A few semesters back I had a class where we wrote a very rudimentary scheme parser and eventually an interpreter. After the class, I converted my parser into a C++ parser that did a reasonably good job of parsing C++ as long as I didn't do anything fancy with the preprocessor or macros. I could use it to read over my classes and functions and do neat things like automatically generate class readers or writers or set up function callbacks from a text file.
However, my program is pretty limited. I'm sure I could spend some time to make it more robust and do more neat things, but I don't want to spend the time and effort if there are already more robust tools available that do the same thing. I figure there has to be something like this out there since parsers are an essential part of compilers, but I haven't seen tools specifically for automatic code generation that make it easy to go through and play with data structures that represent classes, functions and variables for C++ specifically. Are there tools that do this?
Edit:
Hopefully this will clarify a little bit of what I'm looking for. The program I have runs as a prebuild step in visual studio. It reads over my source files, makes a list of classes, their members, their functions, etc. which is then used to generate new code. Currently I just use it to make it easy to read and write my data structures to a plain text file, but I could do other things as well. The file readers and writers are output into plain .cpp and .h files which I include in the rest of my project just as I would any other file. What I'm looking for are tools that do similar things so I can decide if I should continue to use my own or switch to a some better solution. I'm not looking for anything that generates machine code or edits code that I've written.
A complete parser-building tool like ANTLR or YACC is necessary if you want to parse C++ from scratch, but it's overkill for your purposes.
It reads over my source files, makes a list of classes, their members, their functions, etc. which is then used to generate new code.
Two main options:
GCC-XML can generate a list of classes, members, and functions. The distribution version on their web site is quite old; try the CVS version instead. I don't know about the availability of a Windows port.
Doxygen is designed for producing documentation, but it can also produce an XML output, which you should be able to use to do what you want.
Currently I just use it to make it easy to read and write my data structures to a plain text file...
This is known as serialization. Try Boost.Serialization or maybe libs11n or Google Protocol Buffers. Stack Overflow has further discussion.
...but I could do other things as well.
Other cool applications of this kind of automatic code generation include reflection (inspecting your objects' members at runtime, using duck typing with C++, etc.) and generating wrappers for calling C++ from scripting languages. For a C++ reflection library, see Reflex. For an example of generating wrappers for scripting languages, see Boost.Python or SWIG.
The C++ FAQ Lite has references to YACC grammars for C++. YACC is an old-school parser that was used to generate parser output, clumsy and difficult to learn but very powerful. Nowadays, you'd use Gnu Bison instead of YACC.
Don't forget about Cog. It requires you to know Python. In essence it embeds the output of Python scripts into your code. It's absurdly easy to use, but it takes a totally different approach from things like ANTLR and its purpose is somewhat different.
Maybe Boost::Serialize or ANTLR?
I answered a similar question (re splitting source files into separate header and cpp files) by suggesting the use of lzz.
lzz has a very powerful C++ parser that builds a representation for everything except the bodies of functions. As long as you don't need the contents of the function bodies you you could modify 'lzz' so that it performs the generation step you want.
If you want tools that can parse production C++ code, and carry out arbitrary analyses and transformations, see our DMS Software Reengineering Toolkit and its C++ front end.
It would be straightforward to use the information DMS can provide about C++ code, its structures, types, instances, to generate such access functions. If you wanted to generate access functions in another language, DMS provides means to code transformations from the input language (in this case, C++) to that target language.
Mozilla developed Pork for this kind of thing. I can't say it's easy to use (or even to build), but it is in production.
I've already used professionally the Nvelocity engine combined with C# as a prevoius step to coding, with very good results.
Related
I've started long ago to work on a dynamic graph visualizer, editor and algorithm testing platform (graphs with nodes and arcs, not the other kinds).
For the algorithm testing platform i need to let the user write a script or call a script from a file, which will interact with the graph currently loaded. The visualizer would do things like light up nodes while they're being visited by the script algorithm, adding some artificial delay, in order to visualize the algorithm navigating and doing stuff.
Scripts would also be secondly used to add third party features that i could either make available as pre-existing scripts in the program folder OR just integrate inside the program in c++ once they're tested and working.
All my searches for an interpreter to embed in my program sent me to lua;
then i started handwriting my own recursive descent parser for my own C-like syntax scripting language (which i planned to use a subset of C++ grammar so that any code written in my scripting language can be copy-pasted in any C++ code.
It was an interesting crazy idea which i don't regret at all, I have scopes, functions, cycles, gotos, typesafe variables, expressions.
But now that i'm approaching the addition of classes, class methods, inheritance (some default classes would be necessary to interface scripts to the program), i realized it's going to take A LOT of time and effort. A bit too much for a personal project of an ungraduated student with exams to study for… but still i whish to complete this project.
The self-imposed requirement of the scripts being 100% compatible with C++ was all but necessary, it would have been just a little nice extra thing, which i can do without.
Now the question is, is there an alternative to lua with a c-like syntax that supports all i've already done plus classes and inheritance? (being able to add custom "classes" that interface scripts to the program is mandatory)
(i can't assume the user to have a full c++ compiler installed so i cant just compile their "script" at runtime as a dll to load and call it, although i whish i could)
Just-in-time compilation of C++
Parsing C++ is hard. Heck, parsing C is hard. It's difficult to get it right, and there are a lot of edge cases. Thankfully, there are a few libraries out there which can take code and even compile it for you.
libclang
libclang provides a lot of facilities for parsing c++. It's a good, clean library, and it'll parse anything the clang compiler itself will parse. This article here is a good starter
libclang provides a JIT compilation tool that allows you to write and compile C++ at runtime. See this blog post here for a overview of what it does and how to use it. It's very general, very powerful, and user-written code should be fast.
GCC also provides a library called libgccjit for just-in-time compilation during the runtime of a program. libgccjit is a C library, but there's also a C++ wrapper provided by the library maintainers. It can compile abstract syntax trees and link them at runtime, although it's still in Alpha mode.
cppast
If you don't want to use libclang, there's also a library under development called cppast, which is a C++ parser which will give you an abstract syntax tree representation of your c++ code. Unfortunately, it won't parse function bodies.
Other tools
If anyone knows any other libraries for compiling or interpreting C++ at runtime, I encourage them to update this post, or comment them so I can update it!
Here is something that lets you embed a C-like scripting language in your application (and a bunch of other cool things):
http://chaiscript.com/
There is lots of documentation:
https://codedocs.xyz/ChaiScript/ChaiScript/
I want to work on an app that will open up a Visual Studio Project and display all of the classes in the project. It will only read the header files to find classes.
It's taking me forever to parse each data member and each method for display properly.
So I was wondering if there is some sort of API or library that I can use to parse all of the details of a C++ Header file so I can display them.
EDIT:
This is what my app currently looks like. I currently have issues getting User Defined types, which is why you see several unnamed Int32 types.
App Preview
Everybody hopes parsing source code is easy, even C++. It is not.
If you want to accurately parse C++ (header) files, you need a full C++ parser. In fact, parsing header files, especially those from the vendor (e.g., Microsoft's and even GNU's) is particularly nasty because they tend to contain undocumented constructs specific to the compiler.
You have only 4 good choices here:
The GNU compiler. It obviously can read GCC header files. I doubt it can read MS header files because of the vendor-specific extenstions. GCC really, really, wants to be a compiler and will resist your attempts to bend it to other tasks. Melt is a GCC extension that tries to make this easier; I've looked at it, and it doesn't seem that much better, but I'm biased.
Clang. It has a full C++ parser, specializing in GCC-style source files. I don't know what it can do about MS specific constructs let alone MS headers. Clang is at least organized to let you use it for custom tasks. (Apparantly VS2015 includes a copy of Clang to support Intellisense, but you can't get at the information it collects).
EDG. This is a commercial front end. It has a full parser, and is designed to let you build tools around it. I don't know what it does about MS or GNU headers. AFAIK, it doesn't provide anything other than the front end. (That's a lot).
(Our) commercial DMS Software Reengineering Toolkit with its C++ front end. (I obviously know a lot about this). It has a full C++14 parser, and handles both GCC and MS header files. Our front ends are the only ones that make any attempt to preserve preprocessor directives, if that matters to you. DMS is designed to let you build tools around it. DMS provides lots of support for pattern matching and code transformation above and beyond "just parsing". After parsing, information about each class is available in C++'s symbol table; it would be pretty easy to enumerate them and their members, and their relationships to other classes.
No matter what C++ parsing technology you use, "its very complex", don't expect that dealing with C++ is going to be easy. And, expect a high learning curve to understand any of the above frameworks. If you make the investment, and follow through with building a real tool, you'll learn a lot and be ready to build a next, more sophisticated tool with a lot less effort.
If you don't care about accuracy, you could scan files using Perl and regexes to hunt for class declarations. This will probably lead to a useless tool.
I need a good, stable and, maybe, easy to use C++ parser library with C/C++ interface (C is preferred).
I hear that cint is good c++ interpreter. Can I use it (or some part of it) for this purpose?
Any suggestions?
See: http://clang.llvm.org/
It has both a C++ and a C interface (libclang).
C++ parsing is famously hard. AFAIK there are only three parsers that are acceptable by todays standards: EDG (widely used as a frontend in popular C++ compilers), GCC's and Microsoft's. And apparently, Microsoft has started using EDG's parser in VS2010, for Intellisense.
When you're looking at the free options, you're pretty much stuck at GCC. It can produce XML, though, so the easy part is there. (Easy by C++ parsing standards, that is)
Clang is the most up-to-date and mature option, with a decent C++ API (but no plain C). Elsa is a bit out of date and unmaintained, but still a usable choice. Both could be used as libraries as well as standalone XML frontends.
If you want to parse C or C++ code, there are some options:
http://bellard.org/tcc/
http://students.ceid.upatras.gr/~sxanth/ncc/
If you want to create a parser using C/C++, you can try:
http://boost-spirit.com/home/
http://dinosaur.compilertools.net/ Lex and Yacc
http://www.codeguru.com/csharp/.net/net_general/patterns/article.php/c12805 Flex and Bison
Our C++ Front End is able to parse a variety of C++ dialects (ANSI, GCC, MSVS), automatically builds ASTs whose nodes are marked with precise source positions and are decorated with any nearby comment text, and builds a full symbol table. (EDIT Jan 2013: the C++ front end has been able to handle C++11 for quite awhile now).
The C++ front end is built on top of our DMS Software Reengineering Toolkit, generalized compiler technology for program analysis and transformation, designed to support custom tool building. The C++ front end includes a preprocessor, in which the preprocessor directives can be expanded or not collectively or individually as appropriate for the task. It also includes full symbol construction with all the nasty Koenig lookup stuff.
DMS accepts explicit language definitions (that's how it understands C++; there are also fron ends for C, C#, Java, COBOL, and variety of other languages). DMS provides general parsing, symbol table building, flow analysis machinery, procedural APIs for tree navigation/inspection/modification, source-to-source transformation, and AST-to-source text regeneration including the original comments, number radices, etc. All of these capabilities are available for use by the C++ Front End.
DMS is also designed to handle the scale required for serious tasks. Often you need not just one compilation unit (which is what GCC will give you at best) but access to an entire set. DMS has been used to analyze/transform thousands of C++ compilation units, and literally tens of thousands of C compilation units (on a 25 million line application).
"Easy to use library" is an oxymoron when it comes to program manipulation tools. The langauges themselves are complex (C++ being one of the most difficult and getting worse with C++0X) and that induces complexity in the nature of the questions you can ask and what the answers look like (e.g. "are there any template instantions that can modify local variable X in method Y in class C in any namespace N?"). The questions themselves are hard.
What you want is a library with the necessary complexity to let you carry off your task. DMS has been under continuous development for the last 15 years, to provide that necessary complexity. If you want to do serious program processing, I claim you will need that information.
As proof, DMS has been used to carry out massive automated reengineering of C++-based mission avionics software for Boeing. I don't believe there are any other tools that can do this. (Clang looks to be trying, but only for C++. YMMV).
I don't know for cint, but I heard people use gcc-xml for this.
I have been looking for a good stand-alone library too, but haven't found any.
If you're feeling brave the links in the answer to "is there a yacc-able C++ grammar?" might be helpful. Gcc-xml and clang have already been suggested and Swig also has an XML output which depending on what you're trying to achieve might be relevant.
I did not try it, but I think that best choice will be getting modules for parsing from some popular open source compiler like gcc for C++;
Maybe you'll find something interesting here http://www.nobugs.org/developer/parsingcpp/
Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers.
We don’t allow questions seeking recommendations for books, tools, software libraries, and more. You can edit the question so it can be answered with facts and citations.
Closed 6 years ago.
Improve this question
I'm getting a little rusty in scripting languages, provided they're popping like mushrooms lately :)
Today I thought that it would be nice to have a scripting language that talks seamlessly to C++, that is, could use C++ classes, and, the most important for me, could be compiled into C++ or some DLL/.SO (plus its .h) so that I could link it into my C++ program and make use of the classes the script defines or implements.
I know I could embed any popular scripting language such as lua, ruby, python... but the interface usually includes some kind of "eval" function that evaluates the provided scripting code. Depending on the tool used to couple C++ and the scripting language, the integration for callbacks of the script into C++ could be more or less easy to write, but I haven't seen any scripting language that actually allows me to write independent modules that are exposed as a .h and .so/dll to my program (maybe along the lines of a scripting language that generates C++ code).
Do you know any such tool/scripting language?
Thanks in advance.
PD. I've been thinking along the lines of Vala or Haskell's GHC. They generate C, but not C++...
UPDATE 2020: Today I would probably go with Lua + Sol2/3 except if I really want to avoid Lua as a language. Chaiscript becomes a good candidate in this case though it is not optimal performance-wise compared to Lua+Sol2/3 (though it was greatly improved through years so it is still good enough in many cases).
Falcon have been dead for some years, RIP.
The following ones are more C++ integration oriented than language bindings :
ChaiScript - trying at the moment in a little project, interesting, this one is MADE with C++ in mind and works by just including a header! Not sure if it's good for a big project yet but will see, try it to have some taste!
(not maintained anymore) Falcon - trying on a big project, excellent; it's not a "one include embed" as ChaiScript but it's because it's really flexible, and totally thought to be used in C++ (only C++ code in libs) - I've decided to stick with it for my biggest project that require a lot of scripting flexibility (comparable to ruby/python )
AngelScript - didn't try yet
GameMonkey - didn't try yet
Io - didn't try yet
For you, if you really want to write your scripting module in C++ and easily expose it to the scripting language, I would recommand going with Falcon. It's totally MADE in C++, all the modules/libraries are written that way.
The question usually asked in this context is: how do I expose my C++ classes so they can be instantiated from script? And the answer is often something like http://www.swig.org/
You're asking the opposite question and it sounds like you're complicating matters a bit. A scripting engine that produced .h files and .so files wouldn't really be a scripting engine - it would be a compiler! In which case you could use C++.
Scripting engines don't work like that. You pass them a script and some callbacks that provide a set of functions that can be called from the script, and the engine interprets the script.
Try lua: http://www.lua.org/
For using C++ classes in lua you can use:
To generate binding use tolua++: http://www.codenix.com/~tolua/
It takes a cleaned up header as input and outputs a c file that does the hard work. Easy, nice and a pleasure to work with.
For using Lua objects in C++ I'd take the approach of writing a generic Proxy object with methods like (field, setField, callMethod, methods, fields).
If you want a dll you could have the .lua as a resource (in Windows, I don't know what could be a suitable equivalent for Linux) and on your DllMain initialize your proxy object with the lua code.
The c++ code can then use the proxy object to call the lua code, with maybe a few introspection methods in the proxy to make this task easier.
You could just reuse the proxy object for every lua library you want to write, just changing the lua code provided to it.
This is slightly outside my area of expertise, but I'm willing to risk the downvotes. :-)
Boost::Python seems to be what you're looking for. It uses a bit of macro magic to do its stuff, but it does expose Python classes to C++ rather cleanly.
I'm the author of LikeMagic, a C++ binding library for the Io language. (I am not the author of Io.)
http://github.com/dennisferron/LikeMagic
One of my explicit goals with LikeMagic is complete and total C++ interoperability, in both directions. LikeMagic will marshal native Io types as C++ types (including converting between STL containers and Io's native List type) and it will represent C++ classes, methods, fields, and arrays within Io. You can even pass a block of Io code out of the Io environment and use it in C++ as a functor!!
Wrapping C++ types up for consumption in Io script is simple, quick and easy. Accessing script objects from C++ does require an "eval" function like you described, but the template based type conversion and marshaling makes it easy to access the result of executing a script string. And there is the aforementioned ability to turn Io block() objects into C++ functors.
Right now the project is still in the early stages, although it is fully operational. I still need to do things like document its build steps and dependencies, and it can only be built with gcc 4.4.1+ (not Microsoft Visual C++) because it uses C++0x features not yet supported in MSVC. However, it does fully support Linux and Windows, and a Mac port is planned.
Now the bad news: Making the scripts produce .h files and .so or .dll files callable from C++ would not only require a compiler (of a sort) but it would also have to be a JIT compiler. That's because (in many scripting languages, but most especially in Io) an object's methods and fields are not known until runtime - and in Io, methods can even be added and removed from live objects! At first I was going to say that the very fact that you're asking for this makes me wonder if perhaps you don't really understand what a dynamic language is. But I do believe in a way of design in which you first try to imagine the ideal or easiest possible way of doing something, and then work backwards from there to what is actually possible. And so I'll admit from an ease-of-use standpoint, what you describe sounds easier to use.
But while it's ideal, and just barely possible (using a script language with JIT compilation), it isn't very practical, so I'm still unsure if what you're asking for is what you really want. If the .h and .so/.dll files are JITted from the script, and the script changes, you'd need to recompile your C++ program to take advantage of the change! Doesn't that violate the main benefit of using script in the first place?
The only way it is practical would be if the interfaces defined the scripts do not change, and you just are making C++ wrappers for script functions. You'd end up having a lot of C++ functions like:
int get_foo() { return script.eval("get_foo()"); }
int get_bar() { return script.eval("get_bar()"); }
I will admit that's cleaner looking code from the point of view of the callers of the wrapper function. But if that's what you want, why not just use reflection in the scripting language and generate a .h file off of the method lists stored in the script objects? This kind of reflection can be easily done in Io. At some point I plan to integrate the OpenC++ source-to-source translator as a callable library from LikeMagic, which means you could even use a robust C++ code generator instead of writing out strings.
You can do this with Lua, but if you have a lot of classes you'll want a tool like SWIG or toLua++ to generate some of the glue code for you.
None of these tools will handle the unusual part of your problem, which is to have a .h file behind which is hidden a scripting language, and to have your C++ code call scripts without knowing that that are scripts. To accomplish this, you will have to do the following:
Write the glue code yourself. (For Lua, this is relatively easy, until you get into classes, whereupon it's not so easy, which is why tools like SWIG and toLua++ exist.)
Hide behind the interface some kind of global state of the scripting interpreter.
Supposing you have multiple .h files that each are implemented using scripts, you have to decide which ones share state in the scripting language and which ones use separate scripting states. (What you basically have is a VM for the scripting language, and the extremes are (a) all .h files use the same VM in common and (b) each .h file has its own separate, isolated VM. Other choices are more complicated.)
If you decide to do this yourself, writing the glue code to turn Lua tables into C++ classes (so that Lua code looks like C++ to the rest of the program) is fairly straightforward. Going in the other direction, where you wrap your C++ in Lua (so that C++ objects look to the scripts like Lua values) is a big pain in the ass.
No matter what you do, you have some work ahead of you.
Google's V8 engine is written in C++, I expect you might be able to integrate it into a project. They talk about doing that in this article.
Good question, I have often thought about this myself, but alas there is no easy solution to this kind of thing. If you are on Windows (I guess not), then you could achieve something like this by creating COM components in C++ and VB (considering that as a scripting language). The talking happens through COM interfaces, which is a nice way to interop between disparate languages. Same holds for .NET based languages which can interop between themselves.
I too am eager to know if something like this exists for C++, preferably open source.
You might check into embedding Guile (a scheme interpreter) or V8 (Google's javascript interpreter - used in Chrome - which is written in C++).
Try the Ring programming language
http://ring-lang.net
(1) Extension using the C/C++ languages
https://en.wikibooks.org/wiki/Ring/Lessons/Extension_using_the_C/C%2B%2B_languages
(2) Embedding Ring Interpreter in C/C++ Programs
https://en.wikibooks.org/wiki/Ring/Lessons/Embedding_Ring_Interpreter_in_C/C%2B%2B_Programs
(3) Code Generator for wrapping C/C++ Libraries
https://en.wikibooks.org/wiki/Ring/Lessons/Code_Generator_for_wrapping_C/C%2B%2B_Libraries
I'm trying to create an app to search my company's ColdFusion codebase. I'd like to be able to do intelligent searches, for example: find where a function is defined (and not hit everywhere the function is called). In order to do this, I'd need to parse the ColdFusion code to identify things like function declarations, function calls, database queries, etc.
I've looked into using lex and yacc, but I've never used them before and the learning curve seems very steep. I'm hoping there is something already out there that I could use. My other option is a mess of difficult-to-maintain regex-spaghetti code, which I want to avoid.
I used the source to CFEclipse, since it is open source and has a parser. Not sure about the legality of this if we were selling/redistributing it, but we're only using it for an internal tool.
Writing parsers for real langauges is usually difficult because they contain constructs that Lex and Yacc often don't handle well, e.g., the langauge isn't LALR(1). ColdFusion might be easier than some because of its XML-like style.
If you want to build a sophisticated parser quickly, you might consider using our
DMS Software Reengineering Toolkit which has GLR parsing support.
If you want to avoid writing your own or hacking all those Regexps, you could consider our Source Code Search Engine. It has language-sensitive parsers and can search across very large source code bases very quickly. One of its "language sensitive" parsers is AdhocText, which is designed to handle "generic" programming languages such as those you might find in a random programming book; it even understands XML-like tags such as ColdFusion has. You can download a evaluation version from the link provided to try it.
EDIT 4/3/2010: A recent feature added to the SCSE is the ability to tag definitions and uses separately. That would address the OP's desire to find the function definition rather than all the calls.
None existed. Since ColdFusion is more like scripts than code, I'd imagine it'll be hard to write a parser for it.
ColdFusion Builder can parse CFM/CFC to an outline in Eclipse. Maybe you can do some research on whether a CF Builder plugin can do what you want to do.