[RFC 3/8] Add output styles to gdb

[Tom Tromey <tom at tromey dot com>]

This adds some output styling to the CLI.

A style is currently a foreground color, a background color, and an
intensity (dim or bold).  (This list could be expanded depending on
terminal capabilities.)

A style can be applied while printing.  This patch changes cli-out.c
to apply styles just to certain fields, recognized by name.  In
particular, function names and file names are stylized.

This seemed like a reasonable approach, because the names are fixed
due to their use in MI.  That is, the CLI is just as exposed to future
changes as MI is.

Users can control the style via a number of new set/show commands.  In
the interest of not typing many nearly-identical documentation
strings, I automated this.  On the down side, this is not very
i18n-friendly.

I've chose some default colors to use.  I think it would be good to
enable this by default, so that when users start the new gdb, they
will see the new feature.

Stylizing is done if TERM is set and is not "dumb".  This could be
improved when the TUI is available by using the curses has_colors
call.  That is, the lowest layer could call this without committing to
using curses everywhere; see my other patch for TUI colorizing.

I considered adding a new "set_style" method to ui_file.  However,
because the implementation had to interact with the pager code, I
didn't take this approach.  But, one idea might be to put the isatty
check there and then have it defer to the lower layers.
---
 gdb/Makefile.in     |   2 +
 gdb/cli-out.c       |  19 ++++-
 gdb/cli/cli-style.c | 207 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 gdb/cli/cli-style.h |  67 +++++++++++++++++
 gdb/ui-file.h       |  42 +++++++++++
 gdb/utils.c         |  69 +++++++++++++++++-
 gdb/utils.h         |   4 +
 7 files changed, 408 insertions(+), 2 deletions(-)
 create mode 100644 gdb/cli/cli-style.c
 create mode 100644 gdb/cli/cli-style.h

diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index c76a4e4394c..3117bf74094 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -239,6 +239,7 @@ SUBDIR_CLI_SRCS = \
 	cli/cli-logging.c \
 	cli/cli-script.c \
 	cli/cli-setshow.c \
+	cli/cli-style.c \
 	cli/cli-utils.c
 
 SUBDIR_CLI_OBS = $(patsubst %.c,%.o,$(SUBDIR_CLI_SRCS))
@@ -1415,6 +1416,7 @@ HFILES_NO_SRCDIR = \
 	cli/cli-decode.h \
 	cli/cli-script.h \
 	cli/cli-setshow.h \
+	cli/cli-style.h \
 	cli/cli-utils.h \
 	common/buffer.h \
 	common/cleanups.h \
diff --git a/gdb/cli-out.c b/gdb/cli-out.c
index ad0a34ed39f..eeb3a64cbae 100644
--- a/gdb/cli-out.c
+++ b/gdb/cli-out.c
@@ -25,6 +25,7 @@
 #include "cli-out.h"
 #include "completer.h"
 #include "readline/readline.h"
+#include "cli/cli-style.h"
 
 /* These are the CLI output functions */
 
@@ -156,7 +157,23 @@ cli_ui_out::do_field_string (int fldno, int width, ui_align align,
     spaces (before);
 
   if (string)
-    fputs_filtered (string, m_streams.back ());
+    {
+      cli_style_option *style = nullptr;
+      if (fldname == nullptr)
+	{
+	  /* Nothing.  */
+	}
+      else if (!strcmp (fldname, "file"))
+	style = &file_name_style;
+      else if (!strcmp (fldname, "func") || !strcmp (fldname, "function"))
+	style = &function_name_style;
+
+      if (style != nullptr)
+	set_output_style (m_streams.back (), style->style ());
+      fputs_filtered (string, m_streams.back ());
+      if (style != nullptr)
+	set_output_style (m_streams.back (), ui_file_style ());
+    }
 
   if (after)
     spaces (after);
diff --git a/gdb/cli/cli-style.c b/gdb/cli/cli-style.c
new file mode 100644
index 00000000000..9b210863bd3
--- /dev/null
+++ b/gdb/cli/cli-style.c
@@ -0,0 +1,207 @@
+/* CLI colorizing
+
+   Copyright (C) 2018 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include "defs.h"
+#include "cli/cli-cmds.h"
+#include "cli/cli-style.h"
+
+static const char * const cli_colors[] = {
+  "none",
+  "black",
+  "red",
+  "green",
+  "yellow",
+  "blue",
+  "magenta",
+  "cyan",
+  "white",
+  nullptr
+};
+
+static const char * const cli_intensities[] = {
+  "normal",
+  "bold",
+  "dim",
+  nullptr
+};
+
+cli_style_option file_name_style (ui_file_style::GREEN);
+cli_style_option function_name_style (ui_file_style::YELLOW);
+
+cli_style_option::cli_style_option (ui_file_style::color fg)
+  : m_foreground (cli_colors[fg - ui_file_style::NONE]),
+    m_background (cli_colors[0]),
+    m_intensity (cli_intensities[ui_file_style::NORMAL])
+{
+}
+
+static int
+color_number (const char *color)
+{
+  for (int i = 0; i < ARRAY_SIZE (cli_colors); ++i)
+    {
+      if (color == cli_colors[i])
+	return i - 1;
+    }
+  gdb_assert_not_reached ("color not found");
+}
+
+ui_file_style
+cli_style_option::style () const
+{
+  ui_file_style result;
+
+  result.m_foreground = (ui_file_style::color) color_number (m_foreground);
+  result.m_background = (ui_file_style::color) color_number (m_background);
+
+  for (int i = 0; i < ARRAY_SIZE (cli_intensities); ++i)
+    {
+      if (m_intensity == cli_intensities[i])
+	{
+	  result.m_intensity = (ui_file_style::intensity) i;
+	  break;
+	}
+    }
+
+  return result;
+}
+
+void
+cli_style_option::do_set (const char *args, int from_tty)
+{
+}
+
+void
+cli_style_option::do_show (const char *args, int from_tty)
+{
+}
+
+void
+cli_style_option::do_show_foreground (struct ui_file *file, int from_tty,
+				      struct cmd_list_element *cmd,
+				      const char *value)
+{
+  const char *name = (const char *) get_cmd_context (cmd);
+  fprintf_filtered (file, _("The \"%s\" foreground color is: %s\n"),
+		    name, value);
+}
+
+void
+cli_style_option::do_show_background (struct ui_file *file, int from_tty,
+				      struct cmd_list_element *cmd,
+				      const char *value)
+{
+  const char *name = (const char *) get_cmd_context (cmd);
+  fprintf_filtered (file, _("The \"%s\" background color is: %s\n"),
+		    name, value);
+}
+
+void
+cli_style_option::do_show_intensity (struct ui_file *file, int from_tty,
+				     struct cmd_list_element *cmd,
+				     const char *value)
+{
+  const char *name = (const char *) get_cmd_context (cmd);
+  fprintf_filtered (file, _("The \"%s\" display intensity is: %s\n"),
+		    name, value);
+}
+
+void
+cli_style_option::add_setshow_commands (const char *name,
+					enum command_class theclass,
+					const char *prefix_doc,
+					const char *prefixname,
+					struct cmd_list_element **set_list,
+					struct cmd_list_element **show_list)
+{
+  m_show_prefix = std::string ("set ") + prefixname + " ";
+  m_show_prefix = std::string ("show ") + prefixname + " ";
+
+  add_prefix_cmd (name, no_class, do_set, prefix_doc, &m_set_list, 
+		  m_show_prefix.c_str (), 0, set_list);
+  add_prefix_cmd (name, no_class, do_show, prefix_doc, &m_show_list,
+		  m_set_prefix.c_str (), 0, show_list);
+
+  add_setshow_enum_cmd ("foreground", theclass, cli_colors,
+			&m_foreground,
+			_("Set the foreground color for this property"),
+			_("Show the foreground color for this property"),
+			nullptr,
+			nullptr,
+			do_show_foreground,
+			&m_set_list, &m_show_list, (void *) name);
+  add_setshow_enum_cmd ("background", theclass, cli_colors,
+			&m_background,
+			_("Set the background color for this property"),
+			_("Show the background color for this property"),
+			nullptr,
+			nullptr,
+			do_show_background,
+			&m_set_list, &m_show_list, (void *) name);
+  add_setshow_enum_cmd ("intensity", theclass, cli_intensities,
+			&m_intensity,
+			_("Set the display intensity color for this property"),
+			_("\
+Show the display intensity color for this property"),
+			nullptr,
+			nullptr,
+			do_show_intensity,
+			&m_set_list, &m_show_list, (void *) name);
+}
+
+static void
+set_style (const char *arg, int from_tty)
+{
+}
+
+static void
+show_style (const char *arg, int from_tty)
+{
+}
+
+void
+_initialize_cli_style ()
+{
+  static cmd_list_element *style_set_list;
+  static cmd_list_element *style_show_list;
+
+  add_prefix_cmd ("style", no_class, set_style, _("\
+Style-specific settings\n\
+Configure various style-related variables, such as colors"),
+		  &style_set_list, "set style ", 0, &setlist);
+  add_prefix_cmd ("style", no_class, show_style, _("\
+Style-specific settings\n\
+Configure various style-related variables, such as colors"),
+		  &style_show_list, "show style ", 0, &showlist);
+
+  file_name_style.add_setshow_commands ("filename", no_class,
+					_("\
+Filename display styling\n\
+Configure filename colors and display intensity."),
+					"style filename",
+					&style_set_list,
+					&style_show_list);
+  function_name_style.add_setshow_commands ("function", no_class,
+					    _("\
+Function name display styling\n\
+Configure function name colors and display intensity"),
+					    "style function",
+					    &style_set_list,
+					    &style_show_list);
+}
diff --git a/gdb/cli/cli-style.h b/gdb/cli/cli-style.h
new file mode 100644
index 00000000000..d9c00003bd4
--- /dev/null
+++ b/gdb/cli/cli-style.h
@@ -0,0 +1,67 @@
+/* CLI stylizing
+
+   Copyright (C) 2018 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#ifndef CLI_STYLE_H
+#define CLI_STYLE_H
+
+#include "ui-file.h"
+
+class cli_style_option
+{
+public:
+
+  cli_style_option (ui_file_style::color fg);
+
+  ui_file_style style () const;
+
+  void add_setshow_commands (const char *name,
+			     enum command_class theclass,
+			     const char *prefix_doc,
+			     const char *prefixname,
+			     struct cmd_list_element **set_list,
+			     struct cmd_list_element **show_list);
+
+private:
+
+  const char *m_foreground;
+  const char *m_background;
+  const char *m_intensity;
+
+  std::string m_show_prefix;
+  std::string m_set_prefix;
+  struct cmd_list_element *m_set_list = nullptr;
+  struct cmd_list_element *m_show_list = nullptr;
+
+  static void do_set (const char *args, int from_tty);
+  static void do_show (const char *args, int from_tty);
+  static void do_show_foreground (struct ui_file *file, int from_tty,
+				  struct cmd_list_element *cmd,
+				  const char *value);
+  static void do_show_background (struct ui_file *file, int from_tty,
+				  struct cmd_list_element *cmd,
+				  const char *value);
+  static void do_show_intensity (struct ui_file *file, int from_tty,
+				 struct cmd_list_element *cmd,
+				 const char *value);
+};
+
+extern cli_style_option file_name_style;
+extern cli_style_option function_name_style;
+
+#endif /* CLI_STYLE_H */
diff --git a/gdb/ui-file.h b/gdb/ui-file.h
index 2cf5f83d473..630fcffef69 100644
--- a/gdb/ui-file.h
+++ b/gdb/ui-file.h
@@ -21,6 +21,48 @@
 
 #include <string>
 
+/* Styles that can be applied to a ui_file.  */
+struct ui_file_style
+{
+  enum color
+  {
+    NONE = -1,
+    BLACK,
+    RED,
+    GREEN,
+    YELLOW,
+    BLUE,
+    MAGENTA,
+    CYAN,
+    WHITE
+  };
+
+  enum intensity
+  {
+    NORMAL = 0,
+    BOLD,
+    DIM
+  };
+
+
+  enum color m_foreground = NONE;
+  enum color m_background = NONE;
+  enum intensity m_intensity = NORMAL;
+
+  bool operator== (const ui_file_style &other) const
+  {
+    return (m_foreground == other.m_foreground
+	    && m_background == other.m_background
+	    && m_intensity == other.m_intensity);
+  }
+
+  bool operator!= (const ui_file_style &other) const
+  {
+    return !(*this == other);
+  }
+};
+
+
 /* The abstract ui_file base class.  */
 
 class ui_file
diff --git a/gdb/utils.c b/gdb/utils.c
index 1982fa20e64..ca69d5fc57c 100644
--- a/gdb/utils.c
+++ b/gdb/utils.c
@@ -1422,6 +1422,63 @@ set_screen_width_and_height (int width, int height)
   set_width ();
 }
 
+static ui_file_style applied_style;
+static ui_file_style desired_style;
+
+static void
+emit (const char *str)
+{
+  if (wrap_column)
+    wrap_buffer.append (str);
+  else
+    puts_unfiltered (str);
+}
+
+static void
+emit_style_escape (const ui_file_style &style)
+{
+  if (applied_style == style)
+    return;
+  applied_style = style;
+
+  emit ("\e[");
+  bool need_semi = false;
+  if (style.m_foreground != ui_file_style::NONE)
+    {
+      emit (std::to_string (30 + style.m_foreground).c_str ());
+      need_semi = true;
+    }
+  if (style.m_background != ui_file_style::NONE)
+    {
+      if (need_semi)
+	emit (";");
+      emit (std::to_string (40 + style.m_background).c_str ());
+      need_semi = true;
+    }
+  if (style.m_intensity != ui_file_style::NORMAL)
+    {
+      if (need_semi)
+	emit (";");
+      emit (std::to_string (style.m_intensity).c_str ());
+    }
+  emit ("m");
+}
+
+void
+set_output_style (struct ui_file *stream, const ui_file_style &style)
+{
+  if (stream != gdb_stdout
+      || style == desired_style
+      || !ui_file_isatty (stream))
+    return;
+  const char *term = getenv ("TERM");
+  if (term == nullptr || !strcmp (term, "dumb"))
+    return;
+
+  desired_style = style;
+  emit_style_escape (style);
+}
+
 /* Wait, so the user can read what's on the screen.  Prompt the user
    to continue by pressing RETURN.  'q' is also provided because
    telling users what to do in the prompt is more user-friendly than
@@ -1437,6 +1494,9 @@ prompt_for_continue (void)
   steady_clock::time_point prompt_started = steady_clock::now ();
   bool disable_pagination = pagination_disabled_for_command;
 
+  /* Clear the current styling.  */
+  emit_style_escape (ui_file_style ());
+
   if (annotation_level > 1)
     printf_unfiltered (("\n\032\032pre-prompt-for-continue\n"));
 
@@ -1481,6 +1541,9 @@ prompt_for_continue (void)
   reinitialize_more_filter ();
   pagination_disabled_for_command = disable_pagination;
 
+  /* Restore the current styling.  */
+  emit_style_escape (desired_style);
+
   dont_repeat ();		/* Forget prev cmd -- CR won't repeat it.  */
 }
 
@@ -1709,7 +1772,10 @@ fputs_maybe_filtered (const char *linebuffer, struct ui_file *stream,
 	         if chars_per_line is right, we probably just overflowed
 	         anyway; if it's wrong, let us keep going.  */
 	      if (wrap_column)
-		fputc_unfiltered ('\n', stream);
+		{
+		  emit_style_escape (ui_file_style ());
+		  fputc_unfiltered ('\n', stream);
+		}
 
 	      /* Possible new page.  Note that
 		 PAGINATION_DISABLED_FOR_COMMAND might be set during
@@ -1722,6 +1788,7 @@ fputs_maybe_filtered (const char *linebuffer, struct ui_file *stream,
 	      if (wrap_column)
 		{
 		  fputs_unfiltered (wrap_indent, stream);
+		  emit_style_escape (desired_style);
 		  fputs_unfiltered (wrap_buffer.c_str (), stream);
 		  /* FIXME, this strlen is what prevents wrap_indent from
 		     containing tabs.  However, if we recurse to print it
diff --git a/gdb/utils.h b/gdb/utils.h
index 68523994b94..0c8a2e1da16 100644
--- a/gdb/utils.h
+++ b/gdb/utils.h
@@ -423,6 +423,10 @@ extern void fputstrn_unfiltered (const char *str, int n, int quotr,
 /* Return nonzero if filtered printing is initialized.  */
 extern int filtered_printing_initialized (void);
 
+class ui_file_style;
+extern void set_output_style (struct ui_file *stream,
+			      const ui_file_style &style);
+
 /* Display the host ADDR on STREAM formatted as ``0x%x''.  */
 extern void gdb_print_host_address_1 (const void *addr, struct ui_file *stream);
 
-- 
2.13.6