tweaking

Author: lemire

cppcon2025/cppcon_2025_slides.md

@@ -21,6 +21,9 @@ CppCon 2025
 
 ---
 
+![bg right 95%](images/alice.png)
+
+
 # JSON
 
 * Portable, simple
@@ -33,16 +36,6 @@ CppCon 2025
   * arrays (list)
 
 
----
-
-```json
-{
-    "username": "Alice",
-    "level": 42,
-    "health": 99.5,
-    "inventory": ["sword", "shield", "potion"]
-}
-```
 
 ---
 
@@ -60,8 +53,15 @@ Parsed 0.63 GB in 6.961 seconds (90.72 MB/s)
 
 ---
 
+<style scoped>
+img[alt~="center"] {
+  display: block;
+  margin: 0 auto;
+}
+</style>
+
+![w:700 center](images/gwen.jpeg)
 
-<img src="images/gwen.jpeg" width="55%" />
 
 Source: Gwen (Chen) Shapira
 
@@ -78,7 +78,7 @@ Source: Gwen (Chen) Shapira
 * simdjson was the first library to break the gigabyte per second barrier
     * Parsing Gigabytes of JSON per Second, VLDB Journal 28 (6), 2019
     * On-Demand JSON: A Better Way to Parse Documents? SPE 54 (6), 2024
-* JSON for Modern C++ (nlohmann/json) can be $100\times$ slower!
+* JSON for Modern C++ (nlohmann/json) can be $10\times$ slower!
 
 <img src="images/simdjson.png" width="10%" />
 
@@ -96,12 +96,23 @@ Source: Gwen (Chen) Shapira
 
 # Not All Processors are Equal
 
+<style>
+.center-table {
+  display: flex;
+  justify-content: center;
+}
+</style>
+
+<div class="center-table">
+
 | processor       | year    | arithmetic logic units    | SIMD units     |
 |-----------------|---------|---------------------------|----------------|
 | Apple M*        |  2019   |    6+                     | $4 \times 128$ |
 | Intel Lion Cove |  2024   |    6                      | $4 \times 256$ |
 | AMD Zen 5       |  2024   |    6                      | $4 \times 512$ |
 
+</div>
+
 ---
 
 ![bg right](images/avx.jpeg)
@@ -123,15 +134,15 @@ Source: Gwen (Chen) Shapira
 
 
 * First scan identifies the structural characters, start of all strings at about 10 GB/s using SIMD instructions.
-* Validates Unicode (UTF-8) at 30 GB/s.
+* Validates Unicode at 30 GB/s.
 * Rest of parsing relies on the generated index.
 * Allows fast skipping. (Only parse what we need)
 * Can minify JSON at 10 to 20 GB/s
 
 ---
 
 
-<img src="images/simdjson_benchmark.png" width="80%"/>
+<img src="images/simdjson_benchmark.png" width="85%"/>
 
 https://openbenchmarking.org/test/pts/simdjson
 
@@ -140,7 +151,7 @@ https://openbenchmarking.org/test/pts/simdjson
 
 # Usage
 
-You are probably using simdjson:
+**You are probably using simdjson:**
 
 - Node.js, Electron,...
 - ClickHouse
@@ -277,7 +288,10 @@ section {
 # C#
 
 ```C#
+
 string jsonString = JsonSerializer.Serialize(player, options);
+
+
 Player deserializedPlayer = JsonSerializer.Deserialize<Player>(jsonInput, options);
 ```
 
@@ -507,6 +521,20 @@ void serialize(string_builder& b, const std::set<T>& v) { /* ... */ }
 
 Concepts let us say: **"If it walks like a duck and quacks like a duck..."**
 
+```cpp
+template <typename T>
+concept container_but_not_string =
+    requires(T a) {
+      { a.size() } -> std::convertible_to<std::size_t>;
+      {
+        a[std::declval<std::size_t>()]
+      }; // check if elements are accessible for the subscript operator
+    };
+```
+
+---
+
+
 ```cpp
 template <typename T>
 concept container_but_not_string =
@@ -522,19 +550,50 @@ concept container_but_not_string =
 ---
 
 ```cpp
-template<typename T>
-  requires(has_size_and_subscript<T>)  // "If it has .size() and operator[]"
-void serialize(string_builder& b, const T& container) {
-    b.append('[');
-    for (size_t i = 0; i < container.size(); ++i) {
-        serialize(b, container[i]);
-    }
-    b.append(']');
+template <class T>
+  requires(container_but_not_string<T>)
+constexpr void atom(string_builder &b, const T &t) {
+  if (t.size() == 0) {
+    b.append_raw("[]");
+    return;
+  }
+  b.append('[');
+  atom(b, t[0]);
+  for (size_t i = 1; i < t.size(); ++i) {
+    b.append(',');
+    atom(b, t[i]);
+  }
+  b.append(']');
 }
 ```
 
 ✅ Works with `vector`, `array`, `deque`, custom containers...
 
+
+---
+
+```cpp
+template <typename T>
+concept appendable_containers =
+    (details::supports_emplace_back<T> || details::supports_emplace<T> ||
+    details::supports_push_back<T> || details::supports_push<T> ||
+    details::supports_add<T> || details::supports_append<T> ||
+    details::supports_insert<T>);
+```
+
+---
+
+```cpp
+template <appendable_containers T, typename... Args>
+constexpr decltype(auto) emplace_one(T &vec, Args &&...args) {
+  if constexpr (details::supports_emplace_back<T>) {
+    return vec.emplace_back(std::forward<Args>(args)...);
+  } else if constexpr (details::supports_emplace<T>) {
+    return vec.emplace(std::forward<Args>(args)...);
+  } else if // ...
+}
+```
+
 ---
 
 # Concepts + Reflection = Automatic Support
@@ -566,8 +625,9 @@ The magic:
 
 <img src="images/perf_with_simdjson.png" width="80%"/>
 
-**3.4 GB/s** - 14x faster than nlohmann, 2.5x faster than Serde!
+---
 
+**3.4 GB/s** - 14x faster than nlohmann, 2.5x faster than Serde!
 
 ---
 

cppcon2025/data/parsingtwitterapplem3max.txt

@@ -0,0 +1,35 @@
+=== SimdJSON Reflection (simdjson_to) ===
+# Reading file /Users/random_person/Desktop/simdjson/buildreflect/jsonexamples/twitter.json
+# output volume: 93311 bytes
+bench_simdjson_to                                            :  3598.34 MB/s   0.93 Ms/s
+
+=== SimdJSON Static Reflection ===
+# Reading file /Users/random_person/Desktop/simdjson/buildreflect/jsonexamples/twitter.json
+# output volume: 93311 bytes
+bench_simdjson_static_reflection                             :  4257.15 MB/s   1.09 Ms/s
+
+=== nlohmann::json ===
+# Reading file /Users/random_person/Desktop/simdjson/buildreflect/jsonexamples/twitter.json
+# output volume: 93311 bytes
+bench_nlohmann                                               :  174.58 MB/s   0.00 Ms/s
+
+=== RapidJSON ===
+# Reading file /Users/random_person/Desktop/simdjson/buildreflect/jsonexamples/twitter.json
+# output volume: 93311 bytes
+bench_rapidjson                                              :  529.25 MB/s   0.01 Ms/s
+
+=== YYJson ===
+# Reading file /Users/random_person/Desktop/simdjson/buildreflect/jsonexamples/twitter.json
+# output volume: 93311 bytes
+bench_yyjson                                                 :  1909.87 MB/s   0.02 Ms/s
+
+=== Rust/Serde ===
+# Reading file /Users/random_person/Desktop/simdjson/buildreflect/jsonexamples/twitter.json
+# Note: Rust/Serde may include additional fields not in C++ structure.
+# output volume: 93311 bytes
+bench_rust                                                   :  417.89 MB/s   0.00 Ms/s
+
+=== Reflect-cpp ===
+# Reading file /Users/random_person/Desktop/simdjson/buildreflect/jsonexamples/twitter.json
+# output volume: 93311 bytes
+bench_reflect_cpp                                            :  1517.55 MB/s   0.02 Ms/s

cppcon2025/images/alice.html

@@ -0,0 +1,63 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <title>Formatted JSON Code</title>
+    <style>
+        body {
+            font-family: 'Courier New', Courier, monospace;
+            background-color: #1e1e1e;
+            color: #d4d4d4;
+            display: flex;
+            justify-content: center;
+            align-items: center;
+            min-height: 100vh;
+            margin: 0;
+            padding: 20px;
+        }
+        .code-container {
+            background-color: #252526;
+            border-radius: 8px;
+            padding: 20px;
+            box-shadow: 0 4px 8px rgba(0, 0, 0, 0.3);
+            max-width: 600px;
+            width: 100%;
+        }
+        pre {
+            margin: 0;
+            white-space: pre-wrap;
+            word-wrap: break-word;
+        }
+        code {
+            font-size: 16px;
+            line-height: 1.5;
+        }
+        .key {
+            color: #92b8d7;
+        }
+        .string {
+            color: #f5f1f0;
+        }
+        .number {
+            color: #b5cea8;
+        }
+        .array {
+            color: #d7ba7d;
+        }
+        .punctuation {
+            color: #d4d4d4;
+        }
+    </style>
+</head>
+<body>
+    <div class="code-container">
+        <pre><code><span class="punctuation">{</span>
+    <span class="key">"username"</span><span class="punctuation">: </span><span class="string">"Alice"</span><span class="punctuation">,</span>
+    <span class="key">"level"</span><span class="punctuation">: </span><span class="number">42</span><span class="punctuation">,</span>
+    <span class="key">"health"</span><span class="punctuation">: </span><span class="number">99.5</span><span class="punctuation">,</span>
+    <span class="key">"inventory"</span><span class="punctuation">: </span><span class="array">[<span class="string">"sword"</span><span class="punctuation">, </span><span class="string">"shield"</span><span class="punctuation">, </span><span class="string">"potion"</span>]</span>
+<span class="punctuation">}</span></code></pre>
+    </div>
+</body>
+</html>

cppcon2025/images/alice.png

@@ -70,7 +70,7 @@
 plt.close()
 
 
-# Chart 2b: Parsing only (même style)
+# Chart 2b: Parsing only (same style)
 plt.figure(figsize=(10, 6))
 bars = plt.bar(libraries_with, [172, 658, 1720, 2230, 4090], color=colors_with, edgecolor='black')
 ax = plt.gca()