Expressing and defining logic - logic

I am trying to express a certain logic for a GUI tool to make diagnoses easier.
At the starting Point always the same questions will be asked (Question A). Dependet on the answer to it the questions should get more specific and complex.
Possible Scenario: Question A -> YES -> Question B -> NO -> Question E -> NO -> Question C .....
So the application kind of walks a path dependet on the answers. How can i define such a logic, best in a graphical way? Is it solveable with a domain specific language? I know some DSL-languages like ANTLR, but how can I export the logic and import it to GUI? I would like to write the GUI preferrably in C#, are there some constructs existing that would me help?
Anyone faced a similar issue like this?

Activity diagrams are what you are looking for. Something like this:
Use swim lanes to denote different "actors" in the system. From what it looks like in the image you posted in the question, you may not need swim lanes. Your software career will benefit from knowing UML/SysML, both make use of activity diagrams.
Create the diagram, then write the code to match. Hyperlink the code to the diagram with doxygen comments, so then you can generate a nice html/pdf page to explain how the code works.

Related

Using Datalog by itself, is it possible?

I am currently studying Datalog for my report in class, I only need to discuss basic syntax and a basic example.
I know Datalog is usually used as a query language and is usually only implemented to other languages such as Java, Lua, C, etc. but is it possible to teach Datalog only by itself, or am I required to use another language implementing it to show a simple working program?
There are a few online demos you can use:
http://iris-reasoner.org/demo
http://ysangkok.github.io/mitre-datalog.js/wrapper.html
https://repl.logicblox.com/ (docs here:
https://developer.logicblox.com/content/docs4/tutorial/repl/section/split.html )
I haven't tried it myself yet, but http://abcdatalog.seas.harvard.edu also looks nice and easy to run.
A complete overview is on Wikipedia: https://en.wikipedia.org/wiki/Datalog

Basic Library System in Prolog

I want to make a basic library management system in prolog. The program should answer queries like which book is issued by which student and which date book will be returned. I want guidance in terms what exact components i need to learn for it (as I am very much new to prolog), i wanna develop it rapidly as i dun have time to learn the whole thing. I will be using visual prolog 7.3
Thanks in Advance
MGD
You haven't given us much of an idea what your programming background is, so I've interpolated a couple of comments below to suggest what existing experience might help in doing parts of the Visual-Prolog application asked about.
With Visual-Prolog you have to begin with user-interface design, something that I frankly found discouraging for playing around with the Prolog coding. Think of the "window" elements you want: perhaps an input field to input a user name and another input field to enter a book title, with some buttons for "search" as your "program should answer queries" spec suggests. The output will contain information about whether a book is checked out, when it is due, etc.
Then the functional part of your design can begin. Visual-Prolog asks you to declare certain things: domains (equivalent to datatypes in other languages) and predicates (the names relations and the domains to which their various arguments apply, roughly the equivalent to routines in other languages).
Your library application sounds like it is similar to a database, a "knowledge-base" containing information about users, books, and the relationship between them (e.g. this user has this book checked out), possibly with some history (who checked out a book when, and when was it returned).
Since you want to "develop it rapidly", you will probably want to start with a very simple set of domains and predicates. Perhaps "user" and "book" are the basic domains to start with, and checkOut/2 the basic predicate (indicating the fact that a particular user currently has the particular book). Then you will probably need to add (at least) the feature of storing the book's return date. This kind of design will be easier if you've done some relational database development before.
Connecting the user-interface (UI) to the "knowledge-base" of library users & books is a matter of writing predicates that serve as event-handlers for the visual elements of the UI. This is somewhat easier if you are familiar with Visual Basic. In any case you can "stub out" the event handlers while you are building the "look and feel" part of the UI, replacing them with substantive implementations as your design moves into developing the "knowledge-base".

How to build a static code analysis tool?

I m in process of understanding and building a static code analysis tool for a proprietary language from a big company. Reason for doing this , I have to review a rather large code base , and a static code analysis would help a lot and they do not have one for the language so far.
I would like to know how does one go about building a static code analysis tool , for e.g. Lint or SpLint for C.
Any books, articles , blogs , sites..etc would help.
Thanks.
I know this is an old post, but the answers don't really seem that satisfactory. This article is a pretty good introduction to the technology behind the static analysis tools, and has several links to examples.
A good book is "Secure Programming with Static Analysis" by Brian Chest and Jacob West.
You need good infrastructrure, such as a parser, a tree builder, tree analyzers, symbol table builders, flow analyzers, and then to get on with your specific task you need to code specific checks for the specific problems of interest to you, using all the infrastructure machinery.
Building all that foundation machinery is actually pretty hard, and it doesn't help you do your specific task. People don't write the operating system for every application they code; why should you build all the infrastructure? Like an OS, it is better if you simply acquire good infrastructure.
People will tell you to lex and yacc. That's kind of like suggesting you use the real time keneral part of the OS; useful, but far from all the infrastructure you really need.
Our DMS Software Reengineering Toolkit provides all the necessary infracture. It has been used to define many language front ends as well as
many tools for such languages.
Such infrastructure would allow you to define your specific nonstandard language relatively quickly, and then get on with your task of coding your special checks.
There is a blog by DeepSource that covers everything one needs to know to build an understanding of static code analysis and equip you with the basic theory and the right tools so that you can write analyzers on your own.
Here’s the link: https://deepsource.io/blog/introduction-static-code-analysis/
Obviously you need a parser for the language. A good high level AST is useful.
You need to enumerate a set of "mistakes" in the language. Without knowing more about the language in question, we can't help here. Examples: unallocated pointers in C, etc.
Combine the AST with the mistakes in #2.

Which tools can help in translating (as in french -> english and not C++ -> java) source code? [closed]

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I have some code that is written in french, that is the variables, class, function all have french names. The comments are also in french. I'd like to translate the code to english. This will be quite a challenge, since it's a 18K lines project and I'd like to know if there is any tool that could help me, especially with the variables/class/function names, since it will be error prone to rename them all.
Is there any tools that can help me? Advices?
edit : I'm not looking for machine translation. I'm looking for a tool that would help me translate the code. Let's say there is class name C and this class has a method named TraverserLaRue and I rename it CrossTheRoad I'd like all references to TraverserLaRue in all files to be translated as CrossTheRoad. However I don't want the method TraverserLaRue of class B to be translated.
I assume the langauge in question is one of the common ones, such as C, C++, C#, Java, ...
(You don't have a language with French keywords? I once encountered an entirely Swedish version of Pascal, and I gave up on working that).
So you have two problems:
Translating identifiers in the source code
Translating comments
Since comments contain arbitrary natural language text, you'll need an arbitrary translation of them. I don't think you can find an automated tool to do that.
Unlike others, however, I think you have a decent chance at translating the identifiers
and changing them en masse.
SD makes a line of source code "obfuscator" products. These tools don't process the code as raw text, rather they process the source code in terms of the targeted language; they accurately distinguish identifiers from operators, numbers, comments etc. In particular, they
operate reliably as need on just the identifiers.
One of the things these tools do is to replace one identifier name by another (usually a nonsense name) to make the code really hard to understand. Think abstractly of a map of identifier names I -> N. (They do other things, but that's not interesting here). Because you often want to re-obfuscate a file that has changed, the same way as an original, these tools allow you to reuse a previous cycle's identifier map, which is represented as list of I -> N pairs.
I think you can abuse this to do what you want.
Step 1: Run such an obfuscator on your original French code. This will produce a text file containing all the identifiers in the code as a map of the form
I1 -> N1
I2 -> N2
....
You don't care about the Ns, just the I's.
Step 2: Manually translate each French I to an English name E you think fits best.
(I have no specific suggestions about how to do this; some of the other answers here
have suggestions).
Some of the I's are likely to be library calls and are thus already correct.
You can modify the text obfuscation map file to be:
I1 -> E1
I2 -> E2
Step 3: Run the obfuscation tool, and make it use your modified obfuscation map.
It can be told to do that.
Viola, all the identifiers in your code will be changed the way you specify.
[You may get, as a freebie, the re-formatting of your original text. These tools can also format code nicely. Your name changes are likely to screw up the indentation/spacing in the original text so this is a nice bonus].
Any refactoring tool has a rename feature. Many questions on SO address language specific refactoring tools.
For the comments, you will have to handle them manually.
I did this with German code a while ago, but had mixed results because of abbreviations in names, etc. Using regular expressions, I wrote a parser that removed all of the language specific keywords and characters, then separated comments from the rest of the code, and now I had a lot of words that didn't necessarily mean anything to me by themselves. So I wrote a unique word finder that added them all to a ordered text file. Next stop was Google's language tools that attempted to translate every word in the list. I ran through the list to see if each word really translated, and if it did, I did a replace all in the code with the english equivalent. The comments I put back in with the complete translation, if it worked. What I found was that I ended up having to talk with someone who understood "Germish" to translate the abbreviations, slang terms, and mixed language pieces. So in short, regular expressions with a dictionary, unless someone has a real tool for this, which I would be interested in also.
You should definitely look into https://launchpad.net/rosetta
Ubuntu uses this to translate thousands of its packages written in hundreds of programming languages into hundreds of human languages, with updates for each new version. Truly herculean task.
edit: ...to clarify how Rosetta is used at Ubuntu: it modifies all natural language strings occuring in source code of the open-source apps, creating a language-specific source packages, which upon compiling create given kinds of binaries. Of course it does not edit binaries themselves.
First maintainers create "template files" which are something like "Patch with wildcards" - a set of rules what and where in the source tree needs to be translated, but not to what. Then Rosetta displays strings to be translated, and allows volunteering translators to provide translations to their language for each entry. Each entry can be discussed, modified, suggestions submitted and moderated. Stats are provided how much needs to be translated, which translations are unsure, which are missing etc. When the translation is complete, patch of given language is applied to the source creating its version for given language. Then a distribution is compiled from the modified sources.
This allows translation both for sources that use some external resources for multilingual allowing for language change on the fly, and for ones that have literal native language strings right in the source code, mixed with business logic.
When a new version of the package is released, template must be edited to include all new strings but it has quite good automation for preserving the existing ones. Of course only translations for new strings are required.
IMHO automatic tools won't be of any help here. Just translating variable and function names is not enough and will make the code worse because they cannot infer the original programmer intent when he choose a variable name.
Depending on what programming language this code is written to there are modern IDEs that might ease the refactoring but if you want to have good results manual code review is a must.
A good IDE will be able to list classes, methods, variables. There's also documentation generation tools that'll do that such as Javadoc for Java, Doxygen for many languages, etc.
To do the actual translation, there will be no tool that will perform well, or even to a satisfactory level. The only way to get something worthwile is to have a bilingual translator translate the terms. I've been doing freelance translations for many years, and can tell you that trying to have some machine do the translating is a waste of time. Many examples, choice of words, will be relevant to your culture and not the other. And that's just the tip of the iceberg.
Unless you find someone that can do the translation, I suggest you abandon the idea. Leave the source code as is. If a non-French speaker reads it, and needs to understand something, let them do the Google lookup. If they are native English speakers they'll probably do a better job of understanding the automatic translated stuff than you would, being French. When translating, you always want to translate into your native language.
For translating only comments you may try this simple utility I wrote (it's using Microsoft's Translator API): transource.

What tools for migrating programs from a platform A to B

As a pet project, I was thinking about writing a program to migrate applications written in a language A into a language B.
A and B would be object-oriented languages. I suppose it is a very hard task : mapping language constructs that are alike is doable, but mapping libraries concepts will be a very long task.
I was wondering what tools to use, I know this has to do with compilation, but I'm a bit afraid to use Lex and Yacc and all that stuff.
I was thinking of maybe using the Eclipse Modeling Framework, which would help me write models (of application code) transformations in a readable form.
But first I would have to write parsers for creating the models (and also create the metamodel from the language grammar).
Are there tools that exist that would make my task easier?
You can use special transformation tools/languages for that TXL or Stratego/XT.
Also you can have a look and easily try Java to Python and Java to Tcl migrating projects made by me with TXL.
You are right about mapping library concepts. It is rather hard and long task. There are two ways here:
Fully migrate the class library from language A to B
Migrate classes/functions from language A to the corresponding concepts in language B
The approach you will choose depends on your goals and time/resources available. Also in many cases you wont be doing a general A->B migration which will cover all possible cases, you will need just to convert some project/library/etc. so you will see in your particular cases what is better to do with classes/libraries.
I think this is almost impossibly hard, especially as a personal project. But if you are going to do it, don't make life even more difficult for yourself by trying to come up with a general solution. Choose two specific real-life programming languages ind investigate the possibities of converting between them. I think you will be shocked by the number of problems and issues this will expose.
There are some tools for direct migration for some combinations of A and B.
There are a variety of reverse engineering and code generation tools for different languages and platforms. It's fairly rare to see reverse engineering tools which capture all the semantics of the source language, and the semantics of UML are not well defined ( since it's designed to map to different implementation languages, it itself doesn't define a complete execution model for its behavioural representations ), so you're unlikely to be able to reverse engineer and generate code between tools. You may find one tool that does full reverse engineering and full code generation for your A and B languages, and so may be able to get somewhere.
In general you don't use the same idioms on different platforms, so you're more likely to get something which emulates A code on B rather than something which corresponds to a native B solution.
If you want to use Java as the source language(that language you try to convert) than you might use Checkstyle AST(its used to write Rules). It gives you tree structure with every operation done in the source code. This will be much more easier than writing your own paser or using regex.
You can run com.puppycrawl.tools.checkstyle.gui.Main from checkstyle-4.4.jar to launch Swing GUI that parse Java Source Code.
Based on your comment
I'm not sure yet, but I think the source language/framework would be Java/Swing and the target some RIA language like Flex or a Javascript/Ajax framework. – Alain Michel 3 hours ago
Google Web Toolkit might be worth a look.
See this answer: What kinds of patterns could I enforce on the code to make it easier to translate to another programming language?

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