Remove tui_expand_tabs

tui_expand_tabs only has a single caller.  This patch removes this
function, in favor of a tab-expanding variant of string_file.  This
simplifies the code somewhat.

gdb/ChangeLog
2020-07-01  Tom Tromey  <tom@tromey.com>

	* tui/tui-regs.h (struct tui_data_item_window) <content>: Now a
	std::string.
	* tui/tui-regs.c (class tab_expansion_file): New.
	(tab_expansion_file::write): New method.
	(tui_register_format): Change return type.  Use
	tab_expansion_file.
	(tui_get_register, tui_data_window::display_registers_from)
	(tui_data_item_window::rerender): Update.
	* tui/tui-io.h (tui_expand_tabs): Don't declare.
	* tui/tui-io.c (tui_expand_tabs): Remove.

5 files changed, 61 insertions, 73 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 6a6260d..9efd8b6 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,18 @@
 2020-07-01  Tom Tromey  <tom@tromey.com>
 
+	* tui/tui-regs.h (struct tui_data_item_window) <content>: Now a
+	std::string.
+	* tui/tui-regs.c (class tab_expansion_file): New.
+	(tab_expansion_file::write): New method.
+	(tui_register_format): Change return type.  Use
+	tab_expansion_file.
+	(tui_get_register, tui_data_window::display_registers_from)
+	(tui_data_item_window::rerender): Update.
+	* tui/tui-io.h (tui_expand_tabs): Don't declare.
+	* tui/tui-io.c (tui_expand_tabs): Remove.
+
+2020-07-01  Tom Tromey  <tom@tromey.com>
+
 	* tui/tui-regs.c (tui_reggroup_completer): Use complete_on_enum.
 
 2020-07-01  Fangrui Song  <maskray@google.com>
diff --git a/gdb/tui/tui-io.c b/gdb/tui/tui-io.c
index 277b560..7698d79 100644
--- a/gdb/tui/tui-io.c
+++ b/gdb/tui/tui-io.c
@@ -1050,55 +1050,3 @@ tui_getc (FILE *fp)
       return 0;
     }
 }
-
-/* See tui-io.h.  */
-
-gdb::unique_xmalloc_ptr<char>
-tui_expand_tabs (const char *string)
-{
-  int n_adjust, ncol;
-  const char *s;
-  char *ret, *q;
-
-  /* 1. How many additional characters do we need?  */
-  for (ncol = 0, n_adjust = 0, s = string; s; )
-    {
-      s = strpbrk (s, "\t");
-      if (s)
-	{
-	  ncol += (s - string) + n_adjust;
-	  /* Adjustment for the next tab stop, minus one for the TAB
-	     we replace with spaces.  */
-	  n_adjust += 8 - (ncol % 8) - 1;
-	  s++;
-	}
-    }
-
-  /* Allocate the copy.  */
-  ret = q = (char *) xmalloc (strlen (string) + n_adjust + 1);
-
-  /* 2. Copy the original string while replacing TABs with spaces.  */
-  for (ncol = 0, s = string; s; )
-    {
-      const char *s1 = strpbrk (s, "\t");
-      if (s1)
-	{
-	  if (s1 > s)
-	    {
-	      strncpy (q, s, s1 - s);
-	      q += s1 - s;
-	      ncol += s1 - s;
-	    }
-	  do {
-	    *q++ = ' ';
-	    ncol++;
-	  } while ((ncol % 8) != 0);
-	  s1++;
-	}
-      else
-	strcpy (q, s);
-      s = s1;
-    }
-
-  return gdb::unique_xmalloc_ptr<char> (ret);
-}
diff --git a/gdb/tui/tui-io.h b/gdb/tui/tui-io.h
index f28cf4e..2cc47ba 100644
--- a/gdb/tui/tui-io.h
+++ b/gdb/tui/tui-io.h
@@ -45,9 +45,6 @@ extern void tui_initialize_io (void);
    changed the edited text.  */
 extern void tui_redisplay_readline (void);
 
-/* Expand TABs into spaces.  */
-extern gdb::unique_xmalloc_ptr<char> tui_expand_tabs (const char *);
-
 /* Enter/leave reverse video mode.  */
 extern void tui_set_reverse_mode (WINDOW *w, bool reverse);
 
diff --git a/gdb/tui/tui-regs.c b/gdb/tui/tui-regs.c
index b99e299..15ce7a0 100644
--- a/gdb/tui/tui-regs.c
+++ b/gdb/tui/tui-regs.c
@@ -42,15 +42,55 @@
 
 #include "gdb_curses.h"
 
+/* A subclass of string_file that expands tab characters.  */
+class tab_expansion_file : public string_file
+{
+public:
+
+  tab_expansion_file () = default;
+
+  void write (const char *buf, long length_buf) override;
+
+private:
+
+  int m_column = 0;
+};
+
+void
+tab_expansion_file::write (const char *buf, long length_buf)
+{
+  for (long i = 0; i < length_buf; ++i)
+    {
+      if (buf[i] == '\t')
+	{
+	  do
+	    {
+	      string_file::write (" ", 1);
+	      ++m_column;
+	    }
+	  while ((m_column % 8) != 0);
+	}
+      else
+	{
+	  string_file::write (&buf[i], 1);
+	  if (buf[i] == '\n')
+	    m_column = 0;
+	  else
+	    ++m_column;
+	}
+    }
+}
+
 /* Get the register from the frame and return a printable
    representation of it.  */
 
-static gdb::unique_xmalloc_ptr<char>
+static std::string
 tui_register_format (struct frame_info *frame, int regnum)
 {
   struct gdbarch *gdbarch = get_frame_arch (frame);
 
-  string_file stream;
+  /* Expand tabs into spaces, since ncurses on MS-Windows doesn't.  */
+  tab_expansion_file stream;
 
   scoped_restore save_pagination
     = make_scoped_restore (&pagination_enabled, 0);
@@ -64,8 +104,7 @@ tui_register_format (struct frame_info *frame, int regnum)
   if (!str.empty () && str.back () == '\n')
     str.resize (str.size () - 1);
 
-  /* Expand tabs into spaces, since ncurses on MS-Windows doesn't.  */
-  return tui_expand_tabs (str.c_str ());
+  return str;
 }
 
 /* Get the register value from the given frame and format it for the
@@ -80,11 +119,9 @@ tui_get_register (struct frame_info *frame,
     *changedp = false;
   if (target_has_registers)
     {
-      gdb::unique_xmalloc_ptr<char> new_content
-	= tui_register_format (frame, regnum);
+      std::string new_content = tui_register_format (frame, regnum);
 
-      if (changedp != NULL
-	  && strcmp (data->content.get (), new_content.get ()) != 0)
+      if (changedp != NULL && data->content != new_content)
 	*changedp = true;
 
       data->content = std::move (new_content);
@@ -244,13 +281,7 @@ tui_data_window::display_registers_from (int start_element_no)
   int max_len = 0;
   for (auto &&data_item_win : m_regs_content)
     {
-      const char *p;
-      int len;
-
-      len = 0;
-      p = data_item_win.content.get ();
-      if (p != 0)
-	len = strlen (p);
+      int len = data_item_win.content.size ();
 
       if (len > max_len)
 	max_len = len;
@@ -488,8 +519,7 @@ tui_data_item_window::rerender ()
   for (i = 1; i < width; i++)
     waddch (handle.get (), ' ');
   wmove (handle.get (), 0, 0);
-  if (content)
-    waddstr (handle.get (), content.get ());
+  waddstr (handle.get (), content.c_str ());
 
   if (highlight)
     /* We ignore the return value, casting it to void in order to avoid
diff --git a/gdb/tui/tui-regs.h b/gdb/tui/tui-regs.h
index df8c273..250f4e7 100644
--- a/gdb/tui/tui-regs.h
+++ b/gdb/tui/tui-regs.h
@@ -52,7 +52,7 @@ struct tui_data_item_window : public tui_gen_win_info
   /* The register number, or data display number.  */
   int item_no = -1;
   bool highlight = false;
-  gdb::unique_xmalloc_ptr<char> content;
+  std::string content;
 };
 
 /* The TUI registers window.  */