From 55fb5c9c008216ba7ce18b4e43252ac1d1cedabe Mon Sep 17 00:00:00 2001
From: Chris Robinson <chris.kcat@gmail.com>
Date: Tue, 23 May 2023 05:49:09 -0700
Subject: Use a variant to call the proper filter handler function

---
 al/filter.h | 44 +++++++++++++++++++++++---------------------
 1 file changed, 23 insertions(+), 21 deletions(-)

(limited to 'al/filter.h')

diff --git a/al/filter.h b/al/filter.h
index 65a9e30f..2ed483cc 100644
--- a/al/filter.h
+++ b/al/filter.h
@@ -1,6 +1,7 @@
 #ifndef AL_FILTER_H
 #define AL_FILTER_H
 
+#include <variant>
 
 #include "AL/al.h"
 #include "AL/alc.h"
@@ -12,6 +13,25 @@
 #define HIGHPASSFREQREF  250.0f
 
 
+template<typename T>
+struct FilterTable {
+    static void setParami(struct ALfilter*, ALenum, int);
+    static void setParamiv(struct ALfilter*, ALenum, const int*);
+    static void setParamf(struct ALfilter*, ALenum, float);
+    static void setParamfv(struct ALfilter*, ALenum, const float*);
+
+    static void getParami(const struct ALfilter*, ALenum, int*);
+    static void getParamiv(const struct ALfilter*, ALenum, int*);
+    static void getParamf(const struct ALfilter*, ALenum, float*);
+    static void getParamfv(const struct ALfilter*, ALenum, float*);
+};
+
+struct NullFilterTable : public FilterTable<NullFilterTable> { };
+struct LowpassFilterTable : public FilterTable<LowpassFilterTable> { };
+struct HighpassFilterTable : public FilterTable<HighpassFilterTable> { };
+struct BandpassFilterTable : public FilterTable<BandpassFilterTable> { };
+
+
 struct ALfilter {
     ALenum type{AL_FILTER_NULL};
 
@@ -21,31 +41,13 @@ struct ALfilter {
     float GainLF{1.0f};
     float LFReference{HIGHPASSFREQREF};
 
-    struct Vtable {
-        void (*const setParami )(ALfilter *filter, ALenum param, int val);
-        void (*const setParamiv)(ALfilter *filter, ALenum param, const int *vals);
-        void (*const setParamf )(ALfilter *filter, ALenum param, float val);
-        void (*const setParamfv)(ALfilter *filter, ALenum param, const float *vals);
-
-        void (*const getParami )(const ALfilter *filter, ALenum param, int *val);
-        void (*const getParamiv)(const ALfilter *filter, ALenum param, int *vals);
-        void (*const getParamf )(const ALfilter *filter, ALenum param, float *val);
-        void (*const getParamfv)(const ALfilter *filter, ALenum param, float *vals);
-    };
-    const Vtable *vtab{nullptr};
+    using TableTypes = std::variant<NullFilterTable,LowpassFilterTable,HighpassFilterTable,
+        BandpassFilterTable>;
+    TableTypes mTypeVariant;
 
     /* Self ID */
     ALuint id{0};
 
-    void setParami(ALenum param, int value) { vtab->setParami(this, param, value); }
-    void setParamiv(ALenum param, const int *values) { vtab->setParamiv(this, param, values); }
-    void setParamf(ALenum param, float value) { vtab->setParamf(this, param, value); }
-    void setParamfv(ALenum param, const float *values) { vtab->setParamfv(this, param, values); }
-    void getParami(ALenum param, int *value) const { vtab->getParami(this, param, value); }
-    void getParamiv(ALenum param, int *values) const { vtab->getParamiv(this, param, values); }
-    void getParamf(ALenum param, float *value) const { vtab->getParamf(this, param, value); }
-    void getParamfv(ALenum param, float *values) const { vtab->getParamfv(this, param, values); }
-
     DISABLE_ALLOC()
 };
 
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