Track nested loop levels in CMake language with a stack of counters

It gets incremented while entering a loop block (e.g. foreach or while)
and gets decremented when leaving the block. Because scope borders for
example at function borders must be taken into account the counter is
put into a stack. With every new scope an empty counter is pushed on the
stack, when leaving the scope the original value is restored.

This will allow easy querying if the break command is properly nested
within a loop scope.

Signed-off-by: Gregor Jasny <gjasny@googlemail.com>

Source/cmForEachCommand.cxx

@@ -27,6 +27,8 @@ IsFunctionBlocked(const cmListFileFunction& lff, cmMakefile &mf,
     // if this is the endofreach for this statement
     if (!this->Depth)
       {
+      cmMakefile::LoopBlockPop loopBlockPop(&mf);
+
       // Remove the function blocker for this scope or bail.
       cmsys::auto_ptr<cmFunctionBlocker>
         fb(mf.RemoveFunctionBlocker(this, lff));
@@ -73,6 +75,7 @@ IsFunctionBlocked(const cmListFileFunction& lff, cmMakefile &mf,
             }
           }
         }
+
       // restore the variable to its prior value
       mf.AddDefinition(this->Args[0],oldDef.c_str());
       return true;
@@ -199,6 +202,8 @@ bool cmForEachCommand
     }
   this->Makefile->AddFunctionBlocker(f);
 
+  this->Makefile->PushLoopBlock();
+
   return true;
 }
 
@@ -242,5 +247,8 @@ bool cmForEachCommand::HandleInMode(std::vector<std::string> const& args)
     }
 
   this->Makefile->AddFunctionBlocker(f.release()); // TODO: pass auto_ptr
+
+  this->Makefile->PushLoopBlock();
+
   return true;
 }

Source/cmMakefile.cxx

@@ -171,6 +171,9 @@ void cmMakefile::Initialize()
   // Protect the directory-level policies.
   this->PushPolicyBarrier();
 
+  // push empty loop block
+  this->PushLoopBlockBarrier();
+
   // By default the check is not done.  It is enabled by
   // cmListFileCache in the top level if necessary.
   this->CheckCMP0000 = false;
@@ -3353,6 +3356,38 @@ void cmMakefile::PopFunctionBlockerBarrier(bool reportError)
   this->FunctionBlockerBarriers.pop_back();
 }
 
+//----------------------------------------------------------------------------
+void cmMakefile::PushLoopBlock()
+{
+  assert(!this->LoopBlockCounter.empty());
+  this->LoopBlockCounter.top()++;
+}
+
+void cmMakefile::PopLoopBlock()
+{
+  assert(!this->LoopBlockCounter.empty());
+  assert(this->LoopBlockCounter.top() > 0);
+  this->LoopBlockCounter.top()--;
+}
+
+void cmMakefile::PushLoopBlockBarrier()
+{
+  this->LoopBlockCounter.push(0);
+}
+
+void cmMakefile::PopLoopBlockBarrier()
+{
+  assert(!this->LoopBlockCounter.empty());
+  assert(this->LoopBlockCounter.top() == 0);
+  this->LoopBlockCounter.pop();
+}
+
+bool cmMakefile::IsLoopBlock() const
+{
+  assert(!this->LoopBlockCounter.empty());
+  return !this->LoopBlockCounter.empty() && this->LoopBlockCounter.top() > 0;
+}
+
 //----------------------------------------------------------------------------
 bool cmMakefile::ExpandArguments(
   std::vector<cmListFileArgument> const& inArgs,
@@ -4487,10 +4522,14 @@ void cmMakefile::PushScope()
   this->Internal->VarStack.push(cmDefinitions(parent));
   this->Internal->VarInitStack.push(init);
   this->Internal->VarUsageStack.push(usage);
+
+  this->PushLoopBlockBarrier();
 }
 
 void cmMakefile::PopScope()
 {
+  this->PopLoopBlockBarrier();
+
   cmDefinitions* current = &this->Internal->VarStack.top();
   std::set<std::string> init = this->Internal->VarInitStack.top();
   std::set<std::string> usage = this->Internal->VarUsageStack.top();

Source/cmMakefile.h

@@ -34,6 +34,8 @@
 # include <cmsys/hash_map.hxx>
 #endif
 
+#include <stack>
+
 class cmFunctionBlocker;
 class cmCommand;
 class cmInstallGenerator;
@@ -123,6 +125,15 @@ public:
   };
   friend class LexicalPushPop;
 
+  class LoopBlockPop
+  {
+  public:
+    LoopBlockPop(cmMakefile* mf) { this->Makefile = mf; }
+    ~LoopBlockPop() { this->Makefile->PopLoopBlock(); }
+  private:
+    cmMakefile* Makefile;
+  };
+
   /**
    * Try running cmake and building a file. This is used for dynalically
    * loaded commands, not as part of the usual build process.
@@ -900,6 +911,10 @@ public:
   void PopScope();
   void RaiseScope(const std::string& var, const char *value);
 
+  // push and pop loop scopes
+  void PushLoopBlockBarrier();
+  void PopLoopBlockBarrier();
+
   /** Helper class to push and pop scopes automatically.  */
   class ScopePushPop
   {
@@ -960,6 +975,10 @@ public:
   void ClearMatches();
   void StoreMatches(cmsys::RegularExpression& re);
 
+  void PushLoopBlock();
+  void PopLoopBlock();
+  bool IsLoopBlock() const;
+
 protected:
   // add link libraries and directories to the target
   void AddGlobalLinkInformation(const std::string& name, cmTarget& target);
@@ -1054,6 +1073,8 @@ private:
   void PushFunctionBlockerBarrier();
   void PopFunctionBlockerBarrier(bool reportError = true);
 
+  std::stack<int> LoopBlockCounter;
+
   typedef std::map<std::string, std::string> StringStringMap;
   StringStringMap MacrosMap;
 

Source/cmWhileCommand.cxx

@@ -27,6 +27,8 @@ IsFunctionBlocked(const cmListFileFunction& lff, cmMakefile &mf,
     // if this is the endwhile for this while loop then execute
     if (!this->Depth)
       {
+      cmMakefile::LoopBlockPop loopBlockPop(&mf);
+
       // Remove the function blocker for this scope or bail.
       cmsys::auto_ptr<cmFunctionBlocker>
         fb(mf.RemoveFunctionBlocker(this, lff));
@@ -138,6 +140,8 @@ bool cmWhileCommand
   f->Args = args;
   this->Makefile->AddFunctionBlocker(f);
 
+  this->Makefile->PushLoopBlock();
+
   return true;
 }