editing source code from within the app

integrated from pong.love via text.love:
  https://merveilles.town/@akkartik/108933336531898243

1 files changed, 377 insertions, 0 deletions

diff --git a/source_edit.lua b/source_edit.lua
new file mode 100644
index 0000000..d454467
--- /dev/null
+++ b/source_edit.lua
@@ -0,0 +1,377 @@
+-- some constants people might like to tweak
+Text_color = {r=0, g=0, b=0}
+Cursor_color = {r=1, g=0, b=0}
+Focus_stroke_color = {r=1, g=0, b=0}  -- what mouse is hovering over
+Highlight_color = {r=0.7, g=0.7, b=0.9}  -- selected text
+Fold_color = {r=0, g=0.6, b=0}
+Fold_background_color = {r=0, g=0.7, b=0}
+
+Margin_top = 15
+Margin_left = 25
+Margin_right = 25
+
+edit = {}
+
+-- run in both tests and a real run
+function edit.initialize_state(top, left, right, font_height, line_height)  -- currently always draws to bottom of screen
+  local result = {
+    -- a line of bifold text consists of an A side and an optional B side, each of which is a string
+    -- expanded: whether to show B side
+    lines = {{data='', dataB=nil, expanded=nil}},  -- array of lines
+
+    -- Lines can be too long to fit on screen, in which case they _wrap_ into
+    -- multiple _screen lines_.
+
+    -- rendering wrapped text lines needs some additional short-lived data per line:
+    --   startpos, the index of data the line starts rendering from, can only be >1 for topmost line on screen
+    --   starty, the y coord in pixels the line starts rendering from
+    --   fragments: snippets of rendered love.graphics.Text, guaranteed to not straddle screen lines
+    --   screen_line_starting_pos: optional array of grapheme indices if it wraps over more than one screen line
+    line_cache = {},
+
+    -- Given wrapping, any potential location for the text cursor can be described in two ways:
+    -- * schema 1: As a combination of line index and position within a line (in utf8 codepoint units)
+    -- * schema 2: As a combination of line index, screen line index within the line, and a position within the screen line.
+    -- Positions (and screen line indexes) can be in either the A or the B side.
+    --
+    -- Most of the time we'll only persist positions in schema 1, translating to
+    -- schema 2 when that's convenient.
+    --
+    -- Make sure these coordinates are never aliased, so that changing one causes
+    -- action at a distance.
+    screen_top1 = {line=1, pos=1, posB=nil},  -- position of start of screen line at top of screen
+    cursor1 = {line=1, pos=1, posB=nil},  -- position of cursor
+    screen_bottom1 = {line=1, pos=1, posB=nil},  -- position of start of screen line at bottom of screen
+
+    -- cursor coordinates in pixels
+    cursor_x = 0,
+    cursor_y = 0,
+
+    font_height = font_height,
+    line_height = line_height,
+    em = App.newText(love.graphics.getFont(), 'm'),  -- widest possible character width
+
+    top = top,
+    left = left,
+    right = right,
+    width = right-left,
+
+    filename = love.filesystem.getUserDirectory()..'/lines.txt',
+    next_save = nil,
+
+    -- undo
+    history = {},
+    next_history = 1,
+
+    -- search
+    search_term = nil,
+    search_text = nil,
+    search_backup = nil,  -- stuff to restore when cancelling search
+  }
+  return result
+end  -- App.initialize_state
+
+function edit.draw(State)
+  State.button_handlers = {}
+  App.color(Text_color)
+  assert(#State.lines == #State.line_cache)
+  if not Text.le1(State.screen_top1, State.cursor1) then
+    print(State.screen_top1.line, State.screen_top1.pos, State.screen_top1.posB, State.cursor1.line, State.cursor1.pos, State.cursor1.posB)
+    assert(false)
+  end
+  State.cursor_x = nil
+  State.cursor_y = nil
+  local y = State.top
+--?   print('== draw')
+  for line_index = State.screen_top1.line,#State.lines do
+    local line = State.lines[line_index]
+--?     print('draw:', y, line_index, line)
+    if y + State.line_height > App.screen.height then break end
+    State.screen_bottom1 = {line=line_index, pos=nil, posB=nil}
+--?     print('text.draw', y, line_index)
+    local startpos, startposB = 1, nil
+    if line_index == State.screen_top1.line then
+      if State.screen_top1.pos then
+        startpos = State.screen_top1.pos
+      else
+        startpos, startposB = nil, State.screen_top1.posB
+      end
+    end
+    y, State.screen_bottom1.pos, State.screen_bottom1.posB = Text.draw(State, line_index, y, startpos, startposB)
+    y = y + State.line_height
+--?     print('=> y', y)
+  end
+  if State.search_term then
+    Text.draw_search_bar(State)
+  end
+end
+
+function edit.update(State, dt)
+  if State.next_save and State.next_save < App.getTime() then
+    save_to_disk(State)
+    State.next_save = nil
+  end
+end
+
+function schedule_save(State)
+  if State.next_save == nil then
+    State.next_save = App.getTime() + 3  -- short enough that you're likely to still remember what you did
+  end
+end
+
+function edit.quit(State)
+  -- make sure to save before quitting
+  if State.next_save then
+    save_to_disk(State)
+  end
+end
+
+function edit.mouse_pressed(State, x,y, mouse_button)
+  if State.search_term then return end
+--?   print('press', State.selection1.line, State.selection1.pos)
+  if mouse_press_consumed_by_any_button_handler(State, x,y, mouse_button) then
+    -- press on a button and it returned 'true' to short-circuit
+    return
+  end
+
+  for line_index,line in ipairs(State.lines) do
+    if Text.in_line(State, line_index, x,y) then
+      local pos,posB = Text.to_pos_on_line(State, line_index, x, y)
+--?       print(x,y, 'setting cursor:', line_index, pos, posB)
+      State.cursor1 = {line=line_index, pos=pos, posB=posB}
+      break
+    end
+  end
+end
+
+function edit.mouse_released(State, x,y, mouse_button)
+end
+
+function edit.textinput(State, t)
+  for _,line_cache in ipairs(State.line_cache) do line_cache.starty = nil end  -- just in case we scroll
+  if State.search_term then
+    State.search_term = State.search_term..t
+    State.search_text = nil
+    Text.search_next(State)
+  else
+    Text.textinput(State, t)
+  end
+  schedule_save(State)
+end
+
+function edit.keychord_pressed(State, chord, key)
+  if State.search_term then
+    if chord == 'escape' then
+      State.search_term = nil
+      State.search_text = nil
+      State.cursor1 = State.search_backup.cursor
+      State.screen_top1 = State.search_backup.screen_top
+      State.search_backup = nil
+      Text.redraw_all(State)  -- if we're scrolling, reclaim all fragments to avoid memory leaks
+    elseif chord == 'return' then
+      State.search_term = nil
+      State.search_text = nil
+      State.search_backup = nil
+    elseif chord == 'backspace' then
+      local len = utf8.len(State.search_term)
+      local byte_offset = Text.offset(State.search_term, len)
+      State.search_term = string.sub(State.search_term, 1, byte_offset-1)
+      State.search_text = nil
+    elseif chord == 'down' then
+      if State.cursor1.pos then
+        State.cursor1.pos = State.cursor1.pos+1
+      else
+        State.cursor1.posB = State.cursor1.posB+1
+      end
+      Text.search_next(State)
+    elseif chord == 'up' then
+      Text.search_previous(State)
+    end
+    return
+  elseif chord == 'C-f' then
+    State.search_term = ''
+    State.search_backup = {
+      cursor={line=State.cursor1.line, pos=State.cursor1.pos, posB=State.cursor1.posB},
+      screen_top={line=State.screen_top1.line, pos=State.screen_top1.pos, posB=State.screen_top1.posB},
+    }
+    assert(State.search_text == nil)
+  -- bifold text
+  elseif chord == 'C-b' then
+    State.expanded = not State.expanded
+    Text.redraw_all(State)
+    if not State.expanded then
+      for _,line in ipairs(State.lines) do
+        line.expanded = nil
+      end
+      edit.eradicate_locations_after_the_fold(State)
+    end
+  elseif chord == 'C-d' then
+    if State.cursor1.posB == nil then
+      local before = snapshot(State, State.cursor1.line)
+      if State.lines[State.cursor1.line].dataB == nil then
+        State.lines[State.cursor1.line].dataB = ''
+      end
+      State.lines[State.cursor1.line].expanded = true
+      State.cursor1.pos = nil
+      State.cursor1.posB = 1
+      if Text.cursor_out_of_screen(State) then
+        Text.snap_cursor_to_bottom_of_screen(State, State.left, State.right)
+      end
+      schedule_save(State)
+      record_undo_event(State, {before=before, after=snapshot(State, State.cursor1.line)})
+    end
+  -- zoom
+  elseif chord == 'C-=' then
+    edit.update_font_settings(State, State.font_height+2)
+    Text.redraw_all(State)
+  elseif chord == 'C--' then
+    edit.update_font_settings(State, State.font_height-2)
+    Text.redraw_all(State)
+  elseif chord == 'C-0' then
+    edit.update_font_settings(State, 20)
+    Text.redraw_all(State)
+  -- undo
+  elseif chord == 'C-z' then
+    for _,line_cache in ipairs(State.line_cache) do line_cache.starty = nil end  -- just in case we scroll
+    local event = undo_event(State)
+    if event then
+      local src = event.before
+      State.screen_top1 = deepcopy(src.screen_top)
+      State.cursor1 = deepcopy(src.cursor)
+      patch(State.lines, event.after, event.before)
+      patch_placeholders(State.line_cache, event.after, event.before)
+      -- if we're scrolling, reclaim all fragments to avoid memory leaks
+      Text.redraw_all(State)
+      schedule_save(State)
+    end
+  elseif chord == 'C-y' then
+    for _,line_cache in ipairs(State.line_cache) do line_cache.starty = nil end  -- just in case we scroll
+    local event = redo_event(State)
+    if event then
+      local src = event.after
+      State.screen_top1 = deepcopy(src.screen_top)
+      State.cursor1 = deepcopy(src.cursor)
+      patch(State.lines, event.before, event.after)
+      -- if we're scrolling, reclaim all fragments to avoid memory leaks
+      Text.redraw_all(State)
+      schedule_save(State)
+    end
+  -- clipboard
+  elseif chord == 'C-c' then
+    local s = Text.selection(State)
+    if s then
+      App.setClipboardText(s)
+    end
+  elseif chord == 'C-x' then
+    for _,line_cache in ipairs(State.line_cache) do line_cache.starty = nil end  -- just in case we scroll
+    local s = Text.cut_selection(State, State.left, State.right)
+    if s then
+      App.setClipboardText(s)
+    end
+    schedule_save(State)
+  elseif chord == 'C-v' then
+    for _,line_cache in ipairs(State.line_cache) do line_cache.starty = nil end  -- just in case we scroll
+    -- We don't have a good sense of when to scroll, so we'll be conservative
+    -- and sometimes scroll when we didn't quite need to.
+    local before_line = State.cursor1.line
+    local before = snapshot(State, before_line)
+    local clipboard_data = App.getClipboardText()
+    for _,code in utf8.codes(clipboard_data) do
+      local c = utf8.char(code)
+      if c == '\n' then
+        Text.insert_return(State)
+      else
+        Text.insert_at_cursor(State, c)
+      end
+    end
+    if Text.cursor_out_of_screen(State) then
+      Text.snap_cursor_to_bottom_of_screen(State, State.left, State.right)
+    end
+    schedule_save(State)
+    record_undo_event(State, {before=before, after=snapshot(State, before_line, State.cursor1.line)})
+  -- dispatch to text
+  else
+    for _,line_cache in ipairs(State.line_cache) do line_cache.starty = nil end  -- just in case we scroll
+    Text.keychord_pressed(State, chord)
+  end
+end
+
+function edit.eradicate_locations_after_the_fold(State)
+  -- eradicate side B from any locations we track
+  if State.cursor1.posB then
+    State.cursor1.posB = nil
+    State.cursor1.pos = utf8.len(State.lines[State.cursor1.line].data)
+    State.cursor1.pos = Text.pos_at_start_of_screen_line(State, State.cursor1)
+  end
+  if State.screen_top1.posB then
+    State.screen_top1.posB = nil
+    State.screen_top1.pos = utf8.len(State.lines[State.screen_top1.line].data)
+    State.screen_top1.pos = Text.pos_at_start_of_screen_line(State, State.screen_top1)
+  end
+end
+
+function edit.key_released(State, key, scancode)
+end
+
+function edit.update_font_settings(State, font_height)
+  State.font_height = font_height
+  love.graphics.setFont(love.graphics.newFont(Editor_state.font_height))
+  State.line_height = math.floor(font_height*1.3)
+  State.em = App.newText(love.graphics.getFont(), 'm')
+  Text_cache = {}
+end
+
+--== some methods for tests
+
+Test_margin_left = 25
+
+function edit.initialize_test_state()
+  -- if you change these values, tests will start failing
+  return edit.initialize_state(
+      15,  -- top margin
+      Test_margin_left,
+      App.screen.width,  -- right margin = 0
+      14,  -- font height assuming default LÖVE font
+      15)  -- line height
+end
+
+-- all textinput events are also keypresses
+-- TODO: handle chords of multiple keys
+function edit.run_after_textinput(State, t)
+  edit.keychord_pressed(State, t)
+  edit.textinput(State, t)
+  edit.key_released(State, t)
+  App.screen.contents = {}
+  edit.draw(State)
+end
+
+-- not all keys are textinput
+function edit.run_after_keychord(State, chord)
+  edit.keychord_pressed(State, chord)
+  edit.key_released(State, chord)
+  App.screen.contents = {}
+  edit.draw(State)
+end
+
+function edit.run_after_mouse_click(State, x,y, mouse_button)
+  App.fake_mouse_press(x,y, mouse_button)
+  edit.mouse_pressed(State, x,y, mouse_button)
+  App.fake_mouse_release(x,y, mouse_button)
+  edit.mouse_released(State, x,y, mouse_button)
+  App.screen.contents = {}
+  edit.draw(State)
+end
+
+function edit.run_after_mouse_press(State, x,y, mouse_button)
+  App.fake_mouse_press(x,y, mouse_button)
+  edit.mouse_pressed(State, x,y, mouse_button)
+  App.screen.contents = {}
+  edit.draw(State)
+end
+
+function edit.run_after_mouse_release(State, x,y, mouse_button)
+  App.fake_mouse_release(x,y, mouse_button)
+  edit.mouse_released(State, x,y, mouse_button)
+  App.screen.contents = {}
+  edit.draw(State)
+end