Use a curses pad for source and disassembly windows

This changes the TUI source and disassembly windows to use a curses
pad for their text.  This is an important step toward properly
handling non-ASCII characters, because it makes it easy to scroll
horizontally without needing gdb to also understand multi-byte
character boundaries -- this can be wholly delegated to curses.
Horizontal scrolling is probably also faster now, because no
re-rendering is required.

gdb/ChangeLog
2020-09-27  Tom Tromey  <tom@tromey.com>

	* unittests/tui-selftests.c: Update.
	* tui/tui-winsource.h (struct tui_source_window_base)
	<extra_margin, show_line_number, refresh_pad>: New methods.
	<m_max_length, m_pad>: New members.
	(tui_copy_source_line): Update.
	* tui/tui-winsource.c (tui_copy_source_line): Remove line_no,
	first_col, line_width, ndigits parameters.  Add length.
	(tui_source_window_base::show_source_line): Write to pad.  Line
	number now 0-based.
	(tui_source_window_base::refresh_pad): New method.
	(tui_source_window_base::show_source_content): Write to pad.  Call
	refresh_pad.
	(tui_source_window_base::do_scroll_horizontal): Call refresh_pad,
	not refill.
	(tui_source_window_base::update_exec_info): Call
	show_line_number.
	* tui/tui-source.h (struct tui_source_window) <extra_margin>: New
	method.
	<m_digits>: New member.
	* tui/tui-source.c (tui_source_window::set_contents): Set m_digits
	and m_max_length.
	(tui_source_window::show_line_number): New method.
	* tui/tui-io.h (tui_puts): Fix comment.
	* tui/tui-disasm.c (tui_disasm_window::set_contents): Set
	m_max_length.

gdb/ChangeLog

@@ -1,3 +1,31 @@
+2020-09-27  Tom Tromey  <tom@tromey.com>
+
+	* unittests/tui-selftests.c: Update.
+	* tui/tui-winsource.h (struct tui_source_window_base)
+	<extra_margin, show_line_number, refresh_pad>: New methods.
+	<m_max_length, m_pad>: New members.
+	(tui_copy_source_line): Update.
+	* tui/tui-winsource.c (tui_copy_source_line): Remove line_no,
+	first_col, line_width, ndigits parameters.  Add length.
+	(tui_source_window_base::show_source_line): Write to pad.  Line
+	number now 0-based.
+	(tui_source_window_base::refresh_pad): New method.
+	(tui_source_window_base::show_source_content): Write to pad.  Call
+	refresh_pad.
+	(tui_source_window_base::do_scroll_horizontal): Call refresh_pad,
+	not refill.
+	(tui_source_window_base::update_exec_info): Call
+	show_line_number.
+	* tui/tui-source.h (struct tui_source_window) <extra_margin>: New
+	method.
+	<m_digits>: New member.
+	* tui/tui-source.c (tui_source_window::set_contents): Set m_digits
+	and m_max_length.
+	(tui_source_window::show_line_number): New method.
+	* tui/tui-io.h (tui_puts): Fix comment.
+	* tui/tui-disasm.c (tui_disasm_window::set_contents): Set
+	m_max_length.
+
 2020-09-27  Tom Tromey  <tom@tromey.com>
 
 	* tui/tui-winsource.c

gdb/tui/tui-disasm.c

@@ -318,8 +318,7 @@ tui_disasm_window::set_contents (struct gdbarch *arch,
 				 const struct symtab_and_line &sal)
 {
   int i;
-  int offset = m_horizontal_offset;
+  int max_lines;
-  int max_lines, line_width;
   CORE_ADDR cur_pc;
   struct tui_locator_window *locator = tui_locator_win_info_ptr ();
   int tab_len = tui_tab_width;
@@ -336,7 +335,6 @@ tui_disasm_window::set_contents (struct gdbarch *arch,
 
   /* Window size, excluding highlight box.  */
   max_lines = height - 2;
-  line_width = width - TUI_EXECINFO_SIZE - 2;
 
   /* Get temporary table that will hold all strings (addr & insn).  */
   std::vector<tui_asm_line> asm_lines;
@@ -348,6 +346,7 @@ tui_disasm_window::set_contents (struct gdbarch *arch,
 
   /* Now construct each line.  */
   m_content.resize (max_lines);
+  m_max_length = -1;
   for (i = 0; i < max_lines; i++)
     {
       tui_source_element *src = &m_content[i];
@@ -370,7 +369,9 @@ tui_disasm_window::set_contents (struct gdbarch *arch,
 	}
 
       const char *ptr = line.c_str ();
-      src->line = tui_copy_source_line (&ptr, -1, offset, line_width, 0);
+      int line_len;
+      src->line = tui_copy_source_line (&ptr, &line_len);
+      m_max_length = std::max (m_max_length, line_len);
 
       src->line_or_addr.loa = LOA_ADDRESS;
       src->line_or_addr.u.addr = addr;

gdb/tui/tui-io.h

@@ -27,7 +27,8 @@
 struct ui_out;
 class cli_ui_out;
 
-/* Print the string in the curses command window.  */
+/* Print the string in the given curses window.  If no window is
+   provided, the command window is used.  */
 extern void tui_puts (const char *, WINDOW * = nullptr);
 
 /* Print LENGTH characters from the buffer pointed to by BUF to the

gdb/tui/tui-source.c

@@ -50,12 +50,9 @@ tui_source_window::set_contents (struct gdbarch *arch,
   if (s == NULL)
     return false;
 
-  int line_width, nlines;
-
-  line_width = width - TUI_EXECINFO_SIZE - 1;
   /* Take hilite (window border) into account, when
      calculating the number of lines.  */
-  nlines = height - 2;
+  int nlines = height - 2;
 
   std::string srclines;
   const std::vector<off_t> *offsets;
@@ -78,15 +75,16 @@ tui_source_window::set_contents (struct gdbarch *arch,
   m_start_line_or_addr.loa = LOA_LINE;
   cur_line_no = m_start_line_or_addr.u.line_no = line_no;
 
-  int digits = 0;
+  m_digits = 7;
   if (compact_source)
     {
       /* Solaris 11+gcc 5.5 has ambiguous overloads of log10, so we
 	 cast to double to get the right one.  */
       double l = log10 ((double) offsets->size ());
-      digits = 1 + (int) l;
+      m_digits = 1 + (int) l;
     }
 
+  m_max_length = -1;
   const char *iter = srclines.c_str ();
   m_content.resize (nlines);
   while (cur_line < nlines)
@@ -95,9 +93,11 @@ tui_source_window::set_contents (struct gdbarch *arch,
 
       std::string text;
       if (*iter != '\0')
-	text = tui_copy_source_line (&iter, cur_line_no,
+	{
-				     m_horizontal_offset,
+	  int line_len;
-				     line_width, digits);
+	  text = tui_copy_source_line (&iter, &line_len);
+	  m_max_length = std::max (m_max_length, line_len);
+	}
 
       /* Set whether element is the execution point
 	 and whether there is a break point on it.  */
@@ -225,3 +225,14 @@ tui_source_window::display_start_addr (struct gdbarch **gdbarch_p,
   *gdbarch_p = m_gdbarch;
   find_line_pc (cursal.symtab, m_start_line_or_addr.u.line_no, addr_p);
 }
+
+/* See tui-winsource.h.  */
+
+void
+tui_source_window::show_line_number (int offset) const
+{
+  int lineno = m_content[0].line_or_addr.u.line_no + offset;
+  char text[20];
+  xsnprintf (text, sizeof (text), "%*d ", m_digits - 1, lineno);
+  waddstr (handle.get (), text);
+}

gdb/tui/tui-source.h

@@ -63,12 +63,23 @@ protected:
   bool set_contents (struct gdbarch *gdbarch,
 		     const struct symtab_and_line &sal) override;
 
+  int extra_margin () const override
+  {
+    return m_digits;
+  }
+
+  void show_line_number (int lineno) const override;
+
 private:
 
   /* Answer whether a particular line number or address is displayed
      in the current source window.  */
   bool line_is_displayed (int line) const;
 
+  /* How many digits to use when formatting the line number.  This
+     includes the trailing space.  */
+  int m_digits;
+
   /* It is the resolved form as returned by symtab_to_fullname.  */
   gdb::unique_xmalloc_ptr<char> m_fullname;
 };

gdb/tui/tui-winsource.c

@@ -65,27 +65,13 @@ tui_display_main ()
 /* See tui-winsource.h.  */
 
 std::string
-tui_copy_source_line (const char **ptr, int line_no, int first_col,
+tui_copy_source_line (const char **ptr, int *length)
-		      int line_width, int ndigits)
 {
   const char *lineptr = *ptr;
 
   /* Init the line with the line number.  */
   std::string result;
 
-  if (line_no > 0)
-    {
-      if (ndigits > 0)
-	result = string_printf ("%*d ", ndigits, line_no);
-      else
-	{
-	  result = string_printf ("%-6d", line_no);
-	  int len = result.size ();
-	  len = len - ((len / tui_tab_width) * tui_tab_width);
-	  result.append (len, ' ');
-	}
-    }
-
   int column = 0;
   char c;
   do
@@ -112,21 +98,11 @@ tui_copy_source_line (const char **ptr, int line_no, int first_col,
 
 	  --column;
 	  for (int j = column % max_tab_len;
-	       j < max_tab_len && column < first_col + line_width;
+	       j < max_tab_len;
 	       column++, j++)
-	    if (column >= first_col)
+	    result.push_back (' ');
-	      result.push_back (' ');
 	};
 
-      /* We have to process all the text in order to pick up all the
-	 escapes.  */
-      if (column <= first_col || column > first_col + line_width)
-	{
-	  if (c == '\t')
-	    process_tab ();
-	  continue;
-	}
-
       if (c == '\n' || c == '\r' || c == '\0')
 	{
 	  /* Nothing.  */
@@ -135,11 +111,13 @@ tui_copy_source_line (const char **ptr, int line_no, int first_col,
 	{
 	  result.push_back ('^');
 	  result.push_back (c + 0100);
+	  ++column;
 	}
       else if (c == 0177)
 	{
 	  result.push_back ('^');
 	  result.push_back ('?');
+	  ++column;
 	}
       else if (c == '\t')
 	process_tab ();
@@ -152,6 +130,9 @@ tui_copy_source_line (const char **ptr, int line_no, int first_col,
     ++lineptr;
   *ptr = lineptr;
 
+  if (length != nullptr)
+    *length = column;
+
   return result;
 }
 
@@ -254,24 +235,31 @@ void
 tui_source_window_base::show_source_line (int lineno)
 {
   struct tui_source_element *line;
-  int x;
 
-  line = &m_content[lineno - 1];
+  line = &m_content[lineno];
   if (line->is_exec_point)
-    tui_set_reverse_mode (handle.get (), true);
+    tui_set_reverse_mode (m_pad.get (), true);
 
-  wmove (handle.get (), lineno, TUI_EXECINFO_SIZE);
+  wmove (m_pad.get (), lineno, 0);
-  tui_puts (line->line.c_str (), handle.get ());
+  tui_puts (line->line.c_str (), m_pad.get ());
   if (line->is_exec_point)
-    tui_set_reverse_mode (handle.get (), false);
+    tui_set_reverse_mode (m_pad.get (), false);
+}
 
-  /* Clear to end of line but stop before the border.  */
+/* See tui-winsource.h.  */
-  x = getcurx (handle.get ());
+
-  while (x + 1 < width)
+void
-    {
+tui_source_window_base::refresh_pad ()
-      waddch (handle.get (), ' ');
+{
-      x = getcurx (handle.get ());
+  int pad_width = std::max (m_max_length, width);
-    }
+  int left_margin = 1 + TUI_EXECINFO_SIZE + extra_margin ();
+  int view_width = width - left_margin - 1;
+  int pad_x = std::min (pad_width - view_width, m_horizontal_offset);
+  /* Ensure that an equal number of scrolls will work if the user
+     scrolled beyond where we clip.  */
+  m_horizontal_offset = pad_x;
+  prefresh (m_pad.get (), 0, pad_x, y + 1, x + left_margin,
+	    y + 1 + m_content.size (), x + left_margin + view_width - 1);
 }
 
 void
@@ -279,10 +267,18 @@ tui_source_window_base::show_source_content ()
 {
   gdb_assert (!m_content.empty ());
 
-  for (int lineno = 1; lineno <= m_content.size (); lineno++)
+  check_and_display_highlight_if_needed ();
+
+  int pad_width = std::max (m_max_length, width);
+  if (m_pad == nullptr || pad_width > getmaxx (m_pad.get ()))
+    m_pad.reset (newpad (m_content.size (), pad_width));
+
+  werase (m_pad.get ());
+  for (int lineno = 0; lineno < m_content.size (); lineno++)
     show_source_line (lineno);
 
-  check_and_display_highlight_if_needed ();
+  refresh_pad ();
+
   refresh_window ();
 }
 
@@ -380,7 +376,7 @@ tui_source_window_base::do_scroll_horizontal (int num_to_scroll)
       if (offset < 0)
 	offset = 0;
       m_horizontal_offset = offset;
-      refill ();
+      refresh_pad ();
     }
 }
 
@@ -519,6 +515,8 @@ tui_source_window_base::update_exec_info ()
 	element[TUI_EXEC_POS] = '>';
 
       mvwaddstr (handle.get (), i + 1, 1, element);
+
+      show_line_number (i);
     }
   refresh_window ();
 }

gdb/tui/tui-winsource.h

@@ -107,6 +107,20 @@ protected:
   virtual bool set_contents (struct gdbarch *gdbarch,
 			     const struct symtab_and_line &sal) = 0;
 
+  /* Return the number of extra margin characters needed by this
+     instance.  */
+  virtual int extra_margin () const
+  {
+    return 0;
+  }
+
+  /* Display the line number in the window margin.  OFFSET indicates
+     which line to display; it is 0-based, with 0 meaning the line at
+     the top of the window.  */
+  virtual void show_line_number (int offset) const
+  {
+  }
+
   /* Redraw the complete line of a source or disassembly window.  */
   void show_source_line (int lineno);
 
@@ -119,6 +133,9 @@ protected:
 
   std::vector<tui_source_element> m_content;
 
+  /* Length of longest line to be displayed.  */
+  int m_max_length;
+
 public:
 
   /* Refill the source window's source cache and update it.  If this
@@ -162,11 +179,17 @@ private:
 
   void show_source_content ();
 
+  /* Re-display the pad in the window.  */
+  void refresh_pad ();
+
   /* Called when the user "set style enabled" setting is changed.  */
   void style_changed ();
 
   /* A token used to register and unregister an observer.  */
   gdb::observers::token m_observable;
+
+  /* Pad used to display fixme mumble  */
+  std::unique_ptr<WINDOW, curses_deleter> m_pad;
 };
 
 
@@ -264,19 +287,15 @@ extern void tui_display_main (void);
 extern void tui_update_source_windows_with_addr (struct gdbarch *, CORE_ADDR);
 extern void tui_update_source_windows_with_line (struct symtab_and_line sal);
 
-/* Extract some source text from PTR.  LINE_NO is the line number.  If
+/* Extract some source text from PTR.  Returns a string holding the
-   it is positive, it is printed at the start of the line.  FIRST_COL
+   desired text.  PTR is updated to point to the start of the next
-   is the first column to extract, and LINE_WIDTH is the number of
+   line.  If LENGTH is non-NULL, then the length of the line is stored
-   characters to display.  NDIGITS is used to format the line number
+   there.  Escape sequences are not counted against the length.
-   (if it is positive).  If NDIGITS is greater than 0, then that many
+   Actually an approximation is used -- each byte of a multi-byte
-   digits are used; otherwise the line number is formatted with 6
+   sequence counts as a character here.  */
-   digits and the text is aligned to the next tab stop.  Returns a
-   string holding the desired text.  PTR is updated to point to the
-   start of the next line.  */
 
 extern std::string tui_copy_source_line (const char **ptr,
-					 int line_no, int first_col,
+					 int *length = nullptr);
-					 int line_width, int ndigits);
 
 /* Constant definitions. */
 #define SCROLL_THRESHOLD 2	/* Threshold for lazy scroll.  */

gdb/unittests/tui-selftests.c

@@ -31,13 +31,13 @@ static void
 run_tests ()
 {
   const char *text = "hello";
-  std::string result = tui_copy_source_line (&text, 0, 0, 50, 0);
+  std::string result = tui_copy_source_line (&text);
   SELF_CHECK (result == "hello");
   SELF_CHECK (*text == '\0');
 
   text = "hello\n";
-  result = tui_copy_source_line (&text, 0, 0, 3, 0);
+  result = tui_copy_source_line (&text);
-  SELF_CHECK (result == "hel");
+  SELF_CHECK (result == "hello");
   SELF_CHECK (*text == '\0');
 }