PHP Internals Deep Dive

• It's a big state machine starting with INITIAL

• States: INITIAL, ST_IN_SCRIPTING, ST_DOUBLE_QUOTES, ST_NOWDOC…

• Tokens can change the state:


<INITIAL>"<?php"([ \t]|{NEWLINE}) {
    HANDLE_NEWLINE(yytext[yyleng-1]);
    BEGIN(ST_IN_SCRIPTING);
    RETURN_TOKEN(T_OPEN_TAG);
}