Refactoring: introduce SymbolResolver to group symbol lookup routines

- Main goal was to avoid use of global state.

1 files changed, 1149 insertions, 0 deletions

diff --git a/src/symbolresolver.cpp b/src/symbolresolver.cpp
new file mode 100644
index 0000000..1c6baf4
--- /dev/null
+++ b/src/symbolresolver.cpp
@@ -0,0 +1,1149 @@
+/******************************************************************************
+ *
+ * Copyright (C) 1997-2020 by Dimitri van Heesch.
+ *
+ * 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.
+ *
+ * Documents produced by Doxygen are derivative works derived from the
+ * input used in their production; they are not affected by this license.
+ *
+ */
+
+#include <unordered_map>
+#include <string>
+#include <vector>
+
+#include "symbolresolver.h"
+#include "util.h"
+#include "doxygen.h"
+#include "namespacedef.h"
+#include "config.h"
+#include "defargs.h"
+
+static std::mutex g_cacheMutex;
+
+//--------------------------------------------------------------------------------------
+
+/** Helper class representing the stack of items considered while resolving
+ *  the scope.
+ */
+class AccessStack
+{
+    /** Element in the stack. */
+    struct AccessElem
+    {
+      AccessElem(const Definition *d,const FileDef *f,const Definition *i,QCString e = QCString()) : scope(d), fileScope(f), item(i), expScope(e) {}
+      const Definition *scope;
+      const FileDef *fileScope;
+      const Definition *item;
+      QCString expScope;
+    };
+  public:
+    void push(const Definition *scope,const FileDef *fileScope,const Definition *item)
+    {
+      m_elements.push_back(AccessElem(scope,fileScope,item));
+    }
+    void push(const Definition *scope,const FileDef *fileScope,const Definition *item,const QCString &expScope)
+    {
+      m_elements.push_back(AccessElem(scope,fileScope,item,expScope));
+    }
+    void pop()
+    {
+      if (!m_elements.empty()) m_elements.pop_back();
+    }
+    bool find(const Definition *scope,const FileDef *fileScope, const Definition *item)
+    {
+      auto it = std::find_if(m_elements.begin(),m_elements.end(),
+                             [&](const AccessElem &e) { return e.scope==scope && e.fileScope==fileScope && e.item==item; });
+      return it!=m_elements.end();
+    }
+    bool find(const Definition *scope,const FileDef *fileScope, const Definition *item,const QCString &expScope)
+    {
+      auto it = std::find_if(m_elements.begin(),m_elements.end(),
+                             [&](const AccessElem &e) { return e.scope==scope && e.fileScope==fileScope && e.item==item && e.expScope==expScope; });
+      return it!=m_elements.end();
+    }
+    void clear()
+    {
+      m_elements.clear();
+    }
+
+  private:
+    std::vector<AccessElem> m_elements;
+};
+
+//--------------------------------------------------------------------------------------
+
+using VisitedNamespaces = std::unordered_map<std::string,const Definition *>;
+
+//--------------------------------------------------------------------------------------
+
+struct SymbolResolver::Private
+{
+  public:
+    Private(const FileDef *f) : m_fileScope(f) {}
+    void reset()
+    {
+      m_resolvedTypedefs.clear();
+      resolvedType.resize(0);
+      typeDef = 0;
+      templateSpec.resize(0);
+    }
+    void setFileScope(const FileDef *fileScope)
+    {
+      m_fileScope = fileScope;
+    }
+
+    QCString          resolvedType;
+    const MemberDef  *typeDef = 0;
+    QCString          templateSpec;
+
+    const ClassDef *getResolvedClassRec(
+                           const Definition *scope,    // in
+                           const char *n,              // in
+                           const MemberDef **pTypeDef, // out
+                           QCString *pTemplSpec,       // out
+                           QCString *pResolvedType);   // out
+
+    int isAccessibleFrom(  AccessStack &accessStack,
+                           const Definition *scope,
+                           const Definition *item);
+
+    int isAccessibleFromWithExpScope(
+                           VisitedNamespaces &visitedNamespaces,
+                           AccessStack       &accessStack,
+                           const Definition *scope,
+                           const Definition *item,
+                           const QCString &explicitScopePart);
+
+  private:
+    void getResolvedSymbol(const Definition *scope,                             // in
+                           const Definition *d,                                 // in
+                           const QCString &explicitScopePart,                   // in
+                           const std::unique_ptr<ArgumentList> &actTemplParams, // in
+                           int &minDistance,                                    // input
+                           const ClassDef *&bestMatch,                          // out
+                           const MemberDef *&bestTypedef,                       // out
+                           QCString &bestTemplSpec,                             // out
+                           QCString &bestResolvedType                           // out
+                          );
+
+    const ClassDef *newResolveTypedef(
+                           const Definition *scope,                             // in
+                           const MemberDef *md,                                 // in
+                           const MemberDef **pMemType,                          // out
+                           QCString *pTemplSpec,                                // out
+                           QCString *pResolvedType,                             // out
+                           const std::unique_ptr<ArgumentList> &actTemplParams = std::unique_ptr<ArgumentList>()
+                          );
+
+    const Definition *followPath(const Definition *start,const QCString &path);
+
+    const Definition *endOfPathIsUsedClass(const SDict<Definition> *cl,const QCString &localName);
+
+    bool accessibleViaUsingNamespace(StringUnorderedSet &visited,
+                                     const NamespaceSDict *nl,
+                                     const Definition *item,
+                                     const QCString &explicitScopePart="");
+    bool accessibleViaUsingClass(const SDict<Definition> *cl,
+                                 const Definition *item,
+                                 const QCString &explicitScopePart=""
+                                );
+    QCString substTypedef(const Definition *scope,const QCString &name,
+                          const MemberDef **pTypeDef=0);
+
+    const FileDef    *m_fileScope;
+    std::unordered_map<std::string,const MemberDef*> m_resolvedTypedefs;
+};
+
+
+
+const ClassDef *SymbolResolver::Private::getResolvedClassRec(
+           const Definition *scope,
+           const char *n,
+           const MemberDef **pTypeDef,
+           QCString *pTemplSpec,
+           QCString *pResolvedType)
+{
+  if (n==0 || *n=='\0') return 0;
+  //static int level=0;
+  //fprintf(stderr,"%d [getResolvedClassRec(%s,%s)\n",level++,scope?scope->name().data():"<global>",n);
+  QCString name;
+  QCString explicitScopePart;
+  QCString strippedTemplateParams;
+  name=stripTemplateSpecifiersFromScope
+                     (removeRedundantWhiteSpace(n),TRUE,
+                      &strippedTemplateParams);
+  std::unique_ptr<ArgumentList> actTemplParams;
+  if (!strippedTemplateParams.isEmpty()) // template part that was stripped
+  {
+    actTemplParams = stringToArgumentList(scope->getLanguage(),strippedTemplateParams);
+  }
+
+  int qualifierIndex = computeQualifiedIndex(name);
+  //printf("name=%s qualifierIndex=%d\n",name.data(),qualifierIndex);
+  if (qualifierIndex!=-1) // qualified name
+  {
+    // split off the explicit scope part
+    explicitScopePart=name.left(qualifierIndex);
+    // todo: improve namespace alias substitution
+    replaceNamespaceAliases(explicitScopePart,explicitScopePart.length());
+    name=name.mid(qualifierIndex+2);
+  }
+
+  if (name.isEmpty())
+  {
+    //fprintf(stderr,"%d ] empty name\n",--level);
+    return 0; // empty name
+  }
+
+  //printf("Looking for symbol %s\n",name.data());
+  auto range = Doxygen::symbolMap.find(name);
+  // the -g (for C# generics) and -p (for ObjC protocols) are now already
+  // stripped from the key used in the symbolMap, so that is not needed here.
+  if (range.first==range.second)
+  {
+    range = Doxygen::symbolMap.find(name+"-p");
+    if (range.first==range.second)
+    {
+      //fprintf(stderr,"%d ] no such symbol!\n",--level);
+      return 0;
+    }
+  }
+  //printf("found symbol!\n");
+
+  bool hasUsingStatements =
+    (m_fileScope && ((m_fileScope->getUsedNamespaces() &&
+                      m_fileScope->getUsedNamespaces()->count()>0) ||
+                     (m_fileScope->getUsedClasses() &&
+                      m_fileScope->getUsedClasses()->count()>0))
+    );
+  //printf("hasUsingStatements=%d\n",hasUsingStatements);
+  // Since it is often the case that the same name is searched in the same
+  // scope over an over again (especially for the linked source code generation)
+  // we use a cache to collect previous results. This is possible since the
+  // result of a lookup is deterministic. As the key we use the concatenated
+  // scope, the name to search for and the explicit scope prefix. The speedup
+  // achieved by this simple cache can be enormous.
+  int scopeNameLen = scope->name().length()+1;
+  int nameLen = name.length()+1;
+  int explicitPartLen = explicitScopePart.length();
+  int fileScopeLen = hasUsingStatements ? 1+m_fileScope->absFilePath().length() : 0;
+
+  // below is a more efficient coding of
+  // QCString key=scope->name()+"+"+name+"+"+explicitScopePart;
+  QCString key(scopeNameLen+nameLen+explicitPartLen+fileScopeLen+1);
+  char *pk=key.rawData();
+  qstrcpy(pk,scope->name()); *(pk+scopeNameLen-1)='+';
+  pk+=scopeNameLen;
+  qstrcpy(pk,name); *(pk+nameLen-1)='+';
+  pk+=nameLen;
+  qstrcpy(pk,explicitScopePart);
+  pk+=explicitPartLen;
+
+  // if a file scope is given and it contains using statements we should
+  // also use the file part in the key (as a class name can be in
+  // two different namespaces and a using statement in a file can select
+  // one of them).
+  if (hasUsingStatements)
+  {
+    // below is a more efficient coding of
+    // key+="+"+m_fileScope->name();
+    *pk++='+';
+    qstrcpy(pk,m_fileScope->absFilePath());
+    pk+=fileScopeLen-1;
+  }
+  *pk='\0';
+
+  LookupInfo *pval = 0;
+  {
+    std::lock_guard<std::mutex> lock(g_cacheMutex);
+    pval=Doxygen::lookupCache->find(key.str());
+    //printf("Searching for %s result=%p\n",key.data(),pval);
+    if (pval)
+    {
+      //printf("LookupInfo %p %p '%s' %p\n",
+      //    pval->classDef, pval->typeDef, pval->templSpec.data(),
+      //    pval->resolvedType.data());
+      if (pTemplSpec)    *pTemplSpec=pval->templSpec;
+      if (pTypeDef)      *pTypeDef=pval->typeDef;
+      if (pResolvedType) *pResolvedType=pval->resolvedType;
+      //fprintf(stderr,"%d ] cachedMatch=%s\n",--level,
+      //    pval->classDef?pval->classDef->name().data():"<none>");
+      //if (pTemplSpec)
+      //  printf("templSpec=%s\n",pTemplSpec->data());
+      return pval->classDef;
+    }
+    else // not found yet; we already add a 0 to avoid the possibility of
+      // endless recursion.
+    {
+      pval = Doxygen::lookupCache->insert(key.str(),LookupInfo());
+    }
+  }
+
+  const ClassDef *bestMatch=0;
+  const MemberDef *bestTypedef=0;
+  QCString bestTemplSpec;
+  QCString bestResolvedType;
+  int minDistance=10000; // init at "infinite"
+
+  for (auto it=range.first ; it!=range.second; ++it)
+  {
+    Definition *d = it->second;
+    getResolvedSymbol(scope,d,explicitScopePart,actTemplParams,
+                      minDistance,bestMatch,bestTypedef,bestTemplSpec,bestResolvedType);
+  }
+
+  if (pTypeDef)
+  {
+    *pTypeDef = bestTypedef;
+  }
+  if (pTemplSpec)
+  {
+    *pTemplSpec = bestTemplSpec;
+  }
+  if (pResolvedType)
+  {
+    *pResolvedType = bestResolvedType;
+  }
+
+  //printf("getResolvedClassRec: bestMatch=%p pval->resolvedType=%s\n",
+  //    bestMatch,bestResolvedType.data());
+
+  if (pval)
+  {
+    std::lock_guard<std::mutex> lock(g_cacheMutex);
+    pval->classDef     = bestMatch;
+    pval->typeDef      = bestTypedef;
+    pval->templSpec    = bestTemplSpec;
+    pval->resolvedType = bestResolvedType;
+  }
+  //fprintf(stderr,"%d ] bestMatch=%s distance=%d\n",--level,
+  //    bestMatch?bestMatch->name().data():"<none>",minDistance);
+  //if (pTemplSpec)
+  //  printf("templSpec=%s\n",pTemplSpec->data());
+  return bestMatch;
+}
+
+void SymbolResolver::Private::getResolvedSymbol(
+                         const Definition *scope,                             // in
+                         const Definition *d,                                 // in
+                         const QCString &explicitScopePart,                   // in
+                         const std::unique_ptr<ArgumentList> &actTemplParams, // in
+                         int &minDistance,                                    // inout
+                         const ClassDef *&bestMatch,                          // out
+                         const MemberDef *&bestTypedef,                       // out
+                         QCString &bestTemplSpec,                             // out
+                         QCString &bestResolvedType                           // out
+                      )
+{
+  //fprintf(stderr,"getResolvedSymbol(%s,%s)\n",scope->name().data(),d->qualifiedName().data());
+  // only look at classes and members that are enums or typedefs
+  if (d->definitionType()==Definition::TypeClass ||
+      (d->definitionType()==Definition::TypeMember &&
+       ((dynamic_cast<const MemberDef*>(d))->isTypedef() ||
+        (dynamic_cast<const MemberDef*>(d))->isEnumerate())
+      )
+     )
+  {
+    VisitedNamespaces visitedNamespaces;
+    AccessStack accessStack;
+    // test accessibility of definition within scope.
+    int distance = isAccessibleFromWithExpScope(visitedNamespaces,accessStack,scope,d,explicitScopePart);
+    //fprintf(stderr,"  %s; distance %s (%p) is %d\n",scope->name().data(),d->name().data(),d,distance);
+    if (distance!=-1) // definition is accessible
+    {
+      // see if we are dealing with a class or a typedef
+      if (d->definitionType()==Definition::TypeClass) // d is a class
+      {
+        const ClassDef *cd = dynamic_cast<const ClassDef *>(d);
+        //printf("cd=%s\n",cd->name().data());
+        if (!cd->isTemplateArgument()) // skip classes that
+          // are only there to
+          // represent a template
+          // argument
+        {
+          //printf("is not a templ arg\n");
+          if (distance<minDistance) // found a definition that is "closer"
+          {
+            minDistance=distance;
+            bestMatch = cd;
+            bestTypedef = 0;
+            bestTemplSpec.resize(0);
+            bestResolvedType = cd->qualifiedName();
+          }
+          else if (distance==minDistance &&
+              m_fileScope && bestMatch &&
+              m_fileScope->getUsedNamespaces() &&
+              d->getOuterScope()->definitionType()==Definition::TypeNamespace &&
+              bestMatch->getOuterScope()==Doxygen::globalScope
+              )
+          {
+            // in case the distance is equal it could be that a class X
+            // is defined in a namespace and in the global scope. When searched
+            // in the global scope the distance is 0 in both cases. We have
+            // to choose one of the definitions: we choose the one in the
+            // namespace if the fileScope imports namespaces and the definition
+            // found was in a namespace while the best match so far isn't.
+            // Just a non-perfect heuristic but it could help in some situations
+            // (kdecore code is an example).
+            minDistance=distance;
+            bestMatch = cd;
+            bestTypedef = 0;
+            bestTemplSpec.resize(0);
+            bestResolvedType = cd->qualifiedName();
+          }
+        }
+        else
+        {
+          //printf("  is a template argument!\n");
+        }
+      }
+      else if (d->definitionType()==Definition::TypeMember)
+      {
+        const MemberDef *md = dynamic_cast<const MemberDef *>(d);
+        //fprintf(stderr,"  member isTypedef()=%d\n",md->isTypedef());
+        if (md->isTypedef()) // d is a typedef
+        {
+          QCString args=md->argsString();
+          if (args.isEmpty()) // do not expand "typedef t a[4];"
+          {
+            //printf("    found typedef!\n");
+
+            // we found a symbol at this distance, but if it didn't
+            // resolve to a class, we still have to make sure that
+            // something at a greater distance does not match, since
+            // that symbol is hidden by this one.
+            if (distance<minDistance)
+            {
+              QCString spec;
+              QCString type;
+              minDistance=distance;
+              const MemberDef *enumType = 0;
+              const ClassDef *cd = newResolveTypedef(scope,md,&enumType,&spec,&type,actTemplParams);
+              if (cd)  // type resolves to a class
+              {
+                //printf("      bestTypeDef=%p spec=%s type=%s\n",md,spec.data(),type.data());
+                bestMatch = cd;
+                bestTypedef = md;
+                bestTemplSpec = spec;
+                bestResolvedType = type;
+              }
+              else if (enumType) // type resolves to a member type
+              {
+                //printf("      is enum\n");
+                bestMatch = 0;
+                bestTypedef = enumType;
+                bestTemplSpec = "";
+                bestResolvedType = enumType->qualifiedName();
+              }
+              else if (md->isReference()) // external reference
+              {
+                bestMatch = 0;
+                bestTypedef = md;
+                bestTemplSpec = spec;
+                bestResolvedType = type;
+              }
+              else
+              {
+                bestMatch = 0;
+                bestTypedef = md;
+                bestTemplSpec.resize(0);
+                bestResolvedType.resize(0);
+                //printf("      no match\n");
+              }
+            }
+            else
+            {
+              //printf("      not the best match %d min=%d\n",distance,minDistance);
+            }
+          }
+          else
+          {
+            //printf("     not a simple typedef\n")
+          }
+        }
+        else if (md->isEnumerate())
+        {
+          if (distance<minDistance)
+          {
+            minDistance=distance;
+            bestMatch = 0;
+            bestTypedef = md;
+            bestTemplSpec = "";
+            bestResolvedType = md->qualifiedName();
+          }
+        }
+      }
+    } // if definition accessible
+    else
+    {
+      //printf("  Not accessible!\n");
+    }
+  } // if definition is a class or member
+  //printf("  bestMatch=%p bestResolvedType=%s\n",bestMatch,bestResolvedType.data());
+}
+
+const ClassDef *SymbolResolver::Private::newResolveTypedef(
+                  const Definition *scope,                             // in
+                  const MemberDef *md,                                 // in
+                  const MemberDef **pMemType,                          // out
+                  QCString *pTemplSpec,                                // out
+                  QCString *pResolvedType,                             // out
+                  const std::unique_ptr<ArgumentList> &actTemplParams) // in
+{
+  //printf("newResolveTypedef(md=%p,cachedVal=%p)\n",md,md->getCachedTypedefVal());
+  bool isCached = md->isTypedefValCached(); // value already cached
+  if (isCached)
+  {
+    //printf("Already cached %s->%s [%s]\n",
+    //    md->name().data(),
+    //    md->getCachedTypedefVal()?md->getCachedTypedefVal()->name().data():"<none>",
+    //    md->getCachedResolvedTypedef()?md->getCachedResolvedTypedef().data():"<none>");
+
+    if (pTemplSpec)    *pTemplSpec    = md->getCachedTypedefTemplSpec();
+    if (pResolvedType) *pResolvedType = md->getCachedResolvedTypedef();
+    return md->getCachedTypedefVal();
+  }
+  //printf("new typedef\n");
+  QCString qname = md->qualifiedName();
+  if (m_resolvedTypedefs.find(qname.str())!=m_resolvedTypedefs.end())
+  {
+    return 0; // typedef already done
+  }
+
+  auto typedef_it = m_resolvedTypedefs.insert({qname.str(),md}).first; // put on the trace list
+
+  const ClassDef *typeClass = md->getClassDef();
+  QCString type = md->typeString(); // get the "value" of the typedef
+  if (typeClass && typeClass->isTemplate() &&
+      actTemplParams && !actTemplParams->empty())
+  {
+    type = substituteTemplateArgumentsInString(type,
+            typeClass->templateArguments(),actTemplParams);
+  }
+  QCString typedefValue = type;
+  int tl=type.length();
+  int ip=tl-1; // remove * and & at the end
+  while (ip>=0 && (type.at(ip)=='*' || type.at(ip)=='&' || type.at(ip)==' '))
+  {
+    ip--;
+  }
+  type=type.left(ip+1);
+  type.stripPrefix("const ");  // strip leading "const"
+  type.stripPrefix("struct "); // strip leading "struct"
+  type.stripPrefix("union ");  // strip leading "union"
+  int sp=0;
+  tl=type.length(); // length may have been changed
+  while (sp<tl && type.at(sp)==' ') sp++;
+  const MemberDef *memTypeDef = 0;
+  const ClassDef  *result = getResolvedClassRec(md->getOuterScope(),type,
+                                                &memTypeDef,0,pResolvedType);
+  // if type is a typedef then return what it resolves to.
+  if (memTypeDef && memTypeDef->isTypedef())
+  {
+    result=newResolveTypedef(m_fileScope,memTypeDef,pMemType,pTemplSpec,0);
+    goto done;
+  }
+  else if (memTypeDef && memTypeDef->isEnumerate() && pMemType)
+  {
+    *pMemType = memTypeDef;
+  }
+
+  //printf("type=%s result=%p\n",type.data(),result);
+  if (result==0)
+  {
+    // try unspecialized version if type is template
+    int si=type.findRev("::");
+    int i=type.find('<');
+    if (si==-1 && i!=-1) // typedef of a template => try the unspecialized version
+    {
+      if (pTemplSpec) *pTemplSpec = type.mid(i);
+      result = getResolvedClassRec(md->getOuterScope(),type.left(i),0,0,pResolvedType);
+      //printf("result=%p pRresolvedType=%s sp=%d ip=%d tl=%d\n",
+      //    result,pResolvedType?pResolvedType->data():"<none>",sp,ip,tl);
+    }
+    else if (si!=-1) // A::B
+    {
+      i=type.find('<',si);
+      if (i==-1) // Something like A<T>::B => lookup A::B
+      {
+        i=type.length();
+      }
+      else // Something like A<T>::B<S> => lookup A::B, spec=<S>
+      {
+        if (pTemplSpec) *pTemplSpec = type.mid(i);
+      }
+      result = getResolvedClassRec(md->getOuterScope(),
+           stripTemplateSpecifiersFromScope(type.left(i),FALSE),0,0,pResolvedType);
+    }
+
+    //if (result) ip=si+sp+1;
+  }
+
+done:
+  if (pResolvedType)
+  {
+    if (result)
+    {
+      *pResolvedType = result->qualifiedName();
+      //printf("*pResolvedType=%s\n",pResolvedType->data());
+      if (sp>0)    pResolvedType->prepend(typedefValue.left(sp));
+      if (ip<tl-1) pResolvedType->append(typedefValue.right(tl-ip-1));
+    }
+    else
+    {
+      *pResolvedType = typedefValue;
+    }
+  }
+
+  // remember computed value for next time
+  if (result && result->getDefFileName()!="<code>")
+    // this check is needed to prevent that temporary classes that are
+    // introduced while parsing code fragments are being cached here.
+  {
+    //printf("setting cached typedef %p in result %p\n",md,result);
+    //printf("==> %s (%s,%d)\n",result->name().data(),result->getDefFileName().data(),result->getDefLine());
+    //printf("*pResolvedType=%s\n",pResolvedType?pResolvedType->data():"<none>");
+    const_cast<MemberDef*>(md)->cacheTypedefVal(result,
+        pTemplSpec ? *pTemplSpec : QCString(),
+        pResolvedType ? *pResolvedType : QCString()
+       );
+  }
+
+  m_resolvedTypedefs.erase(typedef_it); // remove from the trace list
+
+  return result;
+}
+
+int SymbolResolver::Private::isAccessibleFromWithExpScope(
+                                     VisitedNamespaces &visitedNamespaces,
+                                     AccessStack       &accessStack,
+                                     const Definition *scope,
+                                     const Definition *item,
+                                     const QCString &explicitScopePart)
+{
+  if (explicitScopePart.isEmpty())
+  {
+    // handle degenerate case where there is no explicit scope.
+    return isAccessibleFrom(accessStack,scope,item);
+  }
+
+  if (accessStack.find(scope,m_fileScope,item,explicitScopePart))
+  {
+    return -1;
+  }
+  accessStack.push(scope,m_fileScope,item,explicitScopePart);
+
+
+  //printf("  <isAccessibleFromWithExpScope(%s,%s,%s)\n",scope?scope->name().data():"<global>",
+  //                                      item?item->name().data():"<none>",
+  //                                      explicitScopePart.data());
+  int result=0; // assume we found it
+  const Definition *newScope = followPath(scope,explicitScopePart);
+  if (newScope)  // explicitScope is inside scope => newScope is the result
+  {
+    Definition *itemScope = item->getOuterScope();
+    //printf("    scope traversal successful %s<->%s!\n",itemScope->name().data(),newScope->name().data());
+    //if (newScope && newScope->definitionType()==Definition::TypeClass)
+    //{
+    //  ClassDef *cd = (ClassDef *)newScope;
+    //  printf("---> Class %s: bases=%p\n",cd->name().data(),cd->baseClasses());
+    //}
+    if (itemScope==newScope)  // exact match of scopes => distance==0
+    {
+      //printf("> found it\n");
+    }
+    else if (itemScope && newScope &&
+             itemScope->definitionType()==Definition::TypeClass &&
+             newScope->definitionType()==Definition::TypeClass &&
+             (dynamic_cast<const ClassDef*>(newScope))->isBaseClass(dynamic_cast<const ClassDef*>(itemScope),TRUE,0)
+            )
+    {
+      // inheritance is also ok. Example: looking for B::I, where
+      // class A { public: class I {} };
+      // class B : public A {}
+      // but looking for B::I, where
+      // class A { public: class I {} };
+      // class B { public: class I {} };
+      // will find A::I, so we still prefer a direct match and give this one a distance of 1
+      result=1;
+
+      //printf("scope(%s) is base class of newScope(%s)\n",
+      //    scope->name().data(),newScope->name().data());
+    }
+    else
+    {
+      int i=-1;
+      if (newScope->definitionType()==Definition::TypeNamespace)
+      {
+        visitedNamespaces.insert({newScope->name().str(),newScope});
+        // this part deals with the case where item is a class
+        // A::B::C but is explicit referenced as A::C, where B is imported
+        // in A via a using directive.
+        //printf("newScope is a namespace: %s!\n",newScope->name().data());
+        const NamespaceDef *nscope = dynamic_cast<const NamespaceDef*>(newScope);
+        const SDict<Definition> *cl = nscope->getUsedClasses();
+        if (cl)
+        {
+          SDict<Definition>::Iterator cli(*cl);
+          const Definition *cd;
+          for (cli.toFirst();(cd=cli.current());++cli)
+          {
+            //printf("Trying for class %s\n",cd->name().data());
+            if (cd==item)
+            {
+              //printf("> class is used in this scope\n");
+              goto done;
+            }
+          }
+        }
+        const NamespaceSDict *nl = nscope->getUsedNamespaces();
+        if (nl)
+        {
+          NamespaceSDict::Iterator nli(*nl);
+          const NamespaceDef *nd;
+          for (nli.toFirst();(nd=nli.current());++nli)
+          {
+            if (visitedNamespaces.find(nd->name().str())==visitedNamespaces.end())
+            {
+              //printf("Trying for namespace %s\n",nd->name().data());
+              i = isAccessibleFromWithExpScope(visitedNamespaces,accessStack,scope,item,nd->name());
+              if (i!=-1)
+              {
+                //printf("> found via explicit scope of used namespace\n");
+                goto done;
+              }
+            }
+          }
+        }
+      }
+      // repeat for the parent scope
+      if (scope!=Doxygen::globalScope)
+      {
+        i = isAccessibleFromWithExpScope(visitedNamespaces,accessStack,scope->getOuterScope(),item,explicitScopePart);
+      }
+      //printf("  | result=%d\n",i);
+      result = (i==-1) ? -1 : i+2;
+    }
+  }
+  else // failed to resolve explicitScope
+  {
+    //printf("    failed to resolve: scope=%s\n",scope->name().data());
+    if (scope->definitionType()==Definition::TypeNamespace)
+    {
+      const NamespaceDef *nscope = dynamic_cast<const NamespaceDef*>(scope);
+      const NamespaceSDict *nl = nscope->getUsedNamespaces();
+      StringUnorderedSet visited;
+      if (accessibleViaUsingNamespace(visited,nl,item,explicitScopePart))
+      {
+        //printf("> found in used namespace\n");
+        goto done;
+      }
+    }
+    if (scope==Doxygen::globalScope)
+    {
+      if (m_fileScope)
+      {
+        const NamespaceSDict *nl = m_fileScope->getUsedNamespaces();
+        StringUnorderedSet visited;
+        if (accessibleViaUsingNamespace(visited,nl,item,explicitScopePart))
+        {
+          //printf("> found in used namespace\n");
+          goto done;
+        }
+      }
+      //printf("> not found\n");
+      result=-1;
+    }
+    else // continue by looking into the parent scope
+    {
+      int i=isAccessibleFromWithExpScope(visitedNamespaces,accessStack,scope->getOuterScope(),item,explicitScopePart);
+      //printf("> result=%d\n",i);
+      result= (i==-1) ? -1 : i+2;
+    }
+  }
+
+done:
+  //printf("  > result=%d\n",result);
+  accessStack.pop();
+  return result;
+}
+
+const Definition *SymbolResolver::Private::followPath(const Definition *start,const QCString &path)
+{
+  int is,ps;
+  int l;
+  const Definition *current=start;
+  ps=0;
+  //printf("followPath: start='%s' path='%s'\n",start?start->name().data():"<none>",path.data());
+  // for each part of the explicit scope
+  while ((is=getScopeFragment(path,ps,&l))!=-1)
+  {
+    // try to resolve the part if it is a typedef
+    const MemberDef *memTypeDef=0;
+    QCString qualScopePart = substTypedef(current,path.mid(is,l),&memTypeDef);
+    //printf("      qualScopePart=%s\n",qualScopePart.data());
+    if (memTypeDef)
+    {
+      const ClassDef *type = newResolveTypedef(m_fileScope,memTypeDef,0,0,0);
+      if (type)
+      {
+        //printf("Found type %s\n",type->name().data());
+        return type;
+      }
+    }
+    const Definition *next = current->findInnerCompound(qualScopePart);
+    //printf("++ Looking for %s inside %s result %s\n",
+    //     qualScopePart.data(),
+    //     current->name().data(),
+    //     next?next->name().data():"<null>");
+    if (next==0) // failed to follow the path
+    {
+      //printf("==> next==0!\n");
+      if (current->definitionType()==Definition::TypeNamespace)
+      {
+        next = endOfPathIsUsedClass(
+            (dynamic_cast<const NamespaceDef *>(current))->getUsedClasses(),qualScopePart);
+      }
+      else if (current->definitionType()==Definition::TypeFile)
+      {
+        next = endOfPathIsUsedClass(
+            (dynamic_cast<const FileDef *>(current))->getUsedClasses(),qualScopePart);
+      }
+      current = next;
+      if (current==0) break;
+    }
+    else // continue to follow scope
+    {
+      current = next;
+      //printf("==> current = %p\n",current);
+    }
+    ps=is+l;
+  }
+  //printf("followPath(start=%s,path=%s) result=%s\n",
+  //    start->name().data(),path.data(),current?current->name().data():"<null>");
+  return current; // path could be followed
+}
+
+const Definition *SymbolResolver::Private::endOfPathIsUsedClass(const SDict<Definition> *cl,const QCString &localName)
+{
+  if (cl)
+  {
+    SDict<Definition>::Iterator cli(*cl);
+    Definition *cd;
+    for (cli.toFirst();(cd=cli.current());++cli)
+    {
+      if (cd->localName()==localName)
+      {
+        return cd;
+      }
+    }
+  }
+  return 0;
+}
+
+bool SymbolResolver::Private::accessibleViaUsingNamespace(StringUnorderedSet &visited,
+                                 const NamespaceSDict *nl,
+                                 const Definition *item,
+                                 const QCString &explicitScopePart)
+{
+  if (nl) // check used namespaces for the class
+  {
+    NamespaceSDict::Iterator nli(*nl);
+    NamespaceDef *und;
+    int count=0;
+    for (nli.toFirst();(und=nli.current());++nli,count++)
+    {
+      //printf("[Trying via used namespace %s: count=%d/%d\n",und->name().data(),
+      //    count,nl->count());
+      const Definition *sc = explicitScopePart.isEmpty() ? und : followPath(und,explicitScopePart);
+      if (sc && item->getOuterScope()==sc)
+      {
+        //printf("] found it\n");
+        return true;
+      }
+      if (item->getLanguage()==SrcLangExt_Cpp)
+      {
+        QCString key=und->name();
+        if (und->getUsedNamespaces() && visited.find(key.str())==visited.end())
+        {
+          visited.insert(key.str());
+
+          if (accessibleViaUsingNamespace(visited,und->getUsedNamespaces(),item,explicitScopePart))
+          {
+            //printf("] found it via recursion\n");
+            return true;
+          }
+
+          visited.erase(key.str());
+        }
+      }
+      //printf("] Try via used namespace done\n");
+    }
+  }
+  return false;
+}
+
+
+bool SymbolResolver::Private::accessibleViaUsingClass(const SDict<Definition> *cl,
+                                                      const Definition *item,
+                                                      const QCString &explicitScopePart)
+{
+  //printf("accessibleViaUsingClass(%p)\n",cl);
+  if (cl) // see if the class was imported via a using statement
+  {
+    SDict<Definition>::Iterator cli(*cl);
+    Definition *ucd;
+    bool explicitScopePartEmpty = explicitScopePart.isEmpty();
+    for (cli.toFirst();(ucd=cli.current());++cli)
+    {
+      //printf("Trying via used class %s\n",ucd->name().data());
+      const Definition *sc = explicitScopePartEmpty ? ucd : followPath(ucd,explicitScopePart);
+      if (sc && sc==item) return TRUE;
+      //printf("Try via used class done\n");
+    }
+  }
+  return FALSE;
+}
+
+int SymbolResolver::Private::isAccessibleFrom(AccessStack &accessStack,
+                                              const Definition *scope,
+                                              const Definition *item)
+{
+  //printf("<isAccessibleFrom(scope=%s,item=%s itemScope=%s)\n",
+  //    scope->name().data(),item->name().data(),item->getOuterScope()->name().data());
+
+  if (accessStack.find(scope,m_fileScope,item))
+  {
+    return -1;
+  }
+  accessStack.push(scope,m_fileScope,item);
+
+  int result=0; // assume we found it
+  int i;
+
+  Definition *itemScope=item->getOuterScope();
+  bool memberAccessibleFromScope =
+      (item->definitionType()==Definition::TypeMember &&                   // a member
+       itemScope && itemScope->definitionType()==Definition::TypeClass  && // of a class
+       scope->definitionType()==Definition::TypeClass &&                   // accessible
+       (dynamic_cast<const ClassDef*>(scope))->isAccessibleMember(dynamic_cast<const MemberDef *>(item)) // from scope
+      );
+  bool nestedClassInsideBaseClass =
+      (item->definitionType()==Definition::TypeClass &&                    // a nested class
+       itemScope && itemScope->definitionType()==Definition::TypeClass &&  // inside a base
+       scope->definitionType()==Definition::TypeClass &&                   // class of scope
+       (dynamic_cast<const ClassDef*>(scope))->isBaseClass(dynamic_cast<ClassDef*>(itemScope),TRUE)
+      );
+
+  if (itemScope==scope || memberAccessibleFromScope || nestedClassInsideBaseClass)
+  {
+    //printf("> found it\n");
+    if (nestedClassInsideBaseClass) result++; // penalty for base class to prevent
+                                              // this is preferred over nested class in this class
+                                              // see bug 686956
+  }
+  else if (scope==Doxygen::globalScope)
+  {
+    if (m_fileScope)
+    {
+      SDict<Definition> *cl = m_fileScope->getUsedClasses();
+      if (accessibleViaUsingClass(cl,item))
+      {
+        //printf("> found via used class\n");
+        goto done;
+      }
+      NamespaceSDict *nl = m_fileScope->getUsedNamespaces();
+      StringUnorderedSet visited;
+      if (accessibleViaUsingNamespace(visited,nl,item))
+      {
+        //printf("> found via used namespace\n");
+        goto done;
+      }
+    }
+    //printf("> reached global scope\n");
+    result=-1; // not found in path to globalScope
+  }
+  else // keep searching
+  {
+    // check if scope is a namespace, which is using other classes and namespaces
+    if (scope->definitionType()==Definition::TypeNamespace)
+    {
+      const NamespaceDef *nscope = dynamic_cast<const NamespaceDef*>(scope);
+      //printf("  %s is namespace with %d used classes\n",nscope->name().data(),nscope->getUsedClasses());
+      const SDict<Definition> *cl = nscope->getUsedClasses();
+      if (accessibleViaUsingClass(cl,item))
+      {
+        //printf("> found via used class\n");
+        goto done;
+      }
+      const NamespaceSDict *nl = nscope->getUsedNamespaces();
+      StringUnorderedSet visited;
+      if (accessibleViaUsingNamespace(visited,nl,item))
+      {
+        //printf("> found via used namespace\n");
+        goto done;
+      }
+    }
+    // repeat for the parent scope
+    i=isAccessibleFrom(accessStack,scope->getOuterScope(),item);
+    //printf("> result=%d\n",i);
+    result= (i==-1) ? -1 : i+2;
+  }
+done:
+  accessStack.pop();
+  return result;
+}
+
+QCString SymbolResolver::Private::substTypedef(
+                          const Definition *scope,const QCString &name,
+                          const MemberDef **pTypeDef)
+{
+  QCString result=name;
+  if (name.isEmpty()) return result;
+
+  auto range = Doxygen::symbolMap.find(name);
+  if (range.first==range.second)
+    return result; // no matches
+
+  MemberDef *bestMatch=0;
+  int minDistance=10000; // init at "infinite"
+
+  for (auto it = range.first; it!=range.second; ++it)
+  {
+    Definition *d = it->second;
+    // only look at members
+    if (d->definitionType()==Definition::TypeMember)
+    {
+      // that are also typedefs
+      MemberDef *md = dynamic_cast<MemberDef *>(d);
+      if (md->isTypedef()) // d is a typedef
+      {
+        VisitedNamespaces visitedNamespaces;
+        AccessStack accessStack;
+        // test accessibility of typedef within scope.
+        int distance = isAccessibleFromWithExpScope(visitedNamespaces,accessStack,scope,d,"");
+        if (distance!=-1 && distance<minDistance)
+          // definition is accessible and a better match
+        {
+          minDistance=distance;
+          bestMatch = md;
+        }
+      }
+    }
+  }
+
+  if (bestMatch)
+  {
+    result = bestMatch->typeString();
+    if (pTypeDef) *pTypeDef=bestMatch;
+  }
+
+  //printf("substTypedef(%s,%s)=%s\n",scope?scope->name().data():"<global>",
+  //                                  name.data(),result.data());
+  return result;
+}
+
+//----------------------------------------------------------------------------------------------
+
+
+SymbolResolver::SymbolResolver(const FileDef *fileScope)
+  : p(std::make_unique<Private>(fileScope))
+{
+}
+
+SymbolResolver::~SymbolResolver()
+{
+}
+
+
+const ClassDef *SymbolResolver::resolveClass(const Definition *scope,
+                                             const char *name,
+                                             bool mayBeUnlinkable,
+                                             bool mayBeHidden)
+{
+  p->reset();
+
+  if (scope==0 ||
+      (scope->definitionType()!=Definition::TypeClass &&
+       scope->definitionType()!=Definition::TypeNamespace
+      ) ||
+      (scope->getLanguage()==SrcLangExt_Java && QCString(name).find("::")!=-1)
+     )
+  {
+    scope=Doxygen::globalScope;
+  }
+  //fprintf(stderr,"------------ resolveClass(scope=%s,name=%s,mayUnlinkable=%d)\n",
+  //    scope?scope->name().data():"<global>",
+  //    name,
+  //    mayBeUnlinkable
+  //   );
+  const ClassDef *result;
+  if (Config_getBool(OPTIMIZE_OUTPUT_VHDL))
+  {
+    result = getClass(name);
+  }
+  else
+  {
+    result = p->getResolvedClassRec(scope,name,&p->typeDef,&p->templateSpec,&p->resolvedType);
+    if (result==0) // for nested classes imported via tag files, the scope may not
+                   // present, so we check the class name directly as well.
+                   // See also bug701314
+    {
+      result = getClass(name);
+    }
+  }
+  if (!mayBeUnlinkable && result && !result->isLinkable())
+  {
+    if (!mayBeHidden || !result->isHidden())
+    {
+      //printf("result was %s\n",result?result->name().data():"<none>");
+      result=0; // don't link to artificial/hidden classes unless explicitly allowed
+    }
+  }
+  //fprintf(stderr,"ResolvedClass(%s,%s)=%s\n",scope?scope->name().data():"<global>",
+  //                                  name,result?result->name().data():"<none>");
+  return result;
+}
+
+int SymbolResolver::isAccessibleFrom(const Definition *scope,const Definition *item)
+{
+  p->reset();
+  AccessStack accessStack;
+  return p->isAccessibleFrom(accessStack,scope,item);
+}
+
+int SymbolResolver::isAccessibleFromWithExpScope(const Definition *scope,const Definition *item,
+                                                 const QCString &explicitScopePart)
+{
+  p->reset();
+  VisitedNamespaces visitedNamespaces;
+  AccessStack accessStack;
+  return p->isAccessibleFromWithExpScope(visitedNamespaces,accessStack,scope,item,explicitScopePart);
+}
+
+void SymbolResolver::setFileScope(const FileDef *fileScope)
+{
+  p->setFileScope(fileScope);
+}
+
+const MemberDef *SymbolResolver::getTypedef() const
+{
+  return p->typeDef;
+}
+
+QCString SymbolResolver::getTemplateSpec() const
+{
+  return p->templateSpec;
+}
+
+QCString SymbolResolver::getResolvedType() const
+{
+  return p->resolvedType;
+}
+