#This file was created by <kayvan> Sun May  2 15:56:35 1999
#LyX 1.0 (C) 1995-1999 Matthias Ettrich and the LyX Team
\lyxformat 2.15
\textclass literate-article
\begin_preamble
%
% This relaxes the noweb constraint that chunks are
% never broken across pages.
%
% This is from the noweb FAQ
%
\def\nwendcode{\endtrivlist \endgroup}
\let\nwdocspar=\smallbreak
\end_preamble
\language default
\inputencoding default
\fontscheme default
\graphics default
\paperfontsize default
\spacing single 
\papersize Default
\paperpackage a4
\use_geometry 0
\use_amsmath 0
\paperorientation portrait
\secnumdepth 3
\tocdepth 3
\paragraph_separation indent
\defskip medskip
\quotes_language english
\quotes_times 2
\papercolumns 1
\papersides 1
\paperpagestyle default

\layout Title


\noun on 
noweb2lyx
\layout Author

Kayvan A.
 Sylvan <kayvan@sylvan.com>
\layout Date

May 6, 1999
\layout Abstract

This document describes and implements a perl script for importing noweb
 files into LyX
\layout Standard
\pagebreak_bottom 

\begin_inset LatexCommand \tableofcontents{}

\end_inset 


\layout Section

Introduction
\layout Standard

Since version 1.0.1, LyX now supports Literate Programming using 
\noun on 
noweb
\noun default 
.
 This addition to LyX made it very pleasant to write programs in the literate
 style (like this one).
 In addition to being able to write new literate programs, it would be quite
 useful if old 
\noun on 
noweb
\noun default 
 code could be imported into LyX in some fashion.
 That's where this program comes in.
\layout Standard

The purpose of 
\noun on 
noweb2lyx
\noun default 
 is to convert a 
\noun on 
noweb
\noun default 
 file to LyX.
\layout Scrap

<<noweb2lyx.in>>=
\newline 
#!@PERL@
\newline 
# 
\newline 
# Copyright (C) 1999 Kayvan A.
 Sylvan <kayvan@sylvan.com>
\newline 
#
\protected_separator 
You are free to use and modify this code under the terms of
\newline 
# the GNU General Public Licence version 2 or later.
\newline 
#
\newline 
#
\protected_separator 
Written with assistance from:
\newline 
# 
\protected_separator 
 Edmar Wienskoski Jr.
 <edmar-w-jr@technologist.com>
\newline 
# 
\protected_separator 
 Amir Karger <karger@post.harvard.edu>
\newline 
#
\newline 
# $Id: noweb2lyx.lyx,v 1.3 1999/05/06 22:42:39 karger Exp $
\newline 
#
\newline 
# NOTE: This file was automatically generated from noweb2lyx.lyx using noweb.
\newline 
#
\newline 
<<Setup variables from user supplied args>>
\newline 
<<Subroutines>>
\newline 
<<Convert noweb to LyX>>
\newline 
@
\layout Section

The Noweb file defined
\layout Standard

A 
\noun on 
noweb
\noun default 
 file is a collection of documentation and code chunks.
 Documentation chunks simply start with an ``@'' and have no name:
\layout LyX-Code

@ Here is some documentation.
\newline 
We can do arbitrary LaTeX code here.
\newline 
[...
 blah blah blah ...]
\layout Standard

Code chunks look like this:
\layout LyX-Code

<<Name of chunk here>>=
\newline 
{...
 code for the chunk goes here ...}
\newline 
@ 
\layout Standard

The ``@'' is a necessary delimiter to end the code chunk.
 The other form that the ``@'' line takes is as follows:
\layout LyX-Code

<<Name of chunk here>>=
\newline 
{...
 code for the chunk ...}
\newline 
@ %def identifier1 identifier2
\layout Standard

In the latter form, we are declaring to 
\noun on 
noweb
\noun default 
 that this code chunk defines identifier1, identifier2, etc.
\layout Standard

When first tackling this problem, I spoke with members of the LyX team that
 knew about the literate programming extensions and reLyX (the LaTeX importing
 code).
\layout Standard

One of the first ideas was to extend the reLyX code to understand the 
\noun on 
noweb
\noun default 
 code chunks.
 This proved to be too hard and presents other problems
\begin_float footnote 
\layout Standard

Not the least of these problems is the fact that << is a quote in French.
\end_float 
.
 On the other hand, it turns out that reLyX contains a very useful literal
 quoting mechanism.
 If the input file contains the construct
\layout LyX-Code


\backslash 
begin{reLyXskip}
\newline 
{...
 LaTeX stuff ...}
\newline 

\backslash 
end{reLyXskip}
\layout Standard

then reLyX will copy the surrounded code to the output file verbatim.
 Given this, the first part of the translation is easy; we simply have to
 copy the code chunks into an intermediate file that surrounds them with
 
\family typewriter 

\backslash 
begin{reLyXskip}
\family default 
 and 
\family typewriter 

\backslash 
end{reLyXskip}
\family default 
.
\layout Standard

Once reLyX is done with the input file, the problem is reduced to changing
 the code chunks from LyX's LaTeX layout to the Scrap layout.
\layout Standard

There is one final constraint on 
\noun on 
noweb2lyx
\noun default 
.
 We want to be able to run it as a simple pre-processor and post-processor
 from within reLyX.
 We can accomplish this by setting the flags 
\latex latex 
[[pre_only]]
\latex default 
 and 
\latex latex 
[[post_only]]
\latex default 
 before we reach the main conversion code.
\layout Standard

With all that preamble out of the way, we now have the basic high-level
 outline for our code:
\layout Scrap

<<Convert noweb to LyX>>=
\newline 
if (!$post_only) {
\newline 

\protected_separator 

\protected_separator 
<<Transform noweb for reLyX>>
\newline 
}
\newline 
if ((!$pre_only) && (!$post_only)) {
\newline 

\protected_separator 

\protected_separator 
<<Run reLyX on intermediate file>>
\newline 
}
\newline 
if (!$pre_only) {
\newline 

\protected_separator 

\protected_separator 
<<Fix up LyX file>>
\newline 
}
\newline 
<<Clean up>>
\newline 
@
\layout Section

Making a file that reLyX can process
\layout Standard

In this section, we present the code that performs the task of creating
 the intermediate file that reLyX can process, using the algorithm that
 we just outlined.
 This algorithm is outlined in the code that follows:
\layout Scrap

<<Transform noweb for reLyX>>=
\newline 
<<Setup INPUT and OUTPUT>>
\newline 
inputline: while(<INPUT>)
\newline 
{
\newline 

\protected_separator 

\protected_separator 
if (/^
\backslash 
s*
\backslash 
<
\backslash 
<.*
\backslash 
>
\backslash 
>=/) { # Beginning of a noweb scrap
\newline 

\protected_separator 

\protected_separator 

\protected_separator 

\protected_separator 
<<Read in and output the noweb code chunk>>
\newline 

\protected_separator 

\protected_separator 
} elsif (/^@
\backslash 
s+(.*)/) { # Beginning of a documentation chunk
\newline 

\protected_separator 

\protected_separator 

\protected_separator 

\protected_separator 
print OUTPUT $1; # We do not need the ``@'' part
\newline 

\protected_separator 

\protected_separator 
} elsif (/
\backslash 
[
\backslash 
[.+
\backslash 
]
\backslash 
]/) { # noweb quoted code
\newline 

\protected_separator 

\protected_separator 

\protected_separator 

\protected_separator 
<<Perform special input quoting of [[var]]>>
\newline 

\protected_separator 

\protected_separator 
} else {
\newline 

\protected_separator 

\protected_separator 

\protected_separator 

\protected_separator 
print OUTPUT; # Just let the line pass through
\newline 

\protected_separator 

\protected_separator 
}
\newline 
}
\newline 
<<Close INPUT and OUTPUT>>
\newline 
@
\layout Standard

In the code above, we do some pre-processing of the noweb ``[[...]]'' construct.
 This avoids some problems with reLyX confusing lists composed of ``[[...]]''
 constructs.
\layout Scrap

<<Perform special input quoting of [[var]]>>=
\newline 
s/
\backslash 
[
\backslash 
[.+?
\backslash 
]{2,}/{$&}/g;
\newline 
print OUTPUT;
\newline 
@
\layout Standard

While reading in the 
\latex latex 
[[INPUT]]
\latex default 
 file, once we have identified a 
\noun on 
noweb
\noun default 
 code chunk, we transform it into a form that is usable by reLyX.
\layout Scrap

<<Read in and output the noweb code chunk>>= 
\newline 
<<Save the beginning of the scrap to savedScrap>>
\newline 
<<Concatenate the rest of the scrap>>
\newline 
<<print out the scrap in a reLyXskip block>>
\newline 
@
\layout Subsection

File input and output for the pre-processing step
\layout Standard

In 
\noun on 
noweb2lyx
\noun default 
, we will use 
\latex latex 
[[INPUT]]
\latex default 
 and 
\latex latex 
[[OUTPUT]]
\latex default 
 to read and write files.
 In the code fragment above, we need to read from the input file and write
 to a file that will be later transformed by reLyX.
 If we are being called only to pre-process the input file, then there is
 no need to create a temporary file.
\layout Scrap

<<Setup INPUT and OUTPUT>>=
\newline 
if ($pre_only) {
\newline 

\protected_separator 

\protected_separator 
&setup_files($input_file, $output_file);
\newline 
} else {
\newline 

\protected_separator 

\protected_separator 
$relyx_file = "temp$$";
\newline 

\protected_separator 

\protected_separator 
&setup_files($input_file, $relyx_file);
\newline 
}
\newline 
@
\layout Standard

This code uses a small perl subroutine, 
\latex latex 
[[setup_files]]
\latex default 
, which we define below:
\layout Scrap

<<Subroutines>>=
\newline 
sub setup_files {
\newline 

\protected_separator 

\protected_separator 
my($in, $out) = @_;
\newline 

\protected_separator 

\protected_separator 
open(INPUT, "<$in") || die "Can not read $in: $!
\backslash 
n";
\newline 

\protected_separator 

\protected_separator 
open(OUTPUT, ">$out") || die "Can not write $out: $!
\backslash 
n";
\newline 
}
\newline 
@ %def setup_files 
\protected_separator 

\protected_separator 

\layout Subsection

Reading in the 
\noun on 
noweb
\noun default 
 scrap
\layout Standard

After we see the beginning of the scrap, we need to read in and save the
 rest of the scrap for output.
\layout Scrap

<<Save the beginning of the scrap to savedScrap>>=
\newline 
$savedScrap = $_;
\newline 
$endLine = "";
\newline 
@
\layout Scrap

<<Concatenate the rest of the scrap>>=
\newline 
scrapline: while (<INPUT>) {
\newline 

\protected_separator 

\protected_separator 
last scrapline if /^@
\backslash 
s+/;
\newline 

\protected_separator 

\protected_separator 
$savedScrap .= $_;
\newline 
};
\newline 
switch: {
\newline 

\protected_separator 

\protected_separator 
if (/^@
\backslash 
s+$/) {$savedScrap .= $_; last switch; }
\newline 

\protected_separator 

\protected_separator 
if (/^@
\backslash 
s+%def.*$/) {$savedScrap .= $_; last switch; }
\newline 

\protected_separator 

\protected_separator 
if (/^@
\backslash 
s+(.*)$/) {$savedScrap .= "@
\backslash 
n"; $endLine = "$1
\backslash 
n"; }
\newline 
}
\newline 
@
\layout Subsection

Printing out the scrap
\layout Standard

The final piece of the first pass of the conversion is done by this code.
\layout Scrap

<<print out the scrap in a reLyXskip block>>=
\newline 
print OUTPUT "
\backslash 

\backslash 
begin{reLyXskip}
\backslash 
n";
\newline 
print OUTPUT $savedScrap;
\newline 
print OUTPUT "
\backslash 

\backslash 
end{reLyXskip}
\backslash 
n
\backslash 
n";
\newline 
print OUTPUT "$endLine";
\newline 
@
\layout Standard

Finally, we need to close the 
\latex latex 
[[INPUT]]
\latex default 
 and 
\latex latex 
[[OUTPUT]]
\latex default 
 files.
\layout Scrap

<<Close INPUT and OUTPUT>>=
\newline 
close(INPUT);
\newline 
close(OUTPUT);
\newline 
@
\layout Section

Running reLyX
\layout Standard

In this section, we describe and implement the code that runs reLyX on the
 intermediate file 
\latex latex 
[[relyx_file]]
\latex default 
.
 
\layout Subsection

Selecting the document class
\layout Standard

In order to run reLyX, we need to know the article class of the input document
 (to choose the corresponding literate document layout).
 For this, we need to parse the intermediate file.
\layout Scrap

<<Run reLyX on intermediate file>>=
\newline 
<<Parse for document class>>
\newline 
<<Run reLyX with document class>>
\newline 
@
\layout Standard

In the code below, you'll see a strange regular expression to search for
 the document class.
 The reason for this kludge is that without it, we can't run 
\noun on 
noweb2lyx
\noun default 
 on the 
\emph on 
noweb2lyx.nw
\emph default 
 file that is generated by LyX
\begin_float footnote 
\layout Standard

reLyX searches for 
\backslash 

\backslash 
doc
\latex latex 
{}
\latex default 
ument
\latex latex 
{}
\latex default 
class and gets confused, so we have to obfuscate it slightly.
\end_float 
.
 With the regular expression as it is, we can actually run 
\noun on 
noweb2lyx
\noun default 
 on itself and a produce a quite reasonable LyX file.
\layout Scrap

<<Parse for document class>>=
\newline 
open(INPUT, "<$relyx_file") ||
\newline 

\protected_separator 

\protected_separator 
die "Can not read $relyx_file: $!
\backslash 
n";
\newline 
$class = "article"; # default if none found
\newline 
parse: while(<INPUT>) {
\newline 

\protected_separator 

\protected_separator 
if (/
\backslash 

\backslash 
docu[m]entclass{(.*)}/) {
\newline 

\protected_separator 

\protected_separator 

\protected_separator 

\protected_separator 
$class = $1;
\newline 

\protected_separator 

\protected_separator 

\protected_separator 

\protected_separator 
last parse;
\newline 

\protected_separator 

\protected_separator 
}
\newline 
}
\newline 
close(INPUT);
\newline 
@
\layout Subsection

Running reLyX with the corresponding literate document layout
\layout Standard

Now that we know what the document class ought to be, we do:
\layout Scrap

<<Run reLyX with document class>>= 
\newline 
$doc_class = "literate-" .
 $class;
\newline 
die "reLyX returned non-zero: $!
\backslash 
n"
\newline 

\protected_separator 

\protected_separator 
if (system("reLyX -c $doc_class $relyx_file"));
\newline 
@
\layout Standard

reLyX performs the main bulk of the translation work.
 Note that if the ``literate-
\emph on 
class
\emph default 
'' document layout is not found, then reLyX will fail with an error.
 In that case, you may need to modify your 
\noun on 
noweb
\noun default 
 input file to a supported document type.
\layout Section

Fixing the reLyX output
\layout Standard

We need to perform some post-processing of what reLyX produces in order
 to have the best output for our literate document.
 The outline of the post-processing steps are:
\layout Scrap

<<Fix up LyX file>>=
\newline 
<<Setup INPUT and OUTPUT for the final output>>
\newline 
line: while(<INPUT>)
\newline 
{
\newline 

\protected_separator 

\protected_separator 
<<Fix code chunks in latex layout>>
\newline 

\protected_separator 

\protected_separator 
<<Fix [[var]] noweb construct>>
\newline 

\protected_separator 

\protected_separator 
print OUTPUT; # default
\newline 
} 
\newline 
<<Close INPUT and OUTPUT>>
\newline 
@
\layout Standard

Note that in the perl code that is contained in the 
\latex latex 
[[while(<INPUT>)]]
\latex default 
 loop above, the perl construct 
\latex latex 
[[next line]]
\latex default 
 is sufficient to restart the loop.
 We can use this construct to do some relatively complex parsing of the
 reLyX generated file.
\layout Subsection

File input and output for the post-processing
\layout Standard

Setting up the 
\latex latex 
[[INPUT]]
\latex default 
 and 
\latex latex 
[[OUTPUT]]
\latex default 
 is taken care of by this code:
\layout Scrap

<<Setup INPUT and OUTPUT for the final output>>=
\newline 
if ($post_only) {
\newline 

\protected_separator 

\protected_separator 
&setup_files("$input_file", "$output_file");
\newline 
} else {
\newline 

\protected_separator 
 &setup_files("$relyx_file.lyx", "$output_file");
\newline 
}
\newline 
@
\layout Subsection

Making sure the code chunks are in the Scrap layout
\layout Standard

Now, as we outlined before, the final step is transforming the code-chunks
 which have been put into a LaTeX layout by LyX into the scrap layout.
\layout Scrap

<<Fix code chunks in latex layout>>=
\newline 
if (/
\backslash 

\backslash 
latex latex/) { # Beginning of some latex code
\newline 

\protected_separator 

\protected_separator 
if (($line = <INPUT>) =~ /^
\backslash 
s*<</) { # code scrap
\newline 

\protected_separator 

\protected_separator 
 
\protected_separator 
<<Transform this chunk into layout scrap>>
\newline 

\protected_separator 

\protected_separator 
} else {
\newline 

\protected_separator 

\protected_separator 

\protected_separator 

\protected_separator 
# print the 
\backslash 
latex latex line + next line
\newline 

\protected_separator 

\protected_separator 

\protected_separator 

\protected_separator 
print OUTPUT "$_$line";
\newline 

\protected_separator 

\protected_separator 
}
\newline 

\protected_separator 

\protected_separator 
next line;
\newline 
}
\newline 
@
\layout Standard

When we are sure that we are in a code chunk, we must read in the rest of
 the code chunk and output a scrap layout for it:
\layout Scrap

<<Transform this chunk into layout scrap>>=
\newline 
$savedScrap = "
\backslash 

\backslash 
layout Scrap
\backslash 
n
\backslash 
n$line";
\newline 
codeline: while (<INPUT>) {
\newline 

\protected_separator 

\protected_separator 
$savedScrap .= $_;
\newline 

\protected_separator 

\protected_separator 
last codeline if /^@
\backslash 
s+/;
\newline 
};
\newline 
print OUTPUT $savedScrap;
\newline 
<<Slurp up to the end of the latex layout>>
\newline 
@
\layout Standard

Okay, now we just need to eat the rest of the latex layout.
 There should only be a few different types of lines for us to match:
\layout Scrap

<<Slurp up to the end of the latex layout>>=
\newline 
slurp: while (<INPUT>) {
\newline 

\protected_separator 

\protected_separator 
last slurp if /
\backslash 

\backslash 
latex /;
\newline 

\protected_separator 

\protected_separator 
next slurp if /
\backslash 

\backslash 
newline/;
\newline 

\protected_separator 

\protected_separator 
next slurp if /^
\backslash 
s*$/;
\newline 

\protected_separator 

\protected_separator 
warn "confused by line: $_";
\newline 
}
\newline 
@
\layout Subsection

Taking care of the 
\noun on 
noweb
\noun default 
 
\emph on 
[[quoted code]]
\emph default 
 construct
\layout Standard


\noun on 
noweb
\noun default 
 allows the user to use a special code quoting mechanism in documentation
 chunks.
 Fixing this ``[[quoted-code]]'' 
\noun on 
noweb
\noun default 
 syntax means putting the ``[[quoted-code]]'' in a LaTeX layout in the LyX
 file.
 Otherwise, LyX will backslash-quote the brackets, creating ugly output.
 The quoted-code is transformed by 
\noun on 
noweb
\noun default 
 when it generates the final LaTeX code.
\layout Scrap

<<Fix [[var]] noweb construct>>=
\newline 
if (/
\backslash 
[
\backslash 
[.+
\backslash 
]
\backslash 
]/) { # special code for [[var]]
\newline 

\protected_separator 

\protected_separator 
s/
\backslash 
[
\backslash 
[.+?
\backslash 
]{2,}/
\backslash 
n
\backslash 

\backslash 
latex latex
\backslash 
n$&
\backslash 
n
\backslash 

\backslash 
latex default
\backslash 
n/g;
\newline 

\protected_separator 

\protected_separator 
print OUTPUT;
\newline 

\protected_separator 

\protected_separator 
next line;
\newline 
}
\newline 
@
\layout Section

Cleaning up intermediate files
\layout Standard

The cleanup code is very simple:
\layout Scrap

<<Clean up>>=
\newline 
system("rm -f $relyx_file*") unless ($post_only || $pre_only);
\newline 
@
\layout Section

User supplied arguments
\layout Standard

The 
\noun on 
noweb2lyx
\noun default 
 script understands two arguments, input-file and output-file.
 It is also set up to be used internally by reLyX to pre-process or postprocess
 files in the import pipeline.
\layout Scrap

<<Setup variables from user supplied args>>=
\newline 
&usage() if ($#ARGV < 1); # zero or one argument 
\newline 
if ($ARGV[0] eq "-pre") {
\newline 

\protected_separator 

\protected_separator 
&usage unless ($#ARGV == 2);
\newline 

\protected_separator 

\protected_separator 
$input_file = $ARGV[1]; $output_file = $ARGV[2]; $pre_only = 1;
\newline 
} elsif ($ARGV[0] eq "-post") {
\newline 

\protected_separator 

\protected_separator 
&usage unless ($#ARGV == 2);
\newline 

\protected_separator 

\protected_separator 
$input_file = $ARGV[1]; $output_file = $ARGV[2]; $post_only = 1;
\newline 
} else {
\newline 

\protected_separator 

\protected_separator 
&usage unless ($#ARGV == 1);
\newline 

\protected_separator 

\protected_separator 
$input_file = $ARGV[0];
\protected_separator 
$output_file = $ARGV[1];
\newline 

\protected_separator 

\protected_separator 
$pre_only = 0; $post_only = 0;
\newline 
}
\newline 
@ %def input_file output_file pre_only post_only
\layout Scrap

<<Subroutines>>=
\newline 
sub usage() {
\newline 

\protected_separator 

\protected_separator 
print "Usage: noweb2lyx [-pre | -post] input-file output-file
\newline 

\newline 
If -pre is specified, only pre-processes the input-file for reLyX.
\newline 
Similarly, in the case of -post, post-processes reLyX output.
\newline 
In case of bugs, Email Kayvan Sylvan <kayvan
\backslash 
@sylvan.com>.
\backslash 
n";
\newline 

\protected_separator 

\protected_separator 
exit;
\newline 
}
\newline 
@ %def usage
\layout Section

Generating the 
\noun on 
noweb2lyx
\noun default 
 script
\layout Standard

The noweb2lyx script can be tangled from LyX if you set 
\family typewriter 

\backslash 
build_command
\family default 
 to call a generic script that always extracts a scrap named 
\family typewriter 
build-script
\family default 
 and executes it.
 Here is an example of such a script:
\layout LyX-Code

#!/bin/sh
\newline 
notangle -Rbuild-script $1 | sh
\layout Scrap

<<build-script>>=
\newline 
PREFIX=/usr
\newline 
notangle -Rnoweb2lyx.in noweb2lyx.nw > noweb2lyx.in
\newline 
sed -e "s=@PERL@=$PREFIX/bin/perl=" noweb2lyx.in > noweb2lyx
\newline 
chmod +x noweb2lyx
\newline 
@
\layout Section*
\pagebreak_top 
Macros
\layout Standard


\latex latex 

\backslash 
nowebchunks
\layout Section*

Identifiers
\layout Standard


\latex latex 

\backslash 
nowebindex
\the_end
