update

This is the bare minimum implementation of this idea.

CMakeLists.txt

@@ -3,7 +3,7 @@ cmake_minimum_required(VERSION 3.14)
 project(
     simdjson
     # The version number is modified by tools/release.py
-    VERSION 3.10.0
+    VERSION 3.10.1
     DESCRIPTION "Parsing gigabytes of JSON per second"
     HOMEPAGE_URL "https://simdjson.org/"
     LANGUAGES CXX C
@@ -23,7 +23,11 @@ string(
 set(SIMDJSON_LIB_VERSION "23.0.0" CACHE STRING "simdjson library version")
 set(SIMDJSON_LIB_SOVERSION "23" CACHE STRING "simdjson library soversion")
 
-option(SIMDJSON_BUILD_STATIC_LIB "Build simdjson_static library along with simdjson" OFF)
+option(SIMDJSON_BUILD_STATIC_LIB "Build simdjson_static library along with simdjson (only makes sense if BUILD_SHARED_LIBS=ON)" OFF)
+if(SIMDJSON_BUILD_STATIC_LIB AND NOT BUILD_SHARED_LIBS)
+  message(WARNING "SIMDJSON_BUILD_STATIC_LIB only makes sense if BUILD_SHARED_LIBS is set to ON")
+  message(WARNING "You might be building and installing a two identical static libraries.")
+endif()
 
 option(SIMDJSON_ENABLE_THREADS "Link with thread support" ON)
 
@@ -206,6 +210,7 @@ if(SIMDJSON_BUILD_STATIC_LIB)
       TARGETS simdjson_static
       EXPORT simdjson_staticTargets
       ARCHIVE COMPONENT simdjson_Development
+      INCLUDES DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
   )
   install(
       EXPORT simdjson_staticTargets

Doxyfile

@@ -38,7 +38,7 @@ PROJECT_NAME           = simdjson
 # could be handy for archiving the generated documentation or if some version
 # control system is used.
 
-PROJECT_NUMBER         = "3.10.0"
+PROJECT_NUMBER         = "3.10.1"
 
 # Using the PROJECT_BRIEF tag one can provide an optional one line description
 # for a project that appears at the top of each page and should give viewer a

benchmark/kostya/simdjson_ondemand.h

@@ -24,6 +24,35 @@ struct simdjson_ondemand {
 
 BENCHMARK_TEMPLATE(kostya, simdjson_ondemand)->UseManualTime();
 
+
+#if SIMDJSON_SUPPORTS_EXTRACT
+using namespace simdjson::ondemand;
+
+struct simdjson_ondemand_extract {
+  static constexpr diff_flags DiffFlags = diff_flags::NONE;
+
+  ondemand::parser parser{};
+
+  bool run(simdjson::padded_string &json, std::vector<point> &result) {
+    auto doc = parser.iterate(json);
+    for (ondemand::object object_point : doc.find_field("coordinates")) {
+      point p;
+      auto error = object_point.extract(
+        to{"x", p.x},
+        to{"y", p.y},
+        to{"z", p.z}
+      );
+      if(error) { return false; }
+      result.push_back(p);
+    }
+    return true;
+  }
+};
+
+BENCHMARK_TEMPLATE(kostya, simdjson_ondemand_extract)->UseManualTime();
+
+#endif // SIMDJSON_SUPPORTS_EXTRACT
+
 } // namespace kostya
 
 #endif // SIMDJSON_EXCEPTIONS

benchmark/partial_tweets/simdjson_ondemand.h

@@ -9,7 +9,7 @@ namespace partial_tweets {
 using namespace simdjson;
 
 struct simdjson_ondemand {
-  using StringType=std::string_view;
+  using StringType = std::string_view;
 
   ondemand::parser parser{};
 
@@ -43,6 +43,48 @@ struct simdjson_ondemand {
 
 BENCHMARK_TEMPLATE(partial_tweets, simdjson_ondemand)->UseManualTime();
 
+
+#if SIMDJSON_SUPPORTS_EXTRACT
+
+using namespace simdjson::ondemand;
+
+struct simdjson_ondemand_extract {
+  using StringType = std::string_view;
+  ondemand::parser parser{};
+  bool run(simdjson::padded_string &json, std::vector<tweet<std::string_view>> &result) {
+    // Walk the document, parsing the tweets as we go
+    auto doc = parser.iterate(json);
+    for (ondemand::object tweet_object : doc.find_field("statuses")) {
+      tweet<std::string_view> t;
+      auto error = tweet_object.extract(
+        to{"created_at", t.created_at},
+        to{"id", t.id},
+        to{"text", t.result},
+        to{"in_reply_to_status_id", [&t](auto val) {
+          if(val.is_null()) {
+            t.in_reply_to_status_id = 0;
+          } else {
+            t.in_reply_to_status_id = val;
+          }
+         }},
+        to{"user", sub{
+          to{"id", t.user.id},
+          to{"screen_name", t.user.screen_name},
+        }},
+        to{"retweet_count", t.retweet_count},
+        to{"favorite_count", t.favorite_count});
+        if(error) { return false; }
+        result.push_back(t);
+    }
+    return true;
+  }
+};
+
+BENCHMARK_TEMPLATE(partial_tweets, simdjson_ondemand_extract)->UseManualTime();
+
+
+#endif
+
 } // namespace partial_tweets
 
 #endif // SIMDJSON_EXCEPTIONS

include/simdjson/generic/ondemand/object-inl.h

@@ -15,6 +15,134 @@ namespace simdjson {
 namespace SIMDJSON_IMPLEMENTATION {
 namespace ondemand {
 
+
+#ifdef SIMDJSON_SUPPORTS_EXTRACT
+
+template <endpoint ...Funcs>
+simdjson_inline error_code object::extract(Funcs&&... endpoints)
+#ifndef _MSC_VER // msvc thinks noexcept is not the same in definition
+ noexcept((nothrow_endpoint<Funcs> && ...))
+#endif
+{
+  raw_json_string field_key;
+  error_code error = SUCCESS;
+  for(auto pair : *this) {
+    if (error = pair.key().get(field_key); error) {
+      break;
+    }
+    std::ignore = ((field_key.unsafe_is_equal(endpoints.key()) ? (error = endpoints(pair.value())) == SUCCESS : true) && ...);
+    if (error) {
+      break;
+    }
+  }
+  return error;
+}
+
+template <typename T>
+struct to {
+private:
+  T *pointer;
+  std::string_view m_key;
+
+public:
+  constexpr explicit(false)
+      to(std::string_view const inp_key, T &obj_ref) noexcept
+      : pointer{std::addressof(obj_ref)}, m_key{inp_key} {}
+
+  constexpr to(to const &) = default;
+  constexpr to(to &&) noexcept = default;
+  constexpr to &operator=(to const &) = default;
+  constexpr to &operator=(to &&) noexcept = default;
+  constexpr ~to() = default;
+
+  [[nodiscard]] constexpr std::string_view key() const noexcept {
+    return m_key;
+  }
+
+  [[nodiscard]] constexpr error_code operator()(simdjson_result<value> val) noexcept(
+      std::is_nothrow_assignable_v<T, simdjson_result<value>>) {
+    return val.get<T>(*pointer);
+  }
+};
+
+template <typename Func>
+  requires(std::is_invocable_v<Func, simdjson_result<value>>)
+struct to<Func> {
+private:
+  Func func;
+  std::string_view m_key;
+
+public:
+  constexpr explicit(false)
+      to(std::string_view const inp_key,
+         Func &&inp_func) noexcept(std::is_nothrow_copy_assignable_v<Func>)
+      : func{std::forward<Func>(inp_func)}, m_key{inp_key} {}
+
+  constexpr to(to const &) = default;
+  constexpr to(to &&) noexcept = default;
+  constexpr to& operator=(to const &) = default;
+  constexpr to& operator=(to &&) noexcept = default;
+  constexpr ~to() = default;
+
+  [[nodiscard]] constexpr std::string_view key() const noexcept {
+    return m_key;
+  }
+
+  [[nodiscard]] constexpr error_code operator()(simdjson_result<value> val) noexcept(
+      std::is_nothrow_invocable_v<Func, simdjson_result<value>>) {
+    if constexpr (std::is_invocable_r_v<error_code, Func, simdjson_result<value>>) {
+      return func(val);
+    } else {
+      static_cast<void>(func(val));
+      return SUCCESS;
+    }
+  }
+};
+
+template <typename Func>
+  requires(std::is_invocable_v<Func, simdjson_result<value>>)
+to(std::string_view, Func &&) -> to<Func>;
+
+template <typename T>
+to(std::string_view, T&) -> to<T>;
+
+template <endpoint... Tos>
+struct sub {
+private:
+  using tuple_type = std::tuple<Tos...>;
+  tuple_type tos;
+
+public:
+
+  // double templating to make perfect forwarding work
+  template <typename ...T>
+    requires ((std::same_as<T, Tos> && ...))
+  explicit constexpr sub(T&&...inp_tos) noexcept(std::is_nothrow_constructible_v<tuple_type, T...>)
+      : tos{std::forward<T>(inp_tos)...} {}
+
+  constexpr sub(sub const &) = default;
+  constexpr sub(sub &&) noexcept = default;
+  constexpr sub &operator=(sub const &) = default;
+  constexpr sub &operator=(sub &&) = default;
+  constexpr ~sub() = default;
+
+  [[nodiscard]] constexpr error_code operator()(simdjson_result<value> val) noexcept((nothrow_endpoint<Tos> && ...)) {
+    object obj;
+    if (auto const err = val.get_object().get(obj); err) {
+      return err;
+    }
+    return std::apply([&obj]<typename... T>(T &&...app_tos) {
+      return obj.extract(std::forward<T>(app_tos)...);
+    }, tos);
+  }
+};
+
+template <endpoint... Tos>
+sub(Tos&&...) -> sub<Tos...>;
+
+#endif
+
+
 simdjson_inline simdjson_result<value> object::find_field_unordered(const std::string_view key) & noexcept {
   bool has_value;
   SIMDJSON_TRY( iter.find_field_unordered_raw(key).get(has_value) );

include/simdjson/generic/ondemand/object.h

@@ -11,6 +11,20 @@ namespace simdjson {
 namespace SIMDJSON_IMPLEMENTATION {
 namespace ondemand {
 
+#if defined(__cpp_concepts) && defined(__cpp_consteval)
+#define SIMDJSON_SUPPORTS_EXTRACT 1
+
+template <typename T>
+concept endpoint = std::is_invocable_r_v<error_code, T, simdjson_result<value>> &&
+                   std::is_copy_constructible_v<T> && requires(T to) {
+                     { to.key() } noexcept -> std::convertible_to<std::string_view>;
+                   };
+
+template <typename T>
+concept nothrow_endpoint = endpoint<T> && std::is_nothrow_invocable_r_v<error_code, T, simdjson_result<value>>;
+
+#endif
+
 /**
  * A forward-only JSON object field iterator.
  */
@@ -65,6 +79,21 @@ public:
   /** @overload simdjson_inline simdjson_result<value> find_field(std::string_view key) & noexcept; */
   simdjson_inline simdjson_result<value> find_field(std::string_view key) && noexcept;
 
+#ifdef SIMDJSON_SUPPORTS_EXTRACT
+  /**
+   * Extract all the fields in one go
+   * Funcs are invocables that take a simdjson_result<value> as input.
+   */
+  template <endpoint ...Funcs>
+  simdjson_inline error_code extract(Funcs&&... endpoints)
+#ifndef _MSC_VER // msvc thinks noexcept is not the same in definition
+ noexcept((nothrow_endpoint<Funcs> && ...))
+#endif
+ ;
+#endif
+
+
+
   /**
    * Look up a field by name on an object, without regard to key order.
    *

include/simdjson/padded_string-inl.h

@@ -53,6 +53,9 @@ inline padded_string::padded_string(const char *data, size_t length) noexcept
   if ((data != nullptr) && (data_ptr != nullptr)) {
     std::memcpy(data_ptr, data, length);
   }
+  if (data_ptr == nullptr) {
+    viable_size = 0;
+  }
 }
 #ifdef __cpp_char8_t
 inline padded_string::padded_string(const char8_t *data, size_t length) noexcept
@@ -60,12 +63,17 @@ inline padded_string::padded_string(const char8_t *data, size_t length) noexcept
   if ((data != nullptr) && (data_ptr != nullptr)) {
     std::memcpy(data_ptr, reinterpret_cast<const char *>(data), length);
   }
+  if (data_ptr == nullptr) {
+    viable_size = 0;
+  }
 }
 #endif
 // note: do not pass std::string arguments by value
 inline padded_string::padded_string(const std::string & str_ ) noexcept
     : viable_size(str_.size()), data_ptr(internal::allocate_padded_buffer(str_.size())) {
-  if (data_ptr != nullptr) {
+  if (data_ptr == nullptr) {
+    viable_size = 0;
+  } else {
     std::memcpy(data_ptr, str_.data(), str_.size());
   }
 }

include/simdjson/simdjson_version.h

@@ -4,7 +4,7 @@
 #define SIMDJSON_SIMDJSON_VERSION_H
 
 /** The version of simdjson being used (major.minor.revision) */
-#define SIMDJSON_VERSION "3.10.0"
+#define SIMDJSON_VERSION "3.10.1"
 
 namespace simdjson {
 enum {
@@ -19,7 +19,7 @@ enum {
   /**
    * The revision (major.minor.REVISION) of simdjson being used.
    */
-  SIMDJSON_VERSION_REVISION = 0
+  SIMDJSON_VERSION_REVISION = 1
 };
 } // namespace simdjson
 

singleheader/simdjson.cpp

@@ -1,4 +1,4 @@
-/* auto-generated on 2024-08-01 09:31:50 -0400. Do not edit! */
+/* auto-generated on 2024-08-26 09:37:03 -0400. Do not edit! */
 /* including simdjson.cpp:  */
 /* begin file simdjson.cpp */
 #define SIMDJSON_SRC_SIMDJSON_CPP
@@ -332,6 +332,8 @@ double from_chars(const char *first, const char* end) noexcept;
 #define SIMDJSON_ISALIGNED_N(ptr, n) (((uintptr_t)(ptr) & ((n)-1)) == 0)
 
 #if SIMDJSON_REGULAR_VISUAL_STUDIO
+  // We could use [[deprecated]] but it requires C++14
+  #define simdjson_deprecated __declspec(deprecated)
 
   #define simdjson_really_inline __forceinline
   #define simdjson_never_inline __declspec(noinline)
@@ -370,6 +372,8 @@ double from_chars(const char *first, const char* end) noexcept;
   #define SIMDJSON_POP_DISABLE_UNUSED_WARNINGS
 
 #else // SIMDJSON_REGULAR_VISUAL_STUDIO
+  // We could use [[deprecated]] but it requires C++14
+  #define simdjson_deprecated __attribute__((deprecated))
 
   #define simdjson_really_inline inline __attribute__((always_inline))
   #define simdjson_never_inline inline __attribute__((noinline))

tests/ondemand/CMakeLists.txt

@@ -28,6 +28,7 @@ add_cpp_test(ondemand_to_string              LABELS ondemand acceptance per_impl
 add_cpp_test(ondemand_twitter_tests          LABELS ondemand acceptance per_implementation)
 add_cpp_test(ondemand_wrong_type_error_tests LABELS ondemand acceptance per_implementation)
 add_cpp_test(ondemand_iterate_many_csv       LABELS ondemand acceptance per_implementation)
+add_cpp_test(ondemand_extract_tests          LABELS ondemand acceptance per_implementation)
 if(NOT SIMDJSON_SANITIZE)
   add_cpp_test(ondemand_cacheline              LABELS ondemand acceptance per_implementation)
 endif()

tests/ondemand/ondemand_extract_tests.cpp

@@ -0,0 +1,116 @@
+#include "simdjson.h"
+#include "test_ondemand.h"
+
+using namespace simdjson;
+
+namespace multi_get_tests {
+#ifdef __cpp_concepts
+struct Car {
+  std::string_view make;
+  std::string_view model;
+  std::int64_t year = 0;
+  struct wheel_size_type {
+    std::int64_t front = 0;
+    std::int64_t back = 0;
+  } wheels;
+
+  static simdjson_result<Car> create(auto& value) {
+    using ondemand::to;
+    using ondemand::sub;
+
+    simdjson::ondemand::object obj;
+    auto error = value.get_object().get(obj);
+    if (error) {
+      return error;
+    }
+    Car car{};
+    // Instead of this:
+    //     for (auto field : obj) {
+    //       simdjson::ondemand::raw_json_string key;
+    //       error = field.key().get(key);
+    //       if (error) {
+    //         return error;
+    //       }
+    //       if (key == "make") {
+    //         error = field.value().get_string(car.make);
+    //         if (error) {
+    //           return error;
+    //         }
+    //       } else if (key == "model") {
+    //         error = field.value().get_string(car.model);
+    //         if (error) {
+    //           return error;
+    //         }
+    //       } else if (key == "year") {
+    //         error = field.value().get(car.year);
+    //         if (error) {
+    //           return error;
+    //         }
+    //     }
+    //
+    // we can do this now:
+    error = obj.extract(
+      to{"wheels", sub{
+        to{"front", car.wheels.front},
+        to{"back", car.wheels.back},
+      }},
+      to{"make", car.make},
+      to{"model", car.model},
+      to{"year", [&car](auto val) {
+        car.year = val;
+      }});
+    if (error) {
+      return error;
+    }
+    return car;
+  }
+};
+
+bool car_example() {
+  TEST_START();
+  simdjson::padded_string json =
+      R"( [ { "make": "Toyota", "model": "Camry",  "year": 2018,
+       "tire_pressure": [ 40.1, 39.9 ], "wheels": { "front": 10, "back": 10 } },
+  { "make": "Kia",    "model": "Soul",   "year": 2012,
+       "tire_pressure": [ 30.1, 31.0 ], "wheels": { "front": 10, "back": 10 } },
+  { "make": "Toyota", "model": "Tercel", "year": 1999,
+       "tire_pressure": [ 29.8, 30.0 ], "wheels": { "front": 10, "back": 10 } }
+])"_padded;
+
+  simdjson::ondemand::parser parser;
+  simdjson::ondemand::document doc = parser.iterate(json);
+  for (auto val : doc) {
+    auto car = Car::create(val);
+    ASSERT_EQUAL(car.error(), SUCCESS);
+    Car const c(car.value());
+    if (c.make != "Toyota" && c.make != "Kia") {
+      return false;
+    }
+    if (c.model != "Camry" && c.model != "Soul" && c.model != "Tercel") {
+      return false;
+    }
+    if (c.year != 2018 && c.year != 2012 && c.year != 1999) {
+      return false;
+    }
+    if (c.wheels.front != 10 || c.wheels.back != 10) {
+      return false;
+    }
+  }
+
+  TEST_SUCCEED();
+}
+
+#endif
+bool run() {
+  return
+#ifdef __cpp_concepts
+      car_example() &&
+#endif
+      true;
+}
+
+} // namespace multi_get_tests
+
+int main(int argc, char *argv[]) {
+  return test_main(argc, argv, multi_get_tests::run);
+}