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cpponsea2024
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@kris-jusiak
kris-jusiak committed Jul 2, 2024
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72 changes: 41 additions & 31 deletions cpponsea2024/index.html
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Original file line number Diff line number Diff line change
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```
<!-- .element: class="fragment" data-fragment-index="0" -->

```cpp
// ...
```
<!-- .element: class="fragment" data-fragment-index="0" -->

```cpp
// #member-queries
consteval auto enumerators_of(info) -> vector<info>;
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```
<!-- .element: class="fragment" data-fragment-index="3" -->


```cpp
}
```
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---

```cpp
using info = decltype(^::); // type-erased AST info
using info = /*type-erased AST node*/;
```
<!-- .element: class="fragment" data-fragment-index="4" -->

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typeid(^T) == typeid(meta::info)
);
```
<!-- .element: class="fragment" data-fragment-index="4" -->
<!-- .element: class="fragment" data-fragment-index="2" -->

```cpp
static_assert(
typeid(typename[:^int:]) == typeid(int)
);
```
<!-- .element: class="fragment" data-fragment-index="5" -->
<!-- .element: class="fragment" data-fragment-index="3" -->


----
Expand All @@ -206,7 +212,7 @@
<!-- .element: class="fragment" data-fragment-index="0" -->

```cpp
typename [: // splicer (reify)
typename [: // type splicer
```
<!-- .element: class="fragment" data-fragment-index="2" -->

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```cpp
template<class...> struct type_list{ };
```
<!-- .element: class="fragment" data-fragment-index="3" -->
<!-- .element: class="fragment" data-fragment-index="0" -->

```cpp
template<class... Ts>
using reverse_drop_t = typename [:
```
<!-- .element: class="fragment" data-fragment-index="0" -->
<!-- .element: class="fragment" data-fragment-index="1" -->

```cpp
meta::substitute(^type_list,
```
<!-- .element: class="fragment" data-fragment-index="3" -->
<!-- .element: class="fragment" data-fragment-index="4" -->

```cpp
array{^Ts...} // array{meta::info}
```
<!-- .element: class="fragment" data-fragment-index="1" -->
<!-- .element: class="fragment" data-fragment-index="2" -->

```cpp
| views::reverse
| views::drop(1)
| ranges::to<std::vector>()
```
<!-- .element: class="fragment" data-fragment-index="2" -->
<!-- .element: class="fragment" data-fragment-index="3" -->

```cpp
)
```
<!-- .element: class="fragment" data-fragment-index="3" -->
<!-- .element: class="fragment" data-fragment-index="4" -->

```cpp
:];
```
<!-- .element: class="fragment" data-fragment-index="0" -->
<!-- .element: class="fragment" data-fragment-index="1" -->

---

```cpp
static_assert(typeid(reverse_drop_t<int, float, short>) ==
typeid(type_list<float, int>));
```
<!-- .element: class="fragment" data-fragment-index="0" -->
<!-- .element: class="fragment" data-fragment-index="1" -->

----

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```
<!-- .element: class="fragment" data-fragment-index="0" -->

<pre><code class="fragment" data-trim data-noescape data-fragment-index="1" data-line-numbers="2,3,6,10,11,13">
<pre><code class="fragment" data-trim data-noescape data-fragment-index="1" data-line-numbers="2,3,6,7,10,11,13">
[1] [2] [3] [4] [5] [6] Instructions:
1 1 0.33 lea eax, [rdi - 200]
1 1 0.25 cmp eax, 5
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---

```cpp
// Syntax likely to change!
consteval void gen_cases(auto& builder, auto cases) {
for (auto e : constants(cases)) {
append_case(builder, make_decl_ref_expr(e)); // case N:
Expand Down Expand Up @@ -930,18 +938,18 @@
#### Perfect hashing

<table><tr><td>
<a href="https://link.springer.com/chapter/10.1007/978-3-642-04128-0_61"><img src="images/hdc.png" style="width: 100%; background:none; border:none; box-shadow:none;" /></a>
<a class="fragment" href="https://link.springer.com/chapter/10.1007/978-3-642-04128-0_61"><img src="images/hdc.png" style="width: 100%; background:none; border:none; box-shadow:none;" /></a>
</td>
<td>
<a href="https://arxiv.org/pdf/2104.10402"><img src="images/pthash.png" style="width: 100%; background:none; border:none; box-shadow:none;" /></a>
<a class="fragment" href="https://arxiv.org/pdf/2104.10402"><img src="images/pthash.png" style="width: 100%; background:none; border:none; box-shadow:none;" /></a>
</td>
<td>
<a href="https://github.com/serge-sans-paille/frozen"><img src="images/phash.png" style="width: 100%; background:none; border:none; box-shadow:none;" /></a>
<a class="fragment" href="https://github.com/serge-sans-paille/frozen"><img src="images/phash.png" style="width: 100%; background:none; border:none; box-shadow:none;" /></a>
</td>
</tr></table>

##### 'cmph/pthash' can handle large sizes (> 1'000'000)
<!-- .element: class="fragment" data-fragment-index="0" -->
##### Focused on sizes > 1'000'000
<!-- .element: class="fragment" -->

-----

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static constexpr auto lookup = [] {
array<pair<E, string_view>, (1u << popcount(mask))> lookup{};
for (const auto& [enumeration, name] : enumerators<E>) {
lookup[pext(id, mask<E>)] = {enumeration, name};
lookup[pext(to_underlying(enumeration), mask<E>)] =
{enumeration, name};
}
return lookup;
}();
```
<!-- .element: class="fragment" data-fragment-index="1" -->
```cpp
auto&& [rhs, result] = lookup[pext(value, mask<E>)];
auto&& [rhs, result] = lookup[pext(to_underlying(value), mask<E>)];
return value == rhs ? result : {};
```
<!-- .element: class="fragment" data-fragment-index="2" -->
Expand Down Expand Up @@ -1131,7 +1140,7 @@
```cpp
[[assume(contains<enumerators<E>>(value)]];
return lookup[pext(value, mask<E>)];
return lookup[pext(to_underlying(value), mask<E>)];
```
<!-- .element: class="fragment" data-fragment-index="2" -->
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---
```cpp
lookup: // minimal
lookup: /*minimal*/
.quad "red"
.quad "green"
.quad "blue"
Expand Down Expand Up @@ -1212,7 +1221,7 @@
write = (1 << 1), // 0b010
execute = (1 << 2), // 0b100
// ----------------------------//
// mask : 0b111 // size: 2**(popcount(mask))
// mask = 0b111 // size: 2**(popcount(mask))
// ----------------------------//
};
```
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[1] [2] [3] [4] [5] [6] Instructions:
2 2 0.50 tzcnt eax, edi
1 1 0.33 lea rcx, [rip + lookup]
1 5 0.33 * mov rax, qword ptr [rcx + 8*rax]
1 5 0.33 * mov rax, qword ptr [rcx + 8 * rax]
1 5 0.50 U ret
</code></pre>
---
```cpp
lookup: // minimal
lookup: /*minimal*/
.quad "red"
.quad "green"
.quad "blue"
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```
<!-- .element: class="fragment" data-fragment-index="0" -->

##### hash can be a cast (explored later)
<!-- .element: class="fragment" data-fragment-index="2" -->
##### hash/bitcast
<!-- .element: class="fragment" data-fragment-index="1" -->

----

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```
<!-- .element: class="fragment" data-fragment-index="0" -->

##### (constexpr frozen::unordered_map) https://github.com/serge-sans-paille/frozen
##### constexpr frozen::unordered_map - https://github.com/serge-sans-paille/frozen
<!-- .element: class="fragment" data-fragment-index="3" -->

----
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```
<!-- .element: class="fragment" data-fragment-index="0" -->

<pre><code class="fragment" data-trim data-noescape data-fragment-index="1" data-line-numbers="8">
<pre><code class="fragment" data-trim data-noescape data-fragment-index="1" data-line-numbers="9">
static constexpr auto lookup = [] {
array&lt;pair&lt;T, E&gt;, (1u &lt;&lt; popcount(mask))&gt; lookup{};
for (const auto& [enumeration, name] : enumerators&lt;E&gt;) {
lookup[pext(id, mask&lt;E&gt;)] = {to&lt;T&gt;(name), enumeration};
lookup[pext(to_underlying(enumeration), mask&lt;E&gt;)] =
{to&lt;T&gt;(name), enumeration};
}
return lookup;
}();
auto&& value = to&lt;T&gt;(str);
auto&& [rhs, result] = lookup[pext(value, mask&lt;E&gt;)];
auto&& [rhs, result] = lookup[pext(to_underlying(value), mask&lt;E&gt;)];
return value == rhs ? result : {};
</code></pre>

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