[core] cleanup ProgramParameters

src/mbgl/programs/program_parameters.cpp

@@ -0,0 +1,32 @@
+#include <mbgl/programs/program_parameters.hpp>
+
+#include <iomanip>
+#include <sstream>
+
+namespace mbgl {
+
+ProgramParameters::ProgramParameters(const float pixelRatio,
+                                     const bool overdraw,
+                                     std::string cacheDir_)
+    : defines([&] {
+          std::ostringstream ss;
+          ss.imbue(std::locale("C"));
+          ss.setf(std::ios_base::showpoint);
+          ss << "#define DEVICE_PIXEL_RATIO " << pixelRatio << std::endl;
+          if (overdraw) {
+              ss << "#define OVERDRAW_INSPECTOR" << std::endl;
+          }
+          return ss.str();
+      }()),
+      hash(std::hash<std::string>()(defines)),
+      cacheDir(std::move(cacheDir_)) {
+}
+
+std::string ProgramParameters::cachePath(const char* name) const {
+    std::ostringstream ss;
+    ss << cacheDir << "/com.mapbox.gl.shader." << name << "." << std::setfill('0')
+       << std::setw(sizeof(size_t) * 2) << std::hex << hash << ".pbf";
+    return ss.str();
+}
+
+} // namespace mbgl