Exactly, where to draw a line? Explaining a concept of abstract and virtual machines may take a few pages of a dense text, explaining how to parse expressions with precedence may require dozens of pages, explaining C types will add a few more.
So, yes, it's either you're curious enough to dig into a code and find the relevant explanations somewhere else (the said Dragon Book and alike), or you won't get it, regardless of how comprehensive comments are.
So, yes, it's either you're curious enough to dig into a code and find the relevant explanations somewhere else (the said Dragon Book and alike), or you won't get it, regardless of how comprehensive comments are.