urbit/base/pub/doc/hoon/library/2ek.md

section 2eK, formatting (layout)

++re

Pretty-printing engine

++  re
  |_  tac=tank

Pretty-printing engine.

tac is a ++tank.

/~zod/try=> ~(. re leaf/"ham")
<2.ghl [[%leaf ""] <414.gly 100.xkc 1.ypj %164>]>

++ram

Flatten to tape

  ++  ram
    ^-  tape
    ?-    -.tac
        %leaf  p.tac
        %palm  ram(tac [%rose [p.p.tac (weld q.p.tac r.p.tac) s.p.tac] q.tac])
        %rose
      %+  weld
        q.p.tac
      |-  ^-  tape
      ?~  q.tac
        r.p.tac
      =+  voz=$(q.tac t.q.tac)
      (weld ram(tac i.q.tac) ?~(t.q.tac voz (weld p.p.tac voz)))
    ==
  ::

Flatten tank out into a tape.

/~zod/try=> ~(ram re leaf/"foo")
"foo"
/~zod/try=> ~(ram re rose/["." "(" ")"]^~[leaf/"bar" leaf/"baz" leaf/"bam"])
"(bar.baz.bam)"

++win

Render at indent

  ++  win
    |=  [tab=@ edg=@]
    =+  lug=`wall`~
    |^  |-  ^-  wall
        ?-    -.tac
            %leaf  (rig p.tac)
            %palm
          ?:  fit
            (rig ram)
          ?~  q.tac
            (rig q.p.tac)
          ?~  t.q.tac
            (rig(tab (add 2 tab), lug $(tac i.q.tac)) q.p.tac)
          =>  .(q.tac `(list tank)`q.tac)
          =+  lyn=(mul 2 (lent q.tac))
          =+  ^=  qyr
              |-  ^-  wall
              ?~  q.tac
                lug
              %=  ^$
                tac  i.q.tac
                tab  (add tab (sub lyn 2))
                lug  $(q.tac t.q.tac, lyn (sub lyn 2))
              ==
          (wig(lug qyr) q.p.tac)
        ::
            %rose
          ?:  fit
            (rig ram)
          =+  ^=  gyl
            |-  ^-  wall
            ?~  q.tac
              ?:(=(%$ r.p.tac) lug (rig r.p.tac))
            ^$(tac i.q.tac, lug $(q.tac t.q.tac), tab din)
          ?:  =(%$ q.p.tac)
            gyl
          (wig(lug gyl) q.p.tac)
        ==
    ::

Render at indent level tab and width edg.

tab and edg are atoms.

/~zod/try=> (~(win re leaf/"samoltekon-lapdok") 0 20)
<<"samoltekon-lapdok">>
/~zod/try=> (~(win re leaf/"samoltekon-lapdok") 0 10)
<<"\/samolt\/" "  ekon-l" "  apdok" "\/      \/">>
/~zod/try=> (~(win re rose/["--" "[" "]"]^~[leaf/"1423" leaf/"2316"]) 0 20)
<<"[1423--2316]">>
/~zod/try=> (~(win re rose/["--" "[" "]"]^~[leaf/"1423" leaf/"2316"]) 0 10)
<<"[ 1423" "  2316" "]">>

++din

    ++  din  (mod (add 2 tab) (mul 2 (div edg 3)))

XX document

++fit

Fit on one line test

    ++  fit  (lte (lent ram) (sub edg tab))

Determine whether tac fits on one line. Internal to ++win

++rig

Wrap in \/

    ++  rig
      |=  hom=tape
      ^-  wall
      ?:  (lte (lent hom) (sub edg tab))
        [(runt [tab ' '] hom) lug]
      =>  .(tab (add tab 2), edg (sub edg 2))
      =+  mut=(trim (sub edg tab) hom)
      :-  (runt [(sub tab 2) ' '] ['\\' '/' (weld p.mut `_hom`['\\' '/' ~])])
      =>  .(hom q.mut)
      |-
      ?~  hom
        :-  %+  runt
              [(sub tab 2) ' ']
            ['\\' '/' (runt [(sub edg tab) ' '] ['\\' '/' ~])]
        lug
      =>  .(mut (trim (sub edg tab) hom))
      [(runt [tab ' '] p.mut) $(hom q.mut)]
    ::

Wrap tape in \/ if it doesn't fit at current indentation. Internal to ++win

++wig

++win render tape

    ++  wig
      |=  hom=tape
      ^-  wall
      ?~  lug
        (rig hom)
      =+  lin=(lent hom)
      =+  wug=:(add 1 tab lin)
      ?.  =+  mir=i.lug
          |-  ?~  mir
                |
              ?|(=(0 wug) ?&(=(' ' i.mir) $(mir t.mir, wug (dec wug))))
        (rig hom)       :: ^ XX regular form?
      [(runt [tab ' '] (weld hom `tape`[' ' (slag wug i.lug)])) t.lug]
    --
  --

Render tape. Internal to ++win.