Implemented the path::shortest() function which selects the shorter of two given Paths.

Author: Mandrenkov

src/h/path.h

@@ -30,6 +30,19 @@ namespace ctgl {
 
         template <typename T>
         constexpr auto dropPrefix(T, Path<>) noexcept;
+
+        // Chooses the "shorter" of the given Paths using the following tabular expression:
+        // +--------------------------------------------------+     +----+
+        // | p1 == DNE                                        | --> | p2 |
+        // +-----------+--------------------------------------+     +----+
+        // | p1 != DNE | p2 == DNE                            | --> | p1 |
+        // |           +-----------+--------------------------+     +----+
+        // |           | p2 != DNE | length(p1) <  length(p2) | --> | p1 |
+        // |           |           +--------------------------+     +----+
+        // |           |           | length(p1) >= length(p2) | --> | p2 |
+        // +-----------------------+--------------------------+     +----+
+        template <typename... Ts, typename... Us>
+        constexpr auto shortest(Path<Ts...> p1, Path<Us...> p2) noexcept;
     }
 
     // Definitions
@@ -70,6 +83,19 @@ namespace ctgl {
         constexpr auto dropPrefix(T, Path<>) noexcept {
             return Path<>{};
         }
+
+        template <typename... Ts, typename... Us>
+        constexpr auto shortest(Path<Ts...> p1, Path<Us...> p2) noexcept {
+            if constexpr (p1 == DNE) {
+                return p2;
+            } else if constexpr (p2 == DNE) {
+                return p1;
+            } else if constexpr (length(p1) < length(p2)) {
+                return p1;
+            } else {
+                return p2;
+            }
+        }
     }
 
     // Convenient Type Definitions

src/test/path_test.cpp

@@ -6,6 +6,7 @@
 using namespace ctgl;
 using namespace forge;
 
+
 // Unit tests for the ctgl::path::length() function.
 TEST(PathTest, Length) {
     // Empty
@@ -52,4 +53,19 @@ TEST(PathTest, DropPrefix) {
     EXPECT_EQ(path::dropPrefix(N2{}, Path<E12, E23>{}), Path<E23>{});
     EXPECT_EQ(path::dropPrefix(N3{}, Path<E34, E41>{}), (Path<E34, E41>{}));
     EXPECT_EQ(path::dropPrefix(N4{}, Path<E34, E41, E23>{}), (Path<E41, E23>{}));
+}
+
+// Unit tests for the ctgl::path::shortest() function.
+TEST(PathTest, Shortest) {
+    // DNE
+    EXPECT_EQ(path::shortest(path::DNE, path::DNE), path::DNE);
+    EXPECT_EQ(path::shortest(Path<E11>{}, path::DNE), Path<E11>{});
+    EXPECT_EQ(path::shortest(path::DNE, Path<E11>{}), Path<E11>{});
+
+    // Exists
+    EXPECT_EQ(path::shortest(Path<E12>{}, Path<E12>{}), Path<E12>{});
+    EXPECT_EQ(path::shortest(Path<E12>{}, Path<E13>{}), Path<E12>{});
+    EXPECT_EQ(path::shortest(Path<E13>{}, Path<E12>{}), Path<E12>{});
+    EXPECT_EQ(path::shortest(Path<E11, E11>{}, Path<E14>{}), (Path<E11, E11>{}));
+    EXPECT_EQ(path::shortest(Path<E14>{}, Path<E11, E11>{}), (Path<E11, E11>{}));
 }