org.extex.unit.tex.conditional
Class Ifcase

java.lang.Object
  org.extex.interpreter.type.AbstractCode
      org.extex.unit.base.conditional.AbstractIf
          org.extex.unit.tex.conditional.Ifcase

All Implemented Interfaces:

java.io.Serializable, Code, ExpandableCode, PrefixCode

public class Ifcase
extends AbstractIf

This class provides an implementation for the primitive \ifcase.

The Primitive \ifcase

The primitive \ifcase provides a conditional switch on a numeric value. The next tokens are used as a number. This number determines which branch to expand. The first branch follows the number immediately. This branch is associated to the number 0.

The primitive \or advances to the next branch. The primitive \else starts the else branch. The else branch is used if no other branch fits.

Syntax

The formal description of this primitive is the following:

    ⟨ifcase⟩
     → \ifcase ⟨number⟩  ⟨cases⟩ \fi

    ⟨cases⟩
     →
      |  ⟨branch text⟩ \else ⟨else text⟩
      |  ⟨branch text⟩ \or ⟨cases⟩  

Examples

    \ifcase\count0 a\or b\or c\else x\fi  

Version:

$Revision: 4439 $

Author:

Gerd Neugebauer

See Also:

Serialized Form

Nested Class Summary

protected static class

Ifcase.Tag This is an internal class for type-safe values.

Field Summary

protected static Ifcase.Tag	ELSE The constant ELSE contains the value indicating an \else.
protected static Ifcase.Tag	FI The constant FI contains the value indicating a \fi.
protected static Ifcase.Tag	OR The constant OR contains the value indicating an \or.
protected static long	serialVersionUID The constant serialVersionUID contains the id for serialization.

Constructor Summary

Ifcase(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.
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. 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.

Methods inherited from class org.extex.unit.base.conditional.AbstractIf

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

OR

protected static final Ifcase.Tag OR

The constant OR contains the value indicating an \or.

ELSE

protected static final Ifcase.Tag ELSE

The constant ELSE contains the value indicating an \else.

FI

protected static final Ifcase.Tag FI

The constant FI contains the value indicating a \fi.

Constructor Detail

Ifcase

public Ifcase(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 AbstractIf

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:

AbstractIf.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

Overrides:

expand in class AbstractIf

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:

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

conditional

public boolean conditional(Context context,
                           TokenSource source,
                           Typesetter typesetter)
                    throws HelpingException

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

See Also:

AbstractIf.conditional( org.extex.interpreter.context.Context, org.extex.interpreter.TokenSource, org.extex.typesetter.Typesetter)