Implement `::class` static property

This property contains the name of the class in PHP. In the second commit, I also added very barebones namespace tracking, so the class property can be resolved correctly for classes inside namespaces.

See https://secure.php.net/manual/en/language.oop5.basic.php#language.oop5.basic.class.class

This conflicts with !2 (merged), I'll rebase if one of these get merged :)

// input
class Foo {}
namespace Bar { class Xyz {} }
Foo::class;

// output
class Foo {
  static class = "Foo";
};
{//Bar
  class Xyz {
    static class = "Bar\\Xyz";
  };
}
Foo.class;

Thanks for the PR.

My concern is that it's noisy and modifies all classes, even in code that doesn't use that feature.

Is it supposed to work dynamically like $foo::class or $this::class? If not, then instead of making an actual property, you could replace occurrences of Foo + :: + class with string literal "Foo".

Yeah, it is very noisy :( Late-binding static::class does work unfortunately.

<?php
class A {
  static function xyz () {
    return static::class;
  }
}
class B extends A {}

echo A::xyz(); // 'A'
echo B::xyz(); // 'B'

A less noisy way is using the JavaScript .name property on the constructor function, but that wouldn't include namespace names correctly…

One idea is to give the class a name that includes the namespace:

// Input
namespace Hello {
  class Greeting {
    public static function show () {
      echo static::class;
    }
  }
  class World extends Greeting {}
}
namespace {
  Hello\World::show();
}

// Output
{// Hello
  const Greeting = class Hello$Greeting {
    static show () {
      // ::class → .name.replace(...)
      return this.name.replace(/\$/g, '\\')
    }
  }
  const World = class Hello$World extends Greeting {
  }
}
{//
  Hello.World.show()
}

Of course, namespaces aren't implemented yet, so the code won't run, but the result should be correct. Does that sound like a better implementation?

Could you use this.constructor.name?