added MapToFirst implementation

Author: tiberius

cpp4j/cpp4j.pro

@@ -16,5 +16,6 @@ HEADERS += \
     rationalnumberarray.h \
     pair.h \
     less.h \
-    greater.h
+    greater.h \
+    maptofirst.h
 

cpp4j/maptofirst.h

@@ -0,0 +1,20 @@
+#ifndef MAPTOFIRST_H
+#define MAPTOFIRST_H
+
+#include "pair.h"
+
+//        int       string    less
+template <class T1, class T2, template<typename> class Order > class MapToFirst {
+
+public:
+
+                             //int,string
+    bool operator ()(const Pair<T1,T2> &left, const Pair<T1,T2> &right){
+        Order<T1> functor; // less<int>
+        return functor(left.first(),right.first());
+    }
+
+
+};
+
+#endif // MAPTOFIRST_H

cpp4j/testTemplates.cpp

@@ -16,6 +16,7 @@ using namespace std;
 #include "pair.h"
 #include "less.h"
 #include "greater.h"
+#include "maptofirst.h"
 //#include "order.h"
 //#include "tree.h"
 //#include "map.h"
@@ -88,14 +89,13 @@ int testTemplates(void)
 
     Greater<string> greaterString;
     cout << "Hallo > Welt == " << greaterString("Hallo","Welt") << endl;
+    assert(!greaterString("Hallo","Welt"));
 
     /////////////////////////////////////////
     // TEST PAIR ORDER
     MapToFirst< int, float, Less > lessPair;
     cout << i_f << " < " << i_f2 << " == " << lessPair(i_f, i_f2) << endl;
-
-#if 0 // move this line down while your implementation proceeds...
-
+    assert(lessPair(i_f, i_f2));
 
     /////////////////////////////////////////
     // TEST TREE
@@ -105,6 +105,8 @@ int testTemplates(void)
     cout << "empty tree: ";
     assert(printAndCount(t) == 0);
 
+#if 0 // move this line down while your implementation proceeds...
+
     // insert elements in a certain order
     t.insert(4);
     t.insert(3);