PHPでPHPを実装する〜プログラミング言語実装入門〜

PHPerKaigi 2020のセッションの資料です
https://fortee.jp/phperkaigi-2020/proposal/6809fa55-f317-4972-bc6a-a660975abb07

Transcript

1. PHPͰPHPΛ࣮૷͢Δ
   ʙϓϩάϥϛϯάݴޠ࣮૷ೖ໳ʙ
   @tzm_freedom
   

   View Slide

2. ࣗݾ঺հ
   • Twitter: @tzm_freedom
   • GitHub: tzmfreedom
   • Blog: https://blog.freedom-man.com
   • झຯ͸ंྠͷ࠶ൃ໌ͱHello World
   • αʔόʔαΠυΤϯδχΞ
   • PHPྺ2೥͘Β͍ʁ
   • ࠓ݄͔ΒϠϓϦͰಇ͍ͯ·͢
   

   View Slide

3. ϓϩάϥϛϯάݴޠ
   ࣮૷ͨ͜͠ͱ͋Δͻͱ
   

   View Slide

4. ͜ͷηογϣϯͰ఻͍͑ͨ͜ͱ
   • PHPͰPHPΛ࣮૷͢Δ͜ͱͰ…
   • ϓϩάϥϛϯάݴޠ͕ಈ͘࢓૊ΈΛ؆୯ʹ͝঺հ͠·͢
   • ೉͍͠࿩͸͠·ͤΜ
   • εϥΠυͷίʔυΛಡΜͰԿͱͳ͘ཧղͰ͖ͯ
   ͪΐͬͱ΍ͬͯΈΑ͏͔ͳʁͬͯࢥΘͤΔ͜ͱ͕ΰʔϧ
   • ࣮૷ͨ͠΋ͷ͸ͪ͜Βʹ͋Γ·͢
   • https://github.com/tzmfreedom/phphp
   • ղઆهࣄ͸ͪ͜Β
   • https://blog.freedom-man.com/phphp
   

   View Slide

5. ࣮૷͢ΔPHPίʔυ
   • echo
   • ม਺୅ೖ
   • ม਺ࢀর
   • จࣈྻϦςϥϧ
   • ਅِϦςϥϧ
   • ifจ
   echo 'PHPer';
   $str = 'Kaigi';
   echo $str;
   $cond = true;
   if ($cond) {
   echo ‘2020';
   }
   

   View Slide

6. ϓϩάϥϛϯάݴޠॲཧϑϩʔ
   • ίʔυจࣈྻ
   => ࣈ۟ղੳ
   => ߏจղੳʢASTΛ࡞Δʣ
   => ධՁ
   • ධՁ
   • ASTΛͨͲͬͯͦͷ··࣮ߦ
   => ࠓճ͸͜ΕʢTree Walk Interpreterʣ
   • όΠτίʔυʹม׵ɾ࣮ߦ
   • ػցޠʹม׵ɾ࣮ߦ
   

   View Slide

7. 1. ίʔυΛύʔεͯ͠
   ASTΛ࡞Δ
   ʢࣈ۟ղੳɾߏจղੳʣ
   

   View Slide

8. 1. ίʔυΛύʔεͯ͠ASTΛ࡞Δ
   if (true) {
   echo “hello";
   }
   array(
   0: Stmt_If(
   cond: Expr_ConstFetch(
   name: Name(
   parts: array(
   0: true
   )
   )
   )
   stmts: array(
   0: Stmt_Echo(
   exprs: array(
   0: Scalar_String(
   value: hello
   )
   )
   )
   )
   elseifs: array()
   else: null
   )
   )
   • ASTʁ
   • ந৅ߏจ໦
   • Abstract Syntax Tree
   • Treeߏ଄ͷΦϒδΣΫτ
   • ࠓճ͸ιʔείʔυΛද͢
   ΦϒδΣΫτͷ͜ͱ
   

   View Slide

9. PHP Parser(nikic/php-parser)
   • ࠓճ͸PHP ParserΛ࢖ͬͯASTΛ࡞Γ·͢
   • ࣗલͰࣈ۟ղੳɾߏจղੳ͢Δඞཁ͕ͳָͯ͘ʂ
   • PHPStan΍php7ccʹ΋࢖ΘΕ͍ͯΔ
   • PHP5ܥ, 7ܥͷ྆ํʹରԠ
   $parser = (new ParserFactory)
   ->create(ParserFactory::PREFER_PHP7);
   $ast = $parser->parse($code);
   

   View Slide

10. 2. ASTΛͨͲͬͯॲཧ͢Δ
    

    View Slide

11. Hello Worldͯ͠ΈΔ
    • EchoϊʔυͱจࣈྻϦςϥϧϊʔυΛॲཧͰ͖Ε͹OK
    array(
    0: Stmt_Echo(
    exprs: array(
    0: Scalar_String(
    value: hello
    )
    )
    )
    )
    echo “hello";
    ύʔε
    AST
    ίʔυ
    

    View Slide

12. ࣮૷͸͜Μͳײ͡
    function evaluate($node)
    {
    switch (get_class($node)) {
    case PhpParser\Node\Stmt\Echo_::class:
    $ret = evaluate($node->exprs[0]);
    echo $ret['value'];
    return;
    case PhpParser\Node\Scalar\String_::class:
    return ['value' => $node->value];
    }
    }
    $parser = (new ParserFactory)
    ->create(ParserFactory::PREFER_PHP7);
    $ast = $parser->parse($code);
    foreach ($ast as $stmt) {
    evaluate($stmt);
    }
    

    View Slide

13. ม਺ͷ࣮૷
    • ม਺͸KEY͕ม਺໊ɺ
    VALUE͕ධՁޙͷ஋
    ͱͳΔΑ͏ͳ࿈૝഑ྻʹ
    ֨ೲ͢Δ
    • ஋ͷࢀর͸࿈૝഑ྻ͔Β
    औಘ͢Δ
    $s = 'hello';
    echo $s;
    array(
    0: Stmt_Expression(
    expr: Expr_Assign(
    var: Expr_Variable(
    name: s
    )
    expr: Scalar_String(
    value: hello
    )
    )
    )
    1: Stmt_Echo(
    exprs: array(
    0: Expr_Variable(
    name: s
    )
    )
    )
    )
    

    View Slide

14. ม਺ͷ࣮૷
    public function evaluate($node)
    {
    switch (get_class($node)) {
    // ...
    case PhpParser\Node\Stmt\Expression::class:
    $this->evaluate($node->expr);
    return;
    case PhpParser\Node\Expr\Assign::class:
    return $this->variableEnv[$node->var->name]
    = $this->evaluate($node->expr);
    case PhpParser\Node\Expr\Variable::class:
    return $this->variableEnv[$node->name];
    

    View Slide

15. ifͷ࣮૷
    • condΛධՁͯ͠ਅͳΒ
    stmtsΛ࣮ߦ͢Δ
    • condِ͕ͳΒelseifs, else
    Λॱʹ࣮ߦ
    array(
    0: Stmt_If(
    cond: Expr_ConstFetch(
    name: Name(
    parts: array(
    0: true
    )
    )
    )
    stmts: array(
    0: Stmt_Echo(
    exprs: array(
    0: Scalar_String(
    value: hello
    )
    )
    )
    )
    elseifs: array()
    else: null
    )
    )
    if (true) {
    echo “hello";
    }
    

    View Slide

16. ifͷ࣮૷
    public function evaluate($node)
    {
    switch (get_class($node)) {
    // ...
    case PhpParser\Node\Stmt\If_::class:
    $cond = $this->evaluate($node->cond);
    if ($cond['value']) {
    foreach ($node->stmts as $stmt) {
    $this->evaluate($stmt);
    }
    }
    return;
    case PhpParser\Node\Expr\ConstFetch::class:
    if ($node->name->toString() === 'true') {
    return ['value' => true];
    } elseif ($node->name->toString() === 'false') {
    return ['value' => false];
    }
    throw new Exception("no such const");
    

    View Slide

17. ଞͷߏจͷ࣮૷ํ਑
    • for/while
    • ifจʴ܁Γฦ͠ͷॲཧΛ͢Ε͹OK
    • Ϋϥε
    • ϝιουɾϓϩύςΟఆٛΛ࣋ͭΦϒδΣΫτʢclassΦϒ
    δΣΫτʣΛ࡞Δ
    • ΠϯελϯεԽ
    • classΦϒδΣΫτΛࢀরʹ࣋ͭΦϒδΣΫτΛ࡞੒͢Δ
    • ϓϩύςΟɾϝιουݺͼग़͠
    • ࢀরઌͷclassΦϒδΣΫτͷϝιουΛݺͼग़͢
    • ܧঝ΍ΞΫηαͷ࣮૷͸େม…
    

    View Slide

18. PHPΛ௒͑ΔPHP
    

    View Slide

19. ࣗ࡞PHPͩͱ͜Μͳ͜ͱ΋Ͱ͖Δ
    • ಉҰม਺΁ͷೋճ໨ͷ୅ೖېࢭ
    • AssignͷධՁ࣌ʹ͢Ͱʹಉ͡είʔϓ಺ʹม਺͕ఆٛ͞Εͯ
    ͍ͨΒΤϥʔʹ͢Δ
    • ࣮ߦͤͣʹόϦσʔγϣϯ͚ͩೖΕΔͱ੩తղੳʹͳΔ
    • PHPStan, Phan, php7cc...
    • όΠφϦͷ࣮ߦϑΝΠϧʹ͢Δ
    • ASTΛͨͲͬͯػցޠ΍ػցޠʹม׵Ͱ͖ΔݴޠʢC΍Goʣ
    ʹม׵ɾίϯύΠϧ࣮ͯ͠ߦϑΝΠϧԽ
    

    View Slide

20. ·ͱΊ
    • PHPͰPHPΛ࣮૷͢Δํ๏Λ঺հ͠·ͨ͠
    • PHP-ParserΛ࢖͏ͱ؆୯ʹࣈ۟ղੳɾߏจղੳ͕Ͱ͖·͢
    • ASTΛ࢖ͬͯ੩తղੳπʔϧ΋࡞Ε·͢
    • ࣗ࡞PHPͰPHPΛ௒͑ΒΕΔ͔΋͠Εͳ͍ʂʁ
    

    View Slide

21. Let’s implement PHP!
    

    View Slide