[core] refactor util::toString to use RapidJSON's stringification

include/mbgl/util/string.hpp

@@ -1,27 +1,14 @@
 #pragma once
 
 #include <string>
-#include <cassert>
 #include <cstdlib>
-#include <exception>
+#include <type_traits>
 
 // Polyfill needed by Qt when building for Android with GCC
 #if defined(__ANDROID__) && defined(__GLIBCXX__)
 
-// TODO: remove use std::to_string to avoid using <sstream>
-#include <sstream>
-
 namespace std {
 
-template <typename T>
-std::string to_string(T value)
-{
-    std::ostringstream oss;
-    oss << value;
-
-    return oss.str();
-}
-
 inline int stoi(const std::string &str)
 {
     return atoi(str.c_str());
@@ -38,44 +25,70 @@ inline float stof(const std::string &str) {
 namespace mbgl {
 namespace util {
 
-template <class T>
-inline std::string toString(T t) {
-    return std::to_string(t);
+std::string toString(int64_t);
+std::string toString(uint64_t);
+std::string toString(int32_t);
+std::string toString(uint32_t);
+std::string toString(double, bool decimal = false);
+
+inline std::string toString(int16_t t) {
+    return toString(static_cast<int32_t>(t));
 }
 
-inline std::string toString(int8_t num) {
-    return std::to_string(int(num));
+inline std::string toString(uint16_t t) {
+    return toString(static_cast<uint32_t>(t));
 }
 
-inline std::string toString(uint8_t num) {
-    return std::to_string(unsigned(num));
+inline std::string toString(int8_t t) {
+    return toString(static_cast<int32_t>(t));
 }
 
-std::string toString(float, bool decimal = false);
-std::string toString(double, bool decimal = false);
-std::string toString(long double, bool decimal = false);
+inline std::string toString(uint8_t t) {
+    return toString(static_cast<uint32_t>(t));
+}
 
-std::string toHex(size_t);
+template <typename = std::enable_if<!std::is_same<uint64_t, unsigned long>::value>>
+inline std::string toString(unsigned long t) {
+    return toString(static_cast<uint64_t>(t));
+}
 
-inline std::string toString(std::exception_ptr error) {
-    assert(error);
+template <typename = std::enable_if<!std::is_same<uint64_t, unsigned long long>::value>>
+inline std::string toString(unsigned long long t) {
+    return toString(static_cast<uint64_t>(t));
+}
 
-    if (!error) {
-        return "(null)";
-    }
+inline std::string toString(float t, bool decimal = false) {
+    return toString(static_cast<double>(t), decimal);
+}
 
-    try {
-        std::rethrow_exception(error);
-    } catch (const std::exception& ex) {
-        return ex.what();
-    } catch (...) {
-        return "Unknown exception type";
-    }
+inline std::string toString(long double t, bool decimal = false) {
+    return toString(static_cast<double>(t), decimal);
 }
 
+std::string toString(std::exception_ptr);
+
+template <class T>
+std::string toString(T) = delete;
+
+std::string toHex(size_t);
+
 inline float stof(const std::string& str) {
     return std::stof(str);
 }
 
 } // namespace util
 } // namespace mbgl
+
+// Android's libstdc++ doesn't have std::to_string()
+#if defined(__ANDROID__) && defined(__GLIBCXX__)
+
+namespace std {
+
+template <typename T>
+inline std::string to_string(T value) {
+    return mbgl::util::toString(value);
+}
+
+} // namespace std
+
+#endif

platform/android/src/geojson/feature.cpp

@@ -33,7 +33,7 @@ class FeatureIdVisitor {
 public:
     template<class T>
     std::string operator()(const T& i) const {
-        return std::to_string(i);
+        return util::toString(i);
     }
 
     std::string operator()(const std::string& i) const {

platform/android/src/http_file_source.cpp

@@ -151,9 +151,9 @@ void HTTPRequest::onResponse(jni::JNIEnv& env, int code,
         }
         response.error = std::make_unique<Error>(Error::Reason::RateLimit, "HTTP status code 429", http::parseRetryHeaders(retryAfter, xRateLimitReset));
     } else if (code >= 500 && code < 600) {
-        response.error = std::make_unique<Error>(Error::Reason::Server, std::string{ "HTTP status code " } + std::to_string(code));
+        response.error = std::make_unique<Error>(Error::Reason::Server, std::string{ "HTTP status code " } + util::toString(code));
     } else {
-        response.error = std::make_unique<Error>(Error::Reason::Other, std::string{ "HTTP status code " } + std::to_string(code));
+        response.error = std::make_unique<Error>(Error::Reason::Other, std::string{ "HTTP status code " } + util::toString(code));
     }
 
     async.send();

src/mbgl/util/string.cpp

@@ -1,19 +1,67 @@
 #include <mbgl/util/string.hpp>
-#include <mbgl/util/dtoa.hpp>
+
+#include <rapidjson/writer.h>
+#include <rapidjson/stringbuffer.h>
+
+#include <cassert>
 
 namespace mbgl {
 namespace util {
 
-std::string toString(float num, bool decimal) {
-    return dtoa(num, decimal);
+std::string toString(int32_t t) {
+    rapidjson::StringBuffer s;
+    rapidjson::Writer<rapidjson::StringBuffer> writer(s);
+    writer.Int(t);
+    return s.GetString();
+}
+
+std::string toString(uint32_t t) {
+    rapidjson::StringBuffer s;
+    rapidjson::Writer<rapidjson::StringBuffer> writer(s);
+    writer.Uint(t);
+    return s.GetString();
 }
 
-std::string toString(double num, bool decimal) {
-    return dtoa(num, decimal);
+std::string toString(int64_t t) {
+    rapidjson::StringBuffer s;
+    rapidjson::Writer<rapidjson::StringBuffer> writer(s);
+    writer.Int64(t);
+    return s.GetString();
 }
 
-std::string toString(long double num, bool decimal) {
-    return dtoa(num, decimal);
+std::string toString(uint64_t t) {
+    rapidjson::StringBuffer s;
+    rapidjson::Writer<rapidjson::StringBuffer> writer(s);
+    writer.Uint64(t);
+    return s.GetString();
+}
+
+std::string toString(double t, bool decimal) {
+    rapidjson::StringBuffer s;
+    rapidjson::Writer<rapidjson::StringBuffer> writer(s);
+    writer.Double(t);
+    std::string data = s.GetString();
+    if (!decimal && data.length() >= 3 && data[data.length() - 1] == '0' && data[data.length() - 2] == '.') {
+        // Remove trailing ".0" for integers
+        data.resize(data.length() - 2);
+    }
+    return data;
+}
+
+std::string toString(std::exception_ptr error) {
+    assert(error);
+
+    if (!error) {
+        return "(null)";
+    }
+
+    try {
+        std::rethrow_exception(error);
+    } catch (const std::exception& ex) {
+        return ex.what();
+    } catch (...) {
+        return "Unknown exception type";
+    }
 }
 
 namespace {