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java.lang.Object net.sf.saxon.expr.parser.Optimizer
public class Optimizer
This class performs optimizations that vary between different versions of the Saxon product. The optimizer is obtained from the Saxon Configuration. This class is the version used in Saxon-B, which in most cases does no optimization at all: the methods are provided so that they can be overridden in Saxon-EE.
Field Summary | |
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protected Configuration |
config
|
static int |
FULL_OPTIMIZATION
|
static int |
NO_OPTIMIZATION
|
Constructor Summary | |
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Optimizer(Configuration config)
Create an Optimizer. |
Method Summary | |
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Expression |
compileToByteCode(Expression expr,
String objectName,
int evaluationMethods)
Generate Java byte code for an expression |
Expression |
convertPathExpressionToKey(SlashExpression pathExp,
ExpressionVisitor visitor)
Examine a path expression to see whether it can be replaced by a call on the key() function; if so, generate an appropriate key definition and return the call on key(). |
FilterExpression |
convertToFilterExpression(SlashExpression pathExp,
TypeHierarchy th)
Convert a path expression such as a/b/c[predicate] into a filter expression of the form (a/b/c)[predicate]. |
Expression |
extractGlobalVariables(Expression body,
ExpressionVisitor visitor,
PromotionOffer offer)
Extract subexpressions from the body of a function that can be evaluated as global variables |
Expression |
generateMultithreadedInstruction(Expression instruction)
Generate a multi-threaded version of an instruction. |
Configuration |
getConfiguration()
Get the Saxon configuration object |
int |
getOptimizationLevel()
Get the optimization level |
int |
isIndexableFilter(Expression filter)
Test whether a filter predicate is indexable. |
boolean |
isVariableReplaceableByDot(Expression exp,
Binding[] binding)
Determine whether it is possible to rearrange an expression so that all references to a given variable are replaced by a reference to ".". |
Expression |
makeCastableToList(Expression operand,
SchemaType targetType,
boolean allowsEmpty)
Make an expression castable check to a union type. |
Expression |
makeCastableToUnion(Expression operand,
SchemaType targetType,
boolean allowsEmpty)
Make an expression castable check to a union type. |
Expression |
makeCastToList(Expression operand,
SchemaType targetType,
boolean allowsEmpty)
Make an expression that casts to a list type. |
Expression |
makeCastToUnion(Expression operand,
SchemaType targetType,
boolean allowsEmpty)
Make an expression that casts to a union type. |
Expression |
makeConditionalDocumentSorter(DocumentSorter sorter,
SlashExpression path)
Make a conditional document sorter. |
void |
makeCopyOperationsExplicit(Expression parent,
Expression child)
In streaming mode, make the copy operation applied to subexpressions of a complex-content sequence constructor into explicit copy-of operations. |
ValueRepresentation |
makeIndexedValue(SequenceIterator iter)
Create an indexed value |
RuleTarget |
makeInversion(Pattern pattern,
Template template,
NodeTest nodeTest)
Generate the inversion of the expression comprising the body of a template rules. |
Expression |
makeOuterForExpression()
Make an OuterForExpression (Saxon-EE only) |
Expression |
makeStreamingApplyTemplates(ApplyTemplates inst)
Make a streaming applyTemplates instruction. |
Expression |
optimizeCopy(Expression select)
Attempt to optimize a copy operation. |
Expression |
optimizeForExpressionForStreaming(ForExpression expr)
In streaming mode, optimizer a ForExpression for streaming |
BinaryExpression |
optimizeGeneralComparison(GeneralComparison gc,
boolean backwardsCompatible)
Simplify a GeneralComparison expression |
Expression |
optimizeQuantifiedExpressionForStreaming(QuantifiedExpression expr)
In streaming mode, optimizer a QuantifiedExpression for streaming |
Expression |
promoteExpressionsToGlobal(Expression body,
ExpressionVisitor visitor)
Identify expressions within a function or template body that can be promoted to be evaluated as global variables. |
void |
setOptimizationLevel(int level)
Set the optimization level |
void |
trace(String message)
Trace optimization actions |
void |
trace(String message,
Expression exp)
Trace optimization actions |
Expression |
tryIndexedFilter(FilterExpression f,
ExpressionVisitor visitor,
boolean indexFirstOperand)
Try converting a filter expression to a call on the key function. |
Expression |
tryInlineFunctionCall(UserFunctionCall functionCall,
ExpressionVisitor visitor,
ExpressionVisitor.ContextItemType contextItemType)
Replace a function call by the body of the function, assuming all conditions for inlining the function are satisfied |
Expression |
trySwitch(Choose choose,
StaticContext env)
Try to convert a Choose expression into a switch |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
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public static final int NO_OPTIMIZATION
public static final int FULL_OPTIMIZATION
protected Configuration config
Constructor Detail |
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public Optimizer(Configuration config)
config
- the Saxon configurationMethod Detail |
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public Configuration getConfiguration()
public void setOptimizationLevel(int level)
level
- the optimization level, between 0 (no optimization) and 10 (full optimization).
Currently all values greater than zero have the same effect as full optimizationpublic int getOptimizationLevel()
public BinaryExpression optimizeGeneralComparison(GeneralComparison gc, boolean backwardsCompatible)
gc
- the GeneralComparison to be simplifiedbackwardsCompatible
- true if in 1.0 compatibility mode
public Expression optimizeCopy(Expression select) throws XPathException
select
- the expression that selects the items to be copied
XPathException
public Expression convertPathExpressionToKey(SlashExpression pathExp, ExpressionVisitor visitor) throws XPathException
pathExp
- The path expression to be converted.visitor
- The expression visitor
XPathException
public Expression tryIndexedFilter(FilterExpression f, ExpressionVisitor visitor, boolean indexFirstOperand)
f
- the filter expression to be convertedvisitor
- the expression visitor, which must be currently visiting the filter expression findexFirstOperand
- true if the first operand of the filter comparison is to be indexed;
false if it is the second operand
public FilterExpression convertToFilterExpression(SlashExpression pathExp, TypeHierarchy th) throws XPathException
pathExp
- the path expression to be convertedth
- the type hierarchy cache
XPathException
public int isIndexableFilter(Expression filter)
filter
- the predicate expression
public ValueRepresentation makeIndexedValue(SequenceIterator iter) throws XPathException
iter
- the iterator that delivers the sequence of values to be indexed
UnsupportedOperationException:
- this method should not be called in Saxon-B
XPathException
public boolean isVariableReplaceableByDot(Expression exp, Binding[] binding)
exp
- the expression in questionbinding
- an array of bindings defining range variables; the method tests that there are no
references to any of these variables within a predicate or on the rhs of "/"
public Expression makeConditionalDocumentSorter(DocumentSorter sorter, SlashExpression path)
sorter
- the document sorterpath
- the path expression
public Expression tryInlineFunctionCall(UserFunctionCall functionCall, ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType)
functionCall
- the functionCall expressionvisitor
- the expression visitorcontextItemType
- the context item type
public Expression promoteExpressionsToGlobal(Expression body, ExpressionVisitor visitor) throws XPathException
body
- the body of the template or functionvisitor
- the expression visitor
XPathException
public Expression trySwitch(Choose choose, StaticContext env)
choose
- the Choose expressionenv
- the static context
public Expression extractGlobalVariables(Expression body, ExpressionVisitor visitor, PromotionOffer offer) throws XPathException
body
- the body of the functionoffer
- The PromotionOffer. Will be marked to indicate whether any action was taken
XPathException
public Expression makeStreamingApplyTemplates(ApplyTemplates inst) throws XPathException
inst
- the unoptimized applyTemplates instruction
XPathException
public RuleTarget makeInversion(Pattern pattern, Template template, NodeTest nodeTest) throws XPathException
pattern
- the match pattern of this template ruletemplate
- the template to be invertednodeTest
- the static item type of the context node of the template
XPathException
public void makeCopyOperationsExplicit(Expression parent, Expression child) throws XPathException
XPathException
public Expression makeCastToUnion(Expression operand, SchemaType targetType, boolean allowsEmpty)
public Expression makeCastToList(Expression operand, SchemaType targetType, boolean allowsEmpty)
public Expression makeCastableToUnion(Expression operand, SchemaType targetType, boolean allowsEmpty)
public Expression makeCastableToList(Expression operand, SchemaType targetType, boolean allowsEmpty)
public Expression optimizeForExpressionForStreaming(ForExpression expr) throws XPathException
expr
- the expression to be optimized
XPathException
public Expression makeOuterForExpression()
public Expression optimizeQuantifiedExpressionForStreaming(QuantifiedExpression expr) throws XPathException
expr
- the expression to be optimized
XPathException
public Expression generateMultithreadedInstruction(Expression instruction)
instruction
- the instruction to be multi-threaded
public Expression compileToByteCode(Expression expr, String objectName, int evaluationMethods)
expr
- the expression to be compiledobjectName
- the name of the object (e.g. function) being compiledevaluationMethods
- The evaluation modes for which code is generated. Currently a subset of
Expression.PROCESS_METHOD
, Expression.ITERATE_METHOD
. If no code is generated for
a given evaluation method, the fallback implementation from the superclass is used.
public void trace(String message, Expression exp)
message
- the message to be displayedexp
- the expression after being rewrittenpublic void trace(String message)
message
- the message to be displayed
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