Introduce ui_file_style

This introduces the new ui_file_style class and various helpers.  This
class represents a terminal style and provides methods for parsing and
emitting the corresponding ANSI terminal escape sequences.

gdb/ChangeLog
2018-12-28  Tom Tromey  <tom@tromey.com>

	* unittests/style-selftests.c: New file.
	* ui-style.c: New file.
	* ui-style.h: New file.
	* ui-file.h: Include ui-style.h.
	* Makefile.in (COMMON_SFILES): Add ui-style.c.
	(HFILES_NO_SRCDIR): Add ui-style.h.
	(SUBDIR_UNITTESTS_SRCS): Add style-selftests.c.

1 files changed, 213 insertions, 0 deletions

diff --git a/gdb/ui-style.h b/gdb/ui-style.h
new file mode 100644
index 0000000..2d0e516
--- /dev/null
+++ b/gdb/ui-style.h
@@ -0,0 +1,213 @@
+/* Styling for ui_file
+   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 UI_STYLE_H
+#define UI_STYLE_H
+
+/* Styles that can be applied to a ui_file.  */
+struct ui_file_style
+{
+  /* One of the basic colors that can be handled by ANSI
+     terminals.  */
+  enum basic_color
+  {
+    NONE = -1,
+    BLACK,
+    RED,
+    GREEN,
+    YELLOW,
+    BLUE,
+    MAGENTA,
+    CYAN,
+    WHITE
+  };
+
+  /* Representation of a terminal color.  */
+  class color
+  {
+  public:
+
+    color (basic_color c)
+      : m_simple (true),
+	m_value (c)
+    {
+    }
+
+    color (int c)
+      : m_simple (true),
+	m_value (c)
+    {
+      gdb_assert (c >= -1 && c <= 255);
+    }
+
+    color (uint8_t r, uint8_t g, uint8_t b)
+      : m_simple (false),
+	m_red (r),
+	m_green (g),
+	m_blue (b)
+    {
+    }
+
+    bool operator== (const color &other) const
+    {
+      if (m_simple != other.m_simple)
+	return false;
+      if (m_simple)
+	return m_value == other.m_value;
+      return (m_red == other.m_red && m_green == other.m_green
+	      && m_blue == other.m_blue);
+    }
+
+    bool operator< (const color &other) const
+    {
+      if (m_simple != other.m_simple)
+	return m_simple < other.m_simple;
+      if (m_simple)
+	return m_value < other.m_value;
+      if (m_red < other.m_red)
+	return true;
+      if (m_red == other.m_red)
+	{
+	  if (m_green < other.m_green)
+	    return true;
+	  if (m_green == other.m_green)
+	    return m_blue < other.m_blue;
+	}
+      return false;
+    }
+
+    /* Return true if this is the "NONE" color, false otherwise.  */
+    bool is_none () const
+    {
+      return m_simple && m_value == NONE;
+    }
+
+    /* Return true if this is one of the basic colors, false
+       otherwise.  */
+    bool is_basic () const
+    {
+      return m_simple && m_value >= BLACK && m_value <= WHITE;
+    }
+
+    /* Return the value of a basic color.  */
+    int get_value () const
+    {
+      gdb_assert (is_basic ());
+      return m_value;
+    }
+
+    /* Fill in RGB with the red/green/blue values for this color.
+       This may not be called for basic colors or for the "NONE"
+       color.  */
+    void get_rgb (uint8_t *rgb) const;
+
+    /* Append the ANSI terminal escape sequence for this color to STR.
+       IS_FG indicates whether this is a foreground or background
+       color.  Returns true if any characters were written; returns
+       false otherwise (which can only happen for the "NONE"
+       color).  */
+    bool append_ansi (bool is_fg, std::string *str) const;
+
+  private:
+
+    bool m_simple;
+    int m_value;
+    uint8_t m_red, m_green, m_blue;
+  };
+
+  /* Intensity settings that are available.  */
+  enum intensity
+  {
+    NORMAL = 0,
+    BOLD,
+    DIM
+  };
+
+  ui_file_style () = default;
+
+  ui_file_style (color f, color b, intensity i = NORMAL)
+    : m_foreground (f),
+      m_background (b),
+      m_intensity (i)
+  {
+  }
+
+  bool operator== (const ui_file_style &other) const
+  {
+    return (m_foreground == other.m_foreground
+	    && m_background == other.m_background
+	    && m_intensity == other.m_intensity
+	    && m_reverse == other.m_reverse);
+  }
+
+  bool operator!= (const ui_file_style &other) const
+  {
+    return !(*this == other);
+  }
+
+  /* Return the ANSI escape sequence for this style.  */
+  std::string to_ansi () const;
+
+  /* Return true if this style specified reverse display; false
+     otherwise.  */
+  bool is_reverse () const
+  {
+    return m_reverse;
+  }
+
+  /* Return the foreground color of this style.  */
+  const color &get_foreground () const
+  {
+    return m_foreground;
+  }
+
+  /* Return the background color of this style.  */
+  const color &get_background () const
+  {
+    return m_background;
+  }
+
+  /* Return the intensity of this style.  */
+  intensity get_intensity () const
+  {
+    return m_intensity;
+  }
+
+  /* Parse an ANSI escape sequence in BUF, modifying this style.  BUF
+     must begin with an ESC character.  Return true if an escape
+     sequence was successfully parsed; false otherwise.  In either
+     case, N_READ is updated to reflect the number of chars read from
+     BUF.  */
+  bool parse (const char *buf, size_t *n_read);
+
+private:
+
+  color m_foreground = NONE;
+  color m_background = NONE;
+  intensity m_intensity = NORMAL;
+  bool m_reverse = false;
+};
+
+/* Skip an ANSI escape sequence in BUF.  BUF must begin with an ESC
+   character.  Return true if an escape sequence was successfully
+   skipped; false otherwise.  In either case, N_READ is updated to
+   reflect the number of chars read from BUF.  */
+
+extern bool skip_ansi_escape (const char *buf, int *n_read);
+
+#endif /* UI_STYLE_H */