the dependencies of the pattern.
ExecutablegetExecutable()
Get the executable containing this pattern
intgetFingerprint()
Determine the name fingerprint of nodes to which this pattern applies.
intgetHostLanguage()
Get the host language (XSLT, XQuery, XPath) used to implement the code in this container
intgetLineNumber()
Get the line number on which the pattern was defined
LocationProvidergetLocationProvider()
Get the LocationProvider allowing location identifiers to be resolved.
intgetNodeKind()
Determine the types of nodes to which this pattern applies.
abstract NodeTestgetNodeTest()
Get a NodeTest that all the nodes matching this pattern must satisfy
StringgetPublicId()
Get the public ID (always null)
StringgetSystemId()
Get the system id of the entity in which the pattern occurred
protected booleaninternalMatches(NodeInfo node, XPathContext context)
Determine whether this Pattern matches the given Node.
IteratoriterateSubExpressions()
Iterate over the subexpressions within this pattern
static Patternmake(String pattern, StaticContext env, Executable exec)
Static method to make a Pattern by parsing a String.
ExpressionmakeSearchExpression()
Make an expression whose effect is to select all the nodes that match this pattern in a given document.
abstract booleanmatches(NodeInfo node, XPathContext context)
Determine whether this Pattern matches the given Node.
voidpromote(PromotionOffer offer, Expression parent)
Offer promotion for subexpressions within this pattern.
booleanreplaceSubExpression(Expression original, Expression replacement)
Replace a subexpression by a replacement subexpression
SequenceIteratorselectNodes(DocumentInfo doc, XPathContext context)
Select nodes in a document using this PatternFinder.
voidsetExecutable(Executable executable)
Set the executable containing this pattern
voidsetLineNumber(int lineNumber)
Set the line number where the pattern occurred
voidsetOriginalText(String text)
Set the original text of the pattern for use in diagnostics
voidsetSystemId(String systemId)
Set the system ID where the pattern occurred
Patternsimplify(ExpressionVisitor visitor)
Simplify the pattern by applying any context-independent optimisations.
StringtoString()
Get the original pattern text

Method Detail

allocateSlots

public int allocateSlots(StaticContext env, SlotManager slotManager, int nextFree)
Allocate slots to any variables used within the pattern

Parameters: env the static context in the XSLT stylesheet slotManager the slot manager representing the stack frame for local variables nextFree the next slot that is free to be allocated @return the next slot that is free to be allocated

analyze

public Pattern analyze(ExpressionVisitor visitor, ItemType contextItemType)
Type-check the pattern.

Parameters: visitor the expression visitor contextItemType the type of the context item at the point where the pattern is defined. Set to null if it is known that the context item is undefined.

Returns: the optimised Pattern

getColumnNumber

public int getColumnNumber()
Get the column number (always -1)

getContainerGranularity

public int getContainerGranularity()
Get the granularity of the container.

Returns: 0 for a temporary container created during parsing; 1 for a container that operates at the level of an XPath expression; 2 for a container at the level of a global function or template

getDefaultPriority

public double getDefaultPriority()
Determine the default priority to use if this pattern appears as a match pattern for a template with no explicit priority attribute.

Returns: the default priority for the pattern

getDependencies

public int getDependencies()
Get the dependencies of the pattern. The only possible dependency for a pattern is on local variables. This is analyzed in those patterns where local variables may appear.

Returns: the dependencies, as a bit-significant mask

getExecutable

public Executable getExecutable()
Get the executable containing this pattern

Returns: the executable

getFingerprint

public int getFingerprint()
Determine the name fingerprint of nodes to which this pattern applies. Used for optimisation.

Returns: A fingerprint that the nodes must match, or -1 if it can match multiple fingerprints

getHostLanguage

public int getHostLanguage()
Get the host language (XSLT, XQuery, XPath) used to implement the code in this container

Returns: typically XSLT or XQUERY

getLineNumber

public int getLineNumber()
Get the line number on which the pattern was defined

getLocationProvider

public LocationProvider getLocationProvider()
Get the LocationProvider allowing location identifiers to be resolved.

getNodeKind

public int getNodeKind()
Determine the types of nodes to which this pattern applies. Used for optimisation. For patterns that match nodes of several types, return Type.NODE

Returns: the type of node matched by this pattern. e.g. Type.ELEMENT or Type.TEXT

getNodeTest

public abstract NodeTest getNodeTest()
Get a NodeTest that all the nodes matching this pattern must satisfy

Returns: a NodeTest, as specific as possible, which all the matching nodes satisfy

getPublicId

public String getPublicId()
Get the public ID (always null)

getSystemId

public String getSystemId()
Get the system id of the entity in which the pattern occurred

internalMatches

protected boolean internalMatches(NodeInfo node, XPathContext context)
Determine whether this Pattern matches the given Node. This is an internal interface used for matching sub-patterns; it does not alter the value of current(). The default implementation is identical to matches().

Parameters: node The NodeInfo representing the Element or other node to be tested against the Pattern context The dynamic context. Only relevant if the pattern uses variables, or contains calls on functions such as document() or key().

Returns: true if the node matches the Pattern, false otherwise

iterateSubExpressions

public Iterator iterateSubExpressions()
Iterate over the subexpressions within this pattern

Returns: an iterator over the subexpressions. Default implementation returns an empty sequence

make

public static Pattern make(String pattern, StaticContext env, Executable exec)
Static method to make a Pattern by parsing a String.

Parameters: pattern The pattern text as a String env An object defining the compile-time context for the expression exec The executable containing this pattern

Returns: The pattern object

makeSearchExpression

public Expression makeSearchExpression()
Make an expression whose effect is to select all the nodes that match this pattern in a given document. This expression takes the root of the tree (always a document node) as the context node; it takes into account all the constraints expressed by the pattern including the parent and ancestor nodes and the filters

matches

public abstract boolean matches(NodeInfo node, XPathContext context)
Determine whether this Pattern matches the given Node. This is the main external interface for matching patterns: it sets current() to the node being tested

Parameters: node The NodeInfo representing the Element or other node to be tested against the Pattern context The dynamic context. Only relevant if the pattern uses variables, or contains calls on functions such as document() or key().

Returns: true if the node matches the Pattern, false otherwise

promote

public void promote(PromotionOffer offer, Expression parent)
Offer promotion for subexpressions within this pattern. 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.

Unlike the corresponding method on Expression, this method does not return anything: it can make internal changes to the pattern, but cannot return a different pattern. Only certain kinds of promotion are applicable within a pattern: specifically, promotions affecting local variable references within the pattern.

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

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

replaceSubExpression

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

Parameters: original the expression to be replaced replacement the new expression to be inserted in its place

Returns: true if the replacement was carried out

selectNodes

public SequenceIterator selectNodes(DocumentInfo doc, XPathContext context)
Select nodes in a document using this PatternFinder.

Parameters: doc the document node at the root of a tree context the dynamic evaluation context

Returns: an iterator over the selected nodes in the document.

setExecutable

public void setExecutable(Executable executable)
Set the executable containing this pattern

Parameters: executable the executable

setLineNumber

public void setLineNumber(int lineNumber)
Set the line number where the pattern occurred

Parameters: lineNumber the line number of the pattern in the source module

setOriginalText

public void setOriginalText(String text)
Set the original text of the pattern for use in diagnostics

Parameters: text the original text of the pattern

setSystemId

public void setSystemId(String systemId)
Set the system ID where the pattern occurred

Parameters: systemId the URI of the module containing the pattern

simplify

public Pattern simplify(ExpressionVisitor visitor)
Simplify the pattern by applying any context-independent optimisations. Default implementation does nothing.

Parameters: visitor the expression visitor

Returns: the optimised Pattern

toString

public String toString()
Get the original pattern text