org.extex.unit.tex.register
Class CatcodePrimitive

java.lang.Object
  org.extex.interpreter.type.AbstractCode
      org.extex.interpreter.type.AbstractAssignment
          org.extex.unit.tex.register.CatcodePrimitive

All Implemented Interfaces:

java.io.Serializable, CountConvertible, Code, Theable

public class CatcodePrimitive
extends AbstractAssignment
implements CountConvertible, Theable

This class provides an implementation for the primitive \catcode.

The Primitive \catcode

The primitive \catcode can be used to influence the tokenizer of ExTeX. This is done by assigning category codes to single characters. Whenever characters are read tokens are generated and passed on. Those tokens carry the category code into the interpreter. The interpreter considers always tokens, i.e. characters and category codes. Thus the same character can be treated differently depending on the catcode of the token.

The assignment of a catcode for a character is controlled by the prefix primitive \global and the count parameter \globaldefs. Usually the assignment is acting on the current group only. If the count parameter \globaldefs is greater than 0 or the prefix \global is given then the assignment is applied to all groups.

The following table contains the category codes with their meaning and the mapping to numerical values.

ESCAPE	0	This character code signals the beginning of an escape sequence. The following letters are absorbed into the name. If the following token is not a letter then only this single character is absorbed.
LEFTBRACE	1	This character is a left brace. It is used for grouping.
RIGHTBRACE	2	This character is a right brace. It is used for grouping.
MATHSHIFT	3	This character is used to switch to math mode. A single one switches to inline math mode and a double one to display math mode.
TABMARK	4
CR	5
MACROPARAM	6	This character is a macro parameter. It is meaningful under certain circumstances only.
SUPMARK	7	This character is an indicator the the following material should be typeset as superscript. It is meaningful in math mode only. This character class is used to parse characters from their code point as well.
SUBMARK	8	This character is an indicator the the following material should be typeset as subscript. It is meaningful in math mode only.
IGNORE	9	This character is ignored during paring. It is dropped silently.
SPACE	10	This character is a white-space character. It is treated as if a simple space has been found. Under some circumstances it is ignored.
LETTER	11	This character is a letter. As such it can be part of an escape sequence.
OTHER	12	This character is another simple character which is not a letter.
ACTIVE	13	This character is an active character. This means that some code could be bound to it. Active characters do not need the leading escape symbol like escape sequences.
COMMENT	14	This character signals the beginning of a comment. The comment reaches to the end of the current line.
INVALID	15	This character is invalid and will be dropped.

Syntax

The formal description of this primitive is the following:

    ⟨catcode⟩
      → ⟨optional prefix⟩ \catcode ⟨8-bit number⟩ ⟨equals⟩ ⟨4-bit number⟩

    ⟨optional prefix⟩
      →
       |  ⟨global⟩ ⟨optional prefix⟩  

Examples

    \catcode `\%=12  

    \global\catcode `\%=11  

\catcode as a Count Value

\catcode can be used wherever a count value is required.

Version:

$Revision: 4770 $

Author:

Gerd Neugebauer, Michael Niedermair

See Also:

Serialized Form

Field Summary

protected static long

serialVersionUID The constant serialVersionUID contains the id for serialization.

Constructor Summary

CatcodePrimitive(CodeToken token)
Creates a new object.

Method Summary

void	assign(Flags prefix, Context context, TokenSource source, Typesetter typesetter) The method assign is the core of the functionality of execute().
long	convertCount(Context context, TokenSource source, Typesetter typesetter) This method converts a register into a count.
Tokens	the(Context context, TokenSource source, Typesetter typesetter) This method is the getter for the description of the primitive.

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

execute

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

CatcodePrimitive

public CatcodePrimitive(CodeToken token)

Creates a new object.

Parameters:

token - the initial token for the primitive

Method Detail

assign

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

The method assign is the core of the functionality of execute(). This method is preferable to execute() since the execute() method provided in this class takes care of \afterassignment and \globaldefs as well.

Specified by:

assign in class AbstractAssignment

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:

AbstractAssignment.assign( org.extex.interpreter.Flags, org.extex.interpreter.context.Context, org.extex.interpreter.TokenSource, org.extex.typesetter.Typesetter)

convertCount

public long convertCount(Context context,
                         TokenSource source,
                         Typesetter typesetter)
                  throws HelpingException,
                         TypesetterException

This method converts a register into a count. It might be necessary to read further tokens to determine which value to use. For instance an additional register number might be required. In this case the additional arguments Context and TokenSource can be used.

Specified by:

convertCount in interface CountConvertible

Parameters:

context - the interpreter context

source - the source for new tokens

typesetter - the typesetter to use for conversion

Returns:

the converted value

Throws:

HelpingException - in case of an error

TypesetterException - in case of an error in the typesetter

See Also:

CountConvertible.convertCount( org.extex.interpreter.context.Context, org.extex.interpreter.TokenSource, org.extex.typesetter.Typesetter)

the

public Tokens the(Context context,
                  TokenSource source,
                  Typesetter typesetter)
           throws CatcodeException,
                  HelpingException,
                  TypesetterException

This method is the getter for the description of the primitive.

Specified by:

the in interface Theable

Parameters:

context - the interpreter context

source - the source for further tokens to qualify the request

typesetter - the typesetter to use

Returns:

the description of the primitive as list of Tokens

Throws:

CatcodeException - in case of an error in token creation

HelpingException - in case of an error

TypesetterException - in case of an error

See Also:

Theable.the( org.extex.interpreter.context.Context, org.extex.interpreter.TokenSource, org.extex.typesetter.Typesetter)