From cfc9a050e418a9b77a3bffe932b0344f35cbddc9 Mon Sep 17 00:00:00 2001
From: Richard Thier <magosit@outlook.hu>
Date: Thu, 11 Mar 2021 22:34:44 +0100
Subject: [PATCH] removed manual digit usage by recursive template trickz

---
 magyarsort.h | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/magyarsort.h b/magyarsort.h
index 21a28b5..b8be2a9 100644
--- a/magyarsort.h
+++ b/magyarsort.h
@@ -34,13 +34,27 @@ namespace MagyarSort {
 		return shifted & (DIGIT_RANGE - 1);
 	}
 
+	/** Functor: no class should be generated I think (compiler should be smart) */
+	template<int DIGIT>
+	struct OccurenceMagic : public OccurenceMagic<DIGIT - 1> {
+		inline OccurenceMagic(uint32_t arr[], size_t i, size_t *radicsOut) noexcept
+			: OccurenceMagic<DIGIT -1 >(arr, i, radicsOut) {
+			// parents run first so template recursion runs DIGIT=0 first...
+			++radicsOut[getDigit<DIGIT>(arr[i]) + DIGIT_RANGE * DIGIT];
+		}
+	};
+	/** Ends template recursion */
+	template<>
+	struct OccurenceMagic<-1> {
+		inline OccurenceMagic(uint32_t arr[], size_t i, size_t *radicsOut) noexcept {
+			/* empty */
+		}
+	};
+
 	static inline void calcOccurences(uint32_t arr[], size_t size, size_t *radicsOut) {
 		for(size_t i = 0; i < size; ++i) {
-			// TODO: manual digits!
-			++radicsOut[getDigit<0>(arr[i]) + DIGIT_RANGE * 0];
-			++radicsOut[getDigit<1>(arr[i]) + DIGIT_RANGE * 1];
-			++radicsOut[getDigit<2>(arr[i]) + DIGIT_RANGE * 2];
-			++radicsOut[getDigit<3>(arr[i]) + DIGIT_RANGE * 3];
+			// Creates no object, struct is empty
+			OccurenceMagic<DIGITS - 1>(arr, i, radicsOut);
 		}
 	}