1 //: A debugging helper that lets you zoom in/out on a trace.
  2 //: Warning: this tool has zero automated tests.
  3 //:
  4 //: To try it out, first create an example trace:
  5 //:   mu --trace nqueens.mu
  6 //: Then to browse the trace, which was stored in a file called 'last_run':
  7 //:   mu browse-trace last_run
  8 //:
  9 //: You should now find yourself in a UI showing a subsequence of lines from
 10 //: the trace, each line starting with a numeric depth, and ending with a
 11 //: parenthetical count of trace lines hidden after it with greater depths.
 12 //:
 13 //: For example, this line:
 14 //:   2 app: line1 (30)
 15 //: indicates that it was logged with depth 2, and that 30 following lines
 16 //: have been hidden at a depth greater than 2.
 17 //:
 18 //: As an experiment, hidden counts of 1000 or more are in red to highlight
 19 //: where you might be particularly interested in expanding.
 20 //:
 21 //: The UI provides the following hotkeys:
 22 //:
 23 //:   `q` or `ctrl-c`: Quit.
 24 //:
 25 //:   `Enter`: 'Zoom into' this line. Expand some or all of the hidden lines
 26 //:   at the next higher level, updating parenthetical counts of hidden lines.
 27 //:
 28 //:   `Backspace`: 'Zoom out' on a line after zooming in, collapsing expanded
 29 //:   lines below by some series of <Enter> commands.
 30 //:
 31 //:   `j` or `down-arrow`: Move/scroll cursor down one line.
 32 //:   `k` or `up-arrow`: Move/scroll cursor up one line.
 33 //:   `J` or `ctrl-f` or `page-down`: Scroll cursor down one page.
 34 //:   `K` or `ctrl-b` or `page-up`: Scroll cursor up one page.
 35 //:   `h` or `left-arrow`: Scroll cursor left one character.
 36 //:   `l` or `right-arrow`: Scroll cursor right one character.
 37 //:   `H`: Scroll cursor left one screen-width.
 38 //:   `L`: Scroll cursor right one screen-width.
 39 //:
 40 //:   `g` or `home`: Move cursor to start of trace.
 41 //:   `G` or `end`: Move cursor to end of trace.
 42 //:
 43 //:   `t`: Move cursor to top line on screen.
 44 //:   `c`: Move cursor to center line on screen.
 45 //:   `b`: Move cursor to bottom line on screen.
 46 //:   `T`: Scroll line at cursor to top of screen.
 47 //:
 48 //:   `/`: Search forward for a pattern.
 49 //:   '?': Search backward for a pattern.
 50 //:   `n`: Repeat the previous '/' or '?'.
 51 //:   `N`: Repeat the previous '/' or '?' in the opposite direction.
 52 //:
 53 //:   After hitting `/`, a small editor on the bottom-most line supports the
 54 //:   following hotkeys:
 55 //:     ascii characters: add the key to the pattern.
 56 //:     `Enter`: search for the pattern.
 57 //:     `Esc` or `ctrl-c`: cancel the current search, setting the screen back
 58 //:       to its state before the search.
 59 //:     `left-arrow`: move cursor left.
 60 //:     `right-arrow`: move cursor right.
 61 //:     `ctrl-a` or `home`: move cursor to start of search pattern.
 62 //:     `ctrl-e` or `end`: move cursor to end of search pattern.
 63 //:     `ctrl-u`: clear search pattern before cursor
 64 //:     `ctrl-k`: clear search pattern at and after cursor
 65 
 66 :(before "End Primitive Recipe Declarations")
 67 _BROWSE_TRACE,
 68 :(before "End Primitive Recipe Numbers")
 69 put(Recipe_ordinal, "$browse-trace", _BROWSE_TRACE);
 70 :(before "End Primitive Recipe Checks")
 71 case _BROWSE_TRACE: {
 72   break;
 73 }
 74 :(before "End Primitive Recipe Implementations")
 75 case _BROWSE_TRACE: {
 76   start_trace_browser();
 77   break;
 78 }
 79 
 80 //: browse a trace loaded from a file
 81 :(after "Commandline Parsing")
 82 if (argc == 3 && is_equal(argv[1], "browse-trace")) {
 83   load_trace(argv[2]);
 84   start_trace_browser();
 85   return 0;
 86 }
 87 
 88 :(before "End Globals")
 89 set<int> Visible;
 90 int Top_of_screen = 0;
 91 int Left_of_screen = 0;
 92 int Last_printed_row = 0;
 93 map<int, int> Trace_index;  // screen row -> trace index
 94 string Current_search_pattern = "";
 95 :(before "End Types")
 96 enum search_direction { FORWARD, BACKWARD };
 97 :(before "End Globals")
 98 search_direction Current_search_direction = FORWARD;
 99 
100 :(code)
101 void start_trace_browser() {
102   if (!Trace_stream) return;
103   cerr << "computing min depth to display\n";
104   int min_depth = 9999;
105   for (int i = 0;  i < SIZE(Trace_stream->past_lines);  ++i) {
106   ¦ trace_line& curr_line = Trace_stream->past_lines.at(i);
107   ¦ if (curr_line.depth < min_depth) min_depth = curr_line.depth;
108   }
109   cerr << "min depth is " << min_depth << '\n';
110   cerr << "computing lines to display\n";
111   for (int i = 0;  i < SIZE(Trace_stream->past_lines);  ++i) {
112   ¦ if (Trace_stream->past_lines.at(i).depth == min_depth)
113   ¦ ¦ Visible.insert(i);
114   }
115   tb_init();
116   Display_row = Display_column = 0;
117   Top_of_screen = 0;
118   refresh_screen_rows();
119   while (true) {
120   ¦ render();
121   ¦ int key = read_key();
122   ¦ if (key == 'q' || key == 'Q' || key == TB_KEY_CTRL_C) break;
123   ¦ if (key == 'j' || key == TB_KEY_ARROW_DOWN) {
124   ¦ ¦ // move cursor one line down
125   ¦ ¦ if (Display_row < Last_printed_row) ++Display_row;
126   ¦ }
127   ¦ else if (key == 'k' || key == TB_KEY_ARROW_UP) {
128   ¦ ¦ // move cursor one line up
129   ¦ ¦ if (Display_row > 0) --Display_row;
130   ¦ }
131   ¦ else if (key == 't') {
132   ¦ ¦ // move cursor to top of screen
133   ¦ ¦ Display_row = 0;
134   ¦ }
135   ¦ else if (key == 'c') {
136   ¦ ¦ // move cursor to center of screen
137   ¦ ¦ Display_row = tb_height()/2;
138   ¦ ¦ while (!contains_key(Trace_index, Display_row))
139   ¦ ¦ ¦ --Display_row;
140   ¦ }
141   ¦ else if (key == 'b') {
142   ¦ ¦ // move cursor to bottom of screen
143   ¦ ¦ Display_row = tb_height()-1;
144   ¦ ¦ while (!contains_key(Trace_index, Display_row))
145   ¦ ¦ ¦ --Display_row;
146   ¦ }
147   ¦ else if (key == 'T') {
148   ¦ ¦ // scroll line at cursor to top of screen
149   ¦ ¦ Top_of_screen = get(Trace_index, Display_row);
150   ¦ ¦ Display_row = 0;
151   ¦ ¦ refresh_screen_rows();
152   ¦ }
153   ¦ else if (key == 'h' || key == TB_KEY_ARROW_LEFT) {
154   ¦ ¦ // pan screen one character left
155   ¦ ¦ if (Left_of_screen > 0) --Left_of_screen;
156   ¦ }
157   ¦ else if (key == 'l' || key == TB_KEY_ARROW_RIGHT) {
158   ¦ ¦ // pan screen one character right
159   ¦ ¦ ++Left_of_screen;
160   ¦ }
161   ¦ else if (key == 'H') {
162   ¦ ¦ // pan screen one screen-width left
163   ¦ ¦ Left_of_screen -= (tb_width() - 5);
164   ¦ ¦ if (Left_of_screen < 0) Left_of_screen = 0;
165   ¦ }
166   ¦ else if (key == 'L') {
167   ¦ ¦ // pan screen one screen-width right
168   ¦ ¦ Left_of_screen += (tb_width() - 5);
169   ¦ }
170   ¦ else if (key == 'J' || key == TB_KEY_PGDN || key == TB_KEY_CTRL_F) {
171   ¦ ¦ // page-down
172   ¦ ¦ if (Trace_index.find(tb_height()-1) != Trace_index.end()) {
173   ¦ ¦ ¦ Top_of_screen = get(Trace_index, tb_height()-1) + 1;
174   ¦ ¦ ¦ refresh_screen_rows();
175   ¦ ¦ }
176   ¦ }
177   ¦ else if (key == 'K' || key == TB_KEY_PGUP || key == TB_KEY_CTRL_B) {
178   ¦ ¦ // page-up is more convoluted
179   ¦ ¦ for (int screen_row = tb_height();  screen_row > 0 && Top_of_screen > 0;  --screen_row) {
180   ¦ ¦ ¦ --Top_of_screen;
181   ¦ ¦ ¦ if (Top_of_screen <= 0) break;
182   ¦ ¦ ¦ while (Top_of_screen > 0 && !contains_key(Visible, Top_of_screen))
183   ¦ ¦ ¦ ¦ --Top_of_screen;
184   ¦ ¦ }
185   ¦ ¦ if (Top_of_screen >= 0)
186   ¦ ¦ ¦ refresh_screen_rows();
187   ¦ }
188   ¦ else if (key == 'g' || key == TB_KEY_HOME) {
189   ¦ ¦ ¦ Top_of_screen = 0;
190   ¦ ¦ ¦ Last_printed_row = 0;
191   ¦ ¦ ¦ Display_row = 0;
192   ¦ ¦ ¦ refresh_screen_rows();
193   ¦ }
194   ¦ else if (key == 'G' || key == TB_KEY_END) {
195   ¦ ¦ // go to bottom of screen; largely like page-up, interestingly
196   ¦ ¦ Top_of_screen = SIZE(Trace_stream->past_lines)-1;
197   ¦ ¦ for (int screen_row = tb_height();  screen_row > 0 && Top_of_screen > 0;  --screen_row) {
198   ¦ ¦ ¦ --Top_of_screen;
199   ¦ ¦ ¦ if (Top_of_screen <= 0) break;
200   ¦ ¦ ¦ while (Top_of_screen > 0 && !contains_key(Visible, Top_of_screen))
201   ¦ ¦ ¦ ¦ --Top_of_screen;
202   ¦ ¦ }
203   ¦ ¦ refresh_screen_rows();
204   ¦ ¦ // move cursor to bottom
205   ¦ ¦ Display_row = Last_printed_row;
206   ¦ ¦ refresh_screen_rows();
207   ¦ }
208   ¦ else if (key == TB_KEY_CARRIAGE_RETURN) {
209   ¦ ¦ // expand lines under current by one level
210   ¦ ¦ assert(contains_key(Trace_index, Display_row));
211   ¦ ¦ int start_index = get(Trace_index, Display_row);
212   ¦ ¦ int index = 0;
213   ¦ ¦ // simultaneously compute end_index and min_depth
214   ¦ ¦ int min_depth = 9999;
215   ¦ ¦ for (index = start_index+1;  index < SIZE(Trace_stream->past_lines);  ++index) {
216   ¦ ¦ ¦ if (contains_key(Visible, index)) break;
217   ¦ ¦ ¦ trace_line& curr_line = Trace_stream->past_lines.at(index);
218   ¦ ¦ ¦ assert(curr_line.depth > Trace_stream->past_lines.at(start_index).depth);
219   ¦ ¦ ¦ if (curr_line.depth < min_depth) min_depth = curr_line.depth;
220   ¦ ¦ }
221   ¦ ¦ int end_index = index;
222   ¦ ¦ // mark as visible all intervening indices at min_depth
223   ¦ ¦ for (index = start_index;  index < end_index;  ++index) {
224   ¦ ¦ ¦ trace_line& curr_line = Trace_stream->past_lines.at(index);
225   ¦ ¦ ¦ if (curr_line.depth == min_depth) {
226   ¦ ¦ ¦ ¦ Visible.insert(index);
227   ¦ ¦ ¦ }
228   ¦ ¦ }
229   ¦ ¦ refresh_screen_rows();
230   ¦ }
231   ¦ else if (key == TB_KEY_BACKSPACE || key == TB_KEY_BACKSPACE2) {
232   ¦ ¦ // collapse all lines under current
233   ¦ ¦ assert(contains_key(Trace_index, Display_row));
234   ¦ ¦ int start_index = get(Trace_index, Display_row);
235   ¦ ¦ int index = 0;
236   ¦ ¦ // end_index is the next line at a depth same as or lower than start_index
237   ¦ ¦ int initial_depth = Trace_stream->past_lines.at(start_index).depth;
238   ¦ ¦ for (index = start_index+1;  index < SIZE(Trace_stream->past_lines);  ++index) {
239   ¦ ¦ ¦ if (!contains_key(Visible, index)) continue;
240   ¦ ¦ ¦ trace_line& curr_line = Trace_stream->past_lines.at(index);
241   ¦ ¦ ¦ if (curr_line.depth <= initial_depth) break;
242   ¦ ¦ }
243   ¦ ¦ int end_index = index;
244   ¦ ¦ // mark as visible all intervening indices at min_depth
245   ¦ ¦ for (index = start_index+1;  index < end_index;  ++index) {
246   ¦ ¦ ¦ Visible.erase(index);
247   ¦ ¦ }
248   ¦ ¦ refresh_screen_rows();
249   ¦ }
250   ¦ else if (key == '/') {
251   ¦ ¦ if (start_search_editor(FORWARD))
252   ¦ ¦ ¦ search(Current_search_pattern, Current_search_direction);
253   ¦ }
254   ¦ else if (key == '?') {
255   ¦ ¦ if (start_search_editor(BACKWARD))
256   ¦ ¦ ¦ search(Current_search_pattern, Current_search_direction);
257   ¦ }
258   ¦ else if (key == 'n') {
259   ¦ ¦ if (!Current_search_pattern.empty())
260   ¦ ¦ ¦ search(Current_search_pattern, Current_search_direction);
261   ¦ }
262   ¦ else if (key == 'N') {
263   ¦ ¦ if (!Current_search_pattern.empty())
264   ¦ ¦ ¦ search(Current_search_pattern, opposite(Current_search_direction));
265   ¦ }
266   }
267   tb_shutdown();
268 }
269 
270 bool start_search_editor(search_direction dir) {
271   const int bottom_screen_line = tb_height()-1;
272   // run a little editor just in the last line of the screen
273   clear_line(bottom_screen_line);
274   tb_set_cursor(0, bottom_screen_line);
275   int col = 0;  // screen column of cursor on bottom line. also used to update pattern.
276   tb_change_cell(col, bottom_screen_line, '/', TB_WHITE, TB_BLACK);
277   ++col;
278   tb_set_cursor(col, bottom_screen_line);
279   string pattern;
280   while (true) {
281   ¦ int key = read_key();
282   ¦ if (key == TB_KEY_ENTER) {
283   ¦ ¦ if (!pattern.empty()) {
284   ¦ ¦ ¦ Current_search_pattern = pattern;
285   ¦ ¦ ¦ Current_search_direction = dir;
286   ¦ ¦ }
287   ¦ ¦ return true;
288   ¦ }
289   ¦ else if (key == TB_KEY_ESC || key == TB_KEY_CTRL_C) {
290   ¦ ¦ return false;
291   ¦ }
292   ¦ else if (key == TB_KEY_ARROW_LEFT) {
293   ¦ ¦ if (col > /*slash*/1) {
294   ¦ ¦ ¦ --col;
295   ¦ ¦ ¦ tb_set_cursor(col, bottom_screen_line);
296   ¦ ¦ }
297   ¦ }
298   ¦ else if (key == TB_KEY_ARROW_RIGHT) {
299   ¦ ¦ if (col-/*slash*/1 < SIZE(pattern)) {
300   ¦ ¦ ¦ ++col;
301   ¦ ¦ ¦ tb_set_cursor(col, bottom_screen_line);
302   ¦ ¦ }
303   ¦ }
304   ¦ else if (key == TB_KEY_HOME || key == TB_KEY_CTRL_A) {
305   ¦ ¦ col = /*skip slash*/1;
306   ¦ ¦ tb_set_cursor(col, bottom_screen_line);
307   ¦ }
308   ¦ else if (key == TB_KEY_END || key == TB_KEY_CTRL_E) {
309   ¦ ¦ col = SIZE(pattern)+/*skip slash*/1;
310   ¦ ¦ tb_set_cursor(col, bottom_screen_line);
311   ¦ }
312   ¦ else if (key == TB_KEY_BACKSPACE || key == TB_KEY_BACKSPACE2) {
313   ¦ ¦ if (col > /*slash*/1) {
314   ¦ ¦ ¦ --col;
315   ¦ ¦ ¦ // update pattern
316   ¦ ¦ ¦ pattern.erase(col-/*slash*/1, /*len*/1);
317   ¦ ¦ ¦ // update screen
318   ¦ ¦ ¦ if (col > SIZE(pattern)) {
319   ¦ ¦ ¦ ¦ tb_change_cell(col, bottom_screen_line, ' ', TB_WHITE, TB_BLACK);
320   ¦ ¦ ¦ }
321   ¦ ¦ ¦ else {
322   ¦ ¦ ¦ ¦ assert(col <= SIZE(pattern));
323   ¦ ¦ ¦ ¦ for (int x = col;  x < SIZE(pattern)+/*skip slash*/1;  ++x)
324   ¦ ¦ ¦ ¦ ¦ tb_change_cell(x, bottom_screen_line, pattern.at(x-/*slash*/1), TB_WHITE, TB_BLACK);
325   ¦ ¦ ¦ ¦ tb_change_cell(SIZE(pattern)+/*skip slash*/1, bottom_screen_line, ' ', TB_WHITE, TB_BLACK);
326   ¦ ¦ ¦ }
327   ¦ ¦ ¦ tb_set_cursor(col, bottom_screen_line);
328   ¦ ¦ }
329   ¦ }
330   ¦ else if (key == TB_KEY_CTRL_K) {
331   ¦ ¦ int old_pattern_size = SIZE(pattern);
332   ¦ ¦ pattern.erase(col-/*slash*/1, SIZE(pattern) - (col-/*slash*/1));
333   ¦ ¦ for (int x = col;  x < old_pattern_size+/*slash*/1;  ++x)
334   ¦ ¦ ¦ tb_change_cell(x, bottom_screen_line, ' ', TB_WHITE, TB_BLACK);
335   ¦ ¦ tb_set_cursor(col, bottom_screen_line);
336   ¦ }
337   ¦ else if (key == TB_KEY_CTRL_U) {
338   ¦ ¦ int old_pattern_size = SIZE(pattern);
339   ¦ ¦ pattern.erase(0, col-/*slash*/1);
340   ¦ ¦ for (int x = /*slash*/1;  x < SIZE(pattern)+/*skip slash*/1;  ++x)
341   ¦ ¦ ¦ tb_change_cell(x, bottom_screen_line, pattern.at(x-/*slash*/1), TB_WHITE, TB_BLACK);
342   ¦ ¦ for (int x = SIZE(pattern)+/*slash*/1;  x < old_pattern_size+/*skip slash*/1;  ++x)
343   ¦ ¦ ¦ tb_change_cell(x, bottom_screen_line, ' ', TB_WHITE, TB_BLACK);
344   ¦ ¦ tb_set_cursor(/*start of pattern skipping slash*/1, bottom_screen_line);
345   ¦ }
346   ¦ else if (key < 128) {  // ascii only
347   ¦ ¦ // update pattern
348   ¦ ¦ char c = static_cast<char>(key);
349   ¦ ¦ pattern.insert(col-/*slash*/1, /*num*/1, c);
350   ¦ ¦ // update screen
351   ¦ ¦ for (int x = col;  x < SIZE(pattern)+/*skip slash*/1;  ++x)
352   ¦ ¦ ¦ tb_change_cell(x, bottom_screen_line, pattern.at(x-/*slash*/1), TB_WHITE, TB_BLACK);
353   ¦ ¦ ++col;
354   ¦ ¦ tb_set_cursor(col, bottom_screen_line);
355   ¦ }
356   }
357 }
358 
359 void search(const string& pat, search_direction dir) {
360   if (dir == FORWARD) search_next(pat);
361   else search_previous(pat);
362 }
363 
364 search_direction opposite(search_direction dir) {
365   if (dir == FORWARD) return BACKWARD;
366   else return FORWARD;
367 }
368 
369 void search_next(const string& pat) {
370   for (int trace_index = get(Trace_index, Display_row)+1;  trace_index < SIZE(Trace_stream->past_lines);  ++trace_index) {
371   ¦ if (!contains_key(Visible, trace_index)) continue;
372   ¦ const trace_line& line = Trace_stream->past_lines.at(trace_index);
373   ¦ if (line.label.find(pat) == string::npos && line.contents.find(pat) == string::npos) continue;
374   ¦ Top_of_screen = trace_index;
375   ¦ Display_row = 0;
376   ¦ refresh_screen_rows();
377   ¦ return;
378   }
379 }
380 
381 void search_previous(const string& pat) {
382   for (int trace_index = get(Trace_index, Display_row)-1;  trace_index >= 0;  --trace_index) {
383   ¦ if (!contains_key(Visible, trace_index)) continue;
384   ¦ const trace_line& line = Trace_stream->past_lines.at(trace_index);
385   ¦ if (line.label.find(pat) == string::npos && line.contents.find(pat) == string::npos) continue;
386   ¦ Top_of_screen = trace_index;
387   ¦ Display_row = 0;
388   ¦ refresh_screen_rows();
389   ¦ return;
390   }
391 }
392 
393 void clear_line(int screen_row) {
394   for (int col = 0;  col < tb_width();  ++col)
395   ¦ tb_change_cell(col, screen_row, ' ', TB_WHITE, TB_BLACK);
396 }
397 
398 // update Trace_indices for each screen_row on the basis of Top_of_screen and Visible
399 void refresh_screen_rows() {
400   int screen_row = 0, index = 0;
401   Trace_index.clear();
402   for (screen_row = 0, index = Top_of_screen;  screen_row < tb_height() && index < SIZE(Trace_stream->past_lines);  ++screen_row, ++index) {
403   ¦ // skip lines without depth for now
404   ¦ while (!contains_key(Visible, index)) {
405   ¦ ¦ ++index;
406   ¦ ¦ if (index >= SIZE(Trace_stream->past_lines)) goto done;
407   ¦ }
408   ¦ assert(index < SIZE(Trace_stream->past_lines));
409   ¦ put(Trace_index, screen_row, index);
410   }
411 done:;
412 }
413 
414 void render() {
415   int screen_row = 0;
416   for (screen_row = 0;  screen_row < tb_height();  ++screen_row) {
417   ¦ if (!contains_key(Trace_index, screen_row)) break;
418   ¦ trace_line& curr_line = Trace_stream->past_lines.at(get(Trace_index, screen_row));
419   ¦ ostringstream out;
420   ¦ out << std::setw(4) << curr_line.depth << ' ' << curr_line.label << ": " << curr_line.contents;
421   ¦ if (screen_row < tb_height()-1) {
422   ¦ ¦ int delta = lines_hidden(screen_row);
423   ¦ ¦ // home-brew escape sequence for red
424   ¦ ¦ if (delta > 1) {
425   ¦ ¦ ¦ if (delta > 999) out << static_cast<char>(1);
426   ¦ ¦ ¦ out << " (" << delta << ")";
427   ¦ ¦ ¦ if (delta > 999) out << static_cast<char>(2);
428   ¦ ¦ }
429   ¦ }
430   ¦ render_line(screen_row, out.str(), screen_row == Display_row);
431   }
432   // clear rest of screen
433   Last_printed_row = screen_row-1;
434   for (;  screen_row < tb_height();  ++screen_row)
435   ¦ render_line(screen_row, "~", /*cursor_line?*/false);
436   // move cursor back to display row at the end
437   tb_set_cursor(0, Display_row);
438 }
439 
440 int lines_hidden(int screen_row) {
441   assert(contains_key(Trace_index, screen_row));
442   if (!contains_key(Trace_index, screen_row+1))
443   ¦ return SIZE(Trace_stream->past_lines) - get(Trace_index, screen_row);
444   else
445   ¦ return get(Trace_index, screen_row+1) - get(Trace_index, screen_row);
446 }
447 
448 void render_line(int screen_row, const string& s, bool cursor_line) {
449   int col = 0;
450   int color = TB_WHITE;
451   int background_color = cursor_line ? /*subtle grey*/240 : TB_BLACK;
452   vector<pair<size_t, size_t> > highlight_ranges = find_all_occurrences(s, Current_search_pattern);
453   for (col = 0;  col < tb_width() && col+Left_of_screen < SIZE(s);  ++col) {
454   ¦ char c = s.at(col+Left_of_screen);  // todo: unicode
455   ¦ if (c == '\n') c = ';';  // replace newlines with semi-colons
456   ¦ // escapes. hack: can't start a line with them.
457   ¦ if (c == '\1') { color = /*red*/1;  c = ' '; }
458   ¦ if (c == '\2') { color = TB_WHITE;  c = ' '; }
459   ¦ if (in_range(highlight_ranges, col+Left_of_screen))
460   ¦ ¦ tb_change_cell(col, screen_row, c, TB_BLACK, /*yellow*/11);
461   ¦ else
462   ¦ ¦ tb_change_cell(col, screen_row, c, color, background_color);
463   }
464   for (;  col < tb_width();  ++col)
465   ¦ tb_change_cell(col, screen_row, ' ', TB_WHITE, background_color);
466 }
467 
468 vector<pair<size_t, size_t> > find_all_occurrences(const string& s, const string& pat) {
469   vector<pair<size_t, size_t> > result;
470   if (pat.empty()) return result;
471   size_t idx = 0;
472   while (true) {
473   ¦ size_t next_idx = s.find(pat, idx);
474   ¦ if (next_idx == string::npos) break;
475   ¦ result.push_back(pair<size_t, size_t>(next_idx, next_idx+SIZE(pat)));
476   ¦ idx = next_idx+SIZE(pat);
477   }
478   return result;
479 }
480 
481 bool in_range(const vector<pair<size_t, size_t> >& highlight_ranges, size_t idx) {
482   for (int i = 0;  i < SIZE(highlight_ranges);  ++i) {
483   ¦ if (idx >= highlight_ranges.at(i).first && idx < highlight_ranges.at(i).second)
484   ¦ ¦ return true;
485   ¦ if (idx < highlight_ranges.at(i).second) break;
486   }
487   return false;
488 }
489 
490 void load_trace(const char* filename) {
491   ifstream tin(filename);
492   if (!tin) {
493   ¦ cerr << "no such file: " << filename << '\n';
494   ¦ exit(1);
495   }
496   Trace_stream = new trace_stream;
497   while (has_data(tin)) {
498   ¦ tin >> std::noskipws;
499   ¦ ¦ skip_whitespace_but_not_newline(tin);
500   ¦ ¦ if (!isdigit(tin.peek())) {
501   ¦ ¦ ¦ string dummy;
502   ¦ ¦ ¦ getline(tin, dummy);
503   ¦ ¦ ¦ continue;
504   ¦ ¦ }
505   ¦ tin >> std::skipws;
506   ¦ int depth;
507   ¦ tin >> depth;
508   ¦ string label;
509   ¦ tin >> label;
510   ¦ if (*--label.end() == ':') label.erase(--label.end());
511   ¦ string line;
512   ¦ getline(tin, line);
513   ¦ Trace_stream->past_lines.push_back(trace_line(depth, label, line));
514   }
515   cerr << "lines read: " << Trace_stream->past_lines.size() << '\n';
516 }
517 
518 int read_key() {
519   tb_event event;
520   do {
521   ¦ tb_poll_event(&event);
522   } while (event.type != TB_EVENT_KEY);
523   return event.key ? event.key : event.ch;
524 }