Package org.apache.xalan.templates
Class RedundentExprEliminator
- java.lang.Object
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- org.apache.xpath.XPathVisitor
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- org.apache.xalan.templates.XSLTVisitor
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- org.apache.xalan.templates.RedundentExprEliminator
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public class RedundentExprEliminator extends XSLTVisitor
This class eleminates redundent XPaths from a given subtree, and also collects all absolute paths within the subtree. First it must be called as a visitor to the subtree, and then eleminateRedundent must be called.
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Field Summary
Fields Modifier and Type Field Description static boolean
DEBUG
static boolean
DIAGNOSE_MULTISTEPLIST
static boolean
DIAGNOSE_NUM_PATHS_REDUCED
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Constructor Summary
Constructors Constructor Description RedundentExprEliminator()
Construct a RedundentExprEliminator.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
eleminateRedundentGlobals(StylesheetRoot stylesheet)
Method to be called after the all global expressions within a stylesheet have been collected.void
eleminateRedundentLocals(ElemTemplateElement psuedoVarRecipient)
Method to be called after the all expressions within an node context have been visited.boolean
isAbsolute(LocPathIterator path)
Tell if the given LocPathIterator is relative to an absolute path, i.e.boolean
visitInstruction(ElemTemplateElement elem)
Visit an XSLT instruction.boolean
visitLocationPath(ExpressionOwner owner, LocPathIterator path)
Visit a LocationPath.boolean
visitPredicate(ExpressionOwner owner, Expression pred)
Visit a predicate within a location path.boolean
visitTopLevelInstruction(ElemTemplateElement elem)
Visit an XSLT top-level instruction.-
Methods inherited from class org.apache.xalan.templates.XSLTVisitor
visitAVT, visitExtensionElement, visitLiteralResultElement, visitStylesheet, visitTopLevelVariableOrParamDecl, visitVariableOrParamDecl
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Methods inherited from class org.apache.xpath.XPathVisitor
visitBinaryOperation, visitFunction, visitMatchPattern, visitNumberLiteral, visitStep, visitStringLiteral, visitUnaryOperation, visitUnionPath, visitUnionPattern, visitVariableRef
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Field Detail
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DEBUG
public static final boolean DEBUG
- See Also:
- Constant Field Values
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DIAGNOSE_NUM_PATHS_REDUCED
public static final boolean DIAGNOSE_NUM_PATHS_REDUCED
- See Also:
- Constant Field Values
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DIAGNOSE_MULTISTEPLIST
public static final boolean DIAGNOSE_MULTISTEPLIST
- See Also:
- Constant Field Values
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Method Detail
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eleminateRedundentLocals
public void eleminateRedundentLocals(ElemTemplateElement psuedoVarRecipient)
Method to be called after the all expressions within an node context have been visited. It eliminates redundent expressions by creating a variable in the psuedoVarRecipient for each redundent expression, and then rewriting the redundent expression to be a variable reference.- Parameters:
psuedoVarRecipient
- The recipient of the psuedo vars. The variables will be inserted as first children of the element, before any existing variables.
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eleminateRedundentGlobals
public void eleminateRedundentGlobals(StylesheetRoot stylesheet)
Method to be called after the all global expressions within a stylesheet have been collected. It eliminates redundent expressions by creating a variable in the psuedoVarRecipient for each redundent expression, and then rewriting the redundent expression to be a variable reference.
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isAbsolute
public boolean isAbsolute(LocPathIterator path)
Tell if the given LocPathIterator is relative to an absolute path, i.e. in not dependent on the context.- Returns:
- true if the LocPathIterator is not dependent on the context node.
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visitLocationPath
public boolean visitLocationPath(ExpressionOwner owner, LocPathIterator path)
Visit a LocationPath.- Overrides:
visitLocationPath
in classXPathVisitor
- Parameters:
owner
- The owner of the expression, to which the expression can be reset if rewriting takes place.path
- The LocationPath object.- Returns:
- true if the sub expressions should be traversed.
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visitPredicate
public boolean visitPredicate(ExpressionOwner owner, Expression pred)
Visit a predicate within a location path. Note that there isn't a proper unique component for predicates, and that the expression will be called also for whatever type Expression is.- Overrides:
visitPredicate
in classXPathVisitor
- Parameters:
owner
- The owner of the expression, to which the expression can be reset if rewriting takes place.pred
- The predicate object.- Returns:
- true if the sub expressions should be traversed.
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visitTopLevelInstruction
public boolean visitTopLevelInstruction(ElemTemplateElement elem)
Visit an XSLT top-level instruction.- Overrides:
visitTopLevelInstruction
in classXSLTVisitor
- Parameters:
elem
- The xsl instruction element object.- Returns:
- true if the sub expressions should be traversed.
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visitInstruction
public boolean visitInstruction(ElemTemplateElement elem)
Visit an XSLT instruction. Any element that isn't called by one of the other visit methods, will be called by this method.- Overrides:
visitInstruction
in classXSLTVisitor
- Parameters:
elem
- The xsl instruction element object.- Returns:
- true if the sub expressions should be traversed.
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