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CS 403: Programming
Languages
Lecture 16
Fall 2003
Department of
Computer Science
University of Alabama
Joel Jones
Overview
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Announcements
Lecture 16
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M4 Macro Processor
Geoffrey Haynes
m4 is a general purpose macro processor that
can be used to preprocess C and assembly
language programs, among other things.
Besides the straightforward replacement of one
string of text by another, m4 lets you perform
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integer arithmetic
file inclusion
conditional macro expansion
string and substring manipulation
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You can use built-in macros to perform these tasks or define
your own macros. Built-in and user-defined macros work
exactly the same way except that some of the built-in macros
have side effects on the state of the process.
The basic operation of m4 is to read every legal token (string
of ASCII letters and digits and possibly supplementary
characters) and determine if the token is the name of a
macro. The name of the macro is replaced by its defining
text, and the resulting string is pushed back onto the input to
be rescanned. Macros may be called with arguments. The
arguments are collected and substituted into the right places
in the defining text before the defining text is rescanned.
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A small review of Python
Jesse Booth
Named
after Monty Python
Released
Syntax:
to public in 1991
cross between C and the
Modula family
Why Use Python?
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Simple Syntax
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Easy to learn and quick to code
Portable between Unixes and even other
operating systems
 Large Standard Library
 Used for large complex projects with
many different developers
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Why is Python different?
Choice of Object-oriented programming
 Block structure is controlled by actual
indentation not brackets
 Easy to combine with C for performancecritical applications
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Substantial speed gains
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Python
Bin Qiao
Python is a scripting language designed for close
integration with C. Its syntax is rather like a cross
between that of C and the Modula family.
It has a type system comparable in expressive power
to Perl’s.
Python is generally thought to be the least efficient
and slowest of the major scripting languages.
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Considerations of Using Python
Programmability. Python is well suited to functioning as a
glue language which is commonly used to implement the
lower level operations.
Prototyping. Python provides a good environment for
quickly developing an initial prototype.
Simplicity and ease of understanding. Python is powerful
but very simple, which lets you learn the language more
quickly, and then rapidly write code.
Java integration. Jython is a re-implementation of Python
in Java that complies Python codes into Java bytecodes.
The resulting environment has very tight, almost seamless,
integration with Java.
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Ruby
Robert Bradford
created by: Yukihiro Matsumoto
What is Ruby?
 Ruby is a new object oriented programming language.
 Though rarely used in the United States, it has become very popular in
other areas of the world.
What are the advantages to using Ruby as a language?
 Features similar to Perl
o Process text files
o Perform system management tasks
 Few lines of code, but not cryptic
 Syntax and semantics are simple
 Ruby is open source
 Platform independent… can be used on Windows, Unix or Linux
Features
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Simple syntax
Error handling
Blocks in syntax
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o
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Surrounded by either { } or do … end
Can be passed to methods
Integers can be used without counting internal representation
No variable declarations, naming conventions denote scope
o
o
o
'var' = local variable
'@var' = instance variable
'$var' = global variable
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Code Analysis
 First…
o
a definition of Fibonacci
The basic Fibonacci series is a sequence of integers, starting with two 1's, in
which each subsequent term is the sum of the two preceding terms. The series
is sometimes used in sorting algorithms and in analyzing natural phenomena.
 Demonstrated
o
o
o
o
o
by this example:
Parallel assignment
Local variable creation
Looping structure
Function definition
Output
Lecture 16
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Tool Command Language
(Tcl)
By: Steven
Kemp
What is Tcl?
Tcl is a small language interpreter that
can be linked with compiled C libraries.
 It can also be used for embedded scripts,
which are scripts that are called from C
programs.
 It was first released publicly in 1990.
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Advantages of Tcl
 It
is extremely flexible and radically
simple.
 It has a totally consistent syntax.
 The interpreter itself can be
redefined from within Tcl.
 It’s compact design makes it more
efficient for smaller projects
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Minor Disadvantages of Tcl
 The
only data structure is
association lists
 Not good for use on large
programs
 Syntax is slightly odd, even
though it is consistant
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Java
Eric Jackson
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Developed by Sun Microsystems
Created to be “write once, run anywhere”
Automatically handles memory management.
Can inherit from just about anything.
Easy to learn.
Style very similar to C and C++
MySet.java code to implement Set ADT
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Brad Hutchinson
PHP
 Open source, server-side, HTML embedded scripting language used to create
dynamic web pages.
 Created in 1994, but during mid 1997 the development changed hands and the
parser was rewritten from scratch to create PHP version 3.
 Syntax is similar to that of Perl or C++.
 The script is enclosed within special PHP tags, and because PHP is embedded
within tags it is possible to jump between HTML and PHP.
This prevents having to actually write large amounts of HTML code using
PHP.
 Since it is executed on the server, the script cannot be viewed by someone
accessing the web page.
 Can perform any task that any CGI program can do, but its strength lies in its
compatibility with many types of databases.
 Can talk across networks using IMAP, SNMP, NNTP, POP3, or HTTP.
Little Ruby? Big Ruby?
What is Ruby?
The Creator of Ruby
Yukihiro Matsumoto, a.k.a Matz [email protected]
Ruby is the interpreted scripting language for quick and easy
object-oriented programming.
It has many features to process text files and to do system
management tasks (as in Perl). It is simple, straight-forward,
extensible, and portable.
R. Allen Sanford
Features of Ruby
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Ruby has simple syntax, partially inspired by Eiffel and Ada.
Ruby has exception handling features, like Java or Python, to make it easy to handle errors.
Ruby's operators are syntax sugar for the methods. You can redefine them easily.
Ruby is a complete, full, pure object oriented language: OOL. This means all data in Ruby is an object.
Ruby's OO is carefully designed to be both complete and open for improvements.
Ruby features single inheritance only, *on purpose*.
Ruby features blocks in its syntax (code surrounded by '{' ... '}' or 'do' ... 'end'). These blocks can be passed to methods, or
converted into closures.
Ruby features a true mark-and-sweep garbage collector. It works with all Ruby objects. You don't have to care about
maintaining reference counts in extension libraries. This is better for your health. ;-)
Writing C extensions in Ruby is easier than in Perl or Python, due partly to the garbage collector, and partly to the fine
extension API. SWIG interface is also available.
Integers in Ruby can (and should) be used without counting their internal representation.
Ruby needs no variable declarations. It uses simple naming conventions to denote the scope of variables. Examples: simple
'var' = local variable, '@var' = instance variable, '$var' = global variable. So it is also not necessary to use a tiresome 'self.'
prepended to every instance member.
Ruby can load extension libraries dynamically if an OS allows.
Ruby features OS independent threading. Thus, for all platforms on which Ruby runs, you also have multithreading,
regardless of if the OS supports it or not, even on MS-DOS! ;-)
Ruby is highly portable: it is developed mostly on Linux, but works on many types of UNIX, DOS, Windows 95/98/NT, Mac,
BeOS, OS/2, etc.
R. Allen Sanford
Information obtain from http://www.ruby-lang.org/en/
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Documentation
All of the Previous information and more can be found at:
http://www.ruby-lang.org/en/
Other useful links are:
Great intro to ruby!
http://www.math.umd.edu/~dcarrera/ruby/0.3/
Ruby, Gui’s, and Tk toolkit.
http://httpd.chello.nl/k.vangelger/ruby/learntk/
Demonstration on generating html templates using ruby.
http://www.hillmanimages.com/912/tutor01.html
R. Allen Sanford
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Ruby
Charles B. Ward
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Ruby is an interpreted language, similar in a number of
ways to perl, php, and python.
Ruby is an purely object oriented programming
language, like Smalltalk. Everything is an object,
including numbers.
Ruby is *not* strongly typed.
Ruby features only single-inheritance, instead allowing
classes to import modules of methods.
Ruby has automatic memory management (garbage
collector).
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More Ruby
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Ruby naming conventions to denote the scope
of variables.
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'var' = local variable
'@var' = instance variable
'$var' = global variable.
Ruby supports internal threading. (programs
can be multithreaded independently of the
operating system)
Ruby is compatible with LINUX, UNIX, DOS,
Windows 95/98/NT, Mac, BeOS, OS/2, etc.
Lecture 16
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TCL (Tool Command
Language)
Charles Lemont Howard
developed mainly by
John Ousterhout
Pros and Cons of TCL
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PROS
It is a high-level scripting language
~ lot less code to write to get job
done
It runs on many platforms
It is interpreted ~ execute code
without compiling and linking
It is extensible
It is embeddable in your
applications ~ meaning you can
use TCL as an application language
terrific language for database
applications
Tcl is free
Lecture 16
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CONS
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TCL is interpreted ~
programs written in TCL are
slow because TCL only
deals with strings
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Syntax checking only at
runtime
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Fundamental aspects of the
Ruby programming language
Kunal Vyas
About Ruby
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Yukihiro Matsumoto (Matz), a professional programmer working for and open
source company in Japan (netlab.co.ip) invented the Ruby programming
language.
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Ruby is a "pure Object Oriented Language". Everything in Ruby is an object
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Ruby is a "pure Object Oriented Language". Everything in Ruby is an object
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Ruby uses pass-by-reference. Ruby also supports default formal argument
assignment
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Ruby's features are as follows:
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Interpretive
Variables have no type (dynamic typing)
No declaration needed
Simple syntax
No user-level memory management
Everything is object
Class, inheritance, methods
Singleton methods
Mix-in by modules
Iterators
Closures
Text processing and regular expression
Bignums
Dynamic loading
Exception handling
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What made ruby different from other
Programming Languages
Language:
Ruby Added:
Ruby Took Away:
C *Operator
overloading
Object Orientation
In light of the fact that
C is the defining
language for Ruby and
Ruby is extendable
using C, all the
functionality of C is
supported.
Smalltalk
*Object
Orientation
*Everything
is an object!
1.Multiple Inheritance.
2. Ruby isn't as strict as
Smalltalk with regard
to object, inheritance
and class hierarchy
Lecture 16
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Continue
Language:
Ruby Added:
Ruby Took Away:
Perl *Scripting
Power
1. Clean Object
Orientation - Ruby
was initially
designed with OO in
mind, whereas Perl
was extended to
support objects.
1.Scope rules in Ruby
(default: local) eliminate
the need for any 'my'
declarations.
2. Ruby eliminates a lot of
Perl's syntax sugar
without losing
functionality making
Ruby less cryptic.
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Continue
Language:
Ruby Added:
Ruby Took Away:
Python
*Exception
Handling
1. Exception handling
2. Type coercion
between small and long
integers
3. Mark and sweep
garbage collection
instead of a
Ref-counter garbage
collection.
1. Ruby's instance
variables are prefixed by
a at eliminating the need
for 'self' declarations.
4. Inheritance /
subclassing
3. Tuples
Lecture 16
2. Python treats types
and classes differently,
Ruby treats them the
same.
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Continue
Language:
Ruby Added:
Ruby Took Away:
Eiffel *Object
orientation and
simple syntax
Ruby is interpreted
Compilation is not
Required for Ruby.
Lisp *
Lambda
expressions
Object Orientation
All those Parentheses
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For what applications would this
language be suitable?
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Text processing
CGI programming
Network programming
XML programming
GUI applications
AI and Exploratory Mathematics
General programming
Prototyping
Programming education
eXtreme programming
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For what would it not be suitable?
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High traffic web applications
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Operating systems implementation
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Compiler implementation
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Ruby
André Taylor
“The object oriented
scripting language”
André Taylor
Introduction
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Ruby is the interpreted scripting language for quick
and easy object-oriented programming. It has
many features to process text files and to do
system management tasks (as in Perl). It is
simple, straight-forward, extensible, and portable.
Ruby is highly portable: it is developed mostly on
Linux, but works on many types of UNIX, DOS,
Windows 95/98/NT, Mac, BeOS, OS/2, etc.
Lecture 16
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André Taylor
Important features
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Ruby has simple syntax, partially inspired by Eiffel
and Ada.
Ruby has exception handling features, like Java or
Python, to make it easy to handle errors.
Ruby features a true mark-and-sweep garbage
collector. It works with all Ruby objects. You don't
have to care about maintaining reference counts in
extension libraries. This is better for your health. ;-)
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André Taylor
Important features cont.
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Ruby needs no variable declarations.
Examples:
 'var' = local variable
 '@var' = instance variable
 '$var' = global variable.
Ruby features blocks in its syntax (code
surrounded by '{' ... '}' or 'do' ... 'end'). These
blocks can be passed to methods, or converted
into closures.
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André Taylor
Tcl/Tk
David Marshall
•
Tcl (Tool Command Language)
Created in 1989 by John Ousterhout
 An interpreted language with the main
purpose of integrating or tying together other
applications
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Tk
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An extension of Tcl created for componentbased GUI design
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Features of Tcl/Tk
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Extensible – Easy to add your own features
Designed so that added features feel as natural as
the basic features of the language
 Embeddable – Interpreter exists as C Library
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GUI building with Tk toolkit
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Extremely fast to design and implement a GUI out of
components provided by Tk
Cross Platform
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Runs on Windows, Mac, and Unix platforms
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Tcl Compared
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Often compared to Perl
Syntax is much simpler than Perl and has less
of a learning curve
 Easier to maintain – Perl syntax is much more
complex, so reading and maintaining Tcl code
is an easier task
 Tk is available for Perl, but is less intuitive and
clumsier because it was designed for Tcl
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More information available at
http://www.tcl.tk
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Bash, XSLT, Dot, and C
Nathan Wiegand
What to do with
all those tools?
Bash
The Bourne Again SHell - Created by
Ritchie and Thompson from the Bourne
Shell(sh).
 Designed in order for people to better
communicate with the system they were
developing at AT&T
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XSLT
eXtensible Stylesheet Language
Transform
 Used to translate XML (eXtensible
Markup Language) into another format
(e.g. HTML, Word File, Dot)
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Dot
Open graph drawing software developed
at AT&T
 Used to present datastructures and other
things which can be represented as
graphs (i.e. file trees)
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File Tree Viewer
Start with a Bash script which walks your
file tree and creates and XML file from the
files it observes.
 Next, use an XSL Transform to convert
that XML document into a Dot Script.
 Use Dot to convert this script into a nice
Gif image for viewing.
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The Bash Script
#!/bin/bash
dir=$(pwd)
function dirExp {
echo "<node s=\"box\" c=\"red\" value=\"$2\">"
cd "$1/$2"
for i in $(ls -l -1 | grep ^- | gawk '{print $9}')
do
VAL=$($dir/conv $(ls -l -1 $i | gawk '{print $1}'))
if [ $(($VAL/100)) = 7 ]; then
color="green"
else
color="white"
fi
echo "<node s=\"ellipse\" c=\"$color\" value=\"$i\"/>"
done
for i in $(ls -l -1 | grep ^d | gawk '{print $9}')
do
dirExp "$1/$2" $i
done
echo "</node>"
}
dirExp $dir . > "$dir/dir.xml"
cd $dir
xsltproc -o structure.dot graph.xsl dir.xml
dot -Tgif -o structure.gif structure.dot
mv structure.gif ~/public_html
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The C file
#include <stdio.h>
int
main
(int argc,
char *argv[])
{
int
perm[3],
i;
if(argc!=2)
fprintf(stderr,"Error\n");
for(i=1,perm[0]=perm[1]=perm[2]=0;i<strlen(argv[1]);i++) {
perm[(i-1)/3]*=2;
if(argv[1][i]!='-')
perm[(i-1)/3]++;
}
fprintf(stdout,"%d%d%d\n",perm[0],perm[1],perm[2]);
return 0;
}
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The Produced XML
<node s="box" c="red" value=".">
<node s="ellipse" c="green" value="conv"/>
<node s="ellipse" c="white" value="conv.c"/>
<node s="ellipse" c="white" value="dir.xml"/>
<node s="ellipse" c="white" value="graph.xsl"/>
<node s="ellipse" c="white" value="Makefile"/>
<node s="ellipse" c="green" value="new.sh"/>
<node s="ellipse" c="white" value="structure.dot"/>
<node s="box" c="red" value="Project1">
<node s="ellipse" c="green" value="a.out"/>
<node s="ellipse" c="green" value="conv"/>
<node s="ellipse" c="white" value="dir.tree"/>
<node s="ellipse" c="white" value="dir.xml"/>
<node s="ellipse" c="white" value="graph.xsl"/>
<node s="ellipse" c="green" value="NathanWiegand"/>
<node s="ellipse" c="white" value="NathanWiegand.cpp"/>
<node s="ellipse" c="green" value="NathanWiegand.gdb"/>
<node s="ellipse" c="green" value="output.txt"/>
<node s="ellipse" c="green" value="runme.sh"/>
<node s="ellipse" c="white" value="structure.dot"/>
<node s="ellipse" c="white" value="t"/>
</node>
<node s="box" c="red" value="Project2">
<node s="ellipse" c="white" value="dir.tree"/>
<node s="ellipse" c="white" value="dir.xml"/>
<node s="ellipse" c="green" value="example.sh"/>
<node s="ellipse" c="white" value="file.dot"/>
<node s="ellipse" c="white" value="Makefile"/>
<node s="ellipse" c="white" value="structure.gif"/>
<node s="ellipse" c="white" value="t"/>
</node>
</node>
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XSLT
<?xml version = "1.0"?>
<xsl:stylesheet version='1.0'
xmlns:xsl='http://www.w3.org/1999/XSL/Transform'>
<xsl:output method="text" omit-xml-declaration="yes"/>
<xsl:template match="/" xml:space="preserve">
digraph treestruct {
<xsl:for-each select="//node">
<xsl:call-template name="print-node"/>
</xsl:for-each>
}
</xsl:template>
<xsl:template name="print-node">
<xsl:variable name="this">
<xsl:value-of select="generate-id()"/>
</xsl:variable>
<xsl:variable name="label" xml:space="default">
<xsl:text disable-output-escaping="yes">"</xsl:text>
<xsl:value-of select="@value"/>
<xsl:text disable-output-escaping="yes">"</xsl:text>,shape=<xsl:value-of
select="@s"/>,style=filled,fillcolor=<xsl:value-of select="@c"/>
</xsl:variable>
<xsl:value-of select="$this"/> [label=<xsl:value-of select="$label"/>];
<xsl:for-each select="node" xml:space="default">
<xsl:value-of select="$this"/>
<xsl:text disable-output-escaping="yes"> -&gt; </xsl:text>
<xsl:value-of select="generate-id()"/>;
</xsl:for-each>
</xsl:template>
</xsl:stylesheet>
Excerpt of the Dot file
digraph treestruct {
id2588904 [label=".",shape=box,style=filled,fillcolor=red];
id2588904 -> id2588686;
id2588904 -> id2587734;
id2588904 -> id2587745;
id2588904 -> id2587755;
id2588904 -> id2588236;
id2588904 -> id2588246;
id2588904 -> id2588257;
id2588904 -> id2588267;
id2588904 -> id2588406;
id2588686 [label="conv",shape=ellipse,style=filled,fillcolor=green];
id2587734 [label="conv.c",shape=ellipse,style=filled,fillcolor=white];
id2587745 [label="dir.xml",shape=ellipse,style=filled,fillcolor=white];
Lecture 16
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The Product
Lecture 16
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