looks like cpp_ext_0.c is complete, will make soem tweeks

diff --git a/developer/example/cpp_ext_0.c b/developer/example/cpp_ext_0.c
index 0ab2614..f9fe34c 100644 (file)
--- a/developer/example/cpp_ext_0.c
+++ b/developer/example/cpp_ext_0.c
@@ -35,7 +35,7 @@ DEBUG
 
 #include <stdio.h>
 #define DEBUG_CPP
-#define STR(x) #x
+#define STR(...) #__VA_ARGS__
 
 // print the macro and the evaluation of the macro
 #define SHOW(expr) printf("%s -> %s\n", #expr, STR(expr))
@@ -48,7 +48,10 @@ Constants
 #define SEMICOLON ;
 
 #define ZERO 0
-#define ONE 1
+#define ONE  1
+
+#define FALSE 0
+#define TRUE  1
 
 //---------
 
@@ -84,7 +87,7 @@ Primitive Concatenation
 
 
 /*===========================================================================
-Logic
+Existence
 ===========================================================================*/
 
   //----------------------------------------
@@ -160,10 +163,6 @@ Logic Connectors
   #define NOT_EQ(x_item ,y_item) \
     NOT_MATCH_RWR( CAT4(_RWR_EQ__ ,x_item ,__oo__ ,y_item) )
 
-#if 0
-
-
-
 /*===========================================================================
   IF-ELSE construct.
   Usage: IF_ELSE(condition)(<true case>)(<false case>)
@@ -173,47 +172,44 @@ Logic Connectors
 
   The seemingly extra layer prevents BOOL_(condition) from being pasted with a ## which, if done, would prevent it from being evaluated.  Recall, the first step in evaluation is a literal copy in of the arguments.  ===symbol ========================================================================*/
 
-  #define _IF_ELSE(condition)  CAT2(_IF_ ,BOOL(condition))
+  #define IF_ELSE(condition)  CAT2(_IF_ ,BOOL(condition))
   #define _IF_1(...)          __VA_ARGS__ _IF_1_ELSE
   #define _IF_0(...)                      _IF_0_ELSE
   #define _IF_1_ELSE(...)
   #define _IF_0_ELSE(...)      __VA_ARGS__
 
-
 /*===========================================================================
 Access
-    see below the recursion section for Nth .. when it is written ;-)
+    see ext_1 with recursion for `Nth`
 
 ===========================================================================*/
 
   // _FIRST defined in the logic section
   #define FIRST(pad ,...)\
-    If_ELSE \
+    IF_ELSE \
       ( NOT_EXISTS(__VA_ARGS__) ) \
       (pad)                       \
       ( _FIRST(__VA_ARGS__) )  
 
   #define _REST(a ,...) __VA_ARGS__
   #define REST(...)\
-    If_ELSE \
+    IF_ELSE \
       ( NOT_EXISTS(__VA_ARGS__) ) \
       ()                          \
       ( _REST(__VA_ARGS__) )  
 
   // _SECOND defined in the logic section
   #define SECOND(pad ,...) \
-    If_ELSE \
+    IF_ELSE \
       ( NOT_EXISTS(__VA_ARGS__) ) \
       (pad)                       \
       ( _SECOND(__VA_ARGS__ ,pad) )  
 
   #define _THIRD(a ,b ,c ,...) c
   #define THIRD(pad ,...) \
-    If_ELSE \
+    IF_ELSE \
       ( NOT_EXISTS(__VA_ARGS__) ) \
       (pad)                       \
       ( _THIRD(__VA_ARGS__ ,pad, pad) )  
 
-#endif 
-
 #endif

diff --git a/developer/example/try_4_if.c b/developer/example/try_4_if.c
index 6df17ea..cdb60e6 100644 (file)
--- a/developer/example/try_4_if.c
+++ b/developer/example/try_4_if.c
@@ -7,8 +7,8 @@ int main(void){
   //---------------------------------------------------------------------------
 
   SHOW(IF_ELSE(1)(yes)(no)); 
-#if 0
   SHOW(IF_ELSE(0)(yes)(no));        // → no
+  printf("\n");
 
   //---------------------------------------------------------------------------
   // Symbolic identifiers
@@ -16,6 +16,7 @@ int main(void){
   SHOW(IF_ELSE(TRUE)(ok)(fail));    // → ok
   SHOW(IF_ELSE(FALSE)(ok)(fail));   // → fail
   SHOW(IF_ELSE(foo)(alpha)(omega)); // → omega (foo is undefined)
+  printf("\n");
 
   //---------------------------------------------------------------------------
   // Logic expressions
@@ -23,23 +24,27 @@ int main(void){
   SHOW(IF_ELSE(AND(1 ,1))(pass)(fail));  // → pass
   SHOW(IF_ELSE(OR(0 ,0))(yes)(no));      // → no
   SHOW(IF_ELSE(NOT(0))(on)(off));        // → on
+  printf("\n");
 
   //---------------------------------------------------------------------------
   // Code-like output
   //---------------------------------------------------------------------------
   SHOW(IF_ELSE(1)(int x = 1;)(int x = 2;));  // → int x = 1;
   SHOW(IF_ELSE(0)(int x = 1;)(int x = 2;));  // → int x = 2;
+  printf("\n");
 
   //---------------------------------------------------------------------------
   // Comma usage in true/false branches
   //---------------------------------------------------------------------------
   SHOW(IF_ELSE(1)(a ,b ,c)(x ,y ,z));  // → a ,b ,c
   SHOW(IF_ELSE(0)(a ,b ,c)(x ,y ,z));  // → x ,y ,z
+  printf("\n");
 
   //---------------------------------------------------------------------------
   // Empty condition
   //---------------------------------------------------------------------------
   SHOW(IF_ELSE()(true)(false));       // → false (BOOL() = 0)
+  printf("\n");
 
   //---------------------------------------------------------------------------
   // Nested IF_ELSE
@@ -51,7 +56,7 @@ int main(void){
       outer_false
     )
   ); // → inner_false
+  printf("\n");
 
-#endif
   return 0;
 }

diff --git a/developer/example/try_5_access.c b/developer/example/try_5_access.c
new file mode 100644 (file)
index 0000000..e9db0ae
--- /dev/null
+++ b/developer/example/try_5_access.c
@@ -0,0 +1,46 @@
+#include "cpp_ext_0.c"
+
+int main(void){
+
+  //---------------------------------------------------------------------------
+  // FIRST
+  //---------------------------------------------------------------------------
+
+  SHOW(FIRST(foo));                 // → foo         (only pad, no args)
+  SHOW(FIRST(foo ,a));             // → a
+  SHOW(FIRST(foo ,a ,b ,c));       // → a
+  printf("\n");
+
+  //---------------------------------------------------------------------------
+  // REST
+  //---------------------------------------------------------------------------
+
+  SHOW(REST());                    // → (empty)
+  SHOW(REST(a));                  // → (empty)
+  SHOW(REST(a ,b));               // → b
+  SHOW(REST(a ,b ,c ,d));         // → b ,c ,d
+  printf("\n");
+
+  //---------------------------------------------------------------------------
+  // SECOND
+  //---------------------------------------------------------------------------
+
+  SHOW(SECOND(X));                // → X         (only pad)
+  SHOW(SECOND(X ,a));             // → X         (only one arg, fallback to pad)
+  SHOW(SECOND(X ,a ,b));          // → b
+  SHOW(SECOND(X ,a ,b ,c));       // → b
+  printf("\n");
+
+  //---------------------------------------------------------------------------
+  // THIRD
+  //---------------------------------------------------------------------------
+
+  SHOW(THIRD(X));                 // → X         (pad returned)
+  SHOW(THIRD(X ,a));              // → X
+  SHOW(THIRD(X ,a ,b));           // → X
+  SHOW(THIRD(X ,a ,b ,c));        // → c
+  SHOW(THIRD(X ,a ,b ,c ,d));     // → c
+  printf("\n");
+
+  return 0;
+}