org.extex.unit.tex.macro
Class Expandafter

java.lang.Object
  org.extex.interpreter.type.AbstractCode
      org.extex.unit.tex.macro.Expandafter

All Implemented Interfaces:

java.io.Serializable, Code, ExpandableCode, PrefixCode

public class Expandafter
extends AbstractCode
implements ExpandableCode, PrefixCode

This class provides an implementation for the primitive \expandafter.

The Primitive \expandafter

The primitive \expandafter reverses the expansion of the following two tokens. For this purpose the next token following the invocation is read unexpanded and put aside. Then the next token is expanded in whatever way the token requires expansion. This may involve the reading and expansion of further tokens. When this expansion is finished then the saved token is put back into the input stream.

Any prefix argument is saved for the expansion of the following token.

Syntax

The formal description of this primitive is the following:

    ⟨expandafter⟩
     → \expandafter ⟨token⟩ ⟨token⟩  

Examples

    \expandafter ab  

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

Expandafter(CodeToken token)
Creates a new object.

Method Summary

void	execute(Flags prefix, Context context, TokenSource source, Typesetter typesetter) This method takes the first token and executes it. The result is placed on the stack. This operation might have side effects. To execute a token it might be necessary to consume further tokens.
void	expand(Flags prefix, Context context, TokenSource source, Typesetter typesetter) This method takes the first token and expands it.

Methods inherited from class org.extex.interpreter.type.AbstractCode

getLocalizer, getName, getToken, isIf, 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

Expandafter

public Expandafter(CodeToken token)

Creates a new object.

Parameters:

token - the initial token for the primitive

Method Detail

execute

public void execute(Flags prefix,
                    Context context,
                    TokenSource source,
                    Typesetter typesetter)
             throws HelpingException,
                    TypesetterException

This method takes the first token and executes it. The result is placed on the stack. This operation might have side effects. To execute a token it might be necessary to consume further tokens.

Specified by:

execute in interface Code

Overrides:

execute in class AbstractCode

Parameters:

prefix - the prefix controlling the execution

context - the interpreter context

source - the token source

typesetter - the typesetter

Throws:

HelpingException - in case of an error

TypesetterException - in case of an error in the typesetter

See Also:

AbstractCode.execute( org.extex.interpreter.Flags, org.extex.interpreter.context.Context, org.extex.interpreter.TokenSource, org.extex.typesetter.Typesetter)

expand

public void expand(Flags prefix,
                   Context context,
                   TokenSource source,
                   Typesetter typesetter)
            throws HelpingException,
                   TypesetterException

This method takes the first token and expands it. The result is placed on the stack. This means that expandable code does one step of expansion and puts the result on the stack. To expand a token it might be necessary to consume further tokens.

Specified by:

expand in interface ExpandableCode

Parameters:

prefix - the prefix flags controlling the expansion

context - the interpreter context

source - the token source

typesetter - the typesetter

Throws:

HelpingException - in case of an error

TypesetterException - in case of an error in the typesetter

See Also:

ExpandableCode.expand( org.extex.interpreter.Flags, org.extex.interpreter.context.Context, org.extex.interpreter.TokenSource, org.extex.typesetter.Typesetter)