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java.lang.Objectnet.sf.saxon.expr.ComputedExpression
net.sf.saxon.instruct.Instruction
net.sf.saxon.instruct.TraceWrapper
This class is a tracing wrapper around any expression: it delivers the same result as the wrapped expression, but traces its evaluation to a TraceListener
Field Summary |
Fields inherited from class net.sf.saxon.expr.ComputedExpression |
locationId, staticProperties |
Fields inherited from interface net.sf.saxon.expr.Expression |
EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD |
Constructor Summary | |
TraceWrapper()
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Method Summary | |
Expression |
analyze(StaticContext env,
ItemType contextItemType)
I Perform static analysis of an expression and its subexpressions. |
int |
computeDependencies()
Get the static properties of this expression (other than its type). |
boolean |
createsNewNodes()
Determine whether this instruction creates new nodes. |
void |
display(int level,
NamePool pool,
java.io.PrintStream out)
Diagnostic print of expression structure. |
Item |
evaluateItem(XPathContext context)
Evaluate an expression as a single item. |
int |
getCardinality()
Determine the static cardinality of the expression. |
int |
getDependencies()
Determine which aspects of the context the expression depends on. |
int |
getInstructionNameCode()
Get the namecode of the instruction for use in diagnostics |
ItemType |
getItemType()
Get the item type of the items returned by evaluating this instruction |
SequenceIterator |
iterate(XPathContext context)
Return an Iterator to iterate over the values of a sequence. |
java.util.Iterator |
iterateSubExpressions()
Get the immediate sub-expressions of this expression. |
TailCall |
processLeavingTail(XPathContext context)
Execute this instruction, with the possibility of returning tail calls if there are any. |
Expression |
simplify(StaticContext env)
Simplify an expression. |
Methods inherited from class net.sf.saxon.instruct.Instruction |
appendItem, assembleParams, assembleTunnelParams, computeCardinality, computeSpecialProperties, dynamicError, dynamicError, effectiveBooleanValue, evaluateAsString, getImplementationMethod, getInstructionInfo, getSourceLocator, isXSLT, process, promote, promoteInst |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Methods inherited from interface javax.xml.transform.SourceLocator |
getColumnNumber, getLineNumber, getPublicId, getSystemId |
Constructor Detail |
public TraceWrapper()
Method Detail |
public Expression simplify(StaticContext env) throws XPathException
simplify
in interface Expression
simplify
in class Instruction
XPathException
- if an error is discovered during expression
rewritingpublic Expression analyze(StaticContext env, ItemType contextItemType) throws XPathException
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.
analyze
in interface Expression
analyze
in class Instruction
env
- the static context of the expression
XPathException
- if an error is discovered during this phase
(typically a type error)public TailCall processLeavingTail(XPathContext context) throws XPathException
processLeavingTail
in class Instruction
context
- the dynamic execution context
XPathException
public ItemType getItemType()
getItemType
in interface Expression
getItemType
in class Instruction
public int getCardinality()
getCardinality
in interface Expression
getCardinality
in class ComputedExpression
public int getDependencies()
StaticProperty.DEPENDS_ON_CONTEXT_ITEM
and
StaticProperty.DEPENDS_ON_CURRENT_ITEM
. The default implementation combines the intrinsic
dependencies of this expression with the dependencies of the subexpressions,
computed recursively. This is overridden for expressions such as FilterExpression
where a subexpression's dependencies are not necessarily inherited by the parent
expression.
getDependencies
in interface Expression
getDependencies
in class ComputedExpression
public final boolean createsNewNodes()
createsNewNodes
in class Instruction
public int computeDependencies()
computeDependencies
in class ComputedExpression
public Item evaluateItem(XPathContext context) throws XPathException
evaluateItem
in interface Expression
evaluateItem
in class Instruction
context
- The context in which the expression is to be evaluated
XPathException
- if any dynamic error occurs evaluating the
expressionpublic SequenceIterator iterate(XPathContext context) throws XPathException
iterate
in interface Expression
iterate
in class Instruction
context
- supplies the context for evaluation
XPathException
- if any dynamic error occurs evaluating the
expressionpublic java.util.Iterator iterateSubExpressions()
ComputedExpression
iterateSubExpressions
in interface Expression
iterateSubExpressions
in class ComputedExpression
public int getInstructionNameCode()
Instruction
getInstructionNameCode
in class Instruction
public void display(int level, NamePool pool, java.io.PrintStream out)
level
- indentation level for this expressionout
- pool
- NamePool used to expand any names appearing in the expression
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