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<pre id='vimCodeElement'>
<span class="SalientComment">## the basic editor data structure, and how it displays text to the screen</span>

<span class="Comment"># temporary main for this layer: just render the given string at the given</span>
<span class="Comment"># screen dimensions, then stop</span>
<span class="muRecipe">recipe!</span> main text:address:array:character [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  open-console
  hide-screen <span class="Constant">0/screen</span>
  new-editor text, <span class="Constant">0/screen</span>, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
  show-screen <span class="Constant">0/screen</span>
  wait-for-event <span class="Constant">0/console</span>
  close-console
]

<span class="muScenario">scenario</span> editor-initially-prints-string-to-screen [
  assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
  run [
    <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc]</span>
    new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
  ]
  screen-should-contain [
    <span class="Comment"># top line of screen reserved for menu</span>
   <span class="Constant"> .          .</span>
   <span class="Constant"> .abc       .</span>
   <span class="Constant"> .          .</span>
  ]
]

<span class="muData">container</span> editor-data [
  <span class="Comment"># editable text: doubly linked list of characters (head contains a special sentinel)</span>
  data:address:duplex-list:character
  top-of-screen:address:duplex-list:character
  bottom-of-screen:address:duplex-list:character
  <span class="Comment"># location before cursor inside data</span>
  before-cursor:address:duplex-list:character

  <span class="Comment"># raw bounds of display area on screen</span>
  <span class="Comment"># always displays from row 1 (leaving row 0 for a menu) and at most until bottom of screen</span>
  left:number
  right:number
  <span class="Comment"># raw screen coordinates of cursor</span>
  cursor-row:number
  cursor-column:number
]

<span class="Comment"># creates a new editor widget and renders its initial appearance to screen</span>
<span class="Comment">#   top/left/right constrain the screen area available to the new editor</span>
<span class="Comment">#   right is exclusive</span>
<span class="muRecipe">recipe</span> new-editor s:address:array:character, screen:address:screen, left:number, right:number<span class="muRecipe"> -&gt; </span>result:address:editor-data [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  <span class="Comment"># no clipping of bounds</span>
  right<span class="Special"> &lt;- </span>subtract right, <span class="Constant">1</span>
  result<span class="Special"> &lt;- </span>new <span class="Constant">editor-data:type</span>
  <span class="Comment"># initialize screen-related fields</span>
  x:address:number<span class="Special"> &lt;- </span>get-address *result, <span class="Constant">left:offset</span>
  *x<span class="Special"> &lt;- </span>copy left
  x<span class="Special"> &lt;- </span>get-address *result, <span class="Constant">right:offset</span>
  *x<span class="Special"> &lt;- </span>copy right
  <span class="Comment"># initialize cursor</span>
  x<span class="Special"> &lt;- </span>get-address *result, <span class="Constant">cursor-row:offset</span>
  *x<span class="Special"> &lt;- </span>copy <span class="Constant">1/top</span>
  x<span class="Special"> &lt;- </span>get-address *result, <span class="Constant">cursor-column:offset</span>
  *x<span class="Special"> &lt;- </span>copy left
  init:address:address:duplex-list:character<span class="Special"> &lt;- </span>get-address *result, <span class="Constant">data:offset</span>
  *init<span class="Special"> &lt;- </span>push-duplex <span class="Constant">167/§</span>, <span class="Constant">0/tail</span>
  top-of-screen:address:address:duplex-list:character<span class="Special"> &lt;- </span>get-address *result, <span class="Constant">top-of-screen:offset</span>
  *top-of-screen<span class="Special"> &lt;- </span>copy *init
  y:address:address:duplex-list:character<span class="Special"> &lt;- </span>get-address *result, <span class="Constant">before-cursor:offset</span>
  *y<span class="Special"> &lt;- </span>copy *init
  result<span class="Special"> &lt;- </span>insert-text result, s
  <span class="Comment"># initialize cursor to top of screen</span>
  y<span class="Special"> &lt;- </span>get-address *result, <span class="Constant">before-cursor:offset</span>
  *y<span class="Special"> &lt;- </span>copy *init
  <span class="Comment"># initial render to screen, just for some old tests</span>
  _, _, screen, result<span class="Special"> &lt;- </span>render screen, result
<span class="Constant">  &lt;editor-initialization&gt;</span>
]

<span class="muRecipe">recipe</span> insert-text editor:address:editor-data, text:address:array:character<span class="muRecipe"> -&gt; </span>editor:address:editor-data [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  <span class="Comment"># early exit if text is empty</span>
  <span class="muControl">reply-unless</span> text, editor/same-as-ingredient:<span class="Constant">0</span>
  len:number<span class="Special"> &lt;- </span>length *text
  <span class="muControl">reply-unless</span> len, editor/same-as-ingredient:<span class="Constant">0</span>
  idx:number<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>
  <span class="Comment"># now we can start appending the rest, character by character</span>
  curr:address:duplex-list:character<span class="Special"> &lt;- </span>get *editor, <span class="Constant">data:offset</span>
  <span class="Delimiter">{</span>
    done?:boolean<span class="Special"> &lt;- </span>greater-or-equal idx, len
    <span class="muControl">break-if</span> done?
    c:character<span class="Special"> &lt;- </span>index *text, idx
    insert-duplex c, curr
    <span class="Comment"># next iter</span>
    curr<span class="Special"> &lt;- </span>next-duplex curr
    idx<span class="Special"> &lt;- </span>add idx, <span class="Constant">1</span>
    <span class="muControl">loop</span>
  <span class="Delimiter">}</span>
  <span class="muControl">reply</span> editor/same-as-ingredient:<span class="Constant">0</span>
]

<span class="muScenario">scenario</span> editor-initializes-without-data [
  assume-screen <span class="Constant">5/width</span>, <span class="Constant">3/height</span>
  run [
    <span class="Constant">1</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">0/data</span>, screen:address:screen, <span class="Constant">2/left</span>, <span class="Constant">5/right</span>
    <span class="Constant">2</span>:editor-data<span class="Special"> &lt;- </span>copy *<span class="Constant">1</span>:address:editor-data
  ]
  memory-should-contain [
    <span class="Comment"># 2 (data) &lt;- just the § sentinel</span>
    <span class="Comment"># 3 (top of screen) &lt;- the § sentinel</span>
    <span class="Constant">4</span><span class="Special"> &lt;- </span><span class="Constant">0</span>  <span class="Comment"># bottom-of-screen; null since text fits on screen</span>
    <span class="Comment"># 5 (before cursor) &lt;- the § sentinel</span>
    <span class="Constant">6</span><span class="Special"> &lt;- </span><span class="Constant">2</span>  <span class="Comment"># left</span>
    <span class="Constant">7</span><span class="Special"> &lt;- </span><span class="Constant">4</span>  <span class="Comment"># right  (inclusive)</span>
    <span class="Constant">8</span><span class="Special"> &lt;- </span><span class="Constant">1</span>  <span class="Comment"># cursor row</span>
    <span class="Constant">9</span><span class="Special"> &lt;- </span><span class="Constant">2</span>  <span class="Comment"># cursor column</span>
  ]
  screen-should-contain [
   <span class="Constant"> .     .</span>
   <span class="Constant"> .     .</span>
   <span class="Constant"> .     .</span>
  ]
]

<span class="Comment"># Assumes cursor should be at coordinates (cursor-row, cursor-column) and</span>
<span class="Comment"># updates before-cursor to match. Might also move coordinates if they're</span>
<span class="Comment"># outside text.</span>
<span class="muRecipe">recipe</span> render screen:address:screen, editor:address:editor-data<span class="muRecipe"> -&gt; </span>last-row:number, last-column:number, screen:address:screen, editor:address:editor-data [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  <span class="muControl">reply-unless</span> editor, <span class="Constant">1/top</span>, <span class="Constant">0/left</span>, screen/same-as-ingredient:<span class="Constant">0</span>, editor/same-as-ingredient:<span class="Constant">1</span>
  left:number<span class="Special"> &lt;- </span>get *editor, <span class="Constant">left:offset</span>
  screen-height:number<span class="Special"> &lt;- </span>screen-height screen
  right:number<span class="Special"> &lt;- </span>get *editor, <span class="Constant">right:offset</span>
  <span class="Comment"># traversing editor</span>
  curr:address:duplex-list:character<span class="Special"> &lt;- </span>get *editor, <span class="Constant">top-of-screen:offset</span>
  prev:address:duplex-list:character<span class="Special"> &lt;- </span>copy curr  <span class="Comment"># just in case curr becomes null and we can't compute prev-duplex</span>
  curr<span class="Special"> &lt;- </span>next-duplex curr
  <span class="Comment"># traversing screen</span>
<span class="Constant">  +render-loop-initialization</span>
  color:number<span class="Special"> &lt;- </span>copy <span class="Constant">7/white</span>
  row:number<span class="Special"> &lt;- </span>copy <span class="Constant">1/top</span>
  column:number<span class="Special"> &lt;- </span>copy left
  cursor-row:address:number<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">cursor-row:offset</span>
  cursor-column:address:number<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">cursor-column:offset</span>
  before-cursor:address:address:duplex-list:character<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">before-cursor:offset</span>
  screen<span class="Special"> &lt;- </span>move-cursor screen, row, column
  <span class="Delimiter">{</span>
<span class="Constant">    +next-character</span>
    <span class="muControl">break-unless</span> curr
    off-screen?:boolean<span class="Special"> &lt;- </span>greater-or-equal row, screen-height
    <span class="muControl">break-if</span> off-screen?
    <span class="Comment"># update editor-data.before-cursor</span>
    <span class="Comment"># Doing so at the start of each iteration ensures it stays one step behind</span>
    <span class="Comment"># the current character.</span>
    <span class="Delimiter">{</span>
      at-cursor-row?:boolean<span class="Special"> &lt;- </span>equal row, *cursor-row
      <span class="muControl">break-unless</span> at-cursor-row?
      at-cursor?:boolean<span class="Special"> &lt;- </span>equal column, *cursor-column
      <span class="muControl">break-unless</span> at-cursor?
      *before-cursor<span class="Special"> &lt;- </span>copy prev
    <span class="Delimiter">}</span>
    c:character<span class="Special"> &lt;- </span>get *curr, <span class="Constant">value:offset</span>
<span class="Constant">    &lt;character-c-received&gt;</span>
    <span class="Delimiter">{</span>
      <span class="Comment"># newline? move to left rather than 0</span>
      newline?:boolean<span class="Special"> &lt;- </span>equal c, <span class="Constant">10/newline</span>
      <span class="muControl">break-unless</span> newline?
      <span class="Comment"># adjust cursor if necessary</span>
      <span class="Delimiter">{</span>
        at-cursor-row?:boolean<span class="Special"> &lt;- </span>equal row, *cursor-row
        <span class="muControl">break-unless</span> at-cursor-row?
        left-of-cursor?:boolean<span class="Special"> &lt;- </span>lesser-than column, *cursor-column
        <span class="muControl">break-unless</span> left-of-cursor?
        *cursor-column<span class="Special"> &lt;- </span>copy column
        *before-cursor<span class="Special"> &lt;- </span>prev-duplex curr
      <span class="Delimiter">}</span>
      <span class="Comment"># clear rest of line in this window</span>
      clear-line-delimited screen, column, right
      <span class="Comment"># skip to next line</span>
      row<span class="Special"> &lt;- </span>add row, <span class="Constant">1</span>
      column<span class="Special"> &lt;- </span>copy left
      screen<span class="Special"> &lt;- </span>move-cursor screen, row, column
      curr<span class="Special"> &lt;- </span>next-duplex curr
      prev<span class="Special"> &lt;- </span>next-duplex prev
      <span class="muControl">loop</span> <span class="Constant">+next-character:label</span>
    <span class="Delimiter">}</span>
    <span class="Delimiter">{</span>
      <span class="Comment"># at right? wrap. even if there's only one more letter left; we need</span>
      <span class="Comment"># room for clicking on the cursor after it.</span>
      at-right?:boolean<span class="Special"> &lt;- </span>equal column, right
      <span class="muControl">break-unless</span> at-right?
      <span class="Comment"># print wrap icon</span>
      print-character screen, <span class="Constant">8617/loop-back-to-left</span>, <span class="Constant">245/grey</span>
      column<span class="Special"> &lt;- </span>copy left
      row<span class="Special"> &lt;- </span>add row, <span class="Constant">1</span>
      screen<span class="Special"> &lt;- </span>move-cursor screen, row, column
      <span class="Comment"># don't increment curr</span>
      <span class="muControl">loop</span> <span class="Constant">+next-character:label</span>
    <span class="Delimiter">}</span>
    print-character screen, c, color
    curr<span class="Special"> &lt;- </span>next-duplex curr
    prev<span class="Special"> &lt;- </span>next-duplex prev
    column<span class="Special"> &lt;- </span>add column, <span class="Constant">1</span>
    <span class="muControl">loop</span>
  <span class="Delimiter">}</span>
  <span class="Comment"># save first character off-screen</span>
  bottom-of-screen:address:address:duplex-list:character<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">bottom-of-screen:offset</span>
  *bottom-of-screen<span class="Special"> &lt;- </span>copy curr
  <span class="Comment"># is cursor to the right of the last line? move to end</span>
  <span class="Delimiter">{</span>
    at-cursor-row?:boolean<span class="Special"> &lt;- </span>equal row, *cursor-row
    cursor-outside-line?:boolean<span class="Special"> &lt;- </span>lesser-or-equal column, *cursor-column
    before-cursor-on-same-line?:boolean<span class="Special"> &lt;- </span>and at-cursor-row?, cursor-outside-line?
    above-cursor-row?:boolean<span class="Special"> &lt;- </span>lesser-than row, *cursor-row
    before-cursor?:boolean<span class="Special"> &lt;- </span>or before-cursor-on-same-line?, above-cursor-row?
    <span class="muControl">break-unless</span> before-cursor?
    *cursor-row<span class="Special"> &lt;- </span>copy row
    *cursor-column<span class="Special"> &lt;- </span>copy column
    *before-cursor<span class="Special"> &lt;- </span>copy prev
  <span class="Delimiter">}</span>
  <span class="muControl">reply</span> row, column, screen/same-as-ingredient:<span class="Constant">0</span>, editor/same-as-ingredient:<span class="Constant">1</span>
]

<span class="muRecipe">recipe</span> clear-line-delimited screen:address:screen, column:number, right:number [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  <span class="Delimiter">{</span>
    done?:boolean<span class="Special"> &lt;- </span>greater-than column, right
    <span class="muControl">break-if</span> done?
    print-character screen, <span class="Constant">32/space</span>
    column<span class="Special"> &lt;- </span>add column, <span class="Constant">1</span>
    <span class="muControl">loop</span>
  <span class="Delimiter">}</span>
]

<span class="muRecipe">recipe</span> clear-screen-from screen:address:screen, row:number, column:number, left:number, right:number<span class="muRecipe"> -&gt; </span>screen:address:screen [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  <span class="Comment"># if it's the real screen, use the optimized primitive</span>
  <span class="Delimiter">{</span>
    <span class="muControl">break-if</span> screen
    clear-display-from row, column, left, right
    <span class="muControl">reply</span> screen/same-as-ingredient:<span class="Constant">0</span>
  <span class="Delimiter">}</span>
  <span class="Comment"># if not, go the slower route</span>
  screen<span class="Special"> &lt;- </span>move-cursor screen, row, column
  clear-line-delimited screen, column, right
  clear-rest-of-screen screen, row, left, right
  <span class="muControl">reply</span> screen/same-as-ingredient:<span class="Constant">0</span>
]

<span class="muRecipe">recipe</span> clear-rest-of-screen screen:address:screen, row:number, left:number, right:number [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  row<span class="Special"> &lt;- </span>add row, <span class="Constant">1</span>
  screen<span class="Special"> &lt;- </span>move-cursor screen, row, left
  screen-height:number<span class="Special"> &lt;- </span>screen-height screen
  <span class="Delimiter">{</span>
    at-bottom-of-screen?:boolean<span class="Special"> &lt;- </span>greater-or-equal row, screen-height
    <span class="muControl">break-if</span> at-bottom-of-screen?
    screen<span class="Special"> &lt;- </span>move-cursor screen, row, left
    clear-line-delimited screen, left, right
    row<span class="Special"> &lt;- </span>add row, <span class="Constant">1</span>
    <span class="muControl">loop</span>
  <span class="Delimiter">}</span>
]

<span class="muScenario">scenario</span> editor-initially-prints-multiple-lines [
  assume-screen <span class="Constant">5/width</span>, <span class="Constant">5/height</span>
  run [
    s:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc</span>
<span class="Constant">def]</span>
    new-editor s:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
  ]
  screen-should-contain [
   <span class="Constant"> .     .</span>
   <span class="Constant"> .abc  .</span>
   <span class="Constant"> .def  .</span>
   <span class="Constant"> .     .</span>
  ]
]

<span class="muScenario">scenario</span> editor-initially-handles-offsets [
  assume-screen <span class="Constant">5/width</span>, <span class="Constant">5/height</span>
  run [
    s:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc]</span>
    new-editor s:address:array:character, screen:address:screen, <span class="Constant">1/left</span>, <span class="Constant">5/right</span>
  ]
  screen-should-contain [
   <span class="Constant"> .     .</span>
   <span class="Constant"> . abc .</span>
   <span class="Constant"> .     .</span>
  ]
]

<span class="muScenario">scenario</span> editor-initially-prints-multiple-lines-at-offset [
  assume-screen <span class="Constant">5/width</span>, <span class="Constant">5/height</span>
  run [
    s:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc</span>
<span class="Constant">def]</span>
    new-editor s:address:array:character, screen:address:screen, <span class="Constant">1/left</span>, <span class="Constant">5/right</span>
  ]
  screen-should-contain [
   <span class="Constant"> .     .</span>
   <span class="Constant"> . abc .</span>
   <span class="Constant"> . def .</span>
   <span class="Constant"> .     .</span>
  ]
]

<span class="muScenario">scenario</span> editor-initially-wraps-long-lines [
  assume-screen <span class="Constant">5/width</span>, <span class="Constant">5/height</span>
  run [
    s:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc def]</span>
    new-editor s:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
  ]
  screen-should-contain [
   <span class="Constant"> .     .</span>
   <span class="Constant"> .abc ↩.</span>
   <span class="Constant"> .def  .</span>
   <span class="Constant"> .     .</span>
  ]
  screen-should-contain-in-color <span class="Constant">245/grey</span> [
   <span class="Constant"> .     .</span>
   <span class="Constant"> .    ↩.</span>
   <span class="Constant"> .     .</span>
   <span class="Constant"> .     .</span>
  ]
]

<span class="muScenario">scenario</span> editor-initially-wraps-barely-long-lines [
  assume-screen <span class="Constant">5/width</span>, <span class="Constant">5/height</span>
  run [
    s:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abcde]</span>
    new-editor s:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
  ]
  <span class="Comment"># still wrap, even though the line would fit. We need room to click on the</span>
  <span class="Comment"># end of the line</span>
  screen-should-contain [
   <span class="Constant"> .     .</span>
<span class="Constant">    .abcd↩.</span>
   <span class="Constant"> .e    .</span>
   <span class="Constant"> .     .</span>
  ]
  screen-should-contain-in-color <span class="Constant">245/grey</span> [
   <span class="Constant"> .     .</span>
   <span class="Constant"> .    ↩.</span>
   <span class="Constant"> .     .</span>
   <span class="Constant"> .     .</span>
  ]
]

<span class="muScenario">scenario</span> editor-initializes-empty-text [
  assume-screen <span class="Constant">5/width</span>, <span class="Constant">5/height</span>
  run [
    <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[]</span>
    <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
  ]
  screen-should-contain [
   <span class="Constant"> .     .</span>
   <span class="Constant"> .     .</span>
   <span class="Constant"> .     .</span>
  ]
  memory-should-contain [
    <span class="Constant">3</span><span class="Special"> &lt;- </span><span class="Constant">1</span>  <span class="Comment"># cursor row</span>
    <span class="Constant">4</span><span class="Special"> &lt;- </span><span class="Constant">0</span>  <span class="Comment"># cursor column</span>
  ]
]

<span class="Comment"># just a little color for mu code</span>

<span class="muScenario">scenario</span> render-colors-comments [
  assume-screen <span class="Constant">5/width</span>, <span class="Constant">5/height</span>
  run [
    s:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc</span>
<span class="Constant"># de</span>
<span class="Constant">f]</span>
    new-editor s:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
  ]
  screen-should-contain [
   <span class="Constant"> .     .</span>
   <span class="Constant"> .abc  .</span>
   <span class="Constant"> .# de .</span>
   <span class="Constant"> .f    .</span>
   <span class="Constant"> .     .</span>
  ]
  screen-should-contain-in-color <span class="Constant">12/lightblue</span>, [
   <span class="Constant"> .     .</span>
   <span class="Constant"> .     .</span>
   <span class="Constant"> .# de .</span>
   <span class="Constant"> .     .</span>
   <span class="Constant"> .     .</span>
  ]
  screen-should-contain-in-color <span class="Constant">7/white</span>, [
   <span class="Constant"> .     .</span>
   <span class="Constant"> .abc  .</span>
   <span class="Constant"> .     .</span>
   <span class="Constant"> .f    .</span>
   <span class="Constant"> .     .</span>
  ]
]

<span class="muRecipe">after</span> <span class="Constant">&lt;character-c-received&gt;</span> [
  color<span class="Special"> &lt;- </span>get-color color, c
]

<span class="Comment"># so far the previous color is all the information we need; that may change</span>
<span class="muRecipe">recipe</span> get-color color:number, c:character<span class="muRecipe"> -&gt; </span>color:number [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  color-is-white?:boolean<span class="Special"> &lt;- </span>equal color, <span class="Constant">7/white</span>
  <span class="Comment"># if color is white and next character is '#', switch color to blue</span>
  <span class="Delimiter">{</span>
    <span class="muControl">break-unless</span> color-is-white?
    starting-comment?:boolean<span class="Special"> &lt;- </span>equal c, <span class="Constant">35/#</span>
    <span class="muControl">break-unless</span> starting-comment?
    trace <span class="Constant">90</span>, <span class="Constant">[app]</span>, <span class="Constant">[switch color back to blue]</span>
    color<span class="Special"> &lt;- </span>copy <span class="Constant">12/lightblue</span>
    <span class="muControl">jump</span> <span class="Constant">+exit:label</span>
  <span class="Delimiter">}</span>
  <span class="Comment"># if color is blue and next character is newline, switch color to white</span>
  <span class="Delimiter">{</span>
    color-is-blue?:boolean<span class="Special"> &lt;- </span>equal color, <span class="Constant">12/lightblue</span>
    <span class="muControl">break-unless</span> color-is-blue?
    ending-comment?:boolean<span class="Special"> &lt;- </span>equal c, <span class="Constant">10/newline</span>
    <span class="muControl">break-unless</span> ending-comment?
    trace <span class="Constant">90</span>, <span class="Constant">[app]</span>, <span class="Constant">[switch color back to white]</span>
    color<span class="Special"> &lt;- </span>copy <span class="Constant">7/white</span>
    <span class="muControl">jump</span> <span class="Constant">+exit:label</span>
  <span class="Delimiter">}</span>
  <span class="Comment"># if color is white (no comments) and next character is '&lt;', switch color to red</span>
  <span class="Delimiter">{</span>
    <span class="muControl">break-unless</span> color-is-white?
    starting-assignment?:boolean<span class="Special"> &lt;- </span>equal c, <span class="Constant">60/&lt;</span>
    <span class="muControl">break-unless</span> starting-assignment?
    color<span class="Special"> &lt;- </span>copy <span class="Constant">1/red</span>
    <span class="muControl">jump</span> <span class="Constant">+exit:label</span>
  <span class="Delimiter">}</span>
  <span class="Comment"># if color is red and next character is space, switch color to white</span>
  <span class="Delimiter">{</span>
    color-is-red?:boolean<span class="Special"> &lt;- </span>equal color, <span class="Constant">1/red</span>
    <span class="muControl">break-unless</span> color-is-red?
    ending-assignment?:boolean<span class="Special"> &lt;- </span>equal c, <span class="Constant">32/space</span>
    <span class="muControl">break-unless</span> ending-assignment?
    color<span class="Special"> &lt;- </span>copy <span class="Constant">7/white</span>
    <span class="muControl">jump</span> <span class="Constant">+exit:label</span>
  <span class="Delimiter">}</span>
  <span class="Comment"># otherwise no change</span>
<span class="Constant">  +exit</span>
  <span class="muControl">reply</span> color
]

<span class="muScenario">scenario</span> render-colors-assignment [
  assume-screen <span class="Constant">8/width</span>, <span class="Constant">5/height</span>
  run [
    s:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc</span>
<span class="Constant">d &lt;- e</span>
<span class="Constant">f]</span>
    new-editor s:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">8/right</span>
  ]
  screen-should-contain [
   <span class="Constant"> .        .</span>
   <span class="Constant"> .abc     .</span>
   <span class="Constant"> .d &lt;- e  .</span>
   <span class="Constant"> .f       .</span>
   <span class="Constant"> .        .</span>
  ]
  screen-should-contain-in-color <span class="Constant">1/red</span>, [
   <span class="Constant"> .        .</span>
   <span class="Constant"> .        .</span>
   <span class="Constant"> .  &lt;-    .</span>
   <span class="Constant"> .        .</span>
   <span class="Constant"> .        .</span>
  ]
]
</pre>
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