\ VIEW.SEQ      Viewing code for ZF.                    by Tom Zimmer

variable viewlen

: >VIEWLINE     ( n1 --- )      \ move to line n1 of currently open file.
                dup >r 0 shndl @ movepointer
                IBRESET
                errorline off
                r> loadline ! ;

: <viewlines>   ( n1 n2 --- )
                loadline @ >r viewlen off
                swap    0
                do      lineread dup c@ 0= if drop leave then
                        cr count 2- 0 max
                        i 3 pick =
                        if      >attrib2 type >norm  \ underline it.
                        else        type 77 #out @ - spaces
                        then    outbuf c@ viewlen +!
                loop    drop cr r> loadline ! ;

: VIEWLINES     ( n1 n2 --- )   \ n1 lines to view, n2 line to underline.
                >rev shndl @ count type >norm <viewlines> ;

: NAME>PAD      ( A1 --- PAD )
                >r r@ ys: ?cs: pad r> yc@ 31 and 1+ cmovel  \ move name
                pad c@ 31 and pad c!                        \ clip count
                pad count + 1- dup c@ 127 and swap c!       \ mask last ch
                PAD     ;

: ?prepend.vpath ( a1 --- a1 )
                >r r@ 3 + c@ ascii \ =                  \ ? already have path
                if r> exit then                         \ then leave
                r@ count viewpath count + swap cmove
                r@ c@ viewpath c@ +                     \ total length
                dup r@ c!                               \ to a1
                viewpath 1+ r@ 1+ rot cmove             \ move data to a1
                viewpath count + off                    \ erase extra viewpath
                r> ;                                    \ return a1

comment:
: >viewfile     ( cfa --- offset a1 )   \ returns the string name in PAD
                filelist                \ of the file containing cfa as a1
                begin   @ 2dup u> until \ step to proper file name.
                SWAP    >view y@        \ Also returns offset to source def.
                SWAP    BODY> >NAME name>pad ?prepend.vpath ;
comment;

: files_set     ( --- )
                ['] files >body HERE 500 + #THREADS 2* CMOVE ;

: 1file         ( --- false | nfa )
                HERE 500 + #THREADS LARGEST DUP
                if      DUP L>NAME >r Y@ SWAP ! r>
                else    nip
                then    ;

0 constant maxname
0 constant maxcfa

: >viewfile     ( cfa --- offset a1 )
                >r files_set 0 =: maxcfa 0 =: maxname
                begin   1file dup
                while   r@ over name> u>
                        if      dup name> maxcfa u>
                                if      dup =: maxname
                                        dup name> =: maxcfa
                                then
                        then    drop
                repeat  drop r> >view y@
                maxname name>pad ?prepend.vpath ;

: <VIEW>        ( a1 --- f1 )   \ VIEW the name specified by a1 the cfa
                >viewfile       ( --- offset f1 )
                $hopen dup 0=
                if      swap dark cr
                        >viewline 17 0 viewlines  \ show 17 lines from file.
                else    nip
                then    ;

variable foundit

: <HELP>        ( a1 --- f1 )   \ Show the HELP for a word specified by a1
                >viewfile >r drop
                " HLP" ">$ r@ $>ext
                r> $hopen dup 0=
                if      IBRESET
                        0.0 seek loadline off
                        ."  Looking..." foundit off
                        8000 1
                        do      lineread c@ 0= ?leave
                                bl outbuf count + 2- c!
                                     \ have at least 1 blank at end of line.
                                here count outbuf 1+ swap 1+ caps-comp 0=
                                if      dark cr ." Line " i u. ." of "
                                        loadline @ >viewline 17 0 viewlines
                                        foundit on leave
                                then    outbuf c@ loadline +!
                        loop    foundit @ 0=
                        if      ." ..Sorry, no information available"
                        then    cr
                then    ;

: .VIEWHELP     ( --- )
dark
cr cr 24 spaces >rev ."  HELP ME GET STARTED! " >norm
cr cr
." To obtain help on a particular word,        type: HELP <wordname> <enter>" cr
." To see the source code for a word,          type: VIEW <wordname> <enter>" cr
." To find out what commands are available,    type: WORDS <enter>" cr
."    (space pauses, ESC stops list)" cr
." To find out which words contain a" cr
."    particular letter sequence,              type: WORDS <letters> <enter>" cr
." To see a decompiled source for a word,      type: SEE  <wordname> <enter>" cr
." To open a file, use VIEW above, or          type: OPEN <filename> <enter>" cr
." To edit the currently open file,            type: ED <enter>" cr
."    (press ESC to leave the editor)" cr
." To create a file, or select a file to edit, type: SED <enter>" cr
cr
." Type the following command sequence for a couple of examples: cr
cr
10 spaces ." OPEN INTRO <enter>" cr
10 spaces ." L <enter>" cr
cr
." See the accompanying .TXT files for further descriptions of FF." cr ;

: VIEW          ( | name --- )  \ VIEW is followed on the same line by name.
                >in @ span @ 1- >       \ if nothing following command
                if      .viewhelp       \ display the help screen
                else    ' <view>
                        if      cr ." File " .SHNDL ."  is not available."
                        then
                then    ;

' view alias LL         ( | name --- )  \ LL is a pseudonym for VIEW

: HELP          ( | name --- )  \ VIEW is followed on the same line by name.
                >in @ span @ 1- >       \ if nothing following command
                if      .viewhelp       \ display the help screen
                else    ' <help>
                        if      cr ." File " .SHNDL ."  is not available."
                        then
                then    ;

: ?fileopen     ( --- )                 \ Verify a file is open.
                shndl @ >hndle @ 0<
                abort" A file MUST be open to perform this operation." ;

: L             ( --- )         \ display 18 lines starting at current
                ?fileopen
                dark cr           \ loadline marker.
                loadline @ >viewline
                18 -1 viewlines ;

: LIST          ( n1 --- )      \ n1 is the line number to list from
                ?fileopen
                >line L ;

: LOAD          ( n1 --- )      \ n1 is the line number to load from
                ?fileopen
                >line           \ move to line n1
                cr ." Loading.." <load>  ;

: +lines        ( n1 --- )      \ move forward n1 lines in the current file.
                loadline @ >viewline
                0 swap 0
               ?do      lineread c@ + outbuf c@ 0= ?leave
                loop    loadline +! ;

: N             ( --- )         \ go forward 16 lines and display 18 lines.
                ?fileopen
                16 +lines L ;

: -1line        ( --- )      \ backup 1 line from current loadline
                loadline @ dup 0> swap 256 - swap
                if      0 max
                then    0 shndl @ movepointer
                IBRESET
                instart 256 loadline @ dup 0>
                if      min  else drop then
                shndl @ INBSEG EXHREAD =: inlength
                inlength instart over 2- 0 max bounds swap
               ?do      INBSEG  i c@L 10 =       \ is char an LF
                        if      drop instart inlength + i 1+ -
                                leave
                        then
            -1 +loop    negate loadline +! ;

: -lines        ( n1 --- )      \ backup n1 lines in the current file.
                0
               ?do      -1line
               loop     ;

: B             ( --- )         \ backup 16 lines in current file and
                ?fileopen
                16 -lines L ;   \ display 18 lines.

\ installation routine, added to the list of stuff to do when installing
\ FF for a new system.

: setview       ( | name --- )  \ set the path for all views
                >in @ span @ 1- >       \ if nothing following command
                if      viewpath clr-hcb
                        viewpath prepend.path drop
                cr ." ******"
cr ." The current PATH where F-PC searches for system sources when viewing is"
cr cr tab >rev viewpath count type >norm cr
cr ." Type in the New VIEW PATH (where the system sources are located),"
cr ." or press <enter> alone to leave the VIEW PATH the same. "
cr ." VIEW PATH ->"
                        query
                then
                >in @ span @ 1- > 0=
                if      viewpath clr-hcb
                        bl word viewpath over c@ 1+ cmove
                then    cr cr tab
                ." VIEW PATH set to " >rev viewpath count type >norm ;

: installviewpath  ( --- )
                defers installstuff
                span @ >in !
                setview ;

' installviewpath is installstuff