cmGeneratorExpression: Re-write for multi-stage evaluation

The expressions may be parsed and then cached and evaluated multiple
times.  They are evaluated lazily so that literals such as ',' can be
treated as universal parameter separators, and can be processed from
results without appearing literally, and without interfering with the
parsing/evaluation of the entire expression.

1 files changed, 14 insertions, 7 deletions

diff --git a/Source/cmGeneratorExpression.h b/Source/cmGeneratorExpression.h
index a023eb0c9a..00e6907ef8 100644
--- a/Source/cmGeneratorExpression.h
+++ b/Source/cmGeneratorExpression.h
@@ -19,6 +19,8 @@ class cmTarget;
 class cmMakefile;
 class cmListFileBacktrace;
 
+struct cmGeneratorExpressionEvaluator;
+
 /** \class cmGeneratorExpression
  * \brief Evaluate generate-time query expression syntax.
  *
@@ -36,24 +38,29 @@ public:
                         cmListFileBacktrace const& backtrace,
                         bool quiet = false);
 
+  ~cmGeneratorExpression();
+
   /** Evaluate generator expressions in a string.  */
   const char* Process(std::string const& input);
   const char* Process(const char* input);
 
+  void Parse(const char* input);
+  const char* Evaluate(cmMakefile* mf, const char* config,
+                        bool quiet = false);
+
   /** Get set of targets found during evaluations.  */
   std::set<cmTarget*> const& GetTargets() const
     { return this->Targets; }
 private:
+  std::vector<cmGeneratorExpressionEvaluator*> Evaluators;
   cmMakefile* Makefile;
   const char* Config;
   cmListFileBacktrace const& Backtrace;
   bool Quiet;
-  std::vector<char> Data;
-  std::stack<size_t> Barriers;
-  cmsys::RegularExpression TargetInfo;
-  cmsys::RegularExpression TestConfig;
+
   std::set<cmTarget*> Targets;
-  bool Evaluate();
-  bool Evaluate(const char* expr, std::string& result);
-  bool EvaluateTargetInfo(std::string& result);
+  const char* Input;
+  bool NeedsParsing;
+
+  std::string Output;
 };