auto-generate commonly used functors

Author: kevinushey

.Rbuildignore

@@ -11,3 +11,4 @@
 ^src/.*\.o$
 ^examples/
 ^gallery/
+^gen/

gallery/simd-variance.cpp

@@ -11,7 +11,7 @@ class VarianceTransformer : public SimdTransformer<double>
    packed_type initialize(const value_type* begin, const value_type* end)
    {
       n_ = end - begin;
-      mean_ = boost::simd::accumulate(begin, end, 0.0, plus()) / n_;
+      mean_ = boost::simd::accumulate(begin, end, 0.0, boost::simd::functors::plus()) / n_;
       return packed_type(0);
    }
 
@@ -26,16 +26,6 @@ class VarianceTransformer : public SimdTransformer<double>
    }
 
 private:
-   
-   struct plus
-   {
-      template <typename T>
-      T operator()(const T& lhs, const T& rhs)
-      {
-         return lhs + rhs;
-      }
-   };
-   
    double mean_;
    std::size_t n_;
 };

gen/simd-functors.R

@@ -0,0 +1,62 @@
+path <- "inst/include/RcppParallel/simd/functors.h"
+dir.create(dirname(path), recursive = TRUE, showWarnings = FALSE)
+
+template <- paste(c(
+   "// Auto-generated functors for functions provided by Boost.SIMD.",
+   "// See 'gen/simd-functors.R' for implementation.",
+   "",
+   "namespace boost {",
+   "namespace simd {",
+   "namespace functors {",
+   "",
+   "%s",
+   "",
+   "} // namespace functors",
+   "} // namespace simd",
+   "} // namespace boost"
+), collapse = "\n")
+
+code <- NULL
+
+# NOTE: Each function should accept a parameter called 'data'.
+unary <- list(
+   sum = "boost::simd::sum(data)"
+)
+
+unary_template <- paste(c(
+   "struct %s {",
+   "template <typename T>",
+   "inline T operator()(const T& data) {",
+   "    return %s;",
+   "}",
+   "};",
+   ""
+), collapse = "\n")
+
+for (i in seq_along(unary)) {
+   code <- c(code, sprintf(unary_template, names(unary)[i], unary[[i]]))
+}
+
+binary <- list(
+   plus = "lhs + rhs",
+   minus = "lhs - rhs",
+   times = "lhs * rhs",
+   divide = "lhs / rhs"
+)
+
+binary_template <- paste(c(
+   "struct %s {",
+   "template <typename T>",
+   "inline T operator()(const T& lhs, const T& rhs) {",
+   "    return %s;",
+   "}",
+   "};",
+   ""
+), collapse = "\n")
+
+for (i in seq_along(binary)) {
+   code <- c(code, sprintf(binary_template, names(binary)[[i]], binary[[i]]))
+}
+
+compiled <- sprintf(template, paste(code, collapse = "\n"))
+cat(compiled, file = path, sep = "\n")

inst/include/RcppParallel/SIMD.h

@@ -29,10 +29,8 @@
 
 #include <boost/simd/swar/swar.hpp>
 
-
-
-
-
+// Auto-generated functors for use in 'transform()', 'accumulate()'
+#include <RcppParallel/simd/functors.h>
 
 namespace RcppParallel {
 

inst/include/RcppParallel/simd/functors.h

@@ -0,0 +1,46 @@
+// Auto-generated functors for functions provided by Boost.SIMD.
+// See 'gen/simd-functors.R' for implementation.
+
+namespace boost {
+namespace simd {
+namespace functors {
+
+struct sum {
+template <typename T>
+inline T operator()(const T& data) {
+    return boost::simd::sum(data);
+}
+};
+
+struct plus {
+template <typename T>
+inline T operator()(const T& lhs, const T& rhs) {
+    return lhs + rhs;
+}
+};
+
+struct minus {
+template <typename T>
+inline T operator()(const T& lhs, const T& rhs) {
+    return lhs - rhs;
+}
+};
+
+struct times {
+template <typename T>
+inline T operator()(const T& lhs, const T& rhs) {
+    return lhs * rhs;
+}
+};
+
+struct divide {
+template <typename T>
+inline T operator()(const T& lhs, const T& rhs) {
+    return lhs / rhs;
+}
+};
+
+
+} // namespace functors
+} // namespace simd
+} // namespace boost