Add handy utilities

source/ddbus/util.d

@@ -0,0 +1,102 @@
+module ddbus.util;
+import std.typecons;
+import std.range;
+
+template allCanDBus(TS...) {
+  static if (TS.length == 0) {
+    enum allCanDBus = true; 
+  } else static if(!canDBus!(TS[0])) {
+    enum allCanDBus = false;
+  } else {
+    enum allCanDBus = allCanDBus!(TS[1..$]);
+  }
+}
+
+template canDBus(T) {
+  static if(is(T == byte) || is(T == short) || is (T == ushort) || is (T == int)
+            || is (T == uint) || is (T == long) || is (T == ulong)
+            || is (T == double) || is (T == string) || is(T == bool)) {
+    enum canDBus = true;
+    
+  } else static if(isTuple!T) {
+    enum canDBus = allCanDBus!(T.Types);
+  } else static if(isInputRange!T) {
+    enum canDBus = canDBus!(ElementType!T);
+  } else {
+    enum canDBus = false;
+  }
+}
+unittest {
+  import dunit.toolkit;
+  (canDBus!int).assertTrue();
+  (canDBus!(int[])).assertTrue();
+  (allCanDBus!(int,string,bool)).assertTrue();
+  (canDBus!(Tuple!(int[],bool))).assertTrue();
+  (canDBus!(Tuple!(int[],int[string]))).assertFalse();
+  (canDBus!(int[string])).assertFalse();
+}
+
+string typeSig(T)() if(canDBus!T) {
+  static if(is(T == byte)) {
+    return "y";
+  } else static if(is(T == bool)) {
+    return "b";
+  } else static if(is(T == short)) {
+    return "n";
+  } else static if(is(T == ushort)) {
+    return "q";
+  } else static if(is(T == int)) {
+    return "i";
+  } else static if(is(T == uint)) {
+    return "u";
+  } else static if(is(T == long)) {
+    return "x";
+  } else static if(is(T == ulong)) {
+    return "t";
+  } else static if(is(T == double)) {
+    return "d";
+  } else static if(is(T == string)) {
+    return "s";
+  } else static if(isTuple!T) {
+    string sig = "(";
+    foreach(i, S; T.Types) {
+      sig ~= typeSig!S();
+    } 
+    sig ~= ")";
+    return sig;
+  } else static if(isInputRange!T) {
+    return "a" ~ typeSig!(ElementType!T)();
+  }
+}
+
+string typeSigAll(TS...)() if(allCanDBus!TS) {
+  string sig = "";
+  foreach(i,T; TS) {
+    sig ~= typeSig!T();
+  }
+  return sig;
+}
+
+unittest {
+  import dunit.toolkit;
+  // basics
+  typeSig!int().assertEqual("i");
+  typeSig!bool().assertEqual("b");
+  typeSig!string().assertEqual("s");
+  // structs
+  typeSig!(Tuple!(int,string,string)).assertEqual("(iss)");
+  typeSig!(Tuple!(int,string,Tuple!(int,"k",double,"x"))).assertEqual("(is(id))");
+  // arrays
+  typeSig!(int[]).assertEqual("ai");
+  typeSig!(Tuple!(byte)[][]).assertEqual("aa(y)");
+  // multiple arguments
+  typeSigAll!(int,bool).assertEqual("ib");
+  // ctfe-capable
+  static string sig = typeSig!ulong();
+  sig.assertEqual("t");
+  static string sig2 = typeSig!(Tuple!(int,string,string));
+  sig2.assertEqual("(iss)"); 
+  static string sig3 = typeSigAll!(int,string,string);
+  sig3.assertEqual("iss"); 
+}
+