A Guide to PAD Style File

Index

1. The Usage of the Macros

1.1. Drawing Commands

\padbox{text}

Draws a frame for procedure. text is typeset in LR mode.

\padwhile{cond}{proc}

\padrepeat{cond}{proc}

\padwhile draws a frame for pre-conditional loop, while \padrepeat draws a frame for general (or post-conditional) loop. cond specifies its condition. proc specifies its procedure. cond is typeset in LR mode. When proc contains nothing (not even one whitespace), the flow line between condition and procedure would not be drawn.

\padcond{cond}{proc1}{proc2}

Draws a frame for selection. cond specifies its condition. proc1 and proc2 specify its procedures. cond is typeset in LR mode. The same as \padwhile and \padrepeat, the flow line will not be drawn if proc1 and/or proc2 contains nothing.

\padcase{expr}{cases}

Draws a frame for selection. Use this macro, rather than \padcond, if there are more than two conditional cases. expr is typeset in LR mode and is positioned in middle of the frame. cases specifies the case and the corresponding procedure in pairs. These pairs are separated by `,', while their case and procedure are separated by `:'. The cases are typeset in LR mode.

When case or procedure contains `:' or `,', it should be parenthesized by braces.

\padsub{text}

Draws a frame for subroutine. text is typeset in LR mode.

\padseq{procs}

Draws a sequence of the procedures. procs specifies a sequence of procedures. Each procedures are separated by a \\.

You can put some extra space by setting the optional argument len of a \\. This will add len, space between procedures.

\padlabel{label}

Draws a label named label.

\padref{label}

Draws a frame for reference to a label named label.

\padboxss{texts}

\padsubss{texts}

These are defined for writing a text spreading over multiple lines inside \padbox and \padsub. Each line is separated by a \\.

These macros just call the corresponding macro with argument \shortstack{texts}. When you want to write multiple lines inside loop or selection, just call the macro with the same argument.

\padmessage{message}

Writes a comment. Use this macro when you want to write a comment inside \padseq, otherwise the vertical flow line on left won't be drawn.

\padcomment{comment}

Writes a comment on right of the procedure. comment is typeset in LR mode, and is positioned in the middle.

1.2. Box Commands

\savepad{name}{pad}

Saves a PAD specified by pad into the container specified by name. name is a regular command name. You do not need to create a container using LaTeX command \newsavebox.

\usepad{name}

Draws a PAD saved in the container name by \savepad.

To save or draw a PAD, do not use LaTeX command \savebox or \usebox. Instead, use these macros.

1.3. Style Parameters

\padboxrule

Sets the width of lines in a PAD. This does not change width of slanted lines or circles. The width of the frame will be twice as bold as this value.

\padboxsep

Sets the amount of space inserted between the frame of a PAD and its contents.

\padcolsep

Sets the minimum width between columns in \padseq, \padcond and \padcase.

2. Notes

• The size of the PAD frame varies according to the size of its contents. To adjust the size, use \makebox, \raisebox, strut, and so forth. Please note that there is the minimum size, though.
• The baseline of items, such as \padbox, \padcond, and so forth, coincides with the bottom of its bounding box.

  By using the *-variants of these macros, you can coincides the baseline with that of its first argument. With regard to \padseq*, its baseline is located in -0.5ex lower to the center of its body.

  

3. Examples

Figure 1: Nesting test

Figure 2: Ackermann's function

4. Troubleshooting

4.1. Errors in pad.sty

! TeX capacity exceeded, sorry [parameter stack size=...].

This occurs when \padcases are nested too deeply. Save the PAD in the most inner loop using \savepad first, then draw the PAD using \usepad.

! TeX capacity exceeded, sorry [semantic stack size=...].

This also occurs by nesting too deeply. Deal with it in the same manner as previous.

Use BigTeX to process a file with complicated and/or many PADs, because the current version of pad.sty does not maintain resources well.

! No room for a new ....

This occurs when there are too much PADs or switching alternatives to \padcase. I'm sorry that there is no way to deal with it but to reduce the number of PADs or divide the input file.

4.2. Trouble with pad2tex

5. Known Problems

• When minus value is specified in optional argument of a \\ in \padseq, the flow line on the left won't be eliminated.
• When using \padmessage in the last of \padseq, the flow line on the left won't be eliminated.
• The height of the box of \padcomment is ignored.
• Resources are poorly managed.

6. Things to do

• Optimize the usage of resources.
• Support page break in the middle of \padseq.
• Support design customization of PAD.

7. Credit

References

[1] Yoshihiko Futamura. Program Techniques -Structured Programming Using PAD-. Ohm, 1984.

[2] Leslie Lamport. LaTeX: A Document Preparation System. ASCII, 1990.
(The Original: Leslie Lamport. LaTeX: A Document Preparation System. Addison-Wesley, 1986.).

[3] Hideaki Togashi. ASCII Japanese TeX. Super ASCII. ASCII, Aug 1992 - Aug 1993.

Appendix

kind	format	PAD
procedure	\padbox{text}
pre-conditional loop	\padwhile{cond}{proc}
general loop (post-conditional loop)	\padrepeat{cond}{proc}
selection	\padcond{cond}{proc1}{proc2}
selection (has 2 or more conditions)	\padcase{expr}{cases}
subroutine	\padsub{text}
sequence	\padseq{procs}
label	\padlabel{label}
reference to label	\padref{label}
procedure (multiple lines)	\padboxss{texts}
subroutine (multiple lines)	\padsubss{texts}
message	\padmessage{message}
comment	\padcomment{comment}
save PAD	\savepad{name}{pad}	---
use PAD	\usepad{name}	---