vhdljjparser.cpp

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/******************************************************************************
 *
 * Copyright (C) 2014 by M. Kreis
 *
 * Permission to use, copy, modify, and distribute this software and its
 * documentation under the terms of the GNU General Public License is hereby
 * granted. No representations are made about the suitability of this software
 * for any purpose. It is provided "as is" without express or implied warranty.
 * See the GNU General Public License for more details.
 *
 */
 
#include <string>
 
#include "dstring.h"
#include "containers.h"
#include "vhdljjparser.h"
#include "vhdldocgen.h"
#include "message.h"
#include "config.h"
#include "doxygen.h"
#include "util.h"
#include "stringutil.h"
#include "language.h"
#include "commentscan.h"
#include "definition.h"
#include "searchindex.h"
#include "outputlist.h"
#include "arguments.h"
#include "types.h"
#include "markdown.h"
#include "VhdlParserTokenManager.h"
#include "VhdlParserErrorHandler.hpp"
#include "regex.h"
 
using namespace vhdl::parser;
 
struct VHDLDocInfo
{
  DString doc;
  bool brief;
  bool pending = false;
  int iDocLine = 1;
};
 
 
static bool isConstraintFile(const DString &fileName,const DString &ext)
{
  return fileName.right(ext.length())==ext;
}
 
 
//-------------------------------------
 
static EntryList g_instFiles;
 
struct VHDLOutlineParser::Private
{
  void parseVhdlfile(const DString &fileName,const DString &inputBuffer,bool inLine);
 
  VHDLOutlineParser      *thisParser = nullptr;
  VhdlParser             *vhdlParser = nullptr;
  CommentScanner          commentScanner;
 
  DString                yyFileName;
  int                     yyLineNr      = 1;
  IntVector               lineParse;
  int                     iDocLine      = -1;
  DString                inputString;
  Entry*                  gBlock        = nullptr;
  Entry*                  previous      = nullptr;
//-------------------------------------------------------
 
  Entry*                  oldEntry = nullptr;
  bool                    varr = false;
  DString                varName;
  EntryList               libUse;
  EntryList               lineEntry;
  DString                strComment;
  int                     iCodeLen;
  VHDLDocInfo             str_doc;
  VhdlParser::SharedState shared;
  DString                forL;
  size_t                  code = 0;
 
};
 
void VHDLOutlineParser::Private::parseVhdlfile(const DString &fileName,
                                               const DString &inputBuffer,bool inLine)
{
  CharStream *stream = new CharStream(reinterpret_cast<const JJChar*>(inputBuffer.data()), (int)inputBuffer.size(), 1, 1);
  VhdlParserTokenManager *tokenManager = new VhdlParserTokenManager(stream);
  VhdlTokenManagerErrorHandler *tokErrHandler=new VhdlTokenManagerErrorHandler(fileName.data());
  vhdlParser=new VhdlParser(tokenManager);
  vhdlParser->setOutlineParser(thisParser);
  vhdlParser->setSharedState(&shared);
  tokenManager->setLexParser(vhdlParser);
  tokenManager->ReInit(stream,0);
  tokenManager->setErrorHandler(tokErrHandler);
  VhdlErrorHandler *parserErrHandler=new VhdlErrorHandler(fileName.data());
  vhdlParser->setErrorHandler(parserErrHandler);
  try
  {
    if(inLine)
    {
      vhdlParser->parseInline();
    }
    else
    {
     // vhdlParser->interface_variable_declaration(); //interface_declaration() ;
      vhdlParser->design_file();
    }
  }
  catch( std::exception &){ /* fprintf(stderr,"\n[%s]",e.what()); */ }
  //  fprintf(stderr,"\n\nparsed lines: %d\n",yyLineNr);
  //  fprintf(stderr,"\n\nerrors : %d\n\n",myErr->getErrorCount());
  //
  delete vhdlParser;
  delete tokenManager;
  delete stream;
}
 
VHDLOutlineParser::VHDLOutlineParser() : p(std::make_unique<Private>())
{
}
 
VHDLOutlineParser::~VHDLOutlineParser()
{
}
 
void VHDLOutlineParser::parseInput(const DString &fileName,const char *fileBuf,
                                   const std::shared_ptr<Entry> &root, ClangTUParser *)
{
  VhdlParser::SharedState *s = &p->shared;
  p->thisParser=this;
  p->inputString=fileBuf;
 
 // fprintf(stderr,"\n ============= %s\n ==========\n",fileBuf);
 
  bool inLine = fileName.empty();
 
  if (!inLine) msg("Parsing file {}...\n",fileName);
 
  p->yyFileName=fileName;
 
  bool xilinx_ucf=isConstraintFile(p->yyFileName,".ucf");
  bool altera_qsf=isConstraintFile(p->yyFileName,".qsf");
 
  // support XILINX(ucf) and ALTERA (qsf) file
 
  if (xilinx_ucf)
  {
    VhdlDocGen::parseUCF(fileBuf,root.get(),p->yyFileName,false);
    return;
  }
  if (altera_qsf)
  {
    VhdlDocGen::parseUCF(fileBuf,root.get(),p->yyFileName,true);
    return;
  }
  p->yyLineNr=1;
  s->current_root=root;
  s->lastCompound=nullptr;
  s->lastEntity=nullptr;
  p->oldEntry = nullptr;
  s->current=std::make_shared<Entry>();
  initEntry(s->current.get());
  p->commentScanner.enterFile(fileName,p->yyLineNr);
  p->lineParse.reserve(200);
  p->parseVhdlfile(fileName,fileBuf,inLine);
  p->commentScanner.leaveFile(fileName,p->yyLineNr);
 
  s->current.reset();
 
  if (!inLine)
  mapLibPackage(root.get());
 
  p->yyFileName.clear();
  p->libUse.clear();
}
 
void VHDLOutlineParser::lineCount()
{
  p->yyLineNr++;
}
 
void VHDLOutlineParser::lineCount(const DString &text)
{
  if (!text.empty())
  {
    for (const char* c=text.data() ; *c ; ++c )
    {
      if (*c == '\n') p->yyLineNr++;
    }
  }
}
 
void VHDLOutlineParser::initEntry(Entry *e)
{
  e->fileName = p->yyFileName;
  e->lang     = SrcLangExt::VHDL;
  if (p->str_doc.pending)
  {
    p->str_doc.pending=false;
    p->oldEntry=nullptr; // prevents endless recursion
    p->iDocLine=p->str_doc.iDocLine;
    handleCommentBlock(p->str_doc.doc,p->str_doc.brief);
    p->iDocLine=-1;
  }
  p->commentScanner.initGroupInfo(e);
}
 
void VHDLOutlineParser::newEntry()
{
  VhdlParser::SharedState *s = &p->shared;
  p->previous = s->current.get();
  if (s->current->vhdlSpec==VhdlSpecifier::ENTITY ||
      s->current->vhdlSpec==VhdlSpecifier::PACKAGE ||
      s->current->vhdlSpec==VhdlSpecifier::ARCHITECTURE ||
      s->current->vhdlSpec==VhdlSpecifier::PACKAGE_BODY)
  {
    s->current_root->moveToSubEntryAndRefresh(s->current);
  }
  else
  {
    if (s->lastCompound)
    {
      s->lastCompound->moveToSubEntryAndRefresh(s->current);
    }
    else
    {
      if (s->lastEntity)
      {
        s->lastEntity->moveToSubEntryAndRefresh(s->current);
      }
      else
      {
        s->current_root->moveToSubEntryAndRefresh(s->current);
      }
    }
  }
  initEntry(s->current.get());
}
 
static int idCounter;
 
/** returns a unique id for each record member.
*
*  type first_rec is record
*    RE: data_type;
*  end;
*
* type second_rec is record
*    RE: data_type;
*  end;
*/
 
DString VHDLOutlineParser::getNameID()
{
  return DString().setNum(idCounter++);
}
 
void VHDLOutlineParser::handleFlowComment(const DString &doc)
{
  lineCount(doc);
 
  if (VhdlDocGen::getFlowMember())
  {
    DString qcs(doc);
    qcs=qcs.stripWhiteSpace();
    qcs.stripPrefix("--#");
    FlowChart::addFlowChart(FlowChart::COMMENT_NO,DString(),DString(),qcs);
  }
}
 
size_t VHDLOutlineParser::checkInlineCode(DString &doc)
{
  static const reg::Ex csRe(R"([\\@]code)");
  static const reg::Ex cendRe(R"(\s*[\\@]endcode)");
  static const reg::Ex cbriefRe(R"([\\@]brief)");
 
  // helper to simulate behavior of QString.find(const QRegExp &re,int pos)
  auto findRe = [](const DString &str,const reg::Ex &re,size_t pos=0) -> size_t
  {
    if (str.length()<pos) return DString::npos;
    reg::Match match;
    if (reg::search(str.str(),match,re,pos)) // match found
    {
      return match.position();
    }
    else // not found
    {
      return DString::npos;
    }
  };
  auto replaceRe = [](const DString &str,const reg::Ex &re,const DString &replacement) -> DString
  {
    return reg::replace(str.str(), re, replacement.str());
  };
 
  size_t index = findRe(doc,csRe);
 
  if (findRe(doc,cendRe)!=DString::npos)
    return 1;
 
  if (index==DString::npos)
    return index;
 
  VhdlParser::SharedState *s = &p->shared;
  p->strComment += doc;
  p->code = findRe(p->inputString,csRe, p->code + 1);
  size_t com = p->inputString.find(p->strComment);
  size_t ref = findRe(p->inputString,cendRe, p->code + 1);
  size_t len = p->strComment.size();
 
  size_t ll = com + len;
  int diff = static_cast<int>(ref) - static_cast<int>(ll) - 3;
  DString code = p->inputString.mid(ll, diff);
  int iLine = 0;
  code = stripLeadingAndTrailingEmptyLines(code, iLine);
  int val = code.contains('\n');
  VhdlDocGen::prepareComment(p->strComment);
  StringVector ql = split(p->strComment.str(),"\n");
 
  DString co;
  DString na;
  for (const auto &qcs_ : ql)
  {
    DString qcs(qcs_);
    qcs = qcs.simplifyWhiteSpace();
    if (findRe(qcs,csRe)!=DString::npos)
    {
      size_t i = qcs.find('{');
      size_t j = qcs.find('}');
      if (i!=DString::npos && j!=DString::npos && i>0 && j > i)
      {
        na = qcs.mid(i+1, j-i-1);
      }
      continue;
    }
    qcs = replaceRe(qcs,cbriefRe, "");
    co += qcs;
    co += '\n';
  }
 
  VhdlDocGen::prepareComment(co);
 
  Entry gBlock;
  if (!na.empty())
    gBlock.name = na;
  else
    gBlock.name = "misc" + VhdlDocGen::getRecordNumber();
  gBlock.startLine = p->yyLineNr+iLine-1;
  gBlock.bodyLine = p->yyLineNr+iLine-1 ;
  gBlock.doc = code;
  gBlock.inbodyDocs = code;
  gBlock.brief = co;
  gBlock.section = EntryType::makeVariable();
  gBlock.vhdlSpec = VhdlSpecifier::MISCELLANEOUS;
  gBlock.fileName = p->yyFileName;
  gBlock.endBodyLine = p->yyLineNr + val +iLine;
  gBlock.lang = SrcLangExt::VHDL;
  std::shared_ptr<Entry> compound;
 
  if (s->lastEntity)
    compound = s->lastEntity;
  else if (s->lastCompound)
    compound = s->lastCompound;
  else
    compound = nullptr;
 
  if (compound)
  {
    compound->copyToSubEntry(&gBlock);
  }
  else
  {
    gBlock.type = "misc"; // global code like library ieee...
    s->current_root->copyToSubEntry(&gBlock);
  }
  p->strComment.clear();
  return 1;
}
 
void VHDLOutlineParser::handleCommentBlock(const DString &doc1, bool brief)
{
  int position = 0;
  bool needsEntry = false;
  VhdlParser::SharedState *s = &p->shared;
  DString doc = doc1;
 
  if (doc.empty())
    return;
 
  if (checkMultiComment(doc, p->yyLineNr))
  {
    p->strComment.clear();
    return;
  }
 
  if (checkInlineCode(doc) != DString::npos)
  {
    return;
  }
 
  Protection protection = Protection::Public;
  VhdlDocGen::prepareComment(doc);
  if (doc.empty()) return;
 
  if (p->oldEntry == s->current.get())
  {
    p->str_doc.doc = doc;
    p->str_doc.iDocLine = p->iDocLine;
    p->str_doc.brief = brief;
    p->str_doc.pending = true;
    return;
  }
 
  p->oldEntry = s->current.get();
 
  if (brief)
  {
    s->current->briefLine = p->yyLineNr;
  }
  else
  {
    s->current->docLine = p->yyLineNr;
  }
 
 
 
  Markdown markdown(p->yyFileName,p->iDocLine);
  int lineNr = p->iDocLine;
  GuardedSectionStack guards;
  DString processedDoc = Config_getBool(MARKDOWN_SUPPORT) ? markdown.process(doc,lineNr) : doc;
 
   while (p->commentScanner.parseCommentBlock(
      p->thisParser,
      s->current.get(),
      processedDoc,  // text
      p->yyFileName, // file
      lineNr,       // line of block start
      brief,
      0,
      false,
      protection,
      position,
      needsEntry,
      Config_getBool(MARKDOWN_SUPPORT),
      &guards
    ))
  {
    if (needsEntry)
      newEntry();
  }
  if (needsEntry)
  {
    if (p->varr)
    {
      p->varr = false;
      s->current->name = p->varName;
      s->current->section = EntryType::makeVariableDoc();
      p->varName = "";
    }
    newEntry();
  }
  p->iDocLine = -1;
  p->strComment.clear();
}
 
void VHDLOutlineParser::parsePrototype(const DString &text)
{
  p->varName=text;
  p->varr=true;
}
 
void VHDLOutlineParser::addCompInst(const DString &n, const DString &instName, const DString &comp,int iLine)
{
  VhdlParser::SharedState *s = &p->shared;
  s->current->vhdlSpec=VhdlSpecifier::INSTANTIATION;
  s->current->section=EntryType::makeVariable();
  s->current->startLine=iLine;
  s->current->bodyLine=iLine;
  s->current->type=instName;                       // foo:instname e.g proto or work. proto(ttt)
  s->current->exception=s->genLabels.lower();         // |arch|label1:label2...
  s->current->name=n;                              // foo
  if (s->lastCompound)
  {
    s->current->args=s->lastCompound->name;             // architecture name
  }
  s->current->includeName=comp;                    // component/entity/configuration
  size_t u=s->genLabels.find('|',1);
  if (u!=DString::npos && u>0)
  {
    s->current->write=s->genLabels.mid(u);
    s->current->read=s->genLabels.left(u);
  }
  //printf  (" \n genlabel: [%s]  inst: [%s]  name: [%s] %d\n",n,instName,comp,iLine);
 
  if (s->lastCompound)
  {
    s->current->args=s->lastCompound->name;
    if (true) // !findInstant(current->type))
    {
      initEntry(s->current.get());
      // TODO: protect with mutex
      g_instFiles.emplace_back(std::make_shared<Entry>(*s->current));
      // TODO: end protect with mutex
    }
 
    s->current=std::make_shared<Entry>();
  }
  else
  {
    newEntry();
  }
}
 
void VHDLOutlineParser::addVhdlType(const DString &n,int startLine,EntryType section,
    VhdlSpecifier spec,const DString &args,const DString &type,Protection prot)
{
  VhdlParser::SharedState *s = &p->shared;
  if (isFuncProcProced() || VhdlDocGen::getFlowMember())  return;
 
  if (s->parse_sec==VhdlSection::GEN_SEC)
  {
    spec=VhdlSpecifier::GENERIC;
  }
 
  StringVector ql=split(n.str(),",");
 
  for (size_t u=0;u<ql.size();u++)
  {
    s->current->name=ql[u];
    s->current->startLine=startLine;
    s->current->bodyLine=startLine;
    s->current->section=section;
    s->current->vhdlSpec=spec;
    s->current->fileName=p->yyFileName;
    if (s->current->args.empty())
    {
      s->current->args=args;
    }
    s->current->type=type;
    s->current->protection=prot;
 
    if (!s->lastCompound && section.isVariable() &&  (spec == VhdlSpecifier::USE || spec == VhdlSpecifier::LIBRARY) )
    {
      p->libUse.emplace_back(std::make_shared<Entry>(*s->current));
      s->current->reset();
    }
    newEntry();
  }
}
 
void VHDLOutlineParser::createFunction(const DString &impure,VhdlSpecifier spec,const DString &fname)
{
  VhdlParser::SharedState *s = &p->shared;
  s->current->vhdlSpec=spec;
  s->current->section=EntryType::makeFunction();
 
  if (impure=="impure" || impure=="pure")
  {
    s->current->exception=impure;
  }
 
  if (s->parse_sec==VhdlSection::GEN_SEC)
  {
    s->current->vhdlSpec=VhdlSpecifier::GENERIC;
    s->current->section=EntryType::makeFunction();
  }
 
  if (s->currP==VhdlSpecifier::PROCEDURE)
  {
    s->current->name=impure;
    s->current->exception="";
  }
  else
  {
    s->current->name=fname;
  }
 
  if (spec==VhdlSpecifier::PROCESS)
  {
    s->current->args=fname;
    s->current->name=impure;
    VhdlDocGen::deleteAllChars(s->current->args,' ');
    if (!fname.empty())
    {
      StringVector q1=split(fname.str(),",");
      for (const auto &name : q1)
      {
        Argument arg;
        arg.name=name;
        s->current->argList.push_back(arg);
      }
    }
  }
}
 
 
bool VHDLOutlineParser::isFuncProcProced()
{
  VhdlParser::SharedState *s = &p->shared;
  if (s->currP==VhdlSpecifier::FUNCTION  ||
      s->currP==VhdlSpecifier::PROCEDURE ||
      s->currP==VhdlSpecifier::PROCESS
     )
  {
    return true;
  }
  return false;
}
 
void VHDLOutlineParser::pushLabel( DString &label,DString & val)
{
  label+="|";
  label+=val;
}
 
DString VHDLOutlineParser::popLabel(DString & q)
{
  size_t i=q.rfind('|');
  if (i==DString::npos) return DString();
  q = q.left(i);
  return q;
}
 
 
 
void VHDLOutlineParser::addProto(const DString &s1,const DString &s2,const DString &s3,
                                 const DString &s4,const DString &/*s5*/,const DString &s6)
{
  VhdlParser::SharedState *s = &p->shared;
  StringVector ql=split(s2.str(),",");
 
  for (const auto &n : ql)
  {
    Argument arg;
    arg.name=n;
    if (!s3.empty())
    {
      arg.type=s3;
    }
    arg.type+=" ";
    arg.type+=s4;
    if (!s6.empty())
    {
      arg.type+=s6;
    }
    if (s->parse_sec==VhdlSection::GEN_SEC && s->param_sec==VhdlSection::UNKNOWN)
    {
      arg.defval="generic";
    }
 
    if (s->parse_sec==VhdlSection::PARAM_SEC)
    {
    //  assert(false);
    }
 
    arg.defval+=s1;
    arg.attrib="";//s6;
 
    s->current->argList.push_back(arg);
    s->current->args+=s2;
    s->current->args+=",";
  }
}
 
 
/*
 * adds the library|use statements to the next class (entity|package|architecture|package body
 * library ieee
 * entity xxx
 * .....
 * library
 * package
 * entity zzz
 * .....
 * and so on..
 */
void VHDLOutlineParser::mapLibPackage( Entry* root)
{
  for (const auto &rt : p->libUse)
  {
    if (addLibUseClause(rt->name))
    {
      bool bFound=false;
      for (const auto &current : root->children())
      {
        if (VhdlDocGen::isVhdlClass(current.get()))
        {
          if (current->startLine > rt->startLine)
          {
            bFound=true;
            current->copyToSubEntry(rt);
            break;
          }
        }
      }//for
      if (!bFound)
      {
        root->copyToSubEntry(rt);
      }
    } //if
  }// for
}//MapLib
 
bool VHDLOutlineParser::addLibUseClause(const DString &type)
{
  bool showIEEESTD=Config_getBool(FORCE_LOCAL_INCLUDES);
 
  if (showIEEESTD) // all standard packages and libraries will not be shown
  {
    if (type.lower().stripPrefix("ieee")) return false;
    if (type.lower().stripPrefix("std")) return false;
  }
  return true;
}
 
int VHDLOutlineParser::getLine()
{
  return p->yyLineNr;
}
 
void VHDLOutlineParser::setLineParsed(int tok)
{
  if ((int)p->lineParse.size()<=tok) p->lineParse.resize(tok+1);
  p->lineParse[tok]=p->yyLineNr;
}
 
int VHDLOutlineParser::getLine(int tok)
{
  int val=p->lineParse[tok];
  if (val<0) val=0;
  //assert(val>=0 && val<=yyLineNr);
  return val;
}
 
 
void VHDLOutlineParser::createFlow()
{
  VhdlParser::SharedState *s = &p->shared;
  if (!VhdlDocGen::getFlowMember())
  {
    return;
  }
  DString q,ret;
 
  if (s->currP==VhdlSpecifier::FUNCTION)
  {
    q=":function( ";
    FlowChart::alignFuncProc(q,s->tempEntry->argList,true);
    q+=")";
  }
  else if (s->currP==VhdlSpecifier::PROCEDURE)
  {
    q=":procedure (";
    FlowChart::alignFuncProc(q,s->tempEntry->argList,false);
    q+=")";
  }
  else
  {
    q=":process( "+s->tempEntry->args;
    q+=")";
  }
 
  q.prepend(VhdlDocGen::getFlowMember()->name());
 
  FlowChart::addFlowChart(FlowChart::START_NO,q,DString());
 
  if (s->currP==VhdlSpecifier::FUNCTION)
  {
    ret="end function ";
  }
  else if (s->currP==VhdlSpecifier::PROCEDURE)
  {
    ret="end procedure";
  }
  else
  {
    ret="end process ";
  }
 
  FlowChart::addFlowChart(FlowChart::END_NO,ret,DString());
  //  FlowChart::printFlowList();
  FlowChart::writeFlowChart();
  s->currP=VhdlSpecifier::UNKNOWN;
}
 
void VHDLOutlineParser::setMultCommentLine()
{
  p->iDocLine=p->yyLineNr;
}
 
void VHDLOutlineParser::oneLineComment(DString qcs)
{
    if (size_t j=qcs.find("--!"); j!=DString::npos) qcs=qcs.mid(j+3);
    if (!checkMultiComment(qcs,p->iDocLine))
    {
      handleCommentBlock(qcs,true);
    }
}
 
 
bool VHDLOutlineParser::checkMultiComment(DString& qcs,int line)
{
  VhdlParser::SharedState *s = &p->shared;
  insertEntryAtLine(s->current_root,line);
 
  if (p->lineEntry.empty()) return false;
 
  VhdlDocGen::prepareComment(qcs);
  while (!p->lineEntry.empty())
  {
    std::shared_ptr<Entry> e=p->lineEntry.back();
    e->briefLine=line;
    e->brief+=qcs;
 
    p->lineEntry.pop_back();
  }
  return true;
}
 
// returns the vhdl parsed types at line xxx
void VHDLOutlineParser::insertEntryAtLine(std::shared_ptr<Entry> ce,int line)
{
  for (const auto &rt : ce->children())
  {
    if (rt->bodyLine==line)
    {
      p->lineEntry.push_back(rt);
    }
 
    insertEntryAtLine(rt,line);
  }
}
 
const EntryList &getVhdlInstList()
{
  return g_instFiles;
}
 
void VHDLOutlineParser::error_skipto(int kind)
{
  Token *op;
  do
  {
    p->vhdlParser->getNextToken();  // step to next token
    op=p->vhdlParser->getToken(1);  // get first token
    if (op==nullptr) break;
    //fprintf(stderr,"\n %s",qPrint(t->image));
  } while (op->kind != kind);
  p->vhdlParser->clearError();
  // The above loop consumes tokens all the way up to a token of
  // "kind".  We use a do-while loop rather than a while because the
  // current token is the one immediately before the erroneous token
  // (in our case the token immediately before what should have been
  // "if"/"while".
}
 
DString filter2008VhdlComment(const DString &s)
{
  if (s.length()<4) return s;
  DString result;
  result.reserve(s.length());
  const char *p=s.data()+3; // skip /*!
  char c='\0';
  while (*p == ' ' || *p == '\t') p++;
  while ((c=*p++))
  {
    result+=c;
    if (c == '\n')
    {
      // special handling of space followed by * at beginning of line
      while (*p == ' ' || *p == '\t') p++;
      while (*p == '*') p++;
      // special attention in case character at end is /
      if (*p == '/') p++;
    }
  }
  // special attention in case */ at end of last line
  size_t len = result.length();
  if (len>=2 && result[len-1]=='/' && result[len-2]=='*')
  {
    len -= 2;
    while (len>0 && result[len-1] == '*') len--;
    while (len>0 && ((c = result[len-1]) == ' ' || c == '\t')) len--;
    result.resize(len);
  }
  return result;
}