Package net.sf.saxon.expr.instruct

## Class Comment

- java.lang.Object
- - net.sf.saxon.expr.Expression
  - - net.sf.saxon.expr.instruct.Instruction
    - - net.sf.saxon.expr.instruct.SimpleNodeConstructor
      - - net.sf.saxon.expr.instruct.Comment

- All Implemented Interfaces:
    `ExportAgent`, `TailCallReturner`, `Locatable`, `IdentityComparable`, `Traceable`

      public final class Comment
      extends SimpleNodeConstructor

  An instruction representing an xsl:comment element in the stylesheet.

- - ### Field Summary

    - ### Fields inherited from class net.sf.saxon.expr.instruct.SimpleNodeConstructor

      `selectOp`

    - ### Fields inherited from class net.sf.saxon.expr.Expression

      `EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, MAX_COST, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, UPDATE_METHOD, WATCH_METHOD`

  - ### Constructor Summary

    Constructors
    Constructor | Description
    --- | ---
    `Comment()` | Construct the instruction

  - ### Method Summary

    All Methods Static Methods Instance Methods Concrete Methods
    Modifier and Type | Method | Description
    --- | --- | ---
    `protected java.lang.String` | `checkContent​(java.lang.String comment, XPathContext context)` | Check the content of the node, and adjust it if necessary
    `static java.lang.String` | `checkContentXQuery​(java.lang.String comment)` | Check the content of the comment according to the XQuery rules (which throw an error if it is wrong)
    `static java.lang.String` | `checkContentXSLT​(java.lang.String comment)` | Check the content of the comment according to the XSLT rules (which fix it if it is wrong)
    `Expression` | `copy​(RebindingMap rebindings)` | Copy an expression.
    `void` | `export​(ExpressionPresenter out)` | Diagnostic print of expression structure.
    `int` | `getCardinality()` | Determine the static cardinality of the expression.
    `int` | `getInstructionNameCode()` | Get the instruction name, for diagnostics and tracing return the string "xsl:comment"
    `ItemType` | `getItemType()` | Get the item type of the items returned by evaluating this instruction
    `void` | `localTypeCheck​(ExpressionVisitor visitor, ContextItemStaticInfo contextItemType)` | Method to perform type-checking specific to the kind of instruction
    `void` | `processValue​(java.lang.CharSequence value, Outputter output, XPathContext context)` | Process the value of the node, to create the new node.

    - ### Methods inherited from class net.sf.saxon.expr.instruct.SimpleNodeConstructor

      `allowExtractingCommonSubexpressions, alwaysCreatesNewNodes, computeCardinality, computeSpecialProperties, evaluateItem, evaluateNodeName, getSelect, getStreamerName, isLocal, iterate, mayCreateNewNodes, operands, optimize, processLeavingTail, setSelect, typeCheck`

    - ### Methods inherited from class net.sf.saxon.expr.instruct.Instruction

      `assembleParams, assembleTunnelParams, dynamicError, evaluateAsString, getExpressionName, getImplementationMethod, getNetCost, getSourceLocator, isInstruction, isXSLT, process, someOperandCreatesNewNodes`

    - ### Methods inherited from class net.sf.saxon.expr.Expression

      `addToPathMap, adoptChildExpression, checkedOperands, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeHashCode, computeStaticProperties, dynamicError, effectiveBooleanValue, equals, evaluatePendingUpdates, explain, getConfiguration, getCost, getDependencies, getEvaluationMethod, getExtraProperty, getIntegerBounds, getInterpretedExpression, getIntrinsicDependencies, getLocalRetainedStaticContext, getLocation, getObjectName, getPackageData, getParentExpression, getProperties, getProperty, getRetainedStaticContext, getScopingExpression, getSlotsUsed, getSpecialProperties, getStaticBaseURI, getStaticBaseURIString, getStaticType, getStaticUType, getTracingTag, hasCompatibleStaticContext, hashCode, hasSpecialProperty, hasVariableBinding, identityHashCode, implementsStaticTypeCheck, isCallOn, isEqual, isIdentical, isLiftable, isMultiThreaded, isStaticPropertiesKnown, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, markTailFunctionCalls, operandList, operandSparseList, optimizeChildren, prepareForStreaming, resetLocalStaticProperties, restoreParentPointers, setEvaluationMethod, setExtraProperty, setFiltered, setFlattened, setLocation, setParentExpression, setRetainedStaticContext, setRetainedStaticContextLocally, setRetainedStaticContextThoroughly, setStaticProperty, simplify, simplifyChildren, staticTypeCheck, suppressValidation, toPattern, toShortString, toString, typeCheckChildren, typeError, unordered, verifyParentPointers`

    - ### Methods inherited from class java.lang.Object

      `clone, finalize, getClass, notify, notifyAll, wait, wait, wait`

    - ### Methods inherited from interface net.sf.saxon.trace.Traceable

      `gatherProperties`

- - ### Constructor Detail

    - #### Comment

          public Comment()

      Construct the instruction

  - ### Method Detail

    - #### getInstructionNameCode

          public int getInstructionNameCode()

      Get the instruction name, for diagnostics and tracing return the string "xsl:comment"
      Overrides:
        `getInstructionNameCode` in class `Instruction`
      Returns:
        a code identifying the instruction: typically but not always the fingerprint of a name in the XSLT namespace

    - #### getItemType

          public ItemType getItemType()

      Description copied from class: `Instruction`
      Get the item type of the items returned by evaluating this instruction
      Overrides:
        `getItemType` in class `Instruction`
      Returns:
        the static item type of the instruction

    - #### getCardinality

          public int getCardinality()

      Description copied from class: `Expression`
      Determine the static cardinality of the expression. This establishes how many items there will be in the result of the expression, at compile time (i.e., without actually evaluating the result.
      Overrides:
        `getCardinality` in class `Expression`
      Returns:
        one of the values Cardinality.ONE_OR_MORE, Cardinality.ZERO_OR_MORE, Cardinality.EXACTLY_ONE, Cardinality.ZERO_OR_ONE, Cardinality.EMPTY. This default implementation returns ZERO_OR_MORE (which effectively gives no information).

    - #### copy

          public Expression copy​(RebindingMap rebindings)

      Copy an expression. This makes a deep copy.
      Specified by:
        `copy` in class `Expression`
      Parameters:
        `rebindings` -
      Returns:
        the copy of the original expression

    - #### localTypeCheck

          public void localTypeCheck​(ExpressionVisitor visitor,
                                     ContextItemStaticInfo contextItemType)
                              throws XPathException

      Description copied from class: `SimpleNodeConstructor`
      Method to perform type-checking specific to the kind of instruction
      Specified by:
        `localTypeCheck` in class `SimpleNodeConstructor`
      Parameters:
        `visitor` - an expression visitor
        `contextItemType` - the static type of the context item
      Throws:
        `XPathException` - if a type error is detected

    - #### processValue

          public void processValue​(java.lang.CharSequence value,
                                   Outputter output,
                                   XPathContext context)
                            throws XPathException

      Process the value of the node, to create the new node.
      Specified by:
        `processValue` in class `SimpleNodeConstructor`
      Parameters:
        `value` - the string value of the new node
        `output` - the destination for the result
        `context` - the dynamic evaluation context
      Throws:
        `XPathException` - if a dynamic error occurs

    - #### checkContent

          protected java.lang.String checkContent​(java.lang.String comment,
                                                  XPathContext context)
                                           throws XPathException

      Check the content of the node, and adjust it if necessary
      Overrides:
        `checkContent` in class `SimpleNodeConstructor`
      Parameters:
        `comment` - the supplied content
        `context` - the dynamic context
      Returns:
        the original content, unless adjustments are needed
      Throws:
        `XPathException` - if the content is invalid

    - #### checkContentXSLT

          public static java.lang.String checkContentXSLT​(java.lang.String comment)

      Check the content of the comment according to the XSLT rules (which fix it if it is wrong)
      Parameters:
        `comment` - the proposed text of the comment
      Returns:
        the adjusted text of the comment

    - #### checkContentXQuery

          public static java.lang.String checkContentXQuery​(java.lang.String comment)
                                                     throws XPathException

      Check the content of the comment according to the XQuery rules (which throw an error if it is wrong)
      Parameters:
        `comment` - the proposed text of the comment
      Returns:
        the adjusted text of the comment (always the same as the original if there is no error)
      Throws:
        `XPathException` - if the content is invalid

    - #### export

          public void export​(ExpressionPresenter out)
                      throws XPathException

      Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.
      Specified by:
        `export` in interface `ExportAgent`
      Specified by:
        `export` in class `Expression`
      Parameters:
        `out` - the expression presenter used to display the structure
      Throws:
        `XPathException` - if the export fails, for example if an expression is found that won't work in the target environment.