remove use of std::to_string in favor of boost::lexical_cast

std::to_string calls sprintf() internally, which is really slow

include/mbgl/map/tile.hpp

@@ -44,10 +44,6 @@ public:
             return ((std::pow(2, z) * y + x) * 32) + z;
         }
 
-        inline operator std::string() const {
-            return std::to_string(z) + "/" + std::to_string(x) + "/" + std::to_string(y);
-        }
-
         inline bool operator==(const ID& rhs) const {
             return w == rhs.w && z == rhs.z && x == rhs.x && y == rhs.y;
         }
@@ -67,6 +63,7 @@ public:
         ID normalized() const;
         std::forward_list<ID> children(int32_t z) const;
         bool isChildOf(const Tile::ID &id) const;
+        operator std::string() const;
     };
 
     static std::forward_list<Tile::ID> cover(int8_t z, const box& bounds);

include/mbgl/util/string.hpp

@@ -3,9 +3,27 @@
 
 #include <string>
 
+#pragma GCC diagnostic push
+#ifndef __clang__
+#pragma GCC diagnostic ignored "-Wunused-local-typedefs"
+#endif
+#include <boost/lexical_cast.hpp>
+#pragma GCC diagnostic pop
+
 namespace mbgl {
 namespace util {
 
+template <typename... Args>
+inline std::string toString(Args&&... args) {
+    return boost::lexical_cast<std::string>(::std::forward<Args>(args)...);
+}
+
+// boost::lexical_cast() treats this as a character, but we are using it as number types.
+inline std::string toString(int8_t num) {
+    return boost::lexical_cast<std::string>(int(num));
+}
+
+
 template<size_t max, typename... Args>
 inline std::string sprintf(const char *msg, Args... args) {
     char res[max];

platform/default/glfw_view.cpp

@@ -1,8 +1,6 @@
 #include <mbgl/platform/default/glfw_view.hpp>
 #include <mbgl/platform/gl.hpp>
 
-#include <mbgl/util/string.hpp>
-
 GLFWView::GLFWView(bool fullscreen_) : fullscreen(fullscreen_) {
 #ifdef NVIDIA
     glDiscardFramebufferEXT = (PFNGLDISCARDFRAMEBUFFEREXTPROC)glfwGetProcAddress("glDiscardFramebufferEXT");

src/geometry/vao.cpp

@@ -1,5 +1,6 @@
 #include <mbgl/geometry/vao.hpp>
 #include <mbgl/platform/log.hpp>
+#include <mbgl/util/string.hpp>
 
 namespace mbgl {
 
@@ -31,8 +32,8 @@ void VertexArrayObject::verifyBinding(Shader &shader, GLuint vertexBuffer, GLuin
                                       char *offset) {
     if (bound_shader != shader.getID()) {
         throw std::runtime_error(std::string("trying to rebind VAO to another shader from " +
-                                             std::to_string(bound_shader) + "(" + bound_shader_name + ") to " +
-                                             std::to_string(shader.getID()) + "(" + shader.name + ")" ));
+                                             util::toString(bound_shader) + "(" + bound_shader_name + ") to " +
+                                             util::toString(shader.getID()) + "(" + shader.name + ")" ));
     } else if (bound_offset != offset) {
         throw std::runtime_error("trying to bind VAO to another offset");
     } else if (bound_vertex_buffer != vertexBuffer) {

src/map/source.cpp

@@ -88,13 +88,13 @@ size_t Source::getTileCount() const {
 void Source::drawClippingMasks(Painter &painter) {
     for (std::pair<const Tile::ID, std::unique_ptr<Tile>> &pair : tiles) {
         Tile &tile = *pair.second;
-        gl::group group(util::sprintf<32>("mask %d/%d/%d", tile.id.z, tile.id.y, tile.id.z));
+        gl::group group(std::string { "mask: " } + std::string(tile.id));
         painter.drawClippingMask(tile.matrix, tile.clip);
     }
 }
 
 void Source::render(Painter &painter, util::ptr<StyleLayer> layer_desc) {
-    gl::group group(std::string("layer: ") + layer_desc->id);
+    gl::group group(std::string { "layer: " } + layer_desc->id);
     for (const std::pair<const Tile::ID, std::unique_ptr<Tile>> &pair : tiles) {
         Tile &tile = *pair.second;
         if (tile.data && tile.data->state == TileData::State::parsed) {

src/map/tile.cpp

@@ -1,5 +1,7 @@
 #include <mbgl/map/tile.hpp>
 #include <mbgl/util/vec.hpp>
+#include <mbgl/util/string.hpp>
+
 
 #include <cassert>
 
@@ -52,6 +54,11 @@ bool Tile::ID::isChildOf(const Tile::ID &parent_id) const {
 }
 
 
+Tile::ID::operator std::string() const {
+    return util::toString(z) + "/" + util::toString(x) + "/" + util::toString(y);
+}
+
+
 // Taken from polymaps src/Layer.js
 // https://github.com/simplegeo/polymaps/blob/master/src/Layer.js#L333-L383
 

src/map/tile_data.cpp

@@ -11,7 +11,7 @@ using namespace mbgl;
 
 TileData::TileData(Tile::ID const& id_, const SourceInfo& source_)
     : id(id_),
-      name(util::sprintf<32>("%d/%d/%d", id.z, id.x, id.y)),
+      name(id),
       state(State::initial),
       source(source_),
       debugBucket(debugFontBuffer) {
@@ -24,7 +24,7 @@ TileData::~TileData() {
 }
 
 const std::string TileData::toString() const {
-    return util::sprintf<32>("[tile %d/%d/%d]", id.z, id.x, id.y);
+    return std::string { "[tile " } + name + "]";
 }
 
 void TileData::request(uv::worker& worker, FileSource& fileSource,
@@ -34,9 +34,9 @@ void TileData::request(uv::worker& worker, FileSource& fileSource,
 
     std::string url = source.tiles[(id.x + id.y) % source.tiles.size()];
     url = util::replaceTokens(url, [&](const std::string &token) -> std::string {
-        if (token == "z") return std::to_string(id.z);
-        if (token == "x") return std::to_string(id.x);
-        if (token == "y") return std::to_string(id.y);
+        if (token == "z") return util::toString(id.z);
+        if (token == "x") return util::toString(id.x);
+        if (token == "y") return util::toString(id.y);
         if (token == "prefix") {
             std::string prefix { 2 };
             prefix[0] = "0123456789abcdef"[id.x % 16];

src/renderer/painter_debug.cpp

@@ -6,7 +6,7 @@
 using namespace mbgl;
 
 void Painter::renderTileDebug(const Tile& tile) {
-    gl::group group(util::sprintf<32>("debug %d/%d/%d", tile.id.z, tile.id.y, tile.id.z));
+    gl::group group(std::string { "debug " } + std::string(tile.id));
     assert(tile.data);
     if (debug) {
         prepareTile(tile);

src/style/value.cpp

@@ -1,11 +1,5 @@
 #include <mbgl/style/value.hpp>
-
-#pragma GCC diagnostic push
-#ifndef __clang__
-#pragma GCC diagnostic ignored "-Wunused-local-typedefs"
-#endif
-#include <boost/lexical_cast.hpp>
-#pragma GCC diagnostic pop
+#include <mbgl/util/string.hpp>
 
 mbgl::Value mbgl::parseValue(pbf data) {
     while (data.next())
@@ -37,9 +31,9 @@ mbgl::Value mbgl::parseValue(pbf data) {
 std::string mbgl::toString(const mbgl::Value& value) {
     if (value.is<std::string>()) return value.get<std::string>();
     else if (value.is<bool>()) return value.get<bool>() ? "true" : "false";
-    else if (value.is<int64_t>()) return std::to_string(value.get<int64_t>());
-    else if (value.is<uint64_t>()) return std::to_string(value.get<uint64_t>());
-    else if (value.is<double>()) return boost::lexical_cast<std::string>(value.get<double>());
+    else if (value.is<int64_t>()) return util::toString(value.get<int64_t>());
+    else if (value.is<uint64_t>()) return util::toString(value.get<uint64_t>());
+    else if (value.is<double>()) return util::toString(value.get<double>());
     else return "null";
 }
 

src/text/glyph_store.cpp

@@ -143,7 +143,7 @@ GlyphPBF::GlyphPBF(const std::string &glyphURL, const std::string &fontStack, Gl
     // Load the glyph set URL
     std::string url = util::replaceTokens(glyphURL, [&](const std::string &name) -> std::string {
         if (name == "fontstack") return util::percentEncode(fontStack);
-        if (name == "range") return std::to_string(glyphRange.first) + "-" + std::to_string(glyphRange.second);
+        if (name == "range") return util::toString(glyphRange.first) + "-" + util::toString(glyphRange.second);
         return "";
     });
 
@@ -153,7 +153,7 @@ GlyphPBF::GlyphPBF(const std::string &glyphURL, const std::string &fontStack, Gl
         request->onload([&, url](const Response &res) {
             if (res.code != 200) {
                 // Something went wrong with loading the glyph pbf. Pass on the error to the future listeners.
-                const std::string msg = util::sprintf<255>("[ERROR] failed to load glyphs (%d): %s\n", res.code, res.message.c_str());
+                const std::string msg = std::string { "[ERROR] failed to load glyphs (" } + util::toString(res.code) + "): " + res.message;
                 promise.set_exception(std::make_exception_ptr(std::runtime_error(msg)));
             } else {
                 // Transfer the data to the GlyphSet and signal its availability.

src/util/stopwatch.cpp

@@ -1,6 +1,7 @@
 #ifndef DISABLE_STOPWATCH
 #include <mbgl/util/stopwatch.hpp>
 #include <mbgl/util/time.hpp>
+#include <mbgl/util/string.hpp>
 #include <mbgl/platform/log.hpp>
 
 #include <iostream>
@@ -23,7 +24,7 @@ stopwatch::stopwatch(const std::string &name_, EventSeverity severity_, Event ev
 void stopwatch::report(const std::string &name_) {
     timestamp duration = now() - start;
 
-    Log::Record(severity, event, name_ + ": " + std::to_string((double)(duration) / 1_millisecond) + "ms");
+    Log::Record(severity, event, name_ + ": " + util::toString(double(duration) / 1_millisecond) + "ms");
     start += duration;
 }