How can i change the default block language from javascript to batch?
I want to make a block creator that makes batch code .bat file, the default options are javascript, php, lua etc. how can i make a custom one?
You will need to write custom generator for this.
At a high level, for each block you need to write a function which will return the corresponding batch code string. This function will have access to the various inputs that the block is having which will help you build the string. You can check how the existing generators are written and use this as a reference to build another language generator.
The existing generators are placed in generators directory in blockly source.
Writing a custom language generator is a big task in itself especially with the lack of documentation to achieve it. But this comment from Rachel should get you started on it.
Related
I've just started a couple of hours ago reading about DSL modeling.
But right now, I'm tied to using the JetBrains MPS IDE or it's plugin for JetBrains Intellij Idea and I'd like to know how can I export those DSL models to something available to use for e.g. console applications or whatever (in case it's possible or it makes sense).
You can do several things already in MPS without exporting the models:
Analyze the models to check for errors, business rule violations or inconsistencies.
Interpret the models then display the result of the interpretation in MPS directly. Useful if you implement a specification and an example/test of that specification, then you can run tests in MPS and show the results as green/red highlight, for example.
Define a generator to translate the model into text (executable code or input for a tool such as Liquibase to create database schemas for example).
If you're looking to export your data from MPS for use in a different application there are two approaches I would
recommend:
The simplest way: NodeSerializer from MPS-extensions. I have more details on how to use it in a blog post. This lets you quickly export your data in a rather nice XML structure.
The most flexible approach: writing a custom exporter by using the MPS Open
API to recursively traverse a node
tree. You can output any format you want (XML, JSON, YAML, etc.) and customize the output as you like.
Here are two more approaches that you could be considering but that I would NOT recommend:
Accessing the model (*.mps) files directly. While they are already in XML format, their structure is adapted to
MPS' needs. It is normalized, meaning that a given piece of information is generally only stored once, and it also
encodes node IDs in a particular way to save space. The format is also undocumented and could change in the future
(although it hasn't changed for the past several years).
Using the MPS generator to convert your DSL to MPS' built-in XML language, jetbrains.mps.core.xml. I don’t recommend using the MPS generator because the generator’s sweet spot is translating between two different MPS languages, e.g. from your custom DSL to Java. If you try writing generator rules to convert anything to XML you would hit a few problems that are possible to overcome but totally unnecessary.
You can define a generator which transforms a sentence (file, AST) of your language into another MPS language. The target language must exist in MPS first.
Alternatively, you could generate text with the TextGen aspect, but that is more suitable to just print the textual representation of your language. If you would like something more sophisticated (like generating text code of another language), you can use plaintextgen language from MPS-extensions or mbeddr.platform.
If you want to input (import) a textual program into MPS , you can code a paste handler where you could put your parser, or you can change the format in which the AST is stored (from XML to maybe directly your language, but this would again require a parser to read) with custom persistence.
I am currently working on a solution which enables to import an MPS language from a YAJCo model (model-based parser generator, where the input is not a grammar, but Java classes representing the semantic model). Then you can import a sentence (file) which creates and populates a model (AST). From the program in MPS you can generate Java source code which fills the original Java classes. So if you want a textual MPS language and use the IDE but then export the AST into Java objects you can use, maybe YtM is for you.
I want to create a tool that can analyze C and C++ code and detect unwanted behaviors, based on a config file. I thought about using ANTLR for this task, as I already created a simple compiler with it from scratch a few years ago (variables, condition, loops, and functions).
I grabbed C.g4 and CPP14.g4 from ANTLR grammars repository. However, I came to notice that they don't support the pre-processing parsing, as that's a different step in the compilation.
I tried to find a grammar that does the pre-processing part (updated to ANTLR4) with no luck. Moreover, I also understood that if I'll go with two-steps parsing I won't be able to retain the original locations of each character, as I'd already modified the input stream.
I wonder if there's a good ANTLR grammar or program (preferably Python, but can deal with other languages as well) that can help me to pre-process the C code. I also thought about using gcc -E, but then I won't be able to inspect the macro definitions (for example, I want to warn if a user used a #pragma GCC (some students at my university, for which I write this program to, used this to bypass some of the course coding style restrictions). Moreover, gcc -E will include library header contents, which I don't want to process.
My question is, therefore, if you can recommend me a grammar/program that I can use to pre-process C and C++ code. Alternatively, if you can guide me on how to create a grammar myself that'd be perfect. I was able to write the basic #define, #pragma etc. processings, but I'm unable to deal with conditions and with macro functions, as I'm unsure how to deal with them.
Thanks in advance!
This question is almost off-topic as it asks for an external resource. However, it also bears a part that deserves some attention.
The term "preprocessor" already indicates what the handling of macros etc. is about. The parser never sees the disabled parts of the input, which also means it can be anything, which might not be part of the actual language to parse. Hence a good approach for parsing C-like languages is to send the input through a preprocessor (which can be a specialized input stream) to strip out all preprocessing constructs, to resolve macros and remove disabled text. The parse position is not a problem, because you can push the current token position before you open a new input stream and restore that when you are done with it. Store reported errors together with your input stream stack. This way you keep the correct token positions. I have used exactly this approach in my Windows resource file parser.
The lexer/parser file located here is quite large and I'm not sure if it is suitable for just retrieving a list of Rust functions. Perhaps writing my own/using another library would be a better route to take?
The end objective would be to create a kind of execution manager. To contextualise, it would be able to read a list of function calls wrapped in a function. The function calls that are within the function will then be able to be re/ordered from some web interface. Thought it might be nice to manage larger applications this way.
No. I mean, not really. Whether you write your own parser or re-use syntex, you're going to hit a fundamental limitation: macros.
So let's say you go all-out and expand macro_rules!-based macros, including the ones defined in external crates (which means you'll also need to extract rustc's crate metadata loading... which isn't stable). What about procedural macros and custom derive attributes? Those are defined in code and depend on compiler-internal interfaces to function.
The only way this is likely to ever work correctly is if you build on top of the compiler, or duplicate a huge amount of work (which also involves unstable binary interfaces).
You could use syntex to parse the Rust code in a build script.
From a performance/maintenance point of view, is it better to write my custom modules with netsuite all as one big JS, or multiple segmented script files.
If you compare it with a server side javascript language, say - Node.js the most popular, every module is written into separate file.
I generally take the approach of Object oriented javascript and put each class in a separate file which helps to organise the code.
One of the approach you can take is in development keep separate files and finally merge all files using js minifier tool like Google closure compiler when you deploy your code for production usage which can give you best of both worlds, if you are really bothered about every nano/mini seconds of performance.
If you see SuiteScript 2.0 architecture, it encourages module architecture which is easier to manage as load only those modules that you need, and it is easier to maintain multiple code files i.e. one per module considering future enhancements, bug fixes and code reuse.
Performance can never be judge by the line count of your module. We generally maintain modules for maintaining the readability and simplicity of the code. It is a good practice to put all generic functionalities in to an Utility script and use it as a library across all the modules. Again it depends on your code logic and programming style. So if you want to create multiple segments of your js file for more readability I dont think its a bad idea.
I know that its possible to read from a .txt file and then convert various parts of that into string, char, and int values, but is it possible to take a string and use it as real code in the program?
Code:
string codeblock1="cout<<This is a test;";
string codeblock2="int array[5]={0,6,6,3,5};}";
int i;
cin>>i;
if(i)
{
execute(codeblock1);
}
else
{
execute(codeblock2);
}
Where execute is a function that converts from text to actual code (I don't know if there actually is a function called execute, I'm using it for the purpose of my example).
In C++ there's no simple way to do this. This feature is available in higher-level languages like Python, Lisp, Ruby and Perl (usually with some variation of an eval function). However, even in these languages this practice is frowned upon, because it can result in very unreadable code.
It's important you ask yourself (and perhaps tell us) why you want to do it?
Or do you only want to know if it's possible? If so, it is, though in a hairy way. You can write a C++ source file (generate whatever you want into it, as long as it's valid C++), then compile it and link to your code. All of this can be done automatically, of course, as long as a compiler is available to you in runtime (and you just execute it with system). I know someone who did this for some heavy optimization once. It's not pretty, but can be made to work.
You can create a function and parse whatever strings you like and create a data structure from it. This is known as a parse tree. Subsequently you can examine your parse tree and generate the necessary dynamic structures to perform the logic therin. The parse tree is subsequently converted into a runtime representation that is executed.
All compilers do exactly this. They take your code and they produce machine code based on this. In your particular case you want a language to write code for itself. Normally this is done in the context of a code generator and it is part of a larger build process. If you write a program to parse your language (consider flex and bison for this operation) that generates code you can achieve the results you desire.
Many scripting languages offer this sort of feature, going all the way back to eval in LISP - but C and C++ don't expose the compiler at runtime.
There's nothing in the spec that stops you from creating and executing some arbitrary machine language, like so:
char code[] = { 0x2f, 0x3c, 0x17, 0x43 }; // some machine code of some sort
typedef void (FuncType*)(); // define a function pointer type
FuncType func = (FuncType)code; // take the address of the code
func(); // and jump to it!
but most environments will crash if you try this, for security reasons. (Many viruses work by convincing ordinary programs to do something like this.)
In a normal environment, one thing you could do is create a complete program as text, then invoke the compiler to compile it and invoke the resulting executable.
If you want to run code in your own memory space, you could invoke the compiler to build you a DLL (or .so, depending on your platform) and then link in the DLL and jump into it.
First, I wanted to say, that I never implemented something like that myself and I may be way off, however, did you try CodeDomProvider class in System.CodeDom.Compiler namespace? I have a feeling the classes in System.CodeDom can provide you with the functionality you are looking for.
Of course, it will all be .NET code, not any other platform
Go here for sample
Yes, you just have to build a compiler (and possibly a linker) and you're there.
Several languages such as Python can be embedded into C/C++ so that may be an option.
It's kind of sort of possible, but not with just straight C/C++. You'll need some layer underneath such as LLVM.
Check out c-repl and ccons
One way that you could do this is with Boost Python. You wouldn't be using C++ at that point, but it's a good way of allowing the user to use a scripting language to interact with the existing program. I know it's not exactly what you want, but perhaps it might help.
Sounds like you're trying to create "C++Script", which doesn't exist as far as I know. C++ is a compiled language. This means it always must be compiled to native bytecode before being executed. You could wrap the code as a function, run it through a compiler, then execute the resulting DLL dynamically, but you're not going to get access to anything a compiled DLL wouldn't normally get.
You'd be better off trying to do this in Java, JavaScript, VBScript, or .NET, which are at one stage or another interpreted languages. Most of these languages either have an eval or execute function for just that, or can just be included as text.
Of course executing blocks of code isn't the safest idea - it will leave you vulnerable to all kinds of data execution attacks.
My recommendation would be to create a scripting language that serves the purposes of your application. This would give the user a limited set of instructions for security reasons, and allow you to interact with the existing program much more dynamically than a compiled external block.
Not easily, because C++ is a compiled language. Several people have pointed round-about ways to make it work - either execute the compiler, or incorporate a compiler or interpreter into your program. If you want to go the interpreter route, you can save yourself a lot of work by using an existing open source project, such as Lua