define stream insertion for blade, multivector

Change-Id: Icfa9a1df6ac0864932e07902891bf3568941afea
oliverlee · Jan 12, 2024 · d51c769 · d51c769
1 parent 68c1042
commit d51c769
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diff --git a/geometry/src/algebra.hpp b/geometry/src/algebra.hpp
@@ -12,6 +12,7 @@
 #include "geometry/src/detail/type_unique.hpp"
 
 #include <cstddef>
+#include <ostream>
 #include <tuple>
 #include <type_traits>
 #include <utility>
@@ -280,6 +281,27 @@ struct algebra
     {
       return x.coefficient * y.coefficient * e<Is..., Js...>;
     }
+
+    /// stream insertion
+    ///
+    friend auto operator<<(std::ostream& os, blade x) -> std::enable_if_t<
+        (N < 10),
+        decltype(os << std::declval<const scalar_type&>(), os)>
+    {
+      if (sizeof...(Is) == 0) {
+        os << x.coefficient;
+        return os;
+      }
+
+      if (x.coefficient != scalar_type{1}) {
+        os << x.coefficient << "*";
+      }
+
+      os << "e";
+      std::ignore = ((os << Is, true) and ...);
+
+      return os;
+    }
   };
 
   template <class... Bs>
@@ -511,6 +533,22 @@ struct algebra
       return ((x * get<B2s>(y)) + ...);
     }
     /// @}
+
+    /// stream insertion
+    ///
+    friend auto operator<<(std::ostream& os, const multivector& x)
+        -> decltype(((os << std::declval<const Bs&>(), true) and ...), os)
+    {
+      auto first = true;
+
+      std::ignore =
+          ((os << (std::exchange(first, false) ? "" : " + "),
+            os << get<Bs>(x),
+            true) and
+           ...);
+
+      return os;
+    }
   };
 };
 

diff --git a/test/algebra_blade_test.cpp b/test/algebra_blade_test.cpp
@@ -2,6 +2,7 @@
 #include "skytest/skytest.hpp"
 
 #include <cstddef>
+#include <sstream>
 #include <tuple>
 #include <type_traits>
 
@@ -113,4 +114,21 @@ auto main() -> int
   "geometric product"_ctest = [] {
     return expect(eq(6, (2 * e<1>)*(3 * e<1>)));
   };
+
+  "printable"_test = [] {
+    static const auto to_string = [](auto blade) {
+      return (std::stringstream{} << blade).str();
+    };
+
+    return expect(
+        eq("0*e0", to_string(0 * e<0>)) and          //
+        eq("e1", to_string(1 * e<1>)) and            //
+        eq("2*e2", to_string(2 * e<2>)) and          //
+        eq("3*e01", to_string(3 * e<0, 1>)) and      //
+        eq("4*e12", to_string(4 * e<1, 2>)) and      //
+        eq("5*e02", to_string(5 * e<0, 2>)) and      //
+        eq("6*e012", to_string(6 * e<0, 1, 2>)) and  //
+        eq("7", to_string(7 * e<>)) and              //
+        eq("1", to_string(e<>)));
+  };
 }
diff --git a/test/algebra_multivector_test.cpp b/test/algebra_multivector_test.cpp
@@ -1,6 +1,8 @@
 #include "geometry/geometry.hpp"
 #include "skytest/skytest.hpp"
 
+#include <cstddef>
+#include <sstream>
 #include <tuple>
 
 template <std::size_t... Is>
@@ -133,4 +135,16 @@ auto main() -> int
 
         return expect(eq(z, x * y) and eq(-z, y * x));
       };
+
+  "printable"_test = [] {
+    static const auto to_string = [](const auto& mvec) {
+      return (std::stringstream{} << mvec).str();
+    };
+
+    return expect(
+        eq("1", to_string(multivector(e<>))) and
+        eq("2*e0 + 3*e1 + 4*e2", to_string(2 * e<0> + 3 * e<1> + 4 * e<2>))
+
+    );
+  };
 }