Package net.sf.saxon.pattern
Class Pattern
- java.lang.Object
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- net.sf.saxon.expr.Expression
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- net.sf.saxon.expr.PseudoExpression
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- net.sf.saxon.pattern.Pattern
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- All Implemented Interfaces:
ExportAgent,Locatable,IdentityComparable,Traceable
- Direct Known Subclasses:
AncestorQualifiedPattern,AnchorPattern,BasePatternWithPredicate,BooleanExpressionPattern,GeneralNodePattern,GeneralPositionalPattern,ItemTypePattern,NodeSetPattern,NodeTestPattern,PatternThatSetsCurrent,SimplePositionalPattern,StreamingFunctionArgumentPattern,UniversalPattern,VennPattern
public abstract class Pattern extends PseudoExpression
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().
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Field Summary
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Fields inherited from class net.sf.saxon.expr.Expression
EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, MAX_COST, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, UPDATE_METHOD, WATCH_METHOD
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Constructor Summary
Constructors Constructor Description Pattern()
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Method Summary
All Methods Static Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description intallocateSlots(SlotManager slotManager, int nextFree)Allocate slots to any variables used within the patternvoidbindCurrent(LocalBinding binding)Replace any calls on current() by a variable reference bound to the supplied bindingPatternconvertToTypedPattern(java.lang.String val)Convert the pattern to a typed pattern, in which an element name is treated as schema-element(N)abstract Patterncopy(RebindingMap rebindings)Copy an expression.booleaneffectiveBooleanValue(XPathContext context)Evaluate a pattern as a boolean expression, returning true if the context item matches the patternabstract voidexport(ExpressionPresenter presenter)Diagnostic print of expression structure.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.intgetFingerprint()Determine the name fingerprint of nodes to which this pattern applies.HostLanguagegetHostLanguage()Get the host language (XSLT, XQuery, XPath) used to implement the code in this containerabstract ItemTypegetItemType()Get an ItemType that all the items matching this pattern must satisfyjava.lang.StringgetOriginalText()Get the original text of the pattern, if knownabstract UTypegetUType()Get a UType indicating which kinds of items this Pattern can match.protected voidhandleDynamicError(XPathException ex, XPathContext context)Handle a dynamic error occurring in the course of pattern evaluation.booleanisLiftable(boolean forStreaming)Ask whether the expression can be lifted out of a loop, assuming it has no dependencies on the controlling variable/focus of the loopbooleanisMotionless()Test whether a pattern is motionless, that is, whether it can be evaluated against a node without repositioning the input stream.booleanisRecoverable()Ask whether dynamic errors in evaluating the pattern should be recovered.static Patternmake(java.lang.String pattern, StaticContext env, PackageData packageData)Static factory method to make a Pattern by parsing a String.abstract booleanmatches(Item item, XPathContext context)Determine whether this Pattern matches the given item.booleanmatchesBeneathAnchor(NodeInfo node, NodeInfo anchor, XPathContext context)Determine whether this pattern matches a given Node within the subtree rooted at a given anchor node.booleanmatchesCurrentGroup()Ask whether the pattern is anchored on a call on current-group()Patternoptimize(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo)Perform optimisation of an expression and its subexpressions.static booleanpatternContainsVariable(Pattern pattern)Ask whether a pattern has dependencies on local variablesjava.lang.Stringreconstruct()Reconstruct a string representation of the pattern in cases where the original string is not availableprotected static voidreplaceCurrent(Expression exp, LocalBinding binding)Replace any call to current() within a contained expression by a reference to a variableSequenceIteratorselectNodes(TreeInfo document, XPathContext context)Select all nodes in a document that match this pattern.voidsetOriginalText(java.lang.String text)Set the original text of the pattern for use in diagnosticsvoidsetPriority(double priority)Set a priority to override the default priority.voidsetRecoverable(boolean recoverable)Aay whether dynamic errors in evaluating the pattern should be recovered.Patternsimplify()Simplify the pattern by applying any context-independent optimisations.PatterntoPattern(Configuration config)Convert this expression to an equivalent XSLT patternjava.lang.StringtoShortString()Produce a short string identifying the expression for use in error messagesjava.lang.StringtoString()Get a string representation of the pattern.PatterntypeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo)Type-check the pattern.-
Methods inherited from class net.sf.saxon.expr.PseudoExpression
computeCardinality, evaluateAsString, evaluateItem, getImplementationMethod, iterate, process
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Methods inherited from class net.sf.saxon.expr.Expression
addToPathMap, adoptChildExpression, allowExtractingCommonSubexpressions, checkedOperands, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeHashCode, computeSpecialProperties, computeStaticProperties, dynamicError, equals, evaluatePendingUpdates, explain, getCardinality, getConfiguration, getCost, getEvaluationMethod, getExpressionName, getExtraProperty, getIntegerBounds, getInterpretedExpression, getIntrinsicDependencies, getLocalRetainedStaticContext, getLocation, getNetCost, getObjectName, getPackageData, getParentExpression, getProperties, getProperty, getRetainedStaticContext, getScopingExpression, getSlotsUsed, getSpecialProperties, getStaticBaseURI, getStaticBaseURIString, getStaticType, getStaticUType, getStreamerName, getTracingTag, hasCompatibleStaticContext, hashCode, hasSpecialProperty, hasVariableBinding, identityHashCode, implementsStaticTypeCheck, isCallOn, isEqual, isIdentical, isInstruction, isMultiThreaded, isStaticPropertiesKnown, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, markTailFunctionCalls, operandList, operands, operandSparseList, optimizeChildren, prepareForStreaming, resetLocalStaticProperties, restoreParentPointers, setEvaluationMethod, setExtraProperty, setFiltered, setFlattened, setLocation, setParentExpression, setRetainedStaticContext, setRetainedStaticContextLocally, setRetainedStaticContextThoroughly, setStaticProperty, simplifyChildren, staticTypeCheck, suppressValidation, typeCheckChildren, typeError, unordered, verifyParentPointers
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Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
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Methods inherited from interface net.sf.saxon.trace.Traceable
gatherProperties
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Method Detail
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make
public static Pattern make(java.lang.String pattern, StaticContext env, PackageData packageData) throws XPathException
Static factory method to make a Pattern by parsing a String.- Parameters:
pattern- The pattern text as a Stringenv- An object defining the compile-time context for the expressionpackageData- The package containing this pattern- Returns:
- The pattern object
- Throws:
XPathException- if the pattern is invalid
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replaceCurrent
protected static void replaceCurrent(Expression exp, LocalBinding binding)
Replace any call to current() within a contained expression by a reference to a variable- Parameters:
exp- the expression in which the replacement is to take place (which must not itself be a call to current())binding- the binding for the variable reference
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patternContainsVariable
public static boolean patternContainsVariable(Pattern pattern)
Ask whether a pattern has dependencies on local variables- Parameters:
pattern- the pattern (typically a pattern in an xsl:number or xsl:for-each-group); or null- Returns:
- true if the pattern is non-null and has dependencies on local variables
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isLiftable
public boolean isLiftable(boolean forStreaming)
Ask whether the expression can be lifted out of a loop, assuming it has no dependencies on the controlling variable/focus of the loop- Overrides:
isLiftablein classExpression- Parameters:
forStreaming- true if we are generating code for streaming- Returns:
- true if the expression can be loop lifted
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bindCurrent
public void bindCurrent(LocalBinding binding)
Replace any calls on current() by a variable reference bound to the supplied binding
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matchesCurrentGroup
public boolean matchesCurrentGroup()
Ask whether the pattern is anchored on a call on current-group()- Returns:
- true if calls on matchesBeneathAnchor should test with all nodes in the current group as anchor nodes. If false, only the first node in a group is treated as the anchor node
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setOriginalText
public void setOriginalText(java.lang.String text)
Set the original text of the pattern for use in diagnostics- Parameters:
text- the original text of the pattern
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isRecoverable
public boolean isRecoverable()
Ask whether dynamic errors in evaluating the pattern should be recovered. This is the default for normal XSLT patterns, but patterns used internally to represent scannable streaming expressions are non-recoverable- Returns:
- true if dynamic errors in pattern evaluation should be treated as recoverable (if an error occurs, the pattern is treated as non-matching; a warning is sent to the ErrorListener).
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setRecoverable
public void setRecoverable(boolean recoverable)
Aay whether dynamic errors in evaluating the pattern should be recovered. This is the default for normal XSLT patterns, but patterns used internally to represent scannable streaming expressions are non-recoverable- Parameters:
recoverable- true if dynamic errors in pattern evaluation should be treated as recoverable (if an error occurs, the pattern is treated as non-matching; a warning is sent to the ErrorListener).
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handleDynamicError
protected void handleDynamicError(XPathException ex, XPathContext context) throws XPathException
Handle a dynamic error occurring in the course of pattern evaluation. The effect depends on (a) whether the error is a circularity error, and (b) whether the pattern is marked as recoverable or not- Parameters:
ex- the exceptioncontext- the evaluation context- Throws:
XPathException- if the error is found to be non-recoverable
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simplify
public Pattern simplify() throws XPathException
Simplify the pattern by applying any context-independent optimisations. Default implementation does nothing.- Overrides:
simplifyin classExpression- Returns:
- the simplified expression (or the original if unchanged, or if modified in-situ)
- Throws:
XPathException- if an error is discovered during expression rewriting
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typeCheck
public Pattern typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) throws XPathException
Type-check the pattern.- Overrides:
typeCheckin classExpression- Parameters:
visitor- the expression visitorcontextInfo- 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
- Throws:
XPathException- if an error is discovered during this phase (typically a type error)
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getDependencies
public int getDependencies()
Get the dependencies of the pattern. The only interesting dependencies for a pattern are dependencies on local variables or on user-defined functions. These are analyzed in those patterns containing predicates.- Overrides:
getDependenciesin classExpression- Returns:
- the dependencies, as a bit-significant mask
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allocateSlots
public int allocateSlots(SlotManager slotManager, int nextFree)
Allocate slots to any variables used within the pattern- Parameters:
slotManager- the slot manager representing the stack frame for local variablesnextFree- the next slot that is free to be allocated- Returns:
- the next slot that is free to be allocated
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isMotionless
public boolean isMotionless()
Test whether a pattern is motionless, that is, whether it can be evaluated against a node without repositioning the input stream. This is a necessary condition for patterns used as the match pattern of a streamed template rule.- Returns:
- true if the pattern is motionless, that is, if it can be evaluated against a streamed node without changing the position in the streamed input file
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effectiveBooleanValue
public final boolean effectiveBooleanValue(XPathContext context) throws XPathException
Evaluate a pattern as a boolean expression, returning true if the context item matches the pattern- Overrides:
effectiveBooleanValuein classPseudoExpression- Parameters:
context- the evaluation context- Returns:
- true if the context item matches the pattern
- Throws:
XPathException- if an error occurs during pattern matching
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matches
public abstract boolean matches(Item item, XPathContext context) throws XPathException
Determine whether this Pattern matches the given item. This is the main external interface for matching patterns: it sets current() to the node being tested- Parameters:
item- The item to be tested against the Patterncontext- The dynamic context.- Returns:
- true if the node matches the Pattern, false otherwise
- Throws:
XPathException- if an error occurs while matching the pattern (the caller will usually treat this the same as a false result)
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matchesBeneathAnchor
public boolean matchesBeneathAnchor(NodeInfo node, NodeInfo anchor, XPathContext context) throws XPathException
Determine whether this pattern matches a given Node within the subtree rooted at a given anchor node. This method is used when the pattern is used for streaming.- Parameters:
node- The NodeInfo representing the Element or other node to be tested against the Patternanchor- The anchor node, which must match any AnchorPattern subpatterncontext- 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
- Throws:
XPathException- if an error occurs while matching the pattern (the caller will usually treat this the same as a false result)
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selectNodes
public SequenceIterator selectNodes(TreeInfo document, XPathContext context) throws XPathException
Select all nodes in a document that match this pattern.- Parameters:
document- the documentcontext- the dynamic evaluation context- Returns:
- an iterator over the selected nodes in the document.
- Throws:
XPathException
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getUType
public abstract UType getUType()
Get a UType indicating which kinds of items this Pattern can match.- Returns:
- a UType indicating all the primitive types of item that the pattern can match.
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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, or it if matches atomic values
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getItemType
public abstract ItemType getItemType()
Get an ItemType that all the items matching this pattern must satisfy- Overrides:
getItemTypein classPseudoExpression- Returns:
- an ItemType, as specific as possible, which all the matching items satisfy
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setPriority
public void setPriority(double priority)
Set a priority to override the default priority. This is used when the pattern is written in a complex form such as a[true()] justifying a priority of 0.5, but then simplifies down to an NodeTestPattern- Parameters:
priority- the priority to be used if no explicit priority is given in the template rule
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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
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getOriginalText
public java.lang.String getOriginalText()
Get the original text of the pattern, if known- Returns:
- the original text of the pattern as written; this may be null in the case of a pattern constructed programmatically
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toString
public java.lang.String toString()
Get a string representation of the pattern. This will be in a form similar to the original pattern text, but not necessarily identical. It is not guaranteed to be in legal pattern syntax.- Overrides:
toStringin classExpression- Returns:
- a representation of the expression as a string
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reconstruct
public java.lang.String reconstruct()
Reconstruct a string representation of the pattern in cases where the original string is not available
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getHostLanguage
public HostLanguage getHostLanguage()
Get the host language (XSLT, XQuery, XPath) used to implement the code in this container- Returns:
- typically
HostLanguage.XSLTorHostLanguage.XQUERY
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convertToTypedPattern
public Pattern convertToTypedPattern(java.lang.String val) throws XPathException
Convert the pattern to a typed pattern, in which an element name is treated as schema-element(N)- Parameters:
val- either "strict" or "lax" depending on the value of xsl:mode/@typed- Returns:
- either the original pattern unchanged, or a new pattern as the result of the conversion
- Throws:
XPathException- if the pattern cannot be converted
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toPattern
public Pattern toPattern(Configuration config)
Description copied from class:ExpressionConvert this expression to an equivalent XSLT pattern- Overrides:
toPatternin classExpression- Parameters:
config- the Saxon configuration- Returns:
- the equivalent pattern
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export
public abstract void export(ExpressionPresenter presenter) throws XPathException
Description copied from class:ExpressionDiagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.- Specified by:
exportin interfaceExportAgent- Specified by:
exportin classExpression- Parameters:
presenter- the expression presenter used to display the structure- Throws:
XPathException- if the export fails, for example if an expression is found that won't work in the target environment.
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copy
public abstract Pattern copy(RebindingMap rebindings)
Description copied from class:ExpressionCopy an expression. This makes a deep copy.- Specified by:
copyin classExpression- Parameters:
rebindings- a mutable list of (old binding, new binding) pairs that is used to update the bindings held in any local variable references that are copied.- Returns:
- the copy of the original expression
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optimize
public Pattern optimize(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) throws XPathException
Perform optimisation of an expression and its subexpressions. This is the third and final phase of static optimization.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.
- Overrides:
optimizein classExpression- Parameters:
visitor- an expression visitorcontextInfo- 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 toType.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)
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toShortString
public java.lang.String toShortString()
Description copied from class:ExpressionProduce a short string identifying the expression for use in error messages- Overrides:
toShortStringin classExpression- Returns:
- a short string, sufficient to identify the expression
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