org.extex.unit.tex.register.box
Class Dp

java.lang.Object
  extended by org.extex.interpreter.type.AbstractCode
      extended by org.extex.interpreter.type.AbstractAssignment
          extended by org.extex.unit.tex.register.box.Dp
All Implemented Interfaces:
java.io.Serializable, CountConvertible, DimenConvertible, Code, ExpandableCode, Theable

public class Dp
extends AbstractAssignment
implements ExpandableCode, Theable, CountConvertible, DimenConvertible

This class provides an implementation for the primitive \dp.

The Primitive \dp

The primitive \dp refers to the depth of a box register. It can be used in various contexts.

Execution of the Primitive

If the primitive is used in a context it initiated an assignment to the actual depth of the box register. This has an effect only in the case that the box register is not void.

The formal description of this primitive is the following:

    ⟨dp⟩
      → ⟨optional prefix⟩ \dp ⟨box register name⟩ ⟨equals⟩ ⟨dimen⟩

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

Examples

    \dp42 = 12mm  
    \dp42 = \dimen3  

Expansion of the Primitive

In an expansion context the primitive results in the the current depth of the given box register. In case that the box register is empty the result is 0 pt.

Syntax

The formal description of this primitive is the following:

    \dp ⟨8-bit number⟩ 

Examples

    \dimen0 = \dp42  
    \the\dp42  

Conversion to a Count

The primitive is convertible into a count. It can be used wherever an integer quantity is expected.

Interaction with \the

The primitive \the can be applied to this primitive. In this case it results in a token list representing the value in points.

Version:
$Revision:4431 $
Author:
Gerd Neugebauer
See Also:
Serialized Form

Field Summary
protected static long serialVersionUID
          The constant serialVersionUID contains the id for serialization.
 
Constructor Summary
Dp(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.
 long convertDimen(Context context, TokenSource source, Typesetter typesetter)
          This method converts a register into a dimen.
 void expand(Flags prefix, Context context, TokenSource source, Typesetter typesetter)
          This method takes the first token and expands it.
 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

Dp

public Dp(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)

convertDimen

public long convertDimen(Context context,
                         TokenSource source,
                         Typesetter typesetter)
                  throws HelpingException,
                         TypesetterException
This method converts a register into a dimen. 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. The return value is the length in scaled points.

Specified by:
convertDimen in interface DimenConvertible
Parameters:
context - the interpreter context
source - the source for new tokens
typesetter - the typesetter to use for conversion
Returns:
the converted value in sp
Throws:
HelpingException - in case of an error
TypesetterException - in case of an error in the typesetter
See Also:
DimenConvertible.convertDimen( 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)

the

public Tokens the(Context context,
                  TokenSource source,
                  Typesetter typesetter)
           throws 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:
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, Typesetter)