Add support for std::complex<> to C#

Create Lib/csharp/complex.i with simplest possible typemaps mapping
std::complex<> to System.Numerics.Complex.

CHANGES.current

@@ -15,6 +15,9 @@ Version 3.0.13 (in progress)
             [Ruby] Fix #939 - Wrapping std::vector<bool> fix due to incorrect null checks
             on VALUE obj.
 
+2017-03-17: vadz
+            [C#] Add support for std::complex<T>
+
 2017-03-17: wsfulton
             [Go] Fix handling of typedef'd function pointers and typedef'd member function pointers
             such as:

Examples/test-suite/csharp/Makefile.in

@@ -13,6 +13,7 @@ top_srcdir   = ../@top_srcdir@
 top_builddir = ../@top_builddir@
 
 CPP_TEST_CASES = \
+	complextest \
 	csharp_attributes \
 	csharp_swig2_compatibility \
 	csharp_exceptions \
@@ -40,6 +41,7 @@ CSHARPFLAGSSPECIAL =
 
 # Custom tests - tests with additional commandline options
 intermediary_classname.cpptest: SWIGOPT += -dllimport intermediary_classname
+complextest.cpptest: CSHARPFLAGSSPECIAL = -r:System.Numerics.dll
 csharp_lib_arrays.cpptest: CSHARPFLAGSSPECIAL = -unsafe
 csharp_swig2_compatibility.cpptest: SWIGOPT += -DSWIG2_CSHARP
 

Examples/test-suite/csharp/complextest_runme.cs

@@ -0,0 +1,28 @@
+// This is the complex runtime testcase. It checks that the C++ std::complex type works.
+// It requires .NET 4.0 as the previous versions didn't have System.Numerics.Complex type.
+
+using System;
+using System.Numerics;
+
+using complextestNamespace;
+
+public class complextest_runme {
+
+  public static void Main() {
+    var a = new Complex(-1, 2);
+    if ( complextest.Conj(a) != Complex.Conjugate(a) )
+        throw new Exception("std::complex<double> test failed");
+
+    if ( complextest.Conjf(a) != Complex.Conjugate(a) )
+        throw new Exception("std::complex<float> test failed");
+
+    var vec = new VectorStdCplx();
+    vec.Add(new Complex(1, 2));
+    vec.Add(new Complex(2, 3));
+    vec.Add(new Complex(4, 3));
+    vec.Add(new Complex(1, 0));
+
+    if ( complextest.Copy_h(vec).Count != 2 )
+        throw new Exception("vector<complex> test failed");
+  }
+}

Lib/csharp/complex.i

@@ -0,0 +1,44 @@
+#ifndef __cplusplus
+#error C# module only supports complex in C++ mode.
+#endif
+
+%{
+#include <complex>
+%}
+
+namespace std {
+
+// An extremely simplified subset of std::complex<> which contains just the
+// methods we need.
+template<typename T>
+class complex
+{
+public:
+    complex(T re, T im);
+
+    T real() const;
+    T imag() const;
+};
+
+} // namespace std
+
+%define swig_complex_typemaps(T)
+%typemap(cstype) std::complex<T>, const std::complex<T>& "System.Numerics.Complex"
+
+// The casts in "pre" are needed in order to allow creating std::complex<float>
+// from System.Numerics.Complex, which always uses doubles. It relies on the
+// fact that the name of the C++ and C# float/double types are the same.
+%typemap(csin,
+         pre="    var cpp$csinput = new Complex_" #T "((" #T ")$csinput.Real, (" #T ")$csinput.Imaginary);"
+        ) std::complex<T>, const std::complex<T>& "Complex_" #T ".getCPtr(cpp$csinput)"
+
+%typemap(csout, excode=SWIGEXCODE) std::complex<T>, const std::complex<T>& {
+    Complex_##T cppret = new Complex_##T($imcall, $owner);$excode
+    return new System.Numerics.Complex(cppret.real(), cppret.imag());
+  }
+
+%template(Complex_##T) std::complex<T>;
+%enddef
+
+swig_complex_typemaps(double)
+swig_complex_typemaps(float)