Re: Can you shrink it further?

[Stefan Koch via Digitalmars-d]

This version has 24 instructions but these have a smaller 
encoding then and are generally inexpensive
With inline asm and conditional moves it would be possible to 
reduce this even further
to ~20 instructions.

void popFront1(ref char[] s) @trusted pure nothrow {
  immutable c = s[0];
  size_t char_length = 1;
  if (c < 127)
  {
    goto Lend;
  } else {
    if ((c & 0b1100_0000) == 0b1000_0000)
    {
      // This is invalid as a first char
      goto Lerror;
    }
    if (c < 192)
    {
      char_length = 2;
      goto Lend;
    }
    if (c < 240) {
      char_length = 3;
      goto Lend;
    }
    if (c < 248) {
       char_length = 4;
      goto Lend;
    }
    //These characters are also no longer valid
    Lerror : assert(0);
  }
  Lend :
  s = s.ptr[char_length .. s.length];
}