STACK

$S_{str}\ S_{seek}\ --\ S_{post}\ S_{match}\ S_{pre}\ B_{true}$
$S_{str}\ S_{seek}\ --\ S_{str}\ B_{false}$

DESCRIPTION

Red book operator looks for the first occurrence of the string $S_{seek}$ within $S_{str}$ and
returns the results of this search on the operand stack.
The topmost result is a boolean literal that indicates whether the search succeeded.

If search finds a subsequence of $S_{str}$ whose elements are equal to the elements of $S_{seek}$ ,
it splits $S_{str}$ into three segments:

$S_{pre}$ : the portion of string preceding the match,
$S_{match}$ : the portion of $S_{str}$ that matches $S_{seek}$ and
$S_{post}$ : the remainder of $S_{str}$ .

It then pushes the string objects $S_{post}$ , $S_{match}$ , and $S_{pre}$ on the operand stack,
followed by the boolean literal true.

If search does not find a match, it pushes the original $S_{str}$ followed by false.

ORIGIN

Core code registered in systemdict.