pretzel-it - Online in the Cloud

PROGRAM:

NAME

pretzel-it - use Pretzel to build a prettyprinter

SYNOPSIS

pretzel-it [-iqvdnh] language ppname

DESCRIPTION

Pretzel-it is a shell script that uses pretzel(1) to build a simple prettyprinter
executable. It minimizes building a Pretzel prettyprinter to just one shell command. See
pretzel(1) for a general overview and a description of the input files.

You have to provide the same two input files to pretzel-it as to pretzel. These two files
are called the formatted token file (suffix .ft) and the formatted grammar file (suffix
.fg). Both files need to have the same prefix language. From this input, pretzel-it
generates an executable prettyprinter called ppname.

Example
Say, you have written two files foo.ft and foo.fg that contain the prettyprinting
information for your favourite programming language foo. To get an executable
prettyprinter foopp for it, simply type:

pretzel-it foo foopp

OPTIONS

Pretzel-it has the following options:

-i Don't remove intermediate products of pretzeling.

-q Run quietly.

-v Verbose mode, print shell commands before invoking (for debugging).

-d Turn prettyprinter debugging features on by default; also produce a detailed
diagnosis file (suffix .output) that contains a detailed analysis of the
grammar and possible problems with it (to ease debugging the prettyprinting
grammar).

-h Print full usage message.

-n Noweb mode. See section Interfacing with noweb(1) below.

THE GENERATED PRETTYPRINTER

The generated executable will be a program that reads source code from the standard input
and will write prettyprinted code to the standard output. The prettyprinted code can be
typeset using latex together with the pretzel-latex document style.

Example
Say, you have built foopp already and have a scrap of source code in a file bar.foo. Type

foopp <bar.foo >bar.tex

and the prettyprinter will prettyprint the code and write LaTeX code to bar.tex. To use
this code in your documents, simple include the pretzel-latex document style and include
the file inside the new ppcode LaTeX environment. Here's a minimal LaTeX file to look at
the prettyprinted code:

\documenstyle[pretzel-latex]{article}
\begin{document}
\begin{ppcode}
\input{foo.tex}
\end{ppcode}
\end{document}

INTERFACING WITH NOWEB

Using the -n option will produce a prettyprinting filter ppname compatible to Norman
Ramsey's noweb(1) literate programming system. The filter can be inserted into the noweb
pipeline using noweave's -filter option.

For example, you can build a noweb prettyprinting filter for Pascal by issuing

pretzel-it -n pascal prettypascal

inside the languages/pascal directory, you'll get a prettyprinting filter prettypascal .
This filter then can be used within noweave(1) by saying:

noweave -filter prettypascal foo.nw > foo.tex

This will prettyprint all code chunks using the Pascal prettyprinter. You will need to
include the pretzel-noweb.sty LaTeX document style after including the noweb.sty ( see
nowebstyle(1) ) to get the output typeset correctly by LaTeX.

You can get debugging output from the prettyprinting filter by setting the environment
variable PRETZEL_NOWEB_DEBUG to a non-null value, e.g. in the bash(1) shell by saying:

export PRETZEL_NOWEB_DEBUG=on

Debug output stops only when the value is explicitly unset (in bash(1) this is the unset
builtin command.

The noweb option at present works only for LaTeX as target typesetter. If the
prettyprinter experiences problems when prettyprinting a certain code chunk, it
automatically switches to standard verbatim output of noweb. Through the inclusion of code
within rules of the formatted grammar file it is possible to automate indexing. For more
information see chapters 3 and 4 of the Pretzelbook, contained in the Pretzel
distribution.

CAVEATS

The pretzel-it shell script can only be run if the environment variables PRETZEL_LIBDIR
and PRETZEL_INCLUDE are set to the Pretzel library directory (/usr/lib/pretzel on Debian
systems) and the Pretzel include directory (/usr/include/pretzel on Debian systems).
During execution, pretzel-it might issue warnings that are due to the programs it invokes
(pretzel-it invokes pretzel(1), flex(1), bison(1) and the GNU C++ compiler).

The -n (noweb) option works only for LaTeX as target typesetter and is still very much
experimental.

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