net.sf.saxon.instruct
Class SequenceInstruction

java.lang.Object
  |
  +--net.sf.saxon.instruct.Instruction
        |
        +--net.sf.saxon.instruct.ExprInstruction
              |
              +--net.sf.saxon.instruct.SequenceInstruction
All Implemented Interfaces:
Expression, Instr, Locatable, java.io.Serializable, javax.xml.transform.SourceLocator

public class SequenceInstruction
extends ExprInstruction

An xsl:sequence element in the stylesheet; or a wrapper inserted around the sequence constructor inside other instructions such as xsl:attribute.

See Also:
Serialized Form

Field Summary
 
Fields inherited from class net.sf.saxon.instruct.Instruction
children
 
Constructor Summary
SequenceInstruction(Expression select, SequenceType requiredType)
           
 
Method Summary
 Expression analyze(StaticContext env)
          Perform static analysis of an expression and its subexpressions.
static void appendItem(Item it, XPathContext context, SequenceReceiver out)
           
 void display(int level, NamePool pool)
          Display this instruction as an expression, for diagnostics
 java.lang.String getInstructionName()
          Get the name of this instruction for diagnostic and tracing purposes
 Expression getSelectExpression()
           
 void getXPathExpressions(java.util.List list)
          Get all the XPath expressions associated with this instruction (in XSLT terms, the expression present on attributes of the instruction, as distinct from the child instructions in a sequence construction)
 SequenceIterator iterate(XPathContext context)
          Iterate the results, treating this instruction as an expression
 TailCall processLeavingTail(XPathContext context)
          ProcessLeavingTail: called to do the real work of this instruction.
 void promoteInst(PromotionOffer offer)
          Offer promotion for subexpressions.
 void setCloseTextNode(boolean b)
           
 Expression simplify()
          Simplify an expression.
 
Methods inherited from class net.sf.saxon.instruct.ExprInstruction
effectiveBooleanValue, evaluateAsString, evaluateItem, getDependencies, getSpecialProperties, getSubExpressions, promote
 
Methods inherited from class net.sf.saxon.instruct.Instruction
assembleParams, assembleTunnelParams, displayChildren, dynamicError, dynamicError, getCardinality, getChildren, getColumnNumber, getExecutable, getInstructionNamespace, getItemType, getLineNumber, getPublicId, getSourceLocator, getSystemId, process, processChildren, processChildrenLeavingTail, recoverableError, setChildren, setExecutable, setSourceLocation
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 
Methods inherited from interface net.sf.saxon.expr.Expression
getCardinality, getItemType
 

Constructor Detail

SequenceInstruction

public SequenceInstruction(Expression select,
                           SequenceType requiredType)
Method Detail

setCloseTextNode

public void setCloseTextNode(boolean b)

getSelectExpression

public Expression getSelectExpression()

simplify

public Expression simplify()
                    throws XPathException
Description copied from class: ExprInstruction
Simplify an expression. This performs any static optimization (by rewriting the expression as a different expression). The default implementation does nothing.

Specified by:
simplify in interface Expression
Overrides:
simplify in class ExprInstruction
Returns:
the simplified expression
Throws:
XPathException - if an error is discovered during expression rewriting

analyze

public Expression analyze(StaticContext env)
                   throws XPathException
Description copied from class: ExprInstruction
Perform static analysis of an expression and its subexpressions.

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.

Specified by:
analyze in interface Expression
Overrides:
analyze in class ExprInstruction
Parameters:
env - the static context of the expression
Returns:
the original expression, rewritten to perform necessary run-time type checks, and to perform other type-related optimizations
Throws:
XPathException - if an error is discovered during this phase (typically a type error)

getXPathExpressions

public void getXPathExpressions(java.util.List list)
Description copied from class: ExprInstruction
Get all the XPath expressions associated with this instruction (in XSLT terms, the expression present on attributes of the instruction, as distinct from the child instructions in a sequence construction)

Specified by:
getXPathExpressions in class ExprInstruction
Parameters:
list - A list to be populated with the list of XPath expressions

promoteInst

public void promoteInst(PromotionOffer offer)
                 throws XPathException
Offer promotion for subexpressions. 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.

Specified by:
promoteInst in class ExprInstruction
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
Throws:
XPathException - if any error is detected

getInstructionName

public java.lang.String getInstructionName()
Get the name of this instruction for diagnostic and tracing purposes

Specified by:
getInstructionName in class Instruction

processLeavingTail

public TailCall processLeavingTail(XPathContext context)
                            throws javax.xml.transform.TransformerException
Description copied from class: Instruction
ProcessLeavingTail: called to do the real work of this instruction. This method must be implemented in each subclass. The results of the instruction are written to the current Receiver, which can be obtained via the Controller.

Specified by:
processLeavingTail in interface Instr
Specified by:
processLeavingTail in class Instruction
Parameters:
context - The dynamic context of the transformation, giving access to the current node, the current variables, etc.
Returns:
null if the instruction has completed execution; or a TailCall indicating a function call or template call that is delegated to the caller, to be made after the stack has been unwound so as to save stack space.
javax.xml.transform.TransformerException

appendItem

public static void appendItem(Item it,
                              XPathContext context,
                              SequenceReceiver out)
                       throws javax.xml.transform.TransformerException
javax.xml.transform.TransformerException

iterate

public SequenceIterator iterate(XPathContext context)
                         throws XPathException
Iterate the results, treating this instruction as an expression

Specified by:
iterate in interface Expression
Overrides:
iterate in class ExprInstruction
Parameters:
context - supplies the context for evaluation
Returns:
a SequenceIterator that can be used to iterate over the result of the expression
Throws:
XPathException - if any dynamic error occurs evaluating the expression

display

public void display(int level,
                    NamePool pool)
Display this instruction as an expression, for diagnostics

Parameters:
level - indentation level for this expression