Adding simdjson example (#516)

* Adding simdjson example

* Update README.md

Co-authored-by: Lars Melchior <TheLartians@users.noreply.github.com>

* cmake format

---------

Co-authored-by: Lars Melchior <TheLartians@users.noreply.github.com>

Author: lemire

examples/simdjson/CMakeLists.txt

@@ -0,0 +1,14 @@
+cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
+
+project(CPMSIMDJSONExample)
+
+# ---- Dependencies ----
+
+include(../../cmake/CPM.cmake)
+CPMAddPackage("gh:simdjson/simdjson@3.5.0")
+
+# ---- Executable ----
+
+add_executable(CPMSIMDJSONExample main.cpp)
+target_compile_features(CPMSIMDJSONExample PRIVATE cxx_std_17)
+target_link_libraries(CPMSIMDJSONExample simdjson::simdjson)

examples/simdjson/main.cpp

@@ -0,0 +1,31 @@
+#include <iostream>
+
+#include "simdjson.h"
+using namespace simdjson;
+
+int main() {
+  ondemand::parser parser;
+  auto cars_json = R"( [
+    { "make": "Toyota", "model": "Camry",  "year": 2018, "tire_pressure": [ 40.1, 39.9, 37.7, 40.4 ] },
+    { "make": "Kia",    "model": "Soul",   "year": 2012, "tire_pressure": [ 30.1, 31.0, 28.6, 28.7 ] },
+    { "make": "Toyota", "model": "Tercel", "year": 1999, "tire_pressure": [ 29.8, 30.0, 30.2, 30.5 ] }
+  ] )"_padded;
+
+  // Iterating through an array of objects
+  for (ondemand::object car : parser.iterate(cars_json)) {
+    // Accessing a field by name
+    std::cout << "Make/Model: " << std::string_view(car["make"]) << "/"
+              << std::string_view(car["model"]) << std::endl;
+
+    // Casting a JSON element to an integer
+    uint64_t year = car["year"];
+    std::cout << "- This car is " << 2020 - year << " years old." << std::endl;
+
+    // Iterating through an array of floats
+    double total_tire_pressure = 0;
+    for (double tire_pressure : car["tire_pressure"]) {
+      total_tire_pressure += tire_pressure;
+    }
+    std::cout << "- Average tire pressure: " << (total_tire_pressure / 4) << std::endl;
+  }
+}