c++ - 如何使用clang仅获取主要功能的AST

Question

我想在源文件中获取 main 函数的 AST（假设有一个）来构建控制流图。我在这里找到了生成和遍历 AST 的代码： https ://shaharmike.com/cpp/libclang/ 。但问题是它进入了所有包含的文件。我还找到了这个主题：Clang AST visitor, Avoid traversing include files。但似乎在 clang10 中进行了一些更改，建议的解决方案现在不起作用。或者也许还有其他方法可以获取 AST 来构建控制流图？唯一的要求 - 它必须工作 C++ 源代码。

Answer 1

阅读文档告诉我，clang_visitChildren只有在您返回时才会“进入”它所指向的任何内容CXChildVisit_Recurse。因此，您的访问函数应该检查游标类型并返回CXChildVisit_Continue，直到它到达名称为 equals 的函数定义main。它的作用main取决于你，但我建议返回CXChildVisit_Break.

Answer 2

所以，感谢 Botje 和这篇文章（https://www.phototalks.idv.tw/academic/?p=1932）我找到了解决方案。无论如何都不是最好的代码，但它可以工作。我希望它会帮助别人。

#include <iostream>
#include <clang-c/Index.h>
#include <string.h>
using namespace std;

ostream& operator<<(ostream& stream, const CXString& str)
{
  stream << clang_getCString(str);
  clang_disposeString(str);
  return stream;
}

std::string getCursorKindName( CXCursorKind cursorKind )
{
  CXString kindName  = clang_getCursorKindSpelling( cursorKind );
  std::string result = clang_getCString( kindName );

  clang_disposeString( kindName );
  return result;
}

std::string getCursorSpelling( CXCursor cursor )
{
  CXString cursorSpelling = clang_getCursorSpelling( cursor );
  std::string result      = clang_getCString( cursorSpelling );

  clang_disposeString( cursorSpelling );
  return result;
}
CXChildVisitResult visitor1( CXCursor cursor, CXCursor /* parent */, CXClientData clientData )
{
  CXSourceLocation location = clang_getCursorLocation( cursor );
    unsigned int locationstring =0;
     clang_getSpellingLocation  (   location, NULL, &locationstring, NULL,NULL);
  if( clang_Location_isFromMainFile( location ) == 0 )
    return CXChildVisit_Continue;
  CXCursorKind kind = clang_getCursorKind(cursor);
    std::string str2 ("main");
  CXCursorKind cursorKind = clang_getCursorKind( cursor );
  unsigned int curLevel  = *( reinterpret_cast<unsigned int*>( clientData ) );
  unsigned int nextLevel = curLevel + 1;
    std::cout << std::string( curLevel, '-' ) << " " << getCursorKindName(
    cursorKind ) << " (" << getCursorSpelling( cursor ) << ") ";
    std::cout << locationstring ;
    std::cout << endl;

    clang_visitChildren( cursor,
                         visitor1,
                         &nextLevel );
    return CXChildVisit_Continue;

}

CXChildVisitResult visitor( CXCursor cursor, CXCursor /* parent */, CXClientData clientData )
{
  CXSourceLocation location = clang_getCursorLocation( cursor );
  if( clang_Location_isFromMainFile( location ) == 0 )
    return CXChildVisit_Continue;
  CXCursorKind kind = clang_getCursorKind(cursor);
    std::string str2 ("main");
  CXCursorKind cursorKind = clang_getCursorKind( cursor );

  unsigned int curLevel  = *( reinterpret_cast<unsigned int*>( clientData ) );
  unsigned int nextLevel = curLevel + 1;
  if (!((str2.compare(getCursorSpelling(cursor)))))
  {
    std::cout << std::string( curLevel, '-' ) << " " << getCursorKindName(
    cursorKind ) << " (" << getCursorSpelling( cursor ) << ")\n";

    clang_visitChildren( cursor,
                         visitor1,
                         &nextLevel );
    return CXChildVisit_Continue;
  }
  else
  {
  return CXChildVisit_Continue;
  }
}

int main()
{
  CXIndex index = clang_createIndex(0, 0);
  CXTranslationUnit unit = clang_parseTranslationUnit(
     index,
     <source_file_name>, nullptr, 0,
    nullptr, 0,
     CXTranslationUnit_None);
      CXCursor cursor = clang_getTranslationUnitCursor(unit);
      unsigned int treeLevel = 0;
      clang_visitChildren( cursor, visitor, &treeLevel );
  clang_disposeTranslationUnit(unit);
  clang_disposeIndex(index);
}