1418 - starting trace-browser implementation in C++

I still have no idea how it will hook up to the rest. Parsing traces
will be slow. I can't test it like this. Writing the large trace data
structure to mu memory will be slow. But let's at least see the new
algorithm in action. (Not in this commit; so far we just render the
first n lines from the chessboard trace, and wait for a 'q' or 'Q' to
quit.)

2 files changed, 69 insertions, 1 deletions

diff --git a/077trace_browser.cc b/077trace_browser.cc
new file mode 100644
index 00000000..75059481
--- /dev/null
+++ b/077trace_browser.cc
@@ -0,0 +1,66 @@
+:(before "End Primitive Recipe Declarations")
+_BROWSE_TRACE,
+:(before "End Primitive Recipe Numbers")
+Recipe_number["$browse-trace"] = _BROWSE_TRACE;
+:(before "End Primitive Recipe Implementations")
+case _BROWSE_TRACE: {
+  start_trace_browser();
+  break;
+}
+
+:(before "End Globals")
+long long int Top_of_screen = 0;
+
+:(code)
+void start_trace_browser() {
+  if (!Trace_stream) return;
+  tb_init();
+  Display_row = Display_column = 0;
+  struct tb_event event;
+  while (true) {
+    render();
+    do {
+      tb_poll_event(&event);
+    } while (event.type != TB_EVENT_KEY);
+    long long int key = event.key ? event.key : event.ch;
+    if (key == 'q' || key == 'Q') break;
+  }
+  tb_shutdown();
+}
+
+void render() {
+  long long int screen_row = 0, index = 0;
+  for (screen_row = 0, index = Top_of_screen; screen_row < tb_height() && index < SIZE(Trace_stream->past_lines); ++screen_row, ++index) {
+    // skip lines without depth for now
+    while (Trace_stream->past_lines.at(index).depth == 0) {
+      ++index;
+      if (index >= SIZE(Trace_stream->past_lines)) goto done;
+    }
+    assert(index < SIZE(Trace_stream->past_lines));
+    // render trace line at index
+    trace_line& curr_line = Trace_stream->past_lines.at(index);
+    ostringstream out;
+    out << std::setw(4) << curr_line.depth << ' ' << curr_line.label << ": " << curr_line.contents;
+    render_line(screen_row, out.str());
+  }
+done:
+  // clear rest of screen
+  for (; screen_row < tb_height(); ++screen_row) {
+    render_line(screen_row, "~");
+  }
+  // move cursor back to display row at the end
+  tb_set_cursor(0, Display_row);
+  tb_present();
+}
+
+void render_line(int screen_row, const string& s) {
+  long long int col = 0;
+  for (col = 0; col < tb_width() && col < SIZE(s); ++col) {
+    char c = s.at(col);
+    if (c == '\n') c = ';';  // replace newlines with semi-colons
+    tb_change_cell(col, screen_row, s.at(col), TB_WHITE, TB_DEFAULT);
+  }
+  for (; col < tb_width(); ++col) {
+    tb_change_cell(col, screen_row, ' ', TB_WHITE, TB_DEFAULT);
+  }
+}
diff --git a/chessboard.mu b/chessboard.mu
index aac3e1cc..679d4805 100644
--- a/chessboard.mu
+++ b/chessboard.mu
@@ -25,7 +25,7 @@ recipe main [
 ## But enough about mu. Here's what it looks like to run the chessboard program.
 
 scenario print-board-and-read-move [
-  $close-trace  # administrivia: most scenarios save and check traces, but this one gets too large/slow
+#?   $close-trace  # administrivia: most scenarios save and check traces, but this one gets too large/slow
   # we'll make the screen really wide because the program currently prints out a long line
   assume-screen 120:literal/width, 20:literal/height
   # initialize keyboard to type in a move
@@ -33,6 +33,8 @@ scenario print-board-and-read-move [
 ]
   run [
     screen:address, keyboard:address <- chessboard screen:address, keyboard:address
+    $browse-trace
+    $close-trace
     # icon for the cursor
     screen:address <- print-character screen:address, 9251:literal  # '␣'
   ]