## undo/redo # for every undoable event, create a type of *operation* that contains all the # information needed to reverse it exclusive-container operation [ typing:insert-operation move:move-operation delete:delete-operation ] container insert-operation [ before-row:number before-column:number before-top-of-screen:address:duplex-list:character after-row:number after-column:number after-top-of-screen:address:duplex-list:character # inserted text is from 'insert-from' until 'insert-until'; list doesn't have to terminate insert-from:address:duplex-list:character insert-until:address:duplex-list:character tag:number # event causing this operation; might be used to coalesce runs of similar events # 0: no coalesce (enter+indent) # 1: regular alphanumeric characters ] container move-operation [ before-row:number before-column:number before-top-of-screen:address:duplex-list:character after-row:number after-column:number after-top-of-screen:address:duplex-list:character tag:number # event causing this operation; might be used to coalesce runs of similar events # 0: no coalesce (touch events, etc) # 1: left arrow # 2: right arrow # 3: up arrow # 4: down arrow ] container delete-operation [ before-row:number before-column:number before-top-of-screen:address:duplex-list:character after-row:number after-column:number after-top-of-screen:address:duplex-list:character deleted-text:address:duplex-list:character delete-from:address:duplex-list:character delete-until:address:duplex-list:character tag:number # event causing this operation; might be used to coalesce runs of similar events # 0: no coalesce (ctrl-k, ctrl-u) # 1: backspace # 2: delete ] # every editor accumulates a list of operations to undo/redo container editor-data [ undo:address:list:address:operation redo:address:list:address:operation ] # ctrl-z - undo operation after [ { undo?:boolean <- equal c, 26/ctrl-z break-unless undo? undo:address:list:address:operation <- get *editor, undo:offset break-unless undo op:address:operation <- first undo undo <- rest undo *editor <- put *editor, undo:offset, undo redo:address:list:address:operation <- get *editor, redo:offset redo <- push op, redo *editor <- put *editor, redo:offset, redo return screen/same-as-ingredient:0, editor/same-as-ingredient:1, 1/go-render } ] # ctrl-y - redo operation after [ { redo?:boolean <- equal c, 25/ctrl-y break-unless redo? redo:address:list:address:operation <- get *editor, redo:offset break-unless redo op:address:operation <- first redo redo <- rest redo *editor <- put *editor, redo:offset, redo undo:address:list:address:operation <- get *editor, undo:offset undo <- push op, undo *editor <- put *editor, undo:offset, undo return screen/same-as-ingredient:0, editor/same-as-ingredient:1, 1/go-render } ] # undo typing scenario editor-can-undo-typing [ # create an editor and type a character assume-screen 10/width, 5/height 1:address:array:character <- new [] 2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right editor-render screen, 2:address:editor-data assume-console [ type [0] ] editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data # undo assume-console [ press ctrl-z ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] # character should be gone screen-should-contain [ . . . . .┈┈┈┈┈┈┈┈┈┈. . . ] # cursor should be in the right place assume-console [ type [1] ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] screen-should-contain [ . . .1 . .┈┈┈┈┈┈┈┈┈┈. . . ] ] # save operation to undo after [ top-before:address:duplex-list:character <- get *editor, top-of-screen:offset cursor-before:address:duplex-list:character <- get *editor, before-cursor:offset ] before [ top-after:address:duplex-list:character <- get *editor, top-of-screen:offset cursor-row:number <- get *editor, cursor-row:offset cursor-column:number <- get *editor, cursor-column:offset undo:address:list:address:operation <- get *editor, undo:offset { # if previous operation was an insert, coalesce this operation with it break-unless undo op:address:operation <- first undo typing:insert-operation, is-insert?:boolean <- maybe-convert *op, typing:variant break-unless is-insert? previous-coalesce-tag:number <- get typing, tag:offset break-unless previous-coalesce-tag before-cursor:address:duplex-list:character <- get *editor, before-cursor:offset insert-until:address:duplex-list:character <- next before-cursor typing <- put typing, insert-until:offset, insert-until typing <- put typing, after-row:offset, cursor-row typing <- put typing, after-column:offset, cursor-column typing <- put typing, after-top-of-screen:offset, top-after *op <- merge 0/insert-operation, typing break +done-adding-insert-operation:label } # if not, create a new operation insert-from:address:duplex-list:character <- next cursor-before insert-to:address:duplex-list:character <- next insert-from op:address:operation <- new operation:type *op <- merge 0/insert-operation, save-row/before, save-column/before, top-before, cursor-row/after, cursor-column/after, top-after, insert-from, insert-to, 1/coalesce editor <- add-operation editor, op +done-adding-insert-operation ] # enter operations never coalesce with typing before or after after [ cursor-row-before:number <- copy cursor-row cursor-column-before:number <- copy cursor-column top-before:address:duplex-list:character <- get *editor, top-of-screen:offset cursor-before:address:duplex-list:character <- get *editor, before-cursor:offset ] before [ top-after:address:duplex-list:character <- get *editor, top-of-screen:offset cursor-row:number <- get *editor, cursor-row:offset cursor-column:number <- get *editor, cursor-row:offset # never coalesce insert-from:address:duplex-list:character <- next cursor-before before-cursor:address:duplex-list:character <- get *editor, before-cursor:offset insert-to:address:duplex-list:character <- next before-cursor op:address:operation <- new operation:type *op <- merge 0/insert-operation, cursor-row-before, cursor-column-before, top-before, cursor-row/after, cursor-column/after, top-after, insert-from, insert-to, 0/never-coalesce editor <- add-operation editor, op ] # Everytime you add a new operation to the undo stack, be sure to clear the # redo stack, because it's now obsolete. # Beware: since we're counting cursor moves as operations, this means just # moving the cursor can lose work on the undo stack. def add-operation editor:address:editor-data, op:address:operation -> editor:address:editor-data [ local-scope load-ingredients undo:address:list:address:operation <- get *editor, undo:offset undo <- push op undo *editor <- put *editor, undo:offset, undo redo:address:list:address:operation <- get *editor, redo:offset redo <- copy 0 *editor <- put *editor, redo:offset, redo return editor/same-as-ingredient:0 ] after [ { typing:insert-operation, is-insert?:boolean <- maybe-convert *op, typing:variant break-unless is-insert? start:address:duplex-list:character <- get typing, insert-from:offset end:address:duplex-list:character <- get typing, insert-until:offset # assert cursor-row/cursor-column/top-of-screen match after-row/after-column/after-top-of-screen before-cursor:address:duplex-list:character <- prev start *editor <- put *editor, before-cursor:offset, before-cursor remove-between before-cursor, end cursor-row <- get typing, before-row:offset *editor <- put *editor, cursor-row:offset, cursor-row cursor-column <- get typing, before-column:offset *editor <- put *editor, cursor-column:offset, cursor-column top:address:duplex-list:character <- get typing, before-top-of-screen:offset *editor <- put *editor, top-of-screen:offset, top } ] scenario editor-can-undo-typing-multiple [ # create an editor and type multiple characters assume-screen 10/width, 5/height 1:address:array:character <- new [] 2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right editor-render screen, 2:address:editor-data assume-console [ type [012] ] editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data # undo assume-console [ press ctrl-z ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] # all characters must be gone screen-should-contain [ . . . . .┈┈┈┈┈┈┈┈┈┈. . . ] ] scenario editor-can-undo-typing-multiple-2 [ # create an editor with some text assume-screen 10/width, 5/height 1:address:array:character <- new [a] 2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right editor-render screen, 2:address:editor-data # type some characters assume-console [ type [012] ] editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data screen-should-contain [ . . .012a . .┈┈┈┈┈┈┈┈┈┈. . . ] # undo assume-console [ press ctrl-z ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] # back to original text screen-should-contain [ . . .a . .┈┈┈┈┈┈┈┈┈┈. . . ] # cursor should be in the right place assume-console [ type [3] ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] screen-should-contain [ . . .3a . .┈┈┈┈┈┈┈┈┈┈. . . ] ] scenario editor-can-undo-typing-enter [ # create an editor with some text assume-screen 10/width, 5/height 1:address:array:character <- new [ abc] 2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right editor-render screen, 2:address:editor-data # new line assume-console [ left-click 1, 8 press enter ] editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data screen-should-contain [ . . . abc . . . .┈┈┈┈┈┈┈┈┈┈. . . ] # line is indented 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset memory-should-contain [ 3 <- 2 4 <- 2 ] # undo assume-console [ press ctrl-z ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset memory-should-contain [ 3 <- 1 4 <- 5 ] # back to original text screen-should-contain [ . . . abc . .┈┈┈┈┈┈┈┈┈┈. . . ] # cursor should be at end of line assume-console [ type [1] ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] screen-should-contain [ . . . abc1 . .┈┈┈┈┈┈┈┈┈┈. . . ] ] # redo typing scenario editor-redo-typing [ # create an editor, type something, undo assume-screen 10/width, 5/height 1:address:array:character <- new [a] 2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right editor-render screen, 2:address:editor-data assume-console [ type [012] press ctrl-z ] editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data screen-should-contain [ . . .a . .┈┈┈┈┈┈┈┈┈┈. . . ] # redo assume-console [ press ctrl-y ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] # all characters must be back screen-should-contain [ . . .012a . .┈┈┈┈┈┈┈┈┈┈. . . ] # cursor should be in the right place assume-console [ type [3] ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] screen-should-contain [ . . .0123a . .┈┈┈┈┈┈┈┈┈┈. . . ] ] after [ { typing:insert-operation, is-insert?:boolean <- maybe-convert *op, typing:variant break-unless is-insert? before-cursor <- get *editor, before-cursor:offset insert-from:address:duplex-list:character <- get typing, insert-from:offset # ignore insert-to because it's already been spliced away # assert insert-to matches next(before-cursor) insert-range before-cursor, insert-from # assert cursor-row/cursor-column/top-of-screen match after-row/after-column/after-top-of-screen cursor-row <- get typing, after-row:offset *editor <- put *editor, cursor-row:offset, cursor-row cursor-column <- get typing, after-column:offset *editor <- put *editor, cursor-column:offset, cursor-column top:address:duplex-list:character <- get typing, after-top-of-screen:offset *editor <- put *editor, top-of-screen:offset, top } ] scenario editor-redo-typing-empty [ # create an editor, type something, undo assume-screen 10/width, 5/height 1:address:array:character <- new [] 2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right editor-render screen, 2:address:editor-data assume-console [ type [012] press ctrl-z ] editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data screen-should-contain [ . . . . .┈┈┈┈┈┈┈┈┈┈. . . ] # redo assume-console [ press ctrl-y ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] # all characters must be back screen-should-contain [ . . .012 . .┈┈┈┈┈┈┈┈┈┈. . . ] # cursor should be in the right place assume-console [ type [3] ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] screen-should-contain [ . . .0123 . .┈┈┈┈┈┈┈┈┈┈. . . ] ] scenario editor-work-clears-redo-stack [ # create an editor with some text, do some work, undo assume-screen 10/width, 5/height 1:address:array:character <- new [abc def ghi] 2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right editor-render screen, 2:address:editor-data assume-console [ type [1] press ctrl-z ] editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data # do some more work assume-console [ type [0] ] editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data screen-should-contain [ . . .0abc . .def . .ghi . .┈┈┈┈┈┈┈┈┈┈. ] # redo assume-console [ press ctrl-y ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] # nothing should happen screen-should-contain [ . . .0abc . .def . .ghi . .┈┈┈┈┈┈┈┈┈┈. ] ] scenario editor-can-redo-typing-and-enter-and-tab [ # create an editor assume-screen 10/width, 5/height 1:address:array:character <- new [] 2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right editor-render screen, 2:address:editor-data # insert some text and tabs, hit enter, some more text and tabs assume-console [ press tab type [ab] press tab type [cd] press enter press tab type [efg] ] editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data screen-should-contain [ . . . ab cd . . efg . .┈┈┈┈┈┈┈┈┈┈. . . ] 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset memory-should-contain [ 3 <- 2 4 <- 7 ] # undo assume-console [ press ctrl-z ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] # typing in second line deleted, but not indent 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset memory-should-contain [ 3 <- 2 4 <- 2 ] screen-should-contain [ . . . ab cd . . . .┈┈┈┈┈┈┈┈┈┈. . . ] # undo again assume-console [ press ctrl-z ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] # indent and newline deleted 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset memory-should-contain [ 3 <- 1 4 <- 8 ] screen-should-contain [ . . . ab cd . .┈┈┈┈┈┈┈┈┈┈. . . ] # undo again assume-console [ press ctrl-z ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] # empty screen 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset memory-should-contain [ 3 <- 1 4 <- 0 ] screen-should-contain [ . . . . .┈┈┈┈┈┈┈┈┈┈. . . ] # redo assume-console [ press ctrl-y ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] # first line inserted 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset memory-should-contain [ 3 <- 1 4 <- 8 ] screen-should-contain [ . . . ab cd . .┈┈┈┈┈┈┈┈┈┈. . . ] # redo again assume-console [ press ctrl-y ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] # newline and indent inserted 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset memory-should-contain [ 3 <- 2 4 <- 2 ] screen-should-contain [ . . . ab cd . . . .┈┈┈┈┈┈┈┈┈┈. . . ] # redo again assume-console [ press ctrl-y ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] # indent and newline deleted 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset memory-should-contain [ 3 <- 2 4 <- 7 ] screen-should-contain [ . . . ab cd . . efg . .┈┈┈┈┈┈┈┈┈┈. . . ] ] # undo cursor movement and scroll scenario editor-can-undo-touch [ # create an editor with some text assume-screen 10/width, 5/height 1:address:array:character <- new [abc def ghi] 2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right editor-render screen, 2:address:editor-data # move the cursor assume-console [ left-click 3, 1 ] editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data # undo assume-console [ press ctrl-z ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset ] # click undone memory-should-contain [ 3 <- 1 4 <- 0 ] # cursor should be in the right place assume-console [ type [1] ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] screen-should-contain [ . . .1abc . .def . .ghi . .┈┈┈┈┈┈┈┈┈┈. ] ] after [ cursor-row-before:number <- get *editor, cursor-row:offset cursor-column-before:number <- get *editor, cursor-column:offset top-before:address:duplex-list:character <- get *editor, top-of-screen:offset ] before [ top-after:address:duplex-list:character <- get *editor, top-of-screen:offset cursor-row:number <- get *editor, cursor-row:offset cursor-column:number <- get *editor, cursor-column:offset { break-unless undo-coalesce-tag # if previous operation was also a move, and also had the same coalesce # tag, coalesce with it undo:address:list:address:operation <- get *editor, undo:offset break-unless undo op:address:operation <- first undo move:move-operation, is-move?:boolean <- maybe-convert *op, move:variant break-unless is-move? previous-coalesce-tag:number <- get move, tag:offset coalesce?:boolean <- equal undo-coalesce-tag, previous-coalesce-tag break-unless coalesce? move <- put move, after-row:offset, cursor-row move <- put move, after-column:offset, cursor-column move <- put move, after-top-of-screen:offset, top-after *op <- merge 1/move-operation, move break +done-adding-move-operation:label } op:address:operation <- new operation:type *op <- merge 1/move-operation, cursor-row-before, cursor-column-before, top-before, cursor-row/after, cursor-column/after, top-after, undo-coalesce-tag editor <- add-operation editor, op +done-adding-move-operation ] after [ { move:move-operation, is-move?:boolean <- maybe-convert *op, move:variant break-unless is-move? # assert cursor-row/cursor-column/top-of-screen match after-row/after-column/after-top-of-screen cursor-row <- get move, before-row:offset *editor <- put *editor, cursor-row:offset, cursor-row cursor-column <- get move, before-column:offset *editor <- put *editor, cursor-column:offset, cursor-column top:address:duplex-list:character <- get move, before-top-of-screen:offset *editor <- put *editor, top-of-screen:offset, top } ] scenario editor-can-undo-scroll [ # screen has 1 line for menu + 3 lines assume-screen 5/width, 4/height # editor contains a wrapped line 1:address:array:character <- new [a b cdefgh] 2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 5/right # position cursor at end of screen and try to move right assume-console [ left-click 3, 3 press right-arrow ] editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset # screen scrolls screen-should-contain [ . . .b . .cdef↩. .gh . ] memory-should-contain [ 3 <- 3 4 <- 0 ] # undo assume-console [ press ctrl-z ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset ] # cursor moved back memory-should-contain [ 3 <- 3 4 <- 3 ] # scroll undone screen-should-contain [ . . .a . .b . .cdef↩. ] # cursor should be in the right place assume-console [ type [1] ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] screen-should-contain [ . . .b . .cde1↩. .fgh . ] ] scenario editor-can-undo-left-arrow [ # create an editor with some text assume-screen 10/width, 5/height 1:address:array:character <- new [abc def ghi] 2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right editor-render screen, 2:address:editor-data # move the cursor assume-console [ left-click 3, 1 press left-arrow ] editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data # undo assume-console [ press ctrl-z ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset ] # cursor moves back memory-should-contain [ 3 <- 3 4 <- 1 ] # cursor should be in the right place assume-console [ type [1] ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] screen-should-contain [ . . .abc . .def . .g1hi . .┈┈┈┈┈┈┈┈┈┈. ] ] scenario editor-can-undo-up-arrow [ # create an editor with some text assume-screen 10/width, 5/height 1:address:array:character <- new [abc def ghi] 2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right editor-render screen, 2:address:editor-data # move the cursor assume-console [ left-click 3, 1 press up-arrow ] editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset memory-should-contain [ 3 <- 2 4 <- 1 ] # undo assume-console [ press ctrl-z ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset ] # cursor moves back memory-should-contain [ 3 <- 3 4 <- 1 ] # cursor should be in the right place assume-console [ type [1] ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] screen-should-contain [ . . .abc . .def . .g1hi . .┈┈┈┈┈┈┈┈┈┈. ] ] scenario editor-can-undo-down-arrow [ # create an editor with some text assume-screen 10/width, 5/height 1:address:array:character <- new [abc def ghi] 2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right editor-render screen, 2:address:editor-data # move the cursor assume-console [ left-click 2, 1 press down-arrow ] editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data # undo assume-console [ press ctrl-z ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset ] # cursor moves back memory-should-contain [ 3 <- 2 4 <- 1 ] # cursor should be in the right place assume-console [ type [1] ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] screen-should-contain [ . . .abc . .d1ef . .ghi . .┈┈┈┈┈┈┈┈┈┈. ] ] scenario editor-can-undo-ctrl-f [ # create an editor with multiple pages of text assume-screen 10/width, 5/height 1:address:array:character <- new [a b c d e f] 2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right editor-render screen, 2:address:editor-data # scroll the page assume-console [ press ctrl-f ] editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data # undo assume-console [ press ctrl-z ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset ] # screen should again show page 1 screen-should-contain [ . . .a . .b . .c . .d . ] ] scenario editor-can-undo-page-down [ # create an editor with multiple pages of text assume-screen 10/width, 5/height 1:address:array:character <- new [a b c d e f] 2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right editor-render screen, 2:address:editor-data # scroll the page assume-console [ press page-down ] editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data # undo assume-console [ press ctrl-z ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset ] # screen should again show page 1 screen-should-contain [ . . .a . .b . .c . .d . ] ] scenario editor-can-undo-ctrl-b [ # create an editor with multiple pages of text assume-screen 10/width, 5/height 1:address:array:character <- new [a b c d e f] 2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right editor-render screen, 2:address:editor-data # scroll the page down and up assume-console [ press page-down press ctrl-b ] editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data # undo assume-console [ press ctrl-z ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset ] # screen should again show page 2 screen-should-contain [ . . .d . .e . .f . .┈┈┈┈┈┈┈┈┈┈. ] ] scenario editor-can-undo-page-up [ # create an editor with multiple pages of text assume-screen 10/width, 5/height 1:address:array:character <- new [a b c d e f] 2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right editor-render screen, 2:address:editor-data # scroll the page down and up assume-console [ press page-down press page-up ] editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data # undo assume-console [ press ctrl-z ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset ] # screen should again show page 2 screen-should-contain [ . . .d . .e . .f . .┈┈┈┈┈┈┈┈┈┈. ] ] scenario editor-can-undo-ctrl-a [ # create an editor with some text assume-screen 10/width, 5/height 1:address:array:character <- new [abc def ghi] 2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right editor-render screen, 2:address:editor-data # move the cursor, then to start of line assume-console [ left-click 2, 1 press ctrl-a ] editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data # undo assume-console [ press ctrl-z ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset ] # cursor moves back memory-should-contain [ 3 <- 2 4 <- 1 ] # cursor should be in the right place assume-console [ type [1] ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] screen-should-contain [ . . .abc . .d1ef . .ghi . .┈┈┈┈┈┈┈┈┈┈. ] ] scenario editor-can-undo-home [ # create an editor with some text assume-screen 10/width, 5/height 1:address:array:character <- new [abc def ghi] 2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right editor-render screen, 2:address:editor-data # move the cursor, then to start of line assume-console [ left-click 2, 1 press home ] editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data # undo assume-console [ press ctrl-z ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset ] # cursor moves back memory-should-contain [ 3 <- 2 4 <- 1 ] # cursor should be in the right place assume-console [ type [1] ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] screen-should-contain [ . . .abc . .d1ef . .ghi . .┈┈┈┈┈┈┈┈┈┈. ] ] scenario editor-can-undo-ctrl-e [ # create an editor with some text assume-screen 10/width, 5/height 1:address:array:character <- new [abc def ghi] 2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right editor-render screen, 2:address:editor-data # move the cursor, then to start of line assume-console [ left-click 2, 1 press ctrl-e ] editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data # undo assume-console [ press ctrl-z ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset ] # cursor moves back memory-should-contain [ 3 <- 2 4 <- 1 ] # cursor should be in the right place assume-console [ type [1] ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] screen-should-contain [ . . .abc . .d1ef . .ghi . .┈┈┈┈┈┈┈┈┈┈. ] ] scenario editor-can-undo-end [ # create an editor with some text assume-screen 10/width, 5/height 1:address:array:character <- new [abc def ghi] 2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right editor-render screen, 2:address:editor-data # move the cursor, then to start of line assume-console [ left-click 2, 1 press end ] editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data # undo assume-console [ press ctrl-z ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset ] # cursor moves back memory-should-contain [ 3 <- 2 4 <- 1 ] # cursor should be in the right place assume-console [ type [1] ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] screen-should-contain [ . . .abc . .d1ef . .ghi . .┈┈┈┈┈┈┈┈┈┈. ] ] scenario editor-can-undo-multiple-arrows-in-the-same-direction [ # create an editor with some text assume-screen 10/width, 5/height 1:address:array:character <- new [abc def ghi] 2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right editor-render screen, 2:address:editor-data # move the cursor assume-console [ left-click 2, 1 press right-arrow press right-arrow press up-arrow ] editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset memory-should-contain [ 3 <- 1 4 <- 3 ] # undo assume-console [ press ctrl-z ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset ] # up-arrow is undone memory-should-contain [ 3 <- 2 4 <- 3 ] # undo again assume-console [ press ctrl-z ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset ] # both right-arrows are undone memory-should-contain [ 3 <- 2 4 <- 1 ] ] # redo cursor movement and scroll scenario editor-redo-touch [ # create an editor with some text, click on a character, undo assume-screen 10/width, 5/height 1:address:array:character <- new [abc def ghi] 2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right editor-render screen, 2:address:editor-data assume-console [ left-click 3, 1 press ctrl-z ] editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data # redo assume-console [ press ctrl-y ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset ] # cursor moves to left-click memory-should-contain [ 3 <- 3 4 <- 1 ] # cursor should be in the right place assume-console [ type [1] ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] screen-should-contain [ . . .abc . .def . .g1hi . .┈┈┈┈┈┈┈┈┈┈. ] ] after [ { move:move-operation, is-move?:boolean <- maybe-convert *op, move:variant break-unless is-move? # assert cursor-row/cursor-column/top-of-screen match after-row/after-column/after-top-of-screen cursor-row <- get move, after-row:offset *editor <- put *editor, cursor-row:offset, cursor-row cursor-column <- get move, after-column:offset *editor <- put *editor, cursor-column:offset, cursor-column top:address:duplex-list:character <- get move, after-top-of-screen:offset *editor <- put *editor, top-of-screen:offset, top } ] scenario editor-separates-undo-insert-from-undo-cursor-move [ # create an editor, type some text, move the cursor, type some more text assume-screen 10/width, 5/height 1:address:array:character <- new [] 2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right editor-render screen, 2:address:editor-data assume-console [ type [abc] left-click 1, 1 type [d] ] editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset screen-should-contain [ . . .adbc . .┈┈┈┈┈┈┈┈┈┈. . . ] memory-should-contain [ 3 <- 1 4 <- 2 ] # undo assume-console [ press ctrl-z ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset ] # last letter typed is deleted screen-should-contain [ . . .abc . .┈┈┈┈┈┈┈┈┈┈. . . ] memory-should-contain [ 3 <- 1 4 <- 1 ] # undo again assume-console [ press ctrl-z ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset ] # no change to screen; cursor moves screen-should-contain [ . . .abc . .┈┈┈┈┈┈┈┈┈┈. . . ] memory-should-contain [ 3 <- 1 4 <- 3 ] # undo again assume-console [ press ctrl-z ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset ] # screen empty screen-should-contain [ . . . . .┈┈┈┈┈┈┈┈┈┈. . . ] memory-should-contain [ 3 <- 1 4 <- 0 ] # redo assume-console [ press ctrl-y ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset ] # first insert screen-should-contain [ . . .abc . .┈┈┈┈┈┈┈┈┈┈. . . ] memory-should-contain [ 3 <- 1 4 <- 3 ] # redo again assume-console [ press ctrl-y ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset ] # cursor moves screen-should-contain [ . . .abc . .┈┈┈┈┈┈┈┈┈┈. . . ] # cursor moves memory-should-contain [ 3 <- 1 4 <- 1 ] # redo again assume-console [ press ctrl-y ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset ] # second insert screen-should-contain [ . . .adbc . .┈┈┈┈┈┈┈┈┈┈. . . ] memory-should-contain [ 3 <- 1 4 <- 2 ] ] # undo backspace scenario editor-can-undo-and-redo-backspace [ # create an editor assume-screen 10/width, 5/height 1:address:array:character <- new [] 2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right editor-render screen, 2:address:editor-data # insert some text and hit backspace assume-console [ type [abc] press backspace press backspace ] editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data screen-should-contain [ . . .a . .┈┈┈┈┈┈┈┈┈┈. . . ] 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset memory-should-contain [ 3 <- 1 4 <- 1 ] # undo assume-console [ press ctrl-z ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset memory-should-contain [ 3 <- 1 4 <- 3 ] screen-should-contain [ . . .abc . .┈┈┈┈┈┈┈┈┈┈. . . ] # redo assume-console [ press ctrl-y ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset memory-should-contain [ 3 <- 1 4 <- 1 ] screen-should-contain [ . . .a . .┈┈┈┈┈┈┈┈┈┈. . . ] ] # save operation to undo after [ top-before:address:duplex-list:character <- get *editor, top-of-screen:offset ] before [ { break-unless backspaced-cell # backspace failed; don't add an undo operation top-after:address:duplex-list:character <- get *editor, top-of-screen:offset cursor-row:number <- get *editor, cursor-row:offset cursor-column:number <- get *editor, cursor-row:offset before-cursor:address:duplex-list:character <- get *editor, before-cursor:offset undo:address:list:address:operation <- get *editor, undo:offset { # if previous operation was an insert, coalesce this operation with it break-unless undo op:address:operation <- first undo deletion:delete-operation, is-delete?:boolean <- maybe-convert *op, delete:variant break-unless is-delete? previous-coalesce-tag:number <- get deletion, tag:offset coalesce?:boolean <- equal previous-coalesce-tag, 1/coalesce-backspace break-unless coalesce? deletion <- put deletion, delete-from:offset, before-cursor backspaced-so-far:address:duplex-list:character <- get deletion, deleted-text:offset insert-range backspaced-cell, backspaced-so-far deletion <- put deletion, deleted-text:offset, backspaced-cell deletion <- put deletion, after-row:offset, cursor-row deletion <- put deletion, after-column:offset, cursor-column deletion <- put deletion, after-top-of-screen:offset, top-after *op <- merge 2/delete-operation, deletion break +done-adding-backspace-operation:label } # if not, create a new operation op:address:operation <- new operation:type deleted-until:address:duplex-list:character <- next before-cursor *op <- merge 2/delete-operation, save-row/before, save-column/before, top-before, cursor-row/after, cursor-column/after, top-after, backspaced-cell/deleted, before-cursor/delete-from, deleted-until, 1/coalesce-backspace editor <- add-operation editor, op +done-adding-backspace-operation } ] after [ { deletion:delete-operation, is-delete?:boolean <- maybe-convert *op, delete:variant break-unless is-delete? anchor:address:duplex-list:character <- get deletion, delete-from:offset break-unless anchor deleted:address:duplex-list:character <- get deletion, deleted-text:offset old-cursor:address:duplex-list:character <- last deleted insert-range anchor, deleted # assert cursor-row/cursor-column/top-of-screen match after-row/after-column/after-top-of-screen before-cursor <- copy old-cursor cursor-row <- get deletion, before-row:offset *editor <- put *editor, cursor-row:offset, cursor-row cursor-column <- get deletion, before-column:offset *editor <- put *editor, cursor-column:offset, cursor-column top:address:duplex-list:character <- get deletion, before-top-of-screen:offset *editor <- put *editor, top-of-screen:offset, top } ] after [ { deletion:delete-operation, is-delete?:boolean <- maybe-convert *op, delete:variant break-unless is-delete? start:address:duplex-list:character <- get deletion, delete-from:offset end:address:duplex-list:character <- get deletion, delete-until:offset data:address:duplex-list:character <- get *editor, data:offset remove-between start, end # assert cursor-row/cursor-column/top-of-screen match after-row/after-column/after-top-of-screen cursor-row <- get deletion, after-row:offset *editor <- put *editor, cursor-row:offset, cursor-row cursor-column <- get deletion, after-column:offset *editor <- put *editor, cursor-column:offset, cursor-column top:address:duplex-list:character <- get deletion, before-top-of-screen:offset *editor <- put *editor, top-of-screen:offset, top } ] # undo delete scenario editor-can-undo-and-redo-delete [ # create an editor assume-screen 10/width, 5/height 1:address:array:character <- new [] 2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right editor-render screen, 2:address:editor-data # insert some text and hit delete and backspace a few times assume-console [ type [abcdef] left-click 1, 2 press delete press backspace press delete press delete ] editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data screen-should-contain [ . . .af . .┈┈┈┈┈┈┈┈┈┈. . . ] 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset memory-should-contain [ 3 <- 1 4 <- 1 ] # undo deletes assume-console [ press ctrl-z ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset memory-should-contain [ 3 <- 1 4 <- 1 ] screen-should-contain [ . . .adef . .┈┈┈┈┈┈┈┈┈┈. . . ] # undo backspace assume-console [ press ctrl-z ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset memory-should-contain [ 3 <- 1 4 <- 2 ] screen-should-contain [ . . .abdef . .┈┈┈┈┈┈┈┈┈┈. . . ] # undo first delete assume-console [ press ctrl-z ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset memory-should-contain [ 3 <- 1 4 <- 2 ] screen-should-contain [ . . .abcdef . .┈┈┈┈┈┈┈┈┈┈. . . ] # redo first delete assume-console [ press ctrl-y ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] # first line inserted 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset memory-should-contain [ 3 <- 1 4 <- 2 ] screen-should-contain [ . . .abdef . .┈┈┈┈┈┈┈┈┈┈. . . ] # redo backspace assume-console [ press ctrl-y ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] # first line inserted 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset memory-should-contain [ 3 <- 1 4 <- 1 ] screen-should-contain [ . . .adef . .┈┈┈┈┈┈┈┈┈┈. . . ] # redo deletes assume-console [ press ctrl-y ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] # first line inserted 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset memory-should-contain [ 3 <- 1 4 <- 1 ] screen-should-contain [ . . .af . .┈┈┈┈┈┈┈┈┈┈. . . ] ] after [ top-before:address:duplex-list:character <- get *editor, top-of-screen:offset ] before [ { break-unless deleted-cell # delete failed; don't add an undo operation top-after:address:duplex-list:character <- get *editor, top-of-screen:offset cursor-row:number <- get *editor, cursor-row:offset cursor-column:number <- get *editor, cursor-column:offset before-cursor:address:duplex-list:character <- get *editor, before-cursor:offset undo:address:list:address:operation <- get *editor, undo:offset { # if previous operation was an insert, coalesce this operation with it break-unless undo op:address:operation <- first undo deletion:delete-operation, is-delete?:boolean <- maybe-convert *op, delete:variant break-unless is-delete? previous-coalesce-tag:number <- get deletion, tag:offset coalesce?:boolean <- equal previous-coalesce-tag, 2/coalesce-delete break-unless coalesce? delete-until:address:duplex-list:character <- next before-cursor deletion <- put deletion, delete-until:offset, delete-until deleted-so-far:address:duplex-list:character <- get deletion, deleted-text:offset deleted-so-far <- append deleted-so-far, deleted-cell deletion <- put deletion, deleted-text:offset, deleted-so-far deletion <- put deletion, after-row:offset, cursor-row deletion <- put deletion, after-column:offset, cursor-column deletion <- put deletion, after-top-of-screen:offset, top-after *op <- merge 2/delete-operation, deletion break +done-adding-delete-operation:label } # if not, create a new operation op:address:operation <- new operation:type deleted-until:address:duplex-list:character <- next before-cursor *op <- merge 2/delete-operation, save-row/before, save-column/before, top-before, cursor-row/after, cursor-column/after, top-after, deleted-cell/deleted, before-cursor/delete-from, deleted-until, 2/coalesce-delete editor <- add-operation editor, op +done-adding-delete-operation } ] # undo ctrl-k scenario editor-can-undo-and-redo-ctrl-k [ # create an editor assume-screen 10/width, 5/height 1:address:array:character <- new [abc def] 2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right editor-render screen, 2:address:editor-data # insert some text and hit delete and backspace a few times assume-console [ left-click 1, 1 press ctrl-k ] editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data screen-should-contain [ . . .a . .def . .┈┈┈┈┈┈┈┈┈┈. . . ] 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset memory-should-contain [ 3 <- 1 4 <- 1 ] # undo assume-console [ press ctrl-z ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] screen-should-contain [ . . .abc . .def . .┈┈┈┈┈┈┈┈┈┈. . . ] 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset memory-should-contain [ 3 <- 1 4 <- 1 ] # redo assume-console [ press ctrl-y ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] # first line inserted screen-should-contain [ . . .a . .def . .┈┈┈┈┈┈┈┈┈┈. . . ] 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset memory-should-contain [ 3 <- 1 4 <- 1 ] # cursor should be in the right place assume-console [ type [1] ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] screen-should-contain [ . . .a1 . .def . .┈┈┈┈┈┈┈┈┈┈. . . ] ] after [ top-before:address:duplex-list:character <- get *editor, top-of-screen:offset ] before [ { break-unless deleted-cells # delete failed; don't add an undo operation top-after:address:duplex-list:character <- get *editor, top-of-screen:offset cursor-row:number <- get *editor, cursor-row:offset cursor-column:number <- get *editor, cursor-column:offset deleted-until:address:duplex-list:character <- next before-cursor op:address:operation <- new operation:type *op <- merge 2/delete-operation, save-row/before, save-column/before, top-before, cursor-row/after, cursor-column/after, top-after, deleted-cells/deleted, before-cursor/delete-from, deleted-until, 0/never-coalesce editor <- add-operation editor, op +done-adding-delete-operation } ] # undo ctrl-u scenario editor-can-undo-and-redo-ctrl-u [ # create an editor assume-screen 10/width, 5/height 1:address:array:character <- new [abc def] 2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right editor-render screen, 2:address:editor-data # insert some text and hit delete and backspace a few times assume-console [ left-click 1, 2 press ctrl-u ] editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data screen-should-contain [ . . .c . .def . .┈┈┈┈┈┈┈┈┈┈. . . ] 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset memory-should-contain [ 3 <- 1 4 <- 0 ] # undo assume-console [ press ctrl-z ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] screen-should-contain [ . . .abc . .def . .┈┈┈┈┈┈┈┈┈┈. . . ] 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset memory-should-contain [ 3 <- 1 4 <- 2 ] # redo assume-console [ press ctrl-y ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] # first line inserted screen-should-contain [ . . .c . .def . .┈┈┈┈┈┈┈┈┈┈. . . ] 3:number <- get *2:address:editor-data, cursor-row:offset 4:number <- get *2:address:editor-data, cursor-column:offset memory-should-contain [ 3 <- 1 4 <- 0 ] # cursor should be in the right place assume-console [ type [1] ] run [ editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data ] screen-should-contain [ . . .1c . .def . .┈┈┈┈┈┈┈┈┈┈. . . ] ] after [ top-before:address:duplex-list:character <- get *editor, top-of-screen:offset ] before [ { break-unless deleted-cells # delete failed; don't add an undo operation top-after:address:duplex-list:character <- get *editor, top-of-screen:offset op:address:operation <- new operation:type before-cursor:address:duplex-list:character <- get *editor, before-cursor:offset deleted-until:address:duplex-list:character <- next before-cursor cursor-row:number <- get *editor, cursor-row:offset cursor-column:number <- get *editor, cursor-column:offset *op <- merge 2/delete-operation, save-row/before, save-column/before, top-before, cursor-row/after, cursor-column/after, top-after, deleted-cells/deleted, before-cursor/delete-from, deleted-until, 0/never-coalesce editor <- add-operation editor, op +done-adding-delete-operation } ] scenario editor-can-undo-and-redo-ctrl-u-2 [ # create an editor assume-screen 10/width, 5/height 1:address:array:character <- new [] 2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right editor-render screen, 2:address:editor-data # insert some text and hit delete and backspace a few times assume-console [ type [abc] press ctrl-u press ctrl-z ] editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data screen-should-contain [ . . .abc . .┈┈┈┈┈┈┈┈┈┈. . . ] ]