Add an option with a color type.

Colors can be specified as "none" for terminal's default color, as a name of
one of the eight standard colors of ISO/IEC 6429 "black", "red", "green", etc.,
as an RGB hexadecimal tripplet #RRGGBB for 24-bit TrueColor, or as an
integer from 0 to 255.  Integers 0 to 7 are the synonyms for the standard
colors.  Integers 8-15 are used for the so-called bright colors from the
aixterm extended 16-color palette.  Integers 16-255 are the indexes into xterm
extended 256-color palette (usually 6x6x6 cube plus gray ramp).  In
general, 256-color palette is terminal dependent and sometimes can be
changed with OSC 4 sequences, e.g. "\033]4;1;rgb:00/FF/00\033\\".

It is the responsibility of the user to verify that the terminal supports
the specified colors.

PATCH v5 changes: documentation fixed.
PATCH v6 changes: documentation fixed.
PATCH v7 changes: rebase onto master and fixes after review.
PATCH v8 changes: fixes after review.

3 files changed, 240 insertions, 8 deletions

diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 0d55875..726e7ce 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -13009,6 +13009,20 @@ and @code{$_shell_exitsignal} according to the exit status of the last
 launched command.  These variables are set and used similarly to
 the variables @code{$_exitcode} and @code{$_exitsignal}.
 
+@item $_colorsupport
+@vindex $_colorsupport@r{, convenience variable}
+@cindex color space
+Comma-separated list of @dfn{color space} names supported by terminal.  Names
+could be any of @samp{monochrome}, @samp{ansi_8color}, @samp{aixterm_16color},
+@samp{xterm_256color}, @samp{rgb_24bit}.  E.g., for plain linux terminal the
+value could be @samp{monochrome,ansi_8color} and for terminal with truecolor
+support it could be
+@samp{monochrome,ansi_8color,aixterm_16color,xterm_256color,rgb_24bit}.
+@samp{rgb_24bit} availability is determined by the @env{COLORTERM} environment
+variable which may be @samp{truecolor} or @samp{24bit}. Other color spaces are
+determined by the "Co" termcap which in turn depends on the @env{TERM}
+environment variable.
+
 @end table
 
 @node Convenience Funs
@@ -27871,16 +27885,32 @@ For example, the style of file names can be controlled using the
 
 @table @code
 @item set style filename background @var{color}
-Set the background to @var{color}.  Valid colors are @samp{none}
-(meaning the terminal's default color), @samp{black}, @samp{red},
-@samp{green}, @samp{yellow}, @samp{blue}, @samp{magenta}, @samp{cyan},
-and@samp{white}.
+Set the background to @var{color}.  @var{color} can be @samp{none}
+(meaning the terminal's default color), a name of one of the eight standard
+colors of ISO/IEC 6429, index from 0 to 255 into terminal's color
+palette or a hexadecimal RGB triplet in @samp{#RRGGBB} format for
+24-bit TrueColor.
+
+Valid color names are @samp{black}, @samp{red}, @samp{green},
+@samp{yellow}, @samp{blue}, @samp{magenta}, @samp{cyan}, and
+@samp{white}.
+
+Integers 0 to 7 are the synonyms for the standard colors.  Integers 8-15 are
+used for the so-called bright colors from the aixterm extended 16-color
+palette.  Integers 16-255 are the indexes into xterm extended 256-color palette
+(usually 6x6x6 cube plus gray ramp).  In general, 256-color palette is terminal
+dependent and sometimes can be changed with OSC 4 sequences, e.g.
+"\033]4;1;rgb:00/FF/00\033\\". A hexadecimal 24-bit TrueColor is specified in
+the format @samp{#RRGGBB} where RR, GG and BB are the 2-digit hexadecimal
+integers specifiing the intensity of the red, green and blue color components,
+respectively.
+
+It is the responsibility of the user to verify that the terminal supports
+the specified colors.
 
 @item set style filename foreground @var{color}
-Set the foreground to @var{color}.  Valid colors are @samp{none}
-(meaning the terminal's default color), @samp{black}, @samp{red},
-@samp{green}, @samp{yellow}, @samp{blue}, @samp{magenta}, @samp{cyan},
-and@samp{white}.
+Set the foreground to @var{color}.  @var{color} can be given in the same ways
+as for the background.
 
 @item set style filename intensity @var{value}
 Set the intensity to @var{value}.  Valid intensities are @samp{normal}
diff --git a/gdb/doc/guile.texi b/gdb/doc/guile.texi
index bd1262e..f1b638e 100644
--- a/gdb/doc/guile.texi
+++ b/gdb/doc/guile.texi
@@ -155,6 +155,7 @@ from the Guile interactive prompt.
 * I/O Ports in Guile::       GDB I/O ports
 * Memory Ports in Guile::    Accessing memory through ports and bytevectors
 * Iterators In Guile::       Basic iterator support
+* Colors In Guile::          Colorize output with Guile
 @end menu
 
 @node Basic Guile
@@ -408,6 +409,9 @@ as a symbol.
 
 @item <gdb:value>
 @xref{Values From Inferior In Guile}.
+
+@item <gdb:color>
+@xref{Colors In Guile}.
 @end table
 
 The following @value{GDBN} objects are managed internally so that the
@@ -2184,6 +2188,14 @@ The value is a filename.  This is just like
 @item PARAM_ENUM
 The value is a string, which must be one of a collection of string
 constants provided when the parameter is created.
+
+@item PARAM_COLOR
+The value is either a string or an unsigned integer.  Integer from 0 to 255
+means index into terminal's color palette.  String can be a hex RGB triplet in
+@samp{#RRGGBB} format or one of the following color names:
+@samp{none} (meaning the terminal's default color), @samp{black}, @samp{red},
+@samp{green}, @samp{yellow}, @samp{blue}, @samp{magenta}, @samp{cyan},
+or @samp{white}.
 @end vtable
 
 @node Progspaces In Guile
@@ -3820,6 +3832,98 @@ Run @var{iterator} until the result of @code{(pred element)} is true
 and return that as the result.  Otherwise return @code{#f}.
 @end deffn
 
+@node Colors In Guile
+@subsubsection Colors In Guile
+
+@cindex guile colors
+@tindex <gdb:color>
+You can assign instance of @code{<gdb:color>} to the value of
+a @code{<gdb:parameter>} object created with @code{PARAM_COLOR}.
+
+@code{<gdb:color>} may refer to an index from color palette or contain
+components of a color from some colorspace.
+
+@deffn {Scheme Procedure} make-color @w{@r{[}value} @
+    @w{@r{[}#:color-space color-space@r{]}@r{]}}
+
+@var{value} is an integer index of a color in palette, tuple with color
+components or a string.  String can be a hex RGB triplet in @samp{#RRGGBB}
+format or one of the following color names:
+@samp{none} (meaning the terminal's default color), @samp{black}, @samp{red},
+@samp{green}, @samp{yellow}, @samp{blue}, @samp{magenta}, @samp{cyan},
+or @samp{white}.
+
+@var{color-space} should be one of the @samp{COLORSPACE_} constants.  This
+argument tells @value{GDBN} which color space @var{value} belongs.
+@end deffn
+
+@deffn {Scheme Procedure} color? object
+Return @code{#t} if @var{object} is a @code{<gdb:color>} object.
+Otherwise return @code{#f}.
+@end deffn
+
+@deffn {Scheme Procedure} color-none? color
+Return @code{#t} if @var{color} is terminal's default.
+Otherwise return @code{#f}.
+@end deffn
+
+@deffn {Scheme Procedure} color-indexed? color
+Return @code{#t} if @var{color} is indexed, i.e. belongs to some palette.
+Otherwise return @code{#f}.
+@end deffn
+
+@deffn {Scheme Procedure} color-direct? color
+Return @code{#t} if @var{color} is direct in the sense of ISO/IEC 8613-6.
+Otherwise return @code{#f}.
+@end deffn
+
+@deffn {Scheme Procedure} color-string color
+Return the textual representation of a @code{<gdb:color>} object.
+@end deffn
+
+@deffn {Scheme Procedure} color-colorspace color
+Return the color space of a @code{<gdb:color>} object.
+@end deffn
+
+@deffn {Scheme Procedure} color-index color
+Return index of the color of a @code{<gdb:color>} object in a palette.
+@end deffn
+
+@deffn {Scheme Procedure} color-components color
+Return components of the direct @code{<gdb:color>} object.
+@end deffn
+
+@deffn {Scheme Procedure} color-escape-sequence color is_foreground
+Return string to change terminal's color to this.
+
+If @var{is_foreground} is @code{#t}, then the returned sequence will change
+foreground color.  Otherwise, the returned sequence will change background
+color.
+@end deffn
+
+When color is initialized, its color space must be specified.  The
+available color spaces are represented by constants defined in the @code{gdb}
+module:
+
+@vtable @code
+@item COLORSPACE_MONOCHROME
+Palette with only terminal's default color.
+
+@item COLORSPACE_ANSI_8COLOR
+Palette with eight standard colors of ISO/IEC 6429 "black", "red", "green", etc.
+
+@item COLORSPACE_AIXTERM_16COLOR
+Palette with 16 colors.  First eight are standard colors of ISO/IEC 6429
+"black", "red", "green", etc.  Next eight are their bright version.
+
+@item COLORSPACE_XTERM_256COLOR
+Palette with 256 colors.  First 16 are from COLORSPACE_AIXTERM_16COLOR.  Next
+216 colors are 6x6x6 RGB cube.  And last 24 colors form grayscale ramp.
+
+@item COLORSPACE_RGB_24BIT
+Direct 24-bit RGB colors.
+@end vtable
+
 @node Guile Auto-loading
 @subsection Guile Auto-loading
 @cindex guile auto-loading
diff --git a/gdb/doc/python.texi b/gdb/doc/python.texi
index 2e10930..d66cae6 100644
--- a/gdb/doc/python.texi
+++ b/gdb/doc/python.texi
@@ -225,6 +225,7 @@ optional arguments while skipping others.  Example:
 * Finish Breakpoints in Python:: Setting Breakpoints on function return
                                 using Python.
 * Lazy Strings In Python::      Python representation of lazy strings.
+* Colors In Python::            Python representation of colors.
 * Architectures In Python::     Python representation of architectures.
 * Registers In Python::         Python representation of registers.
 * Connections In Python::       Python representation of connections.
@@ -5242,6 +5243,11 @@ except the special value -1 is returned for the setting of ``unlimited''.
 @item gdb.PARAM_ENUM
 The value is a string, which must be one of a collection string
 constants provided when the parameter is created.
+
+@findex PARAM_COLOR
+@findex gdb.PARAM_COLOR
+@item gdb.PARAM_COLOR
+The value is @code{gdb.Color} instance.
 @end table
 
 @node Functions In Python
@@ -7020,6 +7026,98 @@ resolve this to the lazy string's character type, use the type's
 writable.
 @end defvar
 
+@node Colors In Python
+@subsubsection Python representation of colors
+
+@cindex colors in python
+@tindex gdb.Color
+You can assign instance of @code{Color} to the @code{value} of
+a @code{Parameter} instance created with @code{PARAM_COLOR}.
+
+@code{Color} may refer to an index from color palette or contain components
+of a color from some colorspace.
+
+@defun Color.__init__ (@r{[}@var{value} @r{[}, @var{color-space}@r{]}@r{]})
+
+@var{value} is @code{None} (meaning the terminal's default color),
+an integer index of a color in palette, tuple with color components
+or a string.  String can be a hex RGB triplet in @samp{#RRGGBB} format
+or one of the following color names:
+@samp{none} (meaning the terminal's default color), @samp{black}, @samp{red},
+@samp{green}, @samp{yellow}, @samp{blue}, @samp{magenta}, @samp{cyan},
+or @samp{white}.
+
+@var{color-space} should be one of the @samp{COLORSPACE_} constants.  This
+argument tells @value{GDBN} which color space @var{value} belongs.
+@end defun
+
+@defvar Color.is_none
+This atribute is boolean.  If its value is @code{True} then color is terminal's
+default.
+@end defvar
+
+@defvar Color.is_indexed
+This atribute is boolean.  If its value is @code{True} then color is indexed,
+i.e. belongs to some palette.
+@end defvar
+
+@defvar Color.is_direct
+This atribute is boolean.  If its value is @code{True} then this object
+describes direct colour in the sense of ISO/IEC 8613-6.
+@end defvar
+
+@defvar Color.index
+This attribute exist if @code{is_indexed} is @code{True}.  Its integer value is
+index of a color in a palette.
+@end defvar
+
+@defvar Color.components
+This attribute exist if @code{is_direct} is @code{True}.  Its value is tuple
+with integer components of a color.
+@end defvar
+
+@defun Color.escape_sequence (@var{self}, @var{is_foreground})
+Returns string to change terminal's color to this.
+
+If @var{is_foreground} is @code{True}, then the returned sequence will change
+foreground color.  Otherwise, the returned sequence will change background
+color.
+@end defun
+
+When color is initialized, its color space must be specified.  The
+available color spaces are represented by constants defined in the @code{gdb}
+module:
+
+@table @code
+@findex COLORSPACE_MONOCHROME
+@findex gdb.COLORSPACE_MONOCHROME
+@item gdb.COLORSPACE_MONOCHROME
+Palette with only terminal's default color.
+
+@findex COLORSPACE_ANSI_8COLOR
+@findex gdb.COLORSPACE_ANSI_8COLOR
+@item gdb.COLORSPACE_ANSI_8COLOR
+Palette with eight standard colors of ISO/IEC 6429 "black", "red", "green", etc.
+
+@findex COLORSPACE_AIXTERM_16COLOR
+@findex gdb.COLORSPACE_AIXTERM_16COLOR
+@item gdb.COLORSPACE_AIXTERM_16COLOR
+Palette with 16 colors.  First eight are standard colors of ISO/IEC 6429
+"black", "red", "green", etc.  Next eight are their bright version.
+
+@findex COLORSPACE_XTERM_256COLOR
+@findex gdb.COLORSPACE_XTERM_256COLOR
+@item gdb.COLORSPACE_XTERM_256COLOR
+Palette with 256 colors.  First 16 are from COLORSPACE_AIXTERM_16COLOR.  Next
+216 colors are 6x6x6 RGB cube.  And last 24 colors form grayscale ramp.
+
+@findex COLORSPACE_RGB_24BIT
+@findex gdb.COLORSPACE_RGB_24BIT
+@item gdb.COLORSPACE_RGB_24BIT
+Direct 24-bit RGB colors.
+
+@end table
+
 @node Architectures In Python
 @subsubsection Python representation of architectures
 @cindex Python architectures