monotonically accumulate versions of definitions

One old drawback now has a new look. Before, we loaded definitions in
order, so global definitions had to exist before other global
definitions that used them. See window and grid in life.tlv. Now we load
definitions in reverse order, so initialization needs to change. Worse,
if we update window, we need to edit grid just to fix the order.

This implies that we can't yet optimize away bindings where there are no
new changes.

chesstv.tlv

@@ -1,10 +1,16 @@
 teliva_program = {
+  {
     window = [==[
 window = curses.stdscr()
 -- animation-based app
 window:nodelay(true)
 lines, cols = window:getmaxyx()]==],
-    current_game = [==[current_game = {}]==],
+  },
+  {
+    current_game = [==[
+current_game = {}]==],
+  },
+  {
     piece_glyph = [==[
 piece_glyph = {
   -- for legibility, white pieces also use unicode glyphs for black pieces
@@ -22,6 +28,8 @@ piece_glyph = {
   n = 0x265e,
   p = 0x265f,
 }]==],
+  },
+  {
     top_player = [==[
 function top_player(current_game)
   if current_game.players[1].color == "black" then
@@ -29,6 +37,8 @@ function top_player(current_game)
   end
   return current_game.players[2]
 end]==],
+  },
+  {
     bottom_player = [==[
 function bottom_player(current_game)
   if current_game.players[1].color == "white" then
@@ -36,12 +46,16 @@ function bottom_player(current_game)
   end
   return current_game.players[2]
 end]==],
+  },
+  {
     render_player = [==[
 function render_player(y, x, player)
   curses.mvaddstr(y, x, player.user.name)
   curses.addstr(" · ")
   curses.addstr(tostring(player.rating))
 end]==],
+  },
+  {
     render_square = [==[
 function render_square(current_game, rank, file, highlighted_squares)
   -- decide whether to highlight
@@ -62,6 +76,8 @@ function render_square(current_game, rank, file, highlighted_squares)
   curses.mvaddstr((8 - rank + 1)*3+2, file*5, "     ")
   curses.attrset(curses.A_NORMAL)
 end]==],
+  },
+  {
     render_fen_rank = [==[
 function render_fen_rank(rank, fen_rank, highlighted_squares)
   local file = 1
@@ -98,12 +114,16 @@ function render_fen_rank(rank, fen_rank, highlighted_squares)
     end
   end
 end]==],
+  },
+  {
     render_time = [==[
 function render_time(y, x, seconds)
   if seconds == nil then return end
   curses.mvaddstr(y, x, tostring(math.floor(seconds/60)))
   curses.addstr(string.format(":%02d", seconds%60))
 end]==],
+  },
+  {
     render_board = [==[
 function render_board(current_game)
 --?   curses.mvaddstr(1, 50, dump(current_game.fen))
@@ -119,6 +139,8 @@ function render_board(current_game)
   render_player(27, 5, bottom_player(current_game))
   render_time(27, 35, current_game.wc)
 end]==],
+  },
+  {
     parse_lm = [==[
 function parse_lm(move)
 --?   curses.mvaddstr(4, 50, move)
@@ -129,6 +151,8 @@ function parse_lm(move)
 --?   curses.mvaddstr(5, 50, dump({{rank1, file1}, {rank2, file2}}))
   return {from={rank=rank1, file=file1}, to={rank=rank2, file=file2}}
 end]==],
+  },
+  {
     render = [==[
 function render(chunk)
   local o = json.decode(chunk)
@@ -149,6 +173,8 @@ function render(chunk)
   render_board(current_game)
   curses.refresh()
 end]==],
+  },
+  {
     init_colors = [==[
 function init_colors()
   -- colors
@@ -168,6 +194,8 @@ function init_colors()
   curses.init_pair(7, light_piece, dark_last_moved_square)
   curses.init_pair(8, dark_piece, dark_last_moved_square)
 end]==],
+  },
+  {
     main = [==[
 function main()
   init_colors()
@@ -184,6 +212,8 @@ function main()
   }
   http.request(request)
 end]==],
+  },
+  {
     utf8 = [==[
 -- https://stackoverflow.com/questions/7983574/how-to-write-a-unicode-symbol-in-lua
 function utf8(decimal)
@@ -203,6 +233,8 @@ function utf8(decimal)
   end
   return table.concat(charbytes)
 end]==],
+  },
+  {
     split = [==[
 function split(s, pat)
   result = {}
@@ -211,6 +243,8 @@ function split(s, pat)
   end
   return result
 end]==],
+  },
+  {
     dump = [==[
 -- https://stackoverflow.com/questions/9168058/how-to-dump-a-table-to-console
 function dump(o)
@@ -225,4 +259,5 @@ function dump(o)
     return tostring(o)
   end
 end]==],
+  },
 }

counter.tlv

@@ -1,7 +1,14 @@
 teliva_program = {
-    window = [==[window = curses.stdscr()]==],
+  {
-    n = [==[n = 0]==],
+  window = [==[
-    render = [==[
+window = curses.stdscr()]==],
+  },
+  {
+  n = [==[
+n = 0]==],
+  },
+  {
+  render = [==[
 function render(window)
   window:clear()
   window:attron(curses.A_BOLD)
@@ -12,15 +19,22 @@ function render(window)
   window:attroff(curses.A_BOLD)
   curses.refresh()
 end]==],
-    menu = [==[menu = {Enter="increment"}]==],
+  },
-    update = [==[
+  {
+  menu = [==[
+menu = {Enter="increment"}]==],
+  },
+  {
+  update = [==[
 function update(window)
   local key = curses.getch()
   if key == 10 then
     n = n+1
   end
 end]==],
-    main = [==[
+  },
+  {
+  main = [==[
 function main()
   for i=1,7 do
     curses.init_pair(i, 0, i)
@@ -31,4 +45,5 @@ function main()
     update(window)
   end
 end]==],
+  },
 }

hanoi.tlv

@@ -1,4 +1,5 @@
 teliva_program = {
+  {
     render = [==[
 function render(window)
   window:clear()
@@ -10,16 +11,25 @@ function render(window)
   end
   curses.refresh()
 end]==],
+  },
+  {
     lines = [==[
 function lines(window)
   local lines, cols = window:getmaxyx()
   return lines
 end]==],
+  },
+  {
     pop = [==[
 function pop(array)
   return table.remove(array)
 end]==],
-    window = [==[window = curses.stdscr()]==],
+  },
+  {
+    window = [==[
+window = curses.stdscr()]==],
+  },
+  {
     render_tower = [==[
 function render_tower(window, line, col, tower_index, tower)
   window:attron(curses.A_BOLD)
@@ -39,7 +49,12 @@ function render_tower(window, line, col, tower_index, tower)
     line = line - 1
   end
 end]==],
-    tower = [==[tower = {{6, 5, 4, 3, 2}, {}, {}}]==],
+  },
+  {
+    tower = [==[
+tower = {{6, 5, 4, 3, 2}, {}, {}}]==],
+  },
+  {
     render_disk = [==[
 function render_disk(window, line, col, size)
   col = col-size+1
@@ -50,6 +65,8 @@ function render_disk(window, line, col, size)
     col = col+2
   end
 end]==],
+  },
+  {
     main = [==[
 function main()
   for i=1,7 do
@@ -62,6 +79,8 @@ function main()
   end
 end
 ]==],
+  },
+  {
     len = [==[
 function len(array)
   local result = 0
@@ -70,6 +89,8 @@ function len(array)
   end
   return result
 end]==],
+  },
+  {
     update = [==[
 function update(window)
   window:mvaddstr(lines(window)-2, 5, "tower to remove top disk from? ")
@@ -78,14 +99,19 @@ function update(window)
   local to = curses.getch() - 96
   make_move(from, to)
 end]==],
+  },
+  {
     make_move = [==[
 function make_move(from, to)
   local disk = pop(tower[from])
   table.insert(tower[to], disk)
 end]==],
+  },
+  {
     cols = [==[
 function cols(window)
   local lines, cols = window:getmaxyx()
   return cols
 end]==],
+  },
 }

life.tlv

@@ -1,9 +1,5 @@
 teliva_program = {
-    window = [==[
+  {
-window = curses.stdscr()
--- animation-based app
-window:nodelay(true)
-lines, cols = window:getmaxyx()]==],
     grid = [==[
 -- main data structure
 grid = {}
@@ -14,6 +10,15 @@ for i=1,lines*4 do
   end
 end
 ]==],
+  },
+  {
+    window = [==[
+window = curses.stdscr()
+-- animation-based app
+window:nodelay(true)
+lines, cols = window:getmaxyx()]==],
+  },
+  {
     grid_char = [==[
 -- grab a 4x2 chunk of grid
 function grid_char(line, col)
@@ -23,6 +28,8 @@ function grid_char(line, col)
   end
   return result
 end]==],
+  },
+  {
     print_grid_char = [==[
 function print_grid_char(window, x)
   result = {}
@@ -33,6 +40,8 @@ function print_grid_char(window, x)
   end
   return result
 end]==],
+  },
+  {
     glyph = [==[
 -- look up the braille pattern corresponding to a 4x2 chunk of grid
 -- https://en.wikipedia.org/wiki/Braille_Patterns
@@ -56,6 +65,8 @@ glyph = {
   0x28b0, 0x28b1, 0x28b2, 0x28b3, 0x28b4, 0x28b5, 0x28b6, 0x28b7,   0x28f0, 0x28f1, 0x28f2, 0x28f3, 0x28f4, 0x28f5, 0x28f6, 0x28f7,
   0x28b8, 0x28b9, 0x28ba, 0x28bb, 0x28bc, 0x28bd, 0x28be, 0x28bf,   0x28f8, 0x28f9, 0x28fa, 0x28fb, 0x28fc, 0x28fd, 0x28fe, 0x28ff,
 }]==],
+  },
+  {
     utf8 = [==[
 -- https://stackoverflow.com/questions/7983574/how-to-write-a-unicode-symbol-in-lua
 function utf8(decimal)
@@ -75,6 +86,8 @@ function utf8(decimal)
   end
   return table.concat(charbytes)
 end]==],
+  },
+  {
     grid_char_to_glyph_index = [==[
 -- convert a chunk of grid into a number
 function grid_char_to_glyph_index(g)
@@ -82,6 +95,8 @@ function grid_char_to_glyph_index(g)
          g[1][2]*16 + g[2][2]*32 + g[3][2]*64 + g[4][2]*128 +
          1  -- 1-indexing
 end]==],
+  },
+  {
     render = [==[
 function render(window)
   window:clear()
@@ -93,6 +108,8 @@ function render(window)
   curses.refresh()
 end
 ]==],
+  },
+  {
     state = [==[
 function state(line, col)
   if line < 1 or line > table.getn(grid) or col < 1 or col > table.getn(grid[1]) then
@@ -100,12 +117,16 @@ function state(line, col)
   end
   return grid[line][col]
 end]==],
+  },
+  {
     num_live_neighbors = [==[
 function num_live_neighbors(line, col)
   return state(line-1, col-1) + state(line-1, col) + state(line-1, col+1) +
          state(line,   col-1) +                      state(line,   col+1) +
          state(line+1, col-1) + state(line+1, col) + state(line+1, col+1)
 end]==],
+  },
+  {
     step = [==[
 function step()
   local new_grid = {}
@@ -124,12 +145,16 @@ function step()
   end
   grid = new_grid
 end]==],
+  },
+  {
     sleep = [==[
 function sleep(a)
     local sec = tonumber(os.clock() + a);
     while (os.clock() < sec) do
     end
 end]==],
+  },
+  {
     file_exists = [==[
 function file_exists(filename)
   local f = io.open(filename, "r")
@@ -140,6 +165,8 @@ function file_exists(filename)
     return false
   end
 end]==],
+  },
+  {
     load_file = [==[
 function load_file(window, filename)
   io.input(filename)
@@ -160,6 +187,8 @@ function load_file(window, filename)
     end
   end
 end]==],
+  },
+  {
     update = [==[
 menu = {arrow="pan"}
 
@@ -198,6 +227,8 @@ function update(window, c)
     end
   end
 end]==],
+  },
+  {
     main = [==[
 function main()
   for i=1,7 do
@@ -274,4 +305,5 @@ function main()
     step()
   end
 end]==],
+  },
 }

src/lua.c

@@ -280,27 +280,64 @@ void stack_dump (lua_State *L) {
 }
 
 
+static int binding_exists (lua_State *L, const char *name) {
+  int result = 0;
+  lua_getglobal(L, name);
+  result = !lua_isnil(L, -1);
+  lua_pop(L, 1);
+  return result;
+}
+
+
+static const char *look_up_definition (lua_State *L, const char *name) {
+  lua_getglobal(L, "teliva_program");
+  int history_array = lua_gettop(L);
+  /* iterate over mutations in teliva_program history in reverse order */
+  int history_array_size = luaL_getn(L, history_array);
+  for (int i = history_array_size; i > 0; --i) {
+    lua_rawgeti(L, history_array, i);
+    int table = lua_gettop(L);
+    /* iterate over bindings */
+    /* really we expect only one */
+    for (lua_pushnil(L); lua_next(L, table) != 0; lua_pop(L, 1)) {
+      const char* key = lua_tostring(L, -2);
+      if (strcmp(key, name) == 0)
+        return lua_tostring(L, -1);
+    }
+  }
+  lua_pop(L, 1);
+  return NULL;
+}
+
+
 char *Image_name = NULL;
 static int handle_image (lua_State *L, char **argv, int n) {
   int status;
   int narg = getargs(L, argv, n);  /* collect arguments */
   lua_setglobal(L, "arg");
-  /* parse and load file contents (teliva_program table) */
+  /* parse and load file contents (teliva_program array) */
   Image_name = argv[n];
   status = luaL_loadfile(L, Image_name);
   lua_insert(L, -(narg+1));
-  if (status != 0) {
+  if (status != 0) return status;
-    return status;
-  }
   status = docall(L, narg, 0);
   lua_getglobal(L, "teliva_program");
-  int table = lua_gettop(L);
+  int history_array = lua_gettop(L);
-  /* parse and load each binding in teliva_program */
+  /* iterate over mutations in teliva_program history in reverse order */
-  for (lua_pushnil(L); lua_next(L, table) != 0; lua_pop(L, 1)) {
+  int history_array_size = luaL_getn(L, history_array);
-    const char* key = lua_tostring(L, -2);
+  for (int i = history_array_size; i > 0; --i) {
-    const char* value = lua_tostring(L, -1);
+    lua_rawgeti(L, history_array, i);
-    status = dostring(L, value, key);
+    int table = lua_gettop(L);
-    if (status != 0) return report(L, status);
+    /* iterate over bindings */
+    /* really we expect only one */
+    for (lua_pushnil(L); lua_next(L, table) != 0; lua_pop(L, 1)) {
+      const char* key = lua_tostring(L, -2);
+      if (binding_exists(L, key))
+        continue;  // most recent binding trumps older ones
+      const char* value = lua_tostring(L, -1);
+      status = dostring(L, value, key);
+      if (status != 0) return report(L, status);
+    }
   }
   /* call main() */
   lua_getglobal(L, "main");
@@ -314,10 +351,7 @@ static int handle_image (lua_State *L, char **argv, int n) {
 char Current_definition[CURRENT_DEFINITION_LEN+1] = {0};
 void save_to_current_definition_and_editor_buffer (lua_State *L, const char *definition) {
   strncpy(Current_definition, definition, CURRENT_DEFINITION_LEN);
-  lua_getglobal(L, "teliva_program");
+  const char *contents = look_up_definition(L, Current_definition);
-  lua_getfield(L, -1, Current_definition);
-  const char *contents = lua_tostring(L, -1);
-  lua_pop(L, 1);
   FILE *out = fopen("teliva_editbuffer", "w");
   if (contents != NULL)
     fprintf(out, "%s", contents);
@@ -333,27 +367,42 @@ static void read_editor_buffer (char *out) {
 }
 
 
-/* table to update is at top of stack */
+static void update_definition (lua_State *L, const char *name, char *new_contents) {
-static void update_definition (lua_State *L, const char *name, char *out) {
+  assert(lua_gettop(L) == 0);
   lua_getglobal(L, "teliva_program");
-  lua_pushstring(L, out);
+  int history_array = 1;
+  /* create a new table containing a single binding */
+  lua_createtable(L, /*number of fields per mutation*/2, 0);
+  lua_pushstring(L, new_contents);
   assert(strlen(name) > 0);
   lua_setfield(L, -2, name);
+  /* append the new table to the history of mutations */
+  int history_array_size = luaL_getn(L, history_array);
+  ++history_array_size;
+  lua_rawseti(L, history_array, history_array_size);
   lua_settop(L, 0);
 }
 
 
 static void save_image (lua_State *L) {
   lua_getglobal(L, "teliva_program");
-  int table = lua_gettop(L);
+  int history_array = lua_gettop(L);
-  FILE *out = fopen(Image_name, "w");
+  int history_array_size = luaL_getn(L, history_array);
+  FILE* out = fopen(Image_name, "w");
   fprintf(out, "teliva_program = {\n");
-  for (lua_pushnil(L); lua_next(L, table) != 0; lua_pop(L, 1)) {
+  for (int i = 1;  i <= history_array_size; ++i) {
-    const char *key = lua_tostring(L, -2);
+    lua_rawgeti(L, history_array, i);
-    const char *value = lua_tostring(L, -1);
+    int table = lua_gettop(L);
-    fprintf(out, "  %s = [==[", key);
+    fprintf(out, "  {\n");
-    fprintf(out, "%s", value);
+    for (lua_pushnil(L); lua_next(L, table) != 0; lua_pop(L, 1)) {
-    fprintf(out, "]==],\n");
+      const char* key = lua_tostring(L, -2);
+      const char* value = lua_tostring(L, -1);
+      fprintf(out, "    %s = [==[\n", key);
+      fprintf(out, "%s", value);
+      fprintf(out, "]==],\n");
+    }
+    fprintf(out, "  },\n");
+    lua_pop(L, 1);
   }
   fprintf(out, "}\n");
   fclose(out);
@@ -434,46 +483,55 @@ int browse_image (lua_State *L) {
   clear();
   luaL_newmetatable(L, "__teliva_call_graph_depth");
   int cgt = lua_gettop(L);
-  // special-case: we don't instrument the call to main, but it's always 1
+  // special-case: we don't instrument the call to main, but it's always at depth 1
   lua_pushinteger(L, 1);
   lua_setfield(L, cgt, "main");
   // segment definitions by depth
   lua_getglobal(L, "teliva_program");
-  int t = lua_gettop(L);
+  int history_array = lua_gettop(L);
+  int history_array_size = luaL_getn(L, history_array);
 
   int y = 2;
   mvaddstr(y, 0, "data:           ");
   // first: data (non-functions) that's not the Teliva menu or curses variables
-  for (lua_pushnil(L); lua_next(L, t) != 0;) {
+  for (int i = history_array_size; i > 0; --i) {
-    const char *definition_name = lua_tostring(L, -2);
+    lua_rawgeti(L, history_array, i);
-    lua_getglobal(L, definition_name);
+    int t = lua_gettop(L);
-    int is_userdata = lua_isuserdata(L, -1);
+    for (lua_pushnil(L); lua_next(L, t) != 0;) {
-    int is_function = lua_isfunction(L, -1);
+      const char *definition_name = lua_tostring(L, -2);
-    lua_pop(L, 1);
+      lua_getglobal(L, definition_name);
-    if (strcmp(definition_name, "menu") != 0  // required by all Teliva programs
+      int is_userdata = lua_isuserdata(L, -1);
-        && !is_function  // functions are not data
+      int is_function = lua_isfunction(L, -1);
-        && !is_userdata  // including curses window objects
+      lua_pop(L, 1);
-                         // (unlikely to have an interesting definition)
+      if (strcmp(definition_name, "menu") != 0  // required by all Teliva programs
-    ) {
+          && !is_function  // functions are not data
-      browse_definition(definition_name);
+          && !is_userdata  // including curses window objects
+                           // (unlikely to have an interesting definition)
+      ) {
+        browse_definition(definition_name);
+      }
+      lua_pop(L, 1);  // value
+      // leave key on stack for next iteration
     }
-    lua_pop(L, 1);  // value
-    // leave key on stack for next iteration
   }
 
   // second: menu and other userdata
-  for (lua_pushnil(L); lua_next(L, t) != 0;) {
+  for (int i = history_array_size; i > 0; --i) {
-    const char* definition_name = lua_tostring(L, -2);
+    lua_rawgeti(L, history_array, i);
-    lua_getglobal(L, definition_name);
+    int t = lua_gettop(L);
-    int is_userdata = lua_isuserdata(L, -1);
+    for (lua_pushnil(L); lua_next(L, t) != 0;) {
-    lua_pop(L, 1);
+      const char* definition_name = lua_tostring(L, -2);
-    if (strcmp(definition_name, "menu") == 0
+      lua_getglobal(L, definition_name);
-        || is_userdata  // including curses window objects
+      int is_userdata = lua_isuserdata(L, -1);
-    ) {
+      lua_pop(L, 1);
-      browse_definition(definition_name);
+      if (strcmp(definition_name, "menu") == 0
+          || is_userdata  // including curses window objects
+      ) {
+        browse_definition(definition_name);
+      }
+      lua_pop(L, 1);  // value
+      // leave key on stack for next iteration
     }
-    lua_pop(L, 1);  // value
-    // leave key on stack for next iteration
   }
 
   // functions by level
@@ -482,32 +540,40 @@ int browse_image (lua_State *L) {
   y++;
   for (int level = 1; level < 5; ++level) {
     mvaddstr(y, 0, "                ");
-    for (lua_pushnil(L); lua_next(L, t) != 0;) {
+    for (int i = history_array_size; i > 0; --i) {
-      const char* definition_name = lua_tostring(L, -2);
+      lua_rawgeti(L, history_array, i);
-      lua_getfield(L, cgt, definition_name);
+      int t = lua_gettop(L);
-      int depth = lua_tointeger(L, -1);
+      for (lua_pushnil(L); lua_next(L, t) != 0;) {
-      if (depth == level)
+        const char* definition_name = lua_tostring(L, -2);
-        browse_definition(definition_name);
+        lua_getfield(L, cgt, definition_name);
-      lua_pop(L, 1);  // depth of value
+        int depth = lua_tointeger(L, -1);
-      lua_pop(L, 1);  // value
+        if (depth == level)
-      // leave key on stack for next iteration
+          browse_definition(definition_name);
+        lua_pop(L, 1);  // depth of value
+        lua_pop(L, 1);  // value
+        // leave key on stack for next iteration
+      }
     }
     y += 2;
   }
 
   // unused functions
   mvaddstr(y, 0, "                ");
-  for (lua_pushnil(L); lua_next(L, t) != 0;) {
+  for (int i = history_array_size; i > 0; --i) {
-    const char* definition_name = lua_tostring(L, -2);
+    lua_rawgeti(L, history_array, i);
-    lua_getglobal(L, definition_name);
+    int t = lua_gettop(L);
-    int is_function = lua_isfunction(L, -1);
+    for (lua_pushnil(L); lua_next(L, t) != 0;) {
-    lua_pop(L, 1);
+      const char* definition_name = lua_tostring(L, -2);
-    lua_getfield(L, cgt, definition_name);
+      lua_getglobal(L, definition_name);
-    if (is_function && lua_isnoneornil(L, -1))
+      int is_function = lua_isfunction(L, -1);
-      browse_definition(definition_name);
+      lua_pop(L, 1);
-    lua_pop(L, 1);  // depth of value
+      lua_getfield(L, cgt, definition_name);
-    lua_pop(L, 1);  // value
+      if (is_function && lua_isnoneornil(L, -1))
-    // leave key on stack for next iteration
+        browse_definition(definition_name);
+      lua_pop(L, 1);  // depth of value
+      lua_pop(L, 1);  // value
+      // leave key on stack for next iteration
+    }
   }
 
   lua_settop(L, 0);