c++ - Get list of methods in class using clang

Question

In common IDEs (pick one) you often have an outline view showing you the list of methods for a specific class.

Suppose I have a C++ interface class in IFoo.h that looks like this:

#ifndef IFOO_H_
#define IFOO_H_
class IFoo { 
    public:
        virtual ~IFoo() {}
        virtual void bar() = 0;
};
#endif

How (programmatically) can I get such an IDE outliner list for my IFoo.h file above using maybe the clang libraries? For a first start, it would help if I can get a list of names of functions.

I specifically intend to use clang, so any help on how to analyze the my header file with clang would be really appreciated.

Meanwhile I will have a look at the clang tutorial here: https://github.com/loarabia/Clang-tutorial

Thanks in advance for your help.

Answer 1

I went through this tutorial http://clang.llvm.org/docs/LibASTMatchersTutorial.html and found some pretty helpful stuff there, this is what I came up with:

I had to rename my file from IFoo.h to IFoo.hpp to be detected as Cxx and not C code.

I had to call my program with -x c++ to have my IFoo.h file being recognized as C++ code rather than C code (clang interprets *.h files as C by default:

~/Development/llvm-build/bin/mytool ~/IFoo.h -- -x c++

This is my code to dump all virtual functions from the provided class:

// Declares clang::SyntaxOnlyAction.
#include "clang/Frontend/FrontendActions.h"
#include "clang/Tooling/CommonOptionsParser.h"
#include "clang/Tooling/Tooling.h"
#include "clang/ASTMatchers/ASTMatchers.h"
// Declares llvm::cl::extrahelp.
#include "llvm/Support/CommandLine.h"

#include "clang/ASTMatchers/ASTMatchers.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"

#include <cstdio>

using namespace clang;
using namespace clang::ast_matchers;
using namespace clang::tooling;
using namespace llvm;

DeclarationMatcher methodMatcher = methodDecl(isVirtual()).bind("methods");

class MethodPrinter : public MatchFinder::MatchCallback {
public :
  virtual void run(const MatchFinder::MatchResult &Result) {
    if (const CXXMethodDecl *md = Result.Nodes.getNodeAs<clang::CXXMethodDecl>("methods")) {    
      md->dump();
    }
  }
};

// CommonOptionsParser declares HelpMessage with a description of the common
// command-line options related to the compilation database and input files.
// It's nice to have this help message in all tools.
static cl::extrahelp CommonHelp(CommonOptionsParser::HelpMessage);

// A help message for this specific tool can be added afterwards.
static cl::extrahelp MoreHelp("
More help text...");

int main(int argc, const char **argv) {    
  cl::OptionCategory cat("myname", "mydescription");
  CommonOptionsParser optionsParser(argc, argv, cat, 0);    

  ClangTool tool(optionsParser.getCompilations(), optionsParser.getSourcePathList());

  MethodPrinter printer;
  MatchFinder finder;
  finder.addMatcher(methodMatcher, &printer);
  return tool.run(newFrontendActionFactory(&finder));
}

The output looks like this, when passed the IFoo.h file:

CXXDestructorDecl 0x1709c30 <~/IFoo.h:5:3, col:20> ~IFoo 'void (void)' virtual
`-CompoundStmt 0x1758128 <col:19, col:20>
CXXMethodDecl 0x1757e60 <~/IFoo.h:6:3, col:24> bar 'void (void)' virtual pure