org.extex.unit.tex.conditional
Class Ifvoid

java.lang.Object
  extended by org.extex.interpreter.type.AbstractCode
      extended by org.extex.unit.base.conditional.AbstractIf
          extended by org.extex.unit.tex.conditional.Ifvoid
All Implemented Interfaces:
java.io.Serializable, Code, ExpandableCode, PrefixCode

public class Ifvoid
extends AbstractIf

This class provides an implementation for the primitive \ifvoid.

The Primitive \ifvoid

The primitive takes one expanded integer argument. The conditional is true iff the box denoted by the argument is void.

Syntax

The formal description of this primitive is the following:
    ⟨ifvoid⟩
      → \ifvoid ⟨number⟩ ⟨true text⟩ \fi
      | \ifvoid ⟨number⟩ ⟨true text⟩ \else ⟨false text⟩ \fi 

Examples

    \ifvoid255 abc \fi  
    \ifvoid\count120 abc \fi  

Version:
$Revision: 4439 $
Author:
Gerd Neugebauer
See Also:
Serialized Form

Field Summary
protected static long serialVersionUID
          The constant serialVersionUID contains the id for serialization.
 
Constructor Summary
Ifvoid(CodeToken token)
          Creates a new object.
 
Method Summary
 boolean conditional(Context context, TokenSource source, Typesetter typesetter)
          This method computes the boolean value of the conditional.
 
Methods inherited from class org.extex.unit.base.conditional.AbstractIf
execute, expand, getMyLocalizer, isIf, skipToElseOrFi
 
Methods inherited from class org.extex.interpreter.type.AbstractCode
getLocalizer, getName, getToken, isOuter, readResolve, toString, toText, toText
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Field Detail

serialVersionUID

protected static final long serialVersionUID
The constant serialVersionUID contains the id for serialization.

See Also:
Constant Field Values
Constructor Detail

Ifvoid

public Ifvoid(CodeToken token)
Creates a new object.

Parameters:
token - the initial token for the primitive
Method Detail

conditional

public boolean conditional(Context context,
                           TokenSource source,
                           Typesetter typesetter)
                    throws HelpingException,
                           TypesetterException
This method computes the boolean value of the conditional. If the result is true then the then branch is expanded and the else branch is skipped. Otherwise the then branch is skipped and the else branch is expanded.

Specified by:
conditional in class AbstractIf
Parameters:
context - the interpreter context
source - the source for new tokens
typesetter - the typesetter
Returns:
the boolean value
Throws:
HelpingException - in case of an error
TypesetterException - in case of an error in the typesetter
See Also:
AbstractIf.conditional( org.extex.interpreter.context.Context, org.extex.interpreter.TokenSource, org.extex.typesetter.Typesetter)