Clang Tool: rewrite ObjCMessageExpr

Question

I want to rewrite all messages in my code, I need replace only selectors, but I need be able to replace nested expressions f. e. :

[super foo:[someInstance some         


        

Answer 1

You can rewrite selector name by replacing only continuous parts of selector name. For example, replace only underlined parts

[object someMessage:[object2 someMessage:obj3 calculate:obj4]];
        ^~~~~~~~~~~          ^~~~~~~~~~~      ^~~~~~~~~

To achieve this you require only

• number of selector parts - ObjCMessageExpr::getNumSelectorLocs()
• their locations - ObjCMessageExpr::getSelectorLoc(index)
• their lengths - ObjCMessageExpr::getSelector().getNameForSlot(index).size().

Overall, you can rewrite ObjCMessageExpr with the following RecursiveASTVisitor:

#include "clang/AST/ASTConsumer.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/RecursiveASTVisitor.h"
#include "clang/Rewrite/Core/Rewriter.h"

namespace clang_tooling
{

using clang::SourceLocation;

class RewritingVisitor : public clang::ASTConsumer,
                         public clang::RecursiveASTVisitor
{
public:
    // You can obtain SourceManager and LangOptions from CompilerInstance when
    // you are creating visitor (which is also ASTConsumer) in
    // clang::ASTFrontendAction::CreateASTConsumer.
    RewritingVisitor(clang::SourceManager &sourceManager,
                     const clang::LangOptions &langOptions)
        : _sourceManager(sourceManager), _rewriter(sourceManager, langOptions)
    {}

    virtual void HandleTranslationUnit(clang::ASTContext &context)
    {
        TraverseDecl(context.getTranslationUnitDecl());
        _rewriter.overwriteChangedFiles();
    }

    bool VisitObjCMessageExpr(clang::ObjCMessageExpr *messageExpr)
    {
        if (_sourceManager.isInMainFile(messageExpr->getLocStart()))
        {
            clang::Selector selector = messageExpr->getSelector();
            for (unsigned i = 0, end = messageExpr->getNumSelectorLocs();
                 i < end; ++i)
            {
                SourceLocation selectorLoc = messageExpr->getSelectorLoc(i);
                _rewriter.ReplaceText(selectorLoc,
                                      selector.getNameForSlot(i).size(),
                                      "newSelector");
            }
        }
        return Base::VisitObjCMessageExpr(messageExpr);
    }

private:
    typedef clang::RecursiveASTVisitor Base;

    clang::SourceManager &_sourceManager;
    clang::Rewriter _rewriter;
};

} // end namespace clang_tooling