From eb733df1bb781449d4ef1f3e81a7c2c1b4977f1a Mon Sep 17 00:00:00 2001
From: Ichthyostega <prg@ichthyostega.de>
Date: Mon, 4 Apr 2011 02:43:01 +0200
Subject: [PATCH] proof-of-concept: implement simple mutation

---
 src/lib/time/mutation.cpp  | 82 ++++++++++++++++++++++++++++++++++++++
 src/lib/time/mutation.hpp  |  6 +++
 src/lib/time/timevalue.hpp |  3 ++
 3 files changed, 91 insertions(+)

diff --git a/src/lib/time/mutation.cpp b/src/lib/time/mutation.cpp
index e2f5b1ae4..070386c62 100644
--- a/src/lib/time/mutation.cpp
+++ b/src/lib/time/mutation.cpp
@@ -21,7 +21,9 @@
 * *****************************************************/
 
 
+#include "lib/error.hpp"
 #include "lib/time/timevalue.hpp"
+#include "lib/time/timequant.hpp"
 #include "lib/time/mutation.hpp"
 //#include "lib/time.h"
 //#include "lib/util.hpp"
@@ -32,15 +34,95 @@
 //using util::unConst;
 //using util::floorwrap;
 
+namespace error = lumiera::error;
 
 namespace lib {
 namespace time {
   
   
+  LUMIERA_ERROR_DEFINE (INVALID_MUTATION, "Changing a time value in this way was not designated");
+  
+  
   Mutation::~Mutation()   { }  // emit VTable here....
   
   
+  /** @internal actually force a change
+   *  into a target time entity to mutate.
+   *  Mutation is declared fried to TimeValue
+   *  and thus is allowed to influence the basic
+   *  value stored in each time entity
+   */
+  void
+  Mutation::imposeChange (TimeValue& target, TimeValue valueToSet)
+  {
+    target = valueToSet; 
+  }
+  
+  
+  
+  
+  /** 
+   * concrete time value mutation:
+   * impose fixed new start time.
+   */
+  class SetNewStartTime
+    : public Mutation
+    {
+      TimeValue newTime_;
+      
+      virtual void
+      change (Duration&)  const
+        {
+          throw error::Logic ("mutating the start point of a pure Duration doesn't make sense"
+                             , LUMIERA_ERROR_INVALID_MUTATION);
+        }
+      
+      
+      virtual void
+      change (TimeSpan& target)  const
+        {
+          imposeChange (target, newTime_);
+        }
+      
+      
+      /** @note the re-quantisation happens automatically
+       *  when the (changed) QuTime is materialised */
+      virtual void
+      change (QuTime& target)    const
+        {
+          imposeChange (target, newTime_);
+        }
+      
+      
+    public:
+      explicit
+      SetNewStartTime (TimeValue t)
+        : newTime_(t)
+        { }
+    };
+  
+  
+  
   /** */
+  void
+  Mutation::changeTime (Time newStartTime)
+  {
+    UNIMPLEMENTED ("perform a trivial mutation to set a new fixed time value");
+  }
+  
+  
+  void
+  Mutation::changeDuration (Duration)
+  {
+    UNIMPLEMENTED ("perform a trivial mutation to set a new Duration");
+  }
+  
+  
+  void
+  Mutation::nudge (int adjustment)
+  {
+    UNIMPLEMENTED ("Nudge by a predefined nudge amount");
+  }
   
   
   
diff --git a/src/lib/time/mutation.hpp b/src/lib/time/mutation.hpp
index b4d6961df..bbb325911 100644
--- a/src/lib/time/mutation.hpp
+++ b/src/lib/time/mutation.hpp
@@ -53,6 +53,7 @@
 #ifndef LIB_TIME_MUTATION_H
 #define LIB_TIME_MUTATION_H
 
+#include "lib/error.hpp"
 #include "lib/time/timevalue.hpp"
 //#include "lib/symbol.hpp"
 
@@ -68,6 +69,8 @@ namespace time {
 //using std::string;
 //using lib::Literal;
   
+  LUMIERA_ERROR_DECLARE (INVALID_MUTATION); ///< Changing a time value in this way was not designated
+  
   class QuTime;
   
   /**
@@ -91,6 +94,9 @@ namespace time {
       static void changeTime (Time);
       static void changeDuration (Duration);
       static void nudge (int adjustment);
+      
+    protected:
+      static void imposeChange (TimeValue&, TimeValue);
     };
   
   
diff --git a/src/lib/time/timevalue.hpp b/src/lib/time/timevalue.hpp
index 7fd185a62..b6fc7d28f 100644
--- a/src/lib/time/timevalue.hpp
+++ b/src/lib/time/timevalue.hpp
@@ -74,6 +74,9 @@ namespace time {
           return *this;
         }
       
+      /** some subclasses may receive modification messages */
+      friend class Mutation;
+      
     public:
       /** explicit limit of allowed time range */
       static gavl_time_t limited (gavl_time_t raw);