Slightly simplify json_dtype

Reduce redundant code by extracting dtypes into a table.

src/tensors.c

@@ -67,38 +67,31 @@ static char* json_array(char* json, long long* res, int size) {
 }
 
 static int json_dtype(const char* str, enum DType* dtype, int* dsize) {
-	if (strcmp(str, "F32") == 0) {
-		*dtype = dt_f32;
-		*dsize = 4;
-	} else if (strcmp(str, "F16") == 0) {
-		*dtype = dt_f16;
-		*dsize = 2;
-	} else if (strcmp(str, "BF16") == 0) {
-		*dtype = dt_bf16;
-		*dsize = 2;
-	} else if (strcmp(str, "F8_E5M2") == 0) {
-		*dtype = dt_f8e5m2;
-		*dsize = 1;
-	} else if (strcmp(str, "F8_E4M3") == 0) {
-		*dtype = dt_f8e4m3;
-		*dsize = 1;
-	} else if (strcmp(str, "I32") == 0) {
-		*dtype = dt_i32;
-		*dsize = 4;
-	} else if (strcmp(str, "I16") == 0) {
-		*dtype = dt_i16;
-		*dsize = 2;
-	} else if (strcmp(str, "I8") == 0) {
-		*dtype = dt_i8;
-		*dsize = 1;
-	} else if (strcmp(str, "U8") == 0) {
-		*dtype = dt_u8;
-		*dsize = 1;
-	} else {
-		return -1;
+	static const struct {
+		const char* str;
+		enum DType dtype;
+		int dsize;
+	} dtypes[] = {
+	    {"F32", dt_f32, 4},
+	    {"F16", dt_f16, 2},
+	    {"BF16", dt_bf16, 2},
+	    {"F8_E5M2", dt_f8e5m2, 1},
+	    {"F8_E4M3", dt_f8e4m3, 1},
+	    {"I32", dt_i32, 4},
+	    {"I16", dt_i16, 2},
+	    {"I8", dt_i8, 1},
+	    {"U8", dt_u8, 1},
+	};
+
+	for (size_t i = 0; i < sizeof(dtypes) / sizeof(dtypes[0]); ++i) {
+		if (strcmp(str, dtypes[i].str) == 0) {
+			*dtype = dtypes[i].dtype;
+			*dsize = dtypes[i].dsize;
+			return 0;
+		}
 	}
 
-	return 0;
+	return -1;
 }
 
 static bool validate_shape(int dsize, int shape[4], size_t length) {