\ COMMENT.SEQ   Allow multiple line comments in files.  by Tom Zimmer

: ?exec         ( --- )
                state @ abort" Can not be used while Compiling!" ;

: <comment:>    ( --- )
                loading @ 0= abort" COMMENT: can ONLY be used while loading"
                bl word 1+ " comment;" caps-comp 0=
                if      ['] <run> is run
                then    [compile] \ ;

: comment:      ( --- )         \ ignore all lines between.
                [compile] \
                ['] <comment:> is run ;

: <.comment:>   ( --- )
                loading @ 0= abort" .COMMENT: can ONLY be used while loading"
                bl word 1+ " comment;" caps-comp 0=
                if      ['] <run> is run
                else    key? 0=
                        if      cr tib span @ 78 min type
                        then
                then    [compile] \ ;

: .comment:     ( --- )         \ ignore all lines between.
                [compile] \
                ['] <.comment:> is run ;

comment: <- this marks the start line of a multi line comment.

        this is a comment line somewhere in the middle.

comment; <- this marks the end line of a multi line comment.

defer prevrun

: <#if>         ( --- )         \ ignore lines unless #else, or #endif
                begin   bl word dup c@ 0= >r 1+
                        dup " #endif" caps-comp 0= over
                            " #then"  caps-comp 0= or swap
                            " #else"  caps-comp 0= or dup
                        if      @> prevrun is run
                                >r prevrun r>
                        then    r> or
                until   ;

: #else         ( --- )
                ?exec
                @> run is prevrun               \ Save previous value of RUN.
                ['] <#if> is run                \ Ignore following lines
                <#if> ;        immediate        \   and rest of this line.

: #if           ( f1 --- )      \ ignore lines following if false
                ?exec
                0=
                if      @> run is prevrun       \ Save previous value of RUN.
                        ['] <#if> is run        \ Ignore following lines
                        <#if>                   \   and rest of this line.
                then    ;       immediate

: #endif ; immediate    \ just a noop for the #if TRUE case.
: #then ;  immediate

\s      ************* NOT LOADING BEYOND THIS LINE ***********

        \ Here is an example of how the interpreted compiler directives
        \ work

cr cr .( press a T for true ) key bl or 116 =   \ wait for a key

#if .( TRUE)  #else  .( FALSE)  #then .(  always )