org.extex.unit.etex.conditional
Class Ifcsname

java.lang.Object
  org.extex.interpreter.type.AbstractCode
      org.extex.unit.base.conditional.AbstractIf
          org.extex.unit.etex.conditional.Ifcsname

All Implemented Interfaces:

java.io.Serializable, Code, ExpandableCode, PrefixCode

public class Ifcsname
extends AbstractIf

This class provides an implementation for the primitive \ifcsname.

The Primitive \ifcsname

The primitive \ifcsname checks if a certain control sequence is defined. For this purpose it collects tokens in the same way as \csname does until \endcsname is encountered. It does not define the control sequence if it is not defined.

Syntax

The formal description of this primitive is the following:

    ⟨ifcsname⟩
      → \ifcsname ... \endcsname ⟨true text⟩ \fi
       |  \ifcsname ... \endcsname ⟨true text⟩ \else ⟨false text⟩ \fi  

Examples

     \ifcsname def\endcsname ok\fi  

Version:

$Revision: 4770 $

Author:

Gerd Neugebauer

See Also:

Serialized Form

Field Summary

protected static long

serialVersionUID The constant serialVersionUID contains the id for serialization.

Constructor Summary

Ifcsname(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

Ifcsname

public Ifcsname(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)