Stack blocks with different effects to transform one sequence of shapes into another

love-stack-puzzle.lua

-- To run:
--   Download LÖVE from https://love2d.org
--   Download this file to a directory and rename it to `main.lua`
--   Run the program from that directory.
--     * on Linux (using the appimage binary): `chmod +x path/to/love-11.4-x86_64.AppImage; path/to/love-11.4-x86_64.AppImage .`
--     * on Mac: `path/to/love.app/Contents/MacOS/love .`
--
-- Click on rounded rectangles to see what they do.
-- Use ctrl-n and ctrl-p to jump between puzzles.

-- ### a small evaluator for a few operators over a few values

operators = {'dup', 'fill', 'swap'}
values = {'square', 'circle', 'triangle', 'fill-square', 'fill-circle', 'fill-triangle'}

function eval(program, input)
  local x = input
  for _, op in ipairs(program) do
    local out = {}
    if op == 'dup' then
      for _, a in ipairs(x) do
        table.insert(out, a)
        table.insert(out, a)
      end
    elseif op == 'fill' then
      for _, a in ipairs(x) do
        if a:match('fill-') then
          table.insert(out, a)
        else
          table.insert(out, 'fill-'..a)
        end
      end
    elseif op == 'swap' then
      for i=1,#x,2 do
        if i < #x then
          table.insert(out, x[i+1])
        end
        table.insert(out, x[i])
      end
    end
    x = out
  end
  return x
end

function eval_print(program, input)
  local out = eval(program, input)
  for _, x in ipairs(out) do
    print(x)
  end
end

--? eval_print({'swap'}, {'square'})

-- helpers to draw values (20x20 squares) and operators (100x60 buttons)

function draw_value(x,y, value)
  if value == 'square' then
    rect('line', x,y, 20,20)
  elseif value == 'circle' then
    circle('line', x+10,y+10, 10)
  elseif value == 'triangle' then
    polygon('line', x+10,y, x,y+20, x+20,y+20)
  elseif value == 'fill-square' then
    rect('fill', x,y, 20,20)
  elseif value == 'fill-circle' then
    circle('fill', x+10,y+10, 10)
  elseif value == 'fill-triangle' then
    polygon('fill', x+10,y, x,y+20, x+20,y+20)
  end
end

draw = {}

function draw.dup(x, y)
  color(0.5, 0.5, 0.5)
  rect('fill', x,y, 100,60, 5,5)
  color(1, 1, 1)
  draw_value(x+25,y+5, 'square')
  draw_value(x+55,y+5, 'square')
  color(0.75, 0.75, 0.75)
  line(x+5,y+30, x+95,y+30)
  color(1, 1, 1)
  draw_value(x+40,y+35, 'square')
end

function draw.fill(x, y)
  color(0.5, 0.5, 0.5)
  rect('fill', x,y, 100,60, 5,5)
  color(1, 1, 1)
  draw_value(x+40,y+5, 'fill-square')
  color(0.75, 0.75, 0.75)
  line(x+5,y+30, x+95,y+30)
  color(1, 1, 1)
  draw_value(x+40,y+35, 'square')
end

function draw.swap(x, y)
  color(0.5, 0.5, 0.5)
  rect('fill', x,y, 100,60, 5,5)
  color(1, 1, 1)
  draw_value(x+25,y+5, 'square')
  draw_value(x+55,y+5, 'circle')
  color(0.75, 0.75, 0.75)
  line(x+5,y+30, x+95,y+30)
  color(1, 1, 1)
  draw_value(x+25,y+35, 'circle')
  draw_value(x+55,y+35, 'square')
end

-- ### UI

width = 640
height = 480
love.window.setMode(width, height)
love.window.setTitle('Love Stacking')

-- the window has 2 parts: the tray of tools and the stacking area
toolx, tooly = 5, 5
toolw, toolh = 150, height-10
stackx, stacky = 5+toolw+5, 5
stackw, stackh = width-stackx-5, height-10

-- app data
exercises = {
  {
    input = {'square'},
    expected_output = {'square', 'square'},
  },
  {
    input = {'square'},
    expected_output = {'fill-square'},
  },
  {
    input = {'circle'},
    expected_output = {'circle', 'circle'},
  },
  {
    input = {'circle'},
    expected_output = {'fill-circle'},
  },
  {
    input = {'triangle'},
    expected_output = {'triangle', 'triangle'},
  },
  {
    input = {'triangle'},
    expected_output = {'fill-triangle'},
  },
  {
    input = {'circle', 'square'},
    expected_output = {'square', 'circle'},
  },
  {
    input = {'circle', 'square', 'triangle'},
    expected_output = {'circle', 'circle', 'square', 'square', 'triangle', 'triangle'},
  },
  {
    input = {'circle', 'square', 'triangle'},
    expected_output = {'square', 'circle', 'triangle'},
  },
  {
    input = {'triangle'},
    expected_output = {'fill-triangle', 'fill-triangle'},
  },
  {
    input = {'circle', 'square', 'triangle', 'circle'},
    expected_output = {'square', 'circle', 'circle', 'triangle'},
  },
  {
    input = {'triangle', 'square'},
    expected_output = {'fill-square', 'fill-triangle'},
  },
}

stack = {}
exercise_index = 1
input = exercises[exercise_index].input
expected_output = exercises[exercise_index].expected_output

function love.keychord_pressed(key)
  if key == 'C-n' then
    if exercise_index < #exercises then
      exercise_index = exercise_index+1
      input = exercises[exercise_index].input
      expected_output = exercises[exercise_index].expected_output
      stack = {}
    end
  elseif key == 'C-p' then
    if exercise_index > 1 then
      exercise_index = exercise_index-1
      input = exercises[exercise_index].input
      expected_output = exercises[exercise_index].expected_output
      stack = {}
    end
  elseif key == 'C-r' then
    stack = {}
  end
end

button_handlers = {}

function love.draw()
  button_handlers = {}
  draw_tools()
  draw_stack()
end

function draw_tools()
  color(0.2, 0.2, 0.2)
  rect('fill', toolx,tooly, toolw,toolh)

  button_to_push_operator_on_stack('dup', 25)
  button_to_push_operator_on_stack('fill', 100)
  button_to_push_operator_on_stack('swap', 175)
end

function draw_stack()
  -- background
  color(0.25,0.25,0.25)
  rect('fill', stackx,stacky, stackw,stackh)
  -- input and expected output values
  color(1,1,1)
  local output = eval(stack, input)
  if table_equal(output, expected_output) then
    color(0,1,0)
  end
  draw_values(50, expected_output)
  color(1,1,1)
  draw_values(445, input)
  -- stack of operators
  color(1,1,1)
  local y = 425
  for i,op in ipairs(stack) do
    y = y-75
    button_to_remove_operator_from_stack(op, i, y)
    if i < #stack then
      y = y-50
      local out = eval(slice(stack, 1,i), input)
      draw_values(y, out)
    end
  end
  -- color final output differently
  y = y-50
  local output = eval(stack, input)
  if table_equal(output, expected_output) then
    color(0,1,0)
    draw_values(y, output)
  else
    color(1,0,0)
    draw_values(y, output)
  end
end

function button_to_remove_operator_from_stack(name, i, y)
  button(name, {x=225,y=y, w=100,h=60, color={0.50,0.50,0.50},
    icon = draw[name],
    onpress1 = function() table.remove(stack, i) end})
end

function button_to_push_operator_on_stack(name, y)
  button(name, {x=25,y=y, w=100,h=60, color={0.50,0.50,0.50},
    icon = draw[name],
    onpress1 = function() table.insert(stack, name) end})
end

function draw_values(y, values)
  local x = 350
  for _, value in ipairs(values) do
    draw_value(x,y, value)
    x = x+25
  end
end

-- draw button and queue up event handlers
function button(name, params)
  color(params.color[1], params.color[2], params.color[3])
  rect('fill', params.x,params.y, params.w,params.h, 5,5)
  if params.icon then params.icon(params.x, params.y) end
  table.insert(button_handlers, params)
end

-- process button event handlers
function love.mousepressed(x, y, button)
  for _,ev in ipairs(button_handlers) do
    if x>ev.x and x<ev.x+ev.w and y>ev.y and y<ev.y+ev.h then
      if ev.onpress1 and button == 1 then ev.onpress1() end
    end
  end
end

-- misc helpers
line = love.graphics.line
color = love.graphics.setColor
rect = love.graphics.rectangle
circle = love.graphics.circle
polygon = love.graphics.polygon

function table_equal(a, b)
  for k, v in pairs(a) do
    if b[k] ~= v then
      return false
    end
  end
  for k, v in pairs(b) do
    if a[k] ~= v then
      return false
    end
  end
  return true
end

function slice(h, s,e)
  local result = {}
  for i=s,e do
    table.insert(result, h[i])
  end
  return result
end

-- Keyboard driver

function love.keypressed(key, scancode, isrepeat)
  if key == 'lctrl' or key == 'rctrl' or key == 'lalt' or key == 'ralt' or key == 'lshift' or key == 'rshift' or key == 'lgui' or key == 'rgui' then
    -- do nothing when the modifier is pressed
  end
  -- include the modifier(s) when the non-modifer is pressed
  love.keychord_pressed(combine_modifiers(key))
end

function combine_modifiers(key)
  local result = ''
  local down = love.keyboard.isDown
  if down('lctrl') or down('rctrl') then
    result = result..'C-'
  end
  if down('lalt') or down('ralt') then
    result = result..'M-'
  end
  if down('lgui') or down('rgui') then
    result = result..'S-'
  end
  result = result..key
  return result
end