llvm-project/clang/Driver/RewriteTest.cpp

//===--- RewriteTest.cpp - Playground for the code rewriter ---------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file was developed by Chris Lattner and is distributed under the
// University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Hacks and fun related to the code rewriter.
//
//===----------------------------------------------------------------------===//

#include "ASTConsumers.h"
#include "clang/Rewrite/Rewriter.h"
#include "clang/AST/AST.h"
#include "clang/AST/ASTConsumer.h"
#include "clang/Basic/SourceManager.h"
using namespace clang;


namespace {
  class RewriteTest : public ASTConsumer {
    Rewriter Rewrite;
    ASTContext *Context;
    SourceManager *SM;
    unsigned MainFileID;
    SourceLocation LastIncLoc;
    llvm::SmallVector<ObjcImplementationDecl *, 8> ClassImplementation;
    llvm::SmallVector<ObjcCategoryImplDecl *, 8> CategoryImplementation;
    static const int OBJC_ABI_VERSION =7 ;
  public:
    void Initialize(ASTContext &context, unsigned mainFileID) {
      Context = &context;
      SM = &Context->SourceMgr;
      MainFileID = mainFileID;
      Rewrite.setSourceMgr(Context->SourceMgr);
    }
    
    virtual void HandleTopLevelDecl(Decl *D);

    void HandleDeclInMainFile(Decl *D);
    void RewriteInclude(SourceLocation Loc);
    
    void RewriteFunctionBody(Stmt *S);
    void RewriteAtEncode(ObjCEncodeExpr *Exp);

    void WriteObjcClassMetaData(ObjcImplementationDecl *IDecl);
    void WriteObjcMetaData();
    
    ~RewriteTest();
  };
}

ASTConsumer *clang::CreateCodeRewriterTest() { return new RewriteTest(); }

void RewriteTest::HandleTopLevelDecl(Decl *D) {
  // Two cases: either the decl could be in the main file, or it could be in a
  // #included file.  If the former, rewrite it now.  If the later, check to see
  // if we rewrote the #include/#import.
  SourceLocation Loc = D->getLocation();
  Loc = SM->getLogicalLoc(Loc);
  
  // If this is for a builtin, ignore it.
  if (Loc.isInvalid()) return;

  if (SM->getDecomposedFileLoc(Loc).first == MainFileID)
    return HandleDeclInMainFile(D);

  RewriteInclude(Loc);
}

void RewriteTest::RewriteInclude(SourceLocation Loc) {
  // Rip up the #include stack to the main file.
  SourceLocation IncLoc = Loc, NextLoc = Loc;
  do {
    IncLoc = Loc;
    Loc = SM->getLogicalLoc(NextLoc);
    NextLoc = SM->getIncludeLoc(Loc);
  } while (!NextLoc.isInvalid());

  // Loc is now the location of the #include filename "foo" or <foo/bar.h>.
  // IncLoc indicates the header that was included if it is useful.
  IncLoc = SM->getLogicalLoc(IncLoc);
  if (SM->getDecomposedFileLoc(Loc).first != MainFileID ||
      Loc == LastIncLoc)
    return;
  LastIncLoc = Loc;
  
  unsigned IncCol = SM->getColumnNumber(Loc);
  SourceLocation LineStartLoc = Loc.getFileLocWithOffset(-IncCol+1);

  // Replace the #import with #include.
  Rewrite.ReplaceText(LineStartLoc, IncCol-1, "#include ", strlen("#include "));
}

/// HandleDeclInMainFile - This is called for each top-level decl defined in the
/// main file of the input.
void RewriteTest::HandleDeclInMainFile(Decl *D) {
  if (FunctionDecl *FD = dyn_cast<FunctionDecl>(D))
    if (Stmt *Body = FD->getBody())
      RewriteFunctionBody(Body);
  
  if (ObjcImplementationDecl *CI = dyn_cast<ObjcImplementationDecl>(D))
    ClassImplementation.push_back(CI);
  else if (ObjcCategoryImplDecl *CI = dyn_cast<ObjcCategoryImplDecl>(D))
    CategoryImplementation.push_back(CI);
  // Nothing yet.
}


void RewriteTest::RewriteFunctionBody(Stmt *S) {
  // Handle specific things.
  if (ObjCEncodeExpr *AtEncode = dyn_cast<ObjCEncodeExpr>(S))
    return RewriteAtEncode(AtEncode);
  
  // Otherwise, just rewrite all children.
  for (Stmt::child_iterator CI = S->child_begin(), E = S->child_end();
       CI != E; ++CI)
    if (*CI)
      RewriteFunctionBody(*CI);
}
 
void RewriteTest::RewriteAtEncode(ObjCEncodeExpr *Exp) {
  // Create a new string expression.
  QualType StrType = Context->getPointerType(Context->CharTy);
  Expr *Replacement = new StringLiteral("foo", 3, false, StrType, 
                                        SourceLocation(), SourceLocation());
  Rewrite.ReplaceStmt(Exp, Replacement);
  delete Replacement;
}

void RewriteTest::WriteObjcClassMetaData(ObjcImplementationDecl *IDecl) {
  ObjcInterfaceDecl *CDecl = IDecl->getClassInterface();
  
  if (IDecl->getImplDeclNumIvars() > 0 || 
      CDecl&& CDecl->getIntfDeclNumIvars() > 0) {
    static bool objc_ivar = false;
    
    int NumIvars = IDecl->getImplDeclNumIvars() > 0 
                     ? IDecl->getImplDeclNumIvars() 
                     : CDecl->getIntfDeclNumIvars();
    
    if (!objc_ivar) {
      /* struct _objc_ivar {
          char *ivar_name;
          char *ivar_type;
          int ivar_offset;
        };  
       */
      printf("\nstruct _objc_ivar {\n");
      printf("\tchar *ivar_name;\n");
      printf("\tchar *ivar_type;\n");
      printf("\tint ivar_offset;\n");
      printf("};\n");
      objc_ivar = true;
    }

    /* struct _objc_ivar_list {
        int ivar_count;
        struct _objc_ivar ivar_list[ivar_count];
     };  
    */
    printf("\nstatic struct {\n");
    printf("\tint ivar_count;\n");
    printf("\tstruct _objc_ivar ivar_list[%d];\n", NumIvars);
    printf("} _OBJC_INSTANCE_VARIABLES_%s "
      "__attribute__ ((section (\"__OBJC, __instance_vars\")))= "
      "{\n\t%d\n",IDecl->getName(), 
           NumIvars);
    ObjcIvarDecl **Ivars = IDecl->getImplDeclIVars() 
                             ? IDecl->getImplDeclIVars() 
                             : CDecl->getIntfDeclIvars();
    for (int i = 0; i < NumIvars; i++)
      // TODO: 1) ivar names may have to go to another section. 2) encode
      // ivar_type type of each ivar . 3) compute and add ivar offset.
      printf("\t,\"%s\", \"\", 0\n", Ivars[i]->getName());
    printf("};\n");
  }
  
}

void RewriteTest::WriteObjcMetaData() {
  int ClsDefCount = ClassImplementation.size();
  int CatDefCount = CategoryImplementation.size();
  if (ClsDefCount == 0 && CatDefCount == 0)
    return;
  
  // For each defined class, write out all its meta data.
  for (int i = 0; i < ClsDefCount; i++)
    WriteObjcClassMetaData(ClassImplementation[i]);
  
  // Write objc_symtab metadata
  /*
   struct _objc_symtab
   {
   long sel_ref_cnt;
   SEL *refs;
   short cls_def_cnt;
   short cat_def_cnt;
   void *defs[cls_def_cnt + cat_def_cnt];
   }; 
   */
  
  printf("\nstruct _objc_symtab {\n");
  printf("\tlong sel_ref_cnt;\n");
  printf("\tSEL *refs;\n");
  printf("\tshort cls_def_cnt;\n");
  printf("\tshort cat_def_cnt;\n");
  printf("\tvoid *defs[%d];\n", ClsDefCount + CatDefCount);
  printf("};\n\n");
  
  printf("static struct _objc_symtab "
         "_OBJC_SYMBOLS __attribute__ ((section (\"__OBJC, __symbols\")))= {\n");
  printf("\t0, 0, %d, %d\n", ClsDefCount, CatDefCount);
  for (int i = 0; i < ClsDefCount; i++)
    printf("\t,_OBJC_CLASS_%s\n", ClassImplementation[i]->getName());
  
  for (int i = 0; i < CatDefCount; i++)
    printf("\t,_OBJC_CATEGORY_%s_%s\n", 
           CategoryImplementation[i]->getClassInterface()->getName(), 
           CategoryImplementation[i]->getName());
  
  printf("};\n\n");
  
  // Write objc_module metadata
  
  /*
   struct _objc_module {
    long version;
    long size;
    const char *name;
    struct _objc_symtab *symtab;
   }
  */
  
  printf("\nstruct _objc_module {\n");
  printf("\tlong version;\n");
  printf("\tlong size;\n");
  printf("\tconst char *name;\n");
  printf("\tstruct _objc_symtab *symtab;");
  printf("};\n\n");
  printf("static struct _objc_module "
    "_OBJC_MODULES __attribute__ ((section (\"__OBJC, __module_info\")))= {\n");
  printf("\t%d, %d, \"\", &_OBJC_SYMBOLS\n", OBJC_ABI_VERSION, 16);
  printf("};\n\n");
}

RewriteTest::~RewriteTest() {
  // Get the top-level buffer that this corresponds to.
  std::pair<const char*, const char*> MainBuf = SM->getBufferData(MainFileID);
  const char *MainBufStart = MainBuf.first;
  const char *MainBufEnd = MainBuf.second;
  
  // Loop over the whole file, looking for tabs.
  for (const char *BufPtr = MainBufStart; BufPtr != MainBufEnd; ++BufPtr) {
    if (*BufPtr != '\t')
      continue;
    
    // Okay, we found a tab.  This tab will turn into at least one character,
    // but it depends on which 'virtual column' it is in.  Compute that now.
    unsigned VCol = 0;
    while (BufPtr-VCol != MainBufStart && BufPtr[-VCol-1] != '\t' &&
           BufPtr[-VCol-1] != '\n' && BufPtr[-VCol-1] != '\r')
      ++VCol;
    
    // Okay, now that we know the virtual column, we know how many spaces to
    // insert.  We assume 8-character tab-stops.
    unsigned Spaces = 8-(VCol & 7);
    
    // Get the location of the tab.
    SourceLocation TabLoc =
      SourceLocation::getFileLoc(MainFileID, BufPtr-MainBufStart);
    
    // Rewrite the single tab character into a sequence of spaces.
    Rewrite.ReplaceText(TabLoc, 1, "        ", Spaces);
  }
  
  // Get the buffer corresponding to MainFileID.  If we haven't changed it, then
  // we are done.
  if (const RewriteBuffer *RewriteBuf = 
          Rewrite.getRewriteBufferFor(MainFileID)) {
    printf("Changed:\n");
    std::string S(RewriteBuf->begin(), RewriteBuf->end());
    printf("%s\n", S.c_str());
  } else {
    printf("No changes\n");
  }
  // Rewrite Objective-c meta data*
  WriteObjcMetaData();
}