@require: class-slydifi/theme/akasaka
@require: code-printer/code-design
@require: code-printer/code-printer
@require: code-printer/code-syntax
@require: code-printer/code-theme
@require: figbox/figbox

let-block +code-block source keywords =
  let syntax =
    let void-syntax-rule = CodePrinter.syntax-rule-fun (fun _ -> None) in
      CodePrinter.make-syntax (|
        line-comment = void-syntax-rule;
        block-comment = void-syntax-rule;
        string = void-syntax-rule;
        keywords = keywords;
        identifier = void-syntax-rule;
        others = [];
      |)
  in
    '<
      +code-printer?:(
        CodePrinter.make-config syntax CodeTheme.iceberg-light
        |> CodePrinter.set-number-fun CodeDesign.number-fun-null
      )(source);
    >

let-block +code-block-php source =
  '<
    +code-printer?:(
      CodePrinter.make-config CodeSyntax.php CodeTheme.iceberg-light
      |> CodePrinter.set-number-fun CodeDesign.number-fun-null
    )(source);
  >

let catchline-try = `<?php
try {
  f(3);
} catch (Throwable $e) {
  do {
    printf('%c', $e->getLine() + 21);
  } while ($e = $e->getPrevious());
  echo "\n";
}`

let catchline-fn-f = `function f(int $i) {
  if ($i < 0) return;
  try {
    match ($i) {
      0 => X, // 14行目
      // (間の空行は省略)
      2 => X, // 51行目
      // (間の空行は省略)
      1, 3 => X, // 59行目
    };
  } finally {
    f($i - 1);
  }
}`

let catchline-fn-f-with-comments = `function f(int $i) {
  if ($i < 0) return;
  try {
    match ($i) {
      0 => X, // 14行目: エラー！未定義の定数！
      // (間の空行は省略)
      2 => X, // 51行目: エラー！未定義の定数！
      // (間の空行は省略)
      1, 3 => X, // 59行目: エラー！未定義の定数！
    };
  } finally {
    f($i - 1);
  }
}`

let error-chain = `<?php
try {
  throw new \Exception("a");
} finally {
  throw new \Exception("b");
}
`

open FigBox
in

document '<
  +make-title(|
    title = {
      |PHPerKaigi 2023 のトークン問題で
      |ボツにした問題を供養する
      |};
    author = {|nsfisis (いまむら)|};
    date = {|第149回PHP勉強会＠東京|};
  |);

  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

  +frame{自己紹介}<
    +fig-center(vconcat [
      hconcat [
        gap 20pt;
        textbox{nsfisis (いまむら)};
        gap 20pt;
        include-image 50pt `assets/me.jpeg`;
      ];
      gap 20pt;
      textbox{\@ デジタルサーカス株式会社};
    ]);
  >

  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

  +frame{PHPerKaigiとは、トークン問題とは}<
    +fig-center(vconcat [
      gap 20pt;
      textbox{時間がないので省略。長谷川さんに聞いてください};
      gap 20pt;
      textbox{変わったPHPプログラムを持ってきたので解説します};
    ]);
  >

  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

  +frame{Catchline}<
    +code-block-php(catchline-try);
  >

  +frame{Catchline}<
    +code-block-php(catchline-fn-f);
  >

  +frame{Catchline}<
    +code-block-php(catchline-try);
    +p{
      \inline-code(`f()`);を呼び出して\inline-code(`Throwable`);を捕まえ、何かする
    }
  >

  +frame{Catchline}<
    +code-block-php(catchline-fn-f-with-comments);
  >

  +frame{Catchline}<
    +code-block-php(catchline-try);
    +p{
      \inline-code(`\Throwable::getPrevious()`);を順に辿り、(エラーの発生した行数+21)を
    }
    +p{
      ASCIIコード\text-color(Color.gray(0.75)){[1]}と見做して出力
    }
    +p{
      \text-color(Color.gray(0.75)){[1]: VAS Syndrome}
    }
  >

  +frame{Catchline}<
    +p{
      \inline-code(`\Throwable::getPrevious()`);
    }
    +p{
      発生したエラーの1つ前のエラー(=大本の原因)
    }
    +p{
      通常は例外クラスのコンストラクタに渡して設定する
    }
  >

  +frame{Catchline}<
    +code-block-php(error-chain);
    +p{
      \inline-code(`finally`);節の中で例外を発生させると、PHPの処理系が勝手に`$previous`を設定する
    }
  >

  +frame{Catchline}<
    +code-block-php(catchline-fn-f-with-comments);
  >

  +frame{Catchline}<
    +code-block-php(catchline-try);
    +p{
      (エラーの発生した行数+21)をASCIIコードと見做して出力
    }
  >

  +frame{Catchline}<
    +code-block-php(catchline-fn-f-with-comments);
  >

  +frame{Catchline}<
    +p{
      \listing{
        * 14 + 21 = 35 (\inline-code(`#`);)
        * 51 + 21 = 72 (\inline-code(`H`);)
        * 59 + 21 = 80 (\inline-code(`P`);)
      }
    }
    +p{
      組み合わせて\inline-code(`#PHP`);に
    }
  >

  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

  +frame{おわりに}<
    +fig-center(vconcat ?:(align-center) [
      gap 20pt;
      textbox{来たる3月のPHPerKaigi 2023で};
      gap 20pt;
      textbox{これより数段凝った問題を5つ出題します！};
      gap 20pt;
      textbox{みなさまの挑戦をお待ちしております！};
    ]);
  >
>