From 2b99d5f24d891b887338af863f78a84a7231a7c1 Mon Sep 17 00:00:00 2001
From: Robin Haberkorn <robin.haberkorn@googlemail.com>
Date: Wed, 7 Nov 2012 20:12:18 +0100
Subject: simplified/cleaned up undo operations on value stack

 * special undo tokens are private to the ValueStack class and automatically parameterized
 * undo_push() and undo_pop() methods hide the internals of pushing the undo tokens
---
 expressions.cpp |  8 +++---
 expressions.h   | 79 ++++++++++++++++++++++++++++++++-------------------------
 2 files changed, 48 insertions(+), 39 deletions(-)

diff --git a/expressions.cpp b/expressions.cpp
index 38af2fc..6999312 100644
--- a/expressions.cpp
+++ b/expressions.cpp
@@ -28,7 +28,7 @@ Expressions::push(gint64 number)
 
 	push(OP_NUMBER);
 
-	undo.push(new UndoTokenPop<gint64>(numbers));
+	numbers.undo_pop();
 	return numbers.push(number);
 }
 
@@ -40,7 +40,7 @@ Expressions::pop_num(int index)
 	pop_op();
 	if (numbers.items() > 0) {
 		n = numbers.pop(index);
-		undo.push(new UndoTokenPush<gint64>(numbers, n, index));
+		numbers.undo_push(n, index);
 	}
 
 	return n;
@@ -67,7 +67,7 @@ Expressions::add_digit(gchar digit)
 Expressions::Operator
 Expressions::push(Expressions::Operator op)
 {
-	undo.push(new UndoTokenPop<Operator>(operators));
+	operators.undo_pop();
 	return operators.push(op);
 }
 
@@ -90,7 +90,7 @@ Expressions::pop_op(int index)
 
 	if (operators.items() > 0) {
 		op = operators.pop(index);
-		undo.push(new UndoTokenPush<Operator>(operators, op, index));
+		operators.undo_push(op, index);
 	}
 
 	return op;
diff --git a/expressions.h b/expressions.h
index 0f4c9eb..1f1637f 100644
--- a/expressions.h
+++ b/expressions.h
@@ -7,6 +7,40 @@
 
 template <typename Type>
 class ValueStack {
+	class UndoTokenPush : public UndoToken {
+		ValueStack<Type> *stack;
+
+		Type	value;
+		int	index;
+
+	public:
+		UndoTokenPush(ValueStack<Type> *_stack,
+			      Type _value, int _index = 1)
+			     : stack(_stack), value(_value), index(_index) {}
+
+		void
+		run(void)
+		{
+			stack->push(value, index);
+		}
+	};
+
+	class UndoTokenPop : public UndoToken {
+		ValueStack<Type> *stack;
+
+		int index;
+
+	public:
+		UndoTokenPop(ValueStack<Type> *_stack, int _index = 1)
+			    : stack(_stack), index(_index) {}
+
+		void
+		run(void)
+		{
+			stack->pop(index);
+		}
+	};
+
 	int size;
 
 	Type *stack;
@@ -38,6 +72,11 @@ public:
 		top++;
 		return peek(index) = value;
 	}
+	inline void
+	undo_push(Type value, int index = 1)
+	{
+		undo.push(new UndoTokenPush(this, value, index));
+	}
 
 	inline Type
 	pop(int index = 1)
@@ -50,6 +89,11 @@ public:
 
 		return v;
 	}
+	inline void
+	undo_pop(int index = 1)
+	{
+		undo.push(new UndoTokenPop(this, index));
+	}
 
 	inline Type &
 	peek(int index = 1)
@@ -58,41 +102,6 @@ public:
 	}
 };
 
-template <typename Type>
-class UndoTokenPush : public UndoToken {
-	ValueStack<Type> *stack;
-
-	Type	value;
-	int	index;
-
-public:
-	UndoTokenPush(ValueStack<Type> &_stack, Type _value, int _index = 1)
-		     : stack(&_stack), value(_value), index(_index) {}
-
-	void
-	run(void)
-	{
-		stack->push(value, index);
-	}
-};
-
-template <typename Type>
-class UndoTokenPop : public UndoToken {
-	ValueStack<Type> *stack;
-
-	int index;
-
-public:
-	UndoTokenPop(ValueStack<Type> &_stack, int _index = 1)
-		    : stack(&_stack), index(_index) {}
-
-	void
-	run(void)
-	{
-		stack->pop(index);
-	}
-};
-
 /*
  * Arithmetic expression stacks
  */
-- 
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