ENH: add support for a default value, fix case when there is no item except

the own group

Alex

Source/cmCommandArgumentsHelper.cxx

@@ -23,6 +23,7 @@ cmCommandArgument::cmCommandArgument(cmCommandArgumentsHelper* args,
 :Key(key)
 ,Group(group)
 ,WasActive(false)
+,ArgumentsBeforeEmpty(true)
 ,CurrentIndex(0) 
 {
   if (args!=0)
@@ -45,6 +46,7 @@ void cmCommandArgument::Reset()
 
 void cmCommandArgument::Follows(const cmCommandArgument* arg)
 {
+  this->ArgumentsBeforeEmpty = false;
   this->ArgumentsBefore.insert(arg);
 }
 
@@ -52,6 +54,7 @@ void cmCommandArgument::FollowsGroup(const cmCommandArgumentGroup* group)
 {
   if (group!=0)
     {
+    this->ArgumentsBeforeEmpty = false;
     for(std::vector<cmCommandArgument*>::const_iterator 
         argIt= group->ContainedArguments.begin();
         argIt != group->ContainedArguments.end();
@@ -64,7 +67,7 @@ void cmCommandArgument::FollowsGroup(const cmCommandArgumentGroup* group)
 
 bool cmCommandArgument::MayFollow(const cmCommandArgument* current) const
 {
-  if (this->ArgumentsBefore.empty())
+  if (this->ArgumentsBeforeEmpty)
     {
     return true;
     }
@@ -180,7 +183,7 @@ bool cmCAString::DoConsume(const std::string& arg, unsigned int index)
 
 void cmCAString::DoReset()
 {
-  this->String = "";
+  this->String = this->DefaultString;
 }
 
 cmCAEnabler::cmCAEnabler(cmCommandArgumentsHelper* args, 

Source/cmCommandArgumentsHelper.h

@@ -87,6 +87,7 @@ class cmCommandArgument
     std::set<const cmCommandArgument*> ArgumentsBefore;
     cmCommandArgumentGroup* Group;
     bool WasActive;
+    bool ArgumentsBeforeEmpty;
     unsigned int CurrentIndex;
 
     virtual bool DoConsume(const std::string& arg, unsigned int index) = 0;
@@ -128,8 +129,12 @@ class cmCAString : public cmCommandArgument
 
     /// Return the string
     const std::string& GetString() const                 {return this->String;}
+    const char* GetCString() const               {return this->String.c_str();}
+    void SetDefaultString(const char* text)
+                                    {this->DefaultString = (text ? text : "");}
   private:
     std::string String;
+    std::string DefaultString;
     unsigned int DataStart;
     virtual bool DoConsume(const std::string& arg, unsigned int index);
     virtual void DoReset();
@@ -197,7 +202,6 @@ class cmCommandArgumentsHelper
     /// Parse the argument list
     void Parse(const std::vector<std::string>* args, 
                std::vector<std::string>* unconsumedArgs);
-
     /// Add an argument.
     void AddArgument(cmCommandArgument* arg);
   private: