net.sf.saxon.instruct
Class DocumentInstr

java.lang.Object
  extended bynet.sf.saxon.expr.ComputedExpression
      extended bynet.sf.saxon.instruct.Instruction
          extended bynet.sf.saxon.instruct.ParentNodeConstructor
              extended bynet.sf.saxon.instruct.DocumentInstr
All Implemented Interfaces:
Container, Expression, InstructionInfoProvider, java.io.Serializable, javax.xml.transform.SourceLocator, TailCallReturner

public class DocumentInstr
extends ParentNodeConstructor

An instruction to create a document node. This corresponds to the xsl:document-node instruction in XSLT. It is also used to support the document node constructor expression in XQuery, and is generated implicitly within an xsl:variable that constructs a temporary tree.

Conceptually it represents an XSLT instruction xsl:document-node, with no attributes, whose content is a complex content constructor for the children of the document node.

See Also:
Serialized Form

Field Summary
 
Fields inherited from class net.sf.saxon.instruct.ParentNodeConstructor
content
 
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
DocumentInstr(boolean textOnly, java.lang.String constantText, java.lang.String baseURI)
           
 
Method Summary
protected  void checkContentForAttributes(StaticContext env)
          Check statically whether the content of the element creates attributes or namespaces after creating any child nodes
 void display(int level, java.io.PrintStream out, Configuration config)
          Display this instruction as an expression, for diagnostics
 Item evaluateItem(XPathContext context)
          Evaluate as an expression.
 int getImplementationMethod()
          An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process().
 int getInstructionNameCode()
          Get the name of this instruction for diagnostic and tracing purposes (the string "document-constructor")
 ItemType getItemType(TypeHierarchy th)
          Get the item type
 Expression getStringValueExpression(StaticContext env)
          In the case of a text-only instruction (xsl:variable containing a text node or one or more xsl:value-of instructions, return an expression that evaluates to the textual content
 boolean isTextOnly()
          Determine whether this is a "text only" document: essentially, an XSLT xsl:variable that contains a single text node or xsl:value-of instruction.
 TailCall processLeavingTail(XPathContext context)
          ProcessLeavingTail: called to do the real work of this instruction.
 void setValidationAction(int action)
          Set the validation action
 Expression simplify(StaticContext env)
          Simplify an expression.
 Expression typeCheck(StaticContext env, ItemType contextItemType)
          Perform type checking of an expression and its subexpressions.
 
Methods inherited from class net.sf.saxon.instruct.ParentNodeConstructor
createsNewNodes, getBaseURI, getCardinality, getContentExpression, getSchemaType, getValidationAction, isLazyConstruction, isNamespaceSensitive, iterateSubExpressions, optimize, promoteInst, replaceSubExpression, setBaseURI, setContentExpression, setLazyConstruction, setSchemaType
 
Methods inherited from class net.sf.saxon.instruct.Instruction
appendItem, assembleParams, assembleTunnelParams, computeCardinality, computeSpecialProperties, dynamicError, evaluateAsString, getInstructionInfo, getSourceLocator, isXSLT, iterate, process, promote
 
Methods inherited from class net.sf.saxon.expr.ComputedExpression
adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, getColumnNumber, getConstructType, getDependencies, getExecutable, getHostLanguage, getIntrinsicDependencies, getLineNumber, getLocationId, getLocationProvider, getParentExpression, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasBadParentPointer, markTailFunctionCalls, resetStaticProperties, setLocationId, setParentExpression, setParentExpression, suppressValidation, typeError
 
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

DocumentInstr

public DocumentInstr(boolean textOnly,
                     java.lang.String constantText,
                     java.lang.String baseURI)
Method Detail

getImplementationMethod

public int getImplementationMethod()
An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process(). This method indicates which of these methods is prefered. For instructions this is the process() method.

Specified by:
getImplementationMethod in interface Expression
Overrides:
getImplementationMethod in class Instruction

setValidationAction

public void setValidationAction(int action)
Set the validation action


isTextOnly

public boolean isTextOnly()
Determine whether this is a "text only" document: essentially, an XSLT xsl:variable that contains a single text node or xsl:value-of instruction.


simplify

public Expression simplify(StaticContext env)
                    throws XPathException
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 ParentNodeConstructor
Returns:
the simplified expression
Throws:
XPathException - if an error is discovered during expression rewriting

typeCheck

public Expression typeCheck(StaticContext env,
                            ItemType contextItemType)
                     throws XPathException
Description copied from interface: Expression
Perform type checking of an expression and its subexpressions. This is the second phase of static optimization.

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 may not be accurately known if they have not been explicitly declared.

If the implementation returns a value other than "this", then it is required to ensure that the parent pointer and location information in the returned expression have been set up correctly. It should not rely on the caller to do this, although for historical reasons many callers do so.

Specified by:
typeCheck in interface Expression
Overrides:
typeCheck in class ParentNodeConstructor
Throws:
XPathException

checkContentForAttributes

protected void checkContentForAttributes(StaticContext env)
                                  throws XPathException
Check statically whether the content of the element creates attributes or namespaces after creating any child nodes

Specified by:
checkContentForAttributes in class ParentNodeConstructor
Parameters:
env - the static context
Throws:
XPathException

getStringValueExpression

public Expression getStringValueExpression(StaticContext env)
In the case of a text-only instruction (xsl:variable containing a text node or one or more xsl:value-of instructions, return an expression that evaluates to the textual content

Returns:
an expression that evaluates to the textual content

getItemType

public ItemType getItemType(TypeHierarchy th)
Get the item type

Specified by:
getItemType in interface Expression
Overrides:
getItemType in class Instruction
Parameters:
th - The TypeHierarchy
Returns:
the in

processLeavingTail

public TailCall processLeavingTail(XPathContext context)
                            throws XPathException
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 TailCallReturner
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.
Throws:
XPathException

evaluateItem

public Item evaluateItem(XPathContext context)
                  throws XPathException
Evaluate as an expression.

Specified by:
evaluateItem in interface Expression
Overrides:
evaluateItem in class Instruction
Parameters:
context - The context in which the expression is to be evaluated
Returns:
the node or atomic value that results from evaluating the expression; or null to indicate that the result is an empty sequence
Throws:
XPathException - if any dynamic error occurs evaluating the expression

getInstructionNameCode

public int getInstructionNameCode()
Get the name of this instruction for diagnostic and tracing purposes (the string "document-constructor")

Overrides:
getInstructionNameCode in class Instruction

display

public void display(int level,
                    java.io.PrintStream out,
                    Configuration config)
Display this instruction as an expression, for diagnostics

Parameters:
level - indentation level for this expression
out - Output destination
config -