make gcd() not recursive

Author: fuzziqersoftware

CMakeLists.txt

@@ -89,7 +89,7 @@ enable_testing()
 add_executable(ToolsTest src/ToolsTest.cc)
 target_link_libraries(ToolsTest phosg)
 
-foreach(TestName IN ITEMS ArgumentsTest EncodingTest FilesystemTest HashTest ImageTest JSONTest KDTreeTest LRUMapTest LRUSetTest ProcessTest StringsTest TimeTest UnitTestTest)
+foreach(TestName IN ITEMS ArgumentsTest EncodingTest FilesystemTest HashTest ImageTest JSONTest KDTreeTest LRUMapTest LRUSetTest MathTest ProcessTest StringsTest TimeTest UnitTestTest)
   add_executable(${TestName} src/${TestName}.cc)
   target_link_libraries(${TestName} phosg)
   add_test(NAME ${TestName} COMMAND ${TestName})

src/Math.hh

@@ -1,13 +1,19 @@
+#include <string>
 #include <utility>
+#include <vector>
+
+#include "Encoding.hh"
 
 namespace phosg {
 
 template <typename IntT>
 constexpr IntT gcd(IntT a, IntT b) {
-  if (b == 0) {
-    return a;
+  while (b != 0) {
+    IntT m = a % b;
+    a = b;
+    b = m;
   }
-  return gcd(b, a % b);
+  return a;
 }
 
 template <typename IntT>

src/MathTest.cc

@@ -0,0 +1,31 @@
+#include <assert.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "Math.hh"
+#include "UnitTest.hh"
+
+using namespace std;
+using namespace phosg;
+
+int main(int, char**) {
+  {
+    fprintf(stderr, "-- gcd\n");
+    expect_eq(30, gcd(30, 30));
+    expect_eq(10, gcd(30, 80));
+    expect_eq(1, gcd(30, 1));
+  }
+
+  {
+    fprintf(stderr, "-- reduce_fraction\n");
+    expect_eq(make_pair(1, 2), reduce_fraction(4, 8));
+    expect_eq(make_pair(1, 1), reduce_fraction(4, 4));
+    expect_eq(make_pair(1, 1), reduce_fraction(1, 1));
+    expect_eq(make_pair(15, 2), reduce_fraction(45, 6));
+  }
+
+  return 0;
+}