cmMakefile: store the number of last matches in a CMake var

With PushScope and PopScope, keeping track of another bit of data for
each scope isn't easy. Instead, store it as another CMake variable so it
gets implicitly tracked along with everything else.

This works in a revert of commit
7d674b5f0b28a610333644d417c2e8cb796cc9e4.

8 files changed, 83 insertions, 43 deletions

diff --git a/Help/manual/cmake-variables.7.rst b/Help/manual/cmake-variables.7.rst
index 99088e0..2de4103 100644
--- a/Help/manual/cmake-variables.7.rst
+++ b/Help/manual/cmake-variables.7.rst
@@ -47,6 +47,7 @@ Variables that Provide Information
    /variable/CMAKE_LINK_LIBRARY_SUFFIX
    /variable/CMAKE_MAJOR_VERSION
    /variable/CMAKE_MAKE_PROGRAM
+   /variable/CMAKE_MATCH_COUNT
    /variable/CMAKE_MINIMUM_REQUIRED_VERSION
    /variable/CMAKE_MINOR_VERSION
    /variable/CMAKE_PARENT_LIST_FILE
diff --git a/Help/release/dev/cached-regex-clear-fixed.rst b/Help/release/dev/cached-regex-clear-fixed.rst
new file mode 100644
index 0000000..fbf08cc
--- /dev/null
+++ b/Help/release/dev/cached-regex-clear-fixed.rst
@@ -0,0 +1,5 @@
+cached-regex-clear-fixed
+------------------------
+
+* Add :variable:`CMAKE_MATCH_COUNT` for the number of matches made in the last
+  regular expression.
diff --git a/Help/variable/CMAKE_MATCH_COUNT.rst b/Help/variable/CMAKE_MATCH_COUNT.rst
new file mode 100644
index 0000000..8b1c036
--- /dev/null
+++ b/Help/variable/CMAKE_MATCH_COUNT.rst
@@ -0,0 +1,8 @@
+CMAKE_MATCH_COUNT
+-----------------
+
+The number of matches with the last regular expression.
+
+When a regular expression match is used, CMake fills in ``CMAKE_MATCH_<n>``
+variables with the match contents. The ``CMAKE_MATCH_COUNT`` variable holds
+the number of match expressions when these are filled.
diff --git a/Source/cmConditionEvaluator.cxx b/Source/cmConditionEvaluator.cxx
index 6065b8a..aba26de 100644
--- a/Source/cmConditionEvaluator.cxx
+++ b/Source/cmConditionEvaluator.cxx
@@ -11,7 +11,6 @@
 ============================================================================*/
 
 #include "cmConditionEvaluator.h"
-#include "cmStringCommand.h"
 
 cmConditionEvaluator::cmConditionEvaluator(cmMakefile& makefile):
   Makefile(makefile),
@@ -556,7 +555,7 @@ bool cmConditionEvaluator::HandleLevel2(cmArgumentList &newArgs,
         {
         def = this->GetVariableOrString(*arg);
         const char* rex = argP2->c_str();
-        cmStringCommand::ClearMatches(&this->Makefile);
+        this->Makefile.ClearMatches();
         cmsys::RegularExpression regEntry;
         if ( !regEntry.compile(rex) )
           {
@@ -568,7 +567,7 @@ bool cmConditionEvaluator::HandleLevel2(cmArgumentList &newArgs,
           }
         if (regEntry.find(def))
           {
-          cmStringCommand::StoreMatches(&this->Makefile, regEntry);
+          this->Makefile.StoreMatches(regEntry);
           *arg = cmExpandedCommandArgument("1", true);
           }
         else
diff --git a/Source/cmMakefile.cxx b/Source/cmMakefile.cxx
index 53fd56f..a7acc27 100644
--- a/Source/cmMakefile.cxx
+++ b/Source/cmMakefile.cxx
@@ -4841,6 +4841,64 @@ std::vector<cmSourceFile*> cmMakefile::GetQtUiFilesWithOptions() const
   return this->QtUiFilesWithOptions;
 }
 
+static std::string const matchVariables[] = {
+  "CMAKE_MATCH_0",
+  "CMAKE_MATCH_1",
+  "CMAKE_MATCH_2",
+  "CMAKE_MATCH_3",
+  "CMAKE_MATCH_4",
+  "CMAKE_MATCH_5",
+  "CMAKE_MATCH_6",
+  "CMAKE_MATCH_7",
+  "CMAKE_MATCH_8",
+  "CMAKE_MATCH_9"
+};
+
+static std::string const nMatchesVariable = "CMAKE_MATCH_COUNT";
+
+//----------------------------------------------------------------------------
+void cmMakefile::ClearMatches()
+{
+  const char* nMatchesStr = this->GetDefinition(nMatchesVariable);
+  if (!nMatchesStr)
+    {
+    return;
+    }
+  int nMatches = atoi(nMatchesStr);
+  for (int i=0; i<=nMatches; i++)
+    {
+    std::string const& var = matchVariables[i];
+    std::string const& s = this->GetSafeDefinition(var);
+    if(!s.empty())
+      {
+      this->AddDefinition(var, "");
+      this->MarkVariableAsUsed(var);
+      }
+    }
+  this->AddDefinition(nMatchesVariable, "0");
+  this->MarkVariableAsUsed(nMatchesVariable);
+}
+
+//----------------------------------------------------------------------------
+void cmMakefile::StoreMatches(cmsys::RegularExpression& re)
+{
+  char highest = 0;
+  for (int i=0; i<10; i++)
+    {
+    std::string const& m = re.match(i);
+    if(!m.empty())
+      {
+      std::string const& var = matchVariables[i];
+      this->AddDefinition(var, m.c_str());
+      this->MarkVariableAsUsed(var);
+      highest = static_cast<char>('0' + i);
+      }
+    }
+  char nMatches[] = {highest, '\0'};
+  this->AddDefinition(nMatchesVariable, nMatches);
+  this->MarkVariableAsUsed(nMatchesVariable);
+}
+
 //----------------------------------------------------------------------------
 cmPolicies::PolicyStatus
 cmMakefile::GetPolicyStatus(cmPolicies::PolicyID id) const
diff --git a/Source/cmMakefile.h b/Source/cmMakefile.h
index 05b7a37..fcfec8d 100644
--- a/Source/cmMakefile.h
+++ b/Source/cmMakefile.h
@@ -976,6 +976,9 @@ public:
   void PopLoopBlock();
   bool IsLoopBlock() const;
 
+  void ClearMatches();
+  void StoreMatches(cmsys::RegularExpression& re);
+
 protected:
   // add link libraries and directories to the target
   void AddGlobalLinkInformation(const std::string& name, cmTarget& target);
diff --git a/Source/cmStringCommand.cxx b/Source/cmStringCommand.cxx
index 9827c62..8341027 100644
--- a/Source/cmStringCommand.cxx
+++ b/Source/cmStringCommand.cxx
@@ -310,7 +310,7 @@ bool cmStringCommand::RegexMatch(std::vector<std::string> const& args)
     input += args[i];
     }
 
-  this->ClearMatches(this->Makefile);
+  this->Makefile->ClearMatches();
   // Compile the regular expression.
   cmsys::RegularExpression re;
   if(!re.compile(regex.c_str()))
@@ -325,7 +325,7 @@ bool cmStringCommand::RegexMatch(std::vector<std::string> const& args)
   std::string output;
   if(re.find(input.c_str()))
     {
-    this->StoreMatches(this->Makefile, re);
+    this->Makefile->StoreMatches(re);
     std::string::size_type l = re.start();
     std::string::size_type r = re.end();
     if(r-l == 0)
@@ -359,7 +359,7 @@ bool cmStringCommand::RegexMatchAll(std::vector<std::string> const& args)
     input += args[i];
     }
 
-  this->ClearMatches(this->Makefile);
+  this->Makefile->ClearMatches();
   // Compile the regular expression.
   cmsys::RegularExpression re;
   if(!re.compile(regex.c_str()))
@@ -376,7 +376,7 @@ bool cmStringCommand::RegexMatchAll(std::vector<std::string> const& args)
   const char* p = input.c_str();
   while(re.find(p))
     {
-    this->StoreMatches(this->Makefile, re);
+    this->Makefile->StoreMatches(re);
     std::string::size_type l = re.start();
     std::string::size_type r = re.end();
     if(r-l == 0)
@@ -463,7 +463,7 @@ bool cmStringCommand::RegexReplace(std::vector<std::string> const& args)
     input += args[i];
     }
 
-  this->ClearMatches(this->Makefile);
+  this->Makefile->ClearMatches();
   // Compile the regular expression.
   cmsys::RegularExpression re;
   if(!re.compile(regex.c_str()))
@@ -480,7 +480,7 @@ bool cmStringCommand::RegexReplace(std::vector<std::string> const& args)
   std::string::size_type base = 0;
   while(re.find(input.c_str()+base))
     {
-    this->StoreMatches(this->Makefile, re);
+    this->Makefile->StoreMatches(re);
     std::string::size_type l2 = re.start();
     std::string::size_type r = re.end();
 
@@ -541,38 +541,6 @@ bool cmStringCommand::RegexReplace(std::vector<std::string> const& args)
 }
 
 //----------------------------------------------------------------------------
-void cmStringCommand::ClearMatches(cmMakefile* mf)
-{
-  for (unsigned int i=0; i<10; i++)
-    {
-    char name[128];
-    sprintf(name, "CMAKE_MATCH_%d", i);
-    const char* s = mf->GetDefinition(name);
-    if(s && *s != 0)
-      {
-      mf->AddDefinition(name, "");
-      mf->MarkVariableAsUsed(name);
-      }
-    }
-}
-
-//----------------------------------------------------------------------------
-void cmStringCommand::StoreMatches(cmMakefile* mf,cmsys::RegularExpression& re)
-{
-  for (unsigned int i=0; i<10; i++)
-    {
-    std::string m = re.match(i);
-    if(m.size() > 0)
-      {
-      char name[128];
-      sprintf(name, "CMAKE_MATCH_%d", i);
-      mf->AddDefinition(name, re.match(i).c_str());
-      mf->MarkVariableAsUsed(name);
-      }
-    }
-}
-
-//----------------------------------------------------------------------------
 bool cmStringCommand::HandleFindCommand(std::vector<std::string> const&
                                            args)
 {
diff --git a/Source/cmStringCommand.h b/Source/cmStringCommand.h
index a5fe893..9c75095 100644
--- a/Source/cmStringCommand.h
+++ b/Source/cmStringCommand.h
@@ -53,8 +53,6 @@ public:
   virtual std::string GetName() const { return "string";}
 
   cmTypeMacro(cmStringCommand, cmCommand);
-  static void ClearMatches(cmMakefile* mf);
-  static void StoreMatches(cmMakefile* mf, cmsys::RegularExpression& re);
 protected:
   bool HandleConfigureCommand(std::vector<std::string> const& args);
   bool HandleAsciiCommand(std::vector<std::string> const& args);