Add terminal and color escape sequences

- style, foreground and background color enumerators
- true color (24-bit) types
- generation of escape strings via to_string function

Author: awvwgk

doc/specs/index.md

@@ -13,6 +13,7 @@ This is and index/directory of the specifications (specs) for each new module/fe
 
  - [ascii](./stdlib_ascii.html) - Procedures for handling ASCII characters
  - [bitsets](./stdlib_bitsets.html) - Bitset data types and procedures
+ - [colors](./stdlib_colors.html) - Terminal color and style escape sequences
  - [error](./stdlib_error.html) - Catching and handling errors
  - [IO](./stdlib_io.html) - Input/output helper & convenience
  - [kinds](./stdlib_kinds.html) - Kind parameters

doc/specs/stdlib_color.md

@@ -0,0 +1,231 @@
+---
+title: terminal colors
+...
+
+
+# The `stdlib_colors` module
+
+[TOC]
+
+## Introduction
+
+Support terminal escape sequences to produce styled and colored terminal output.
+
+
+## Derived types provided
+
+
+### ``fg_color24`` type
+
+The ``fg_color24`` type represent a true color (24-bit) foreground color.
+It contains the members ``red``, ``blue`` and ``green`` as default integer types.
+
+#### Status
+
+Experimental
+
+
+### ``bg_color24`` type
+
+The ``bg_color24`` type represent a true color (24-bit) background color.
+It contains the members ``red``, ``blue`` and ``green`` as default integer types.
+
+#### Status
+
+Experimental
+
+
+## Constants provided
+
+### ``style_reset``
+
+Style enumerator representing a reset escape code.
+
+
+### ``style_bold``
+
+Style enumerator representing a bold escape code.
+
+
+### ``style_dim``
+
+Style enumerator representing a dim escape code.
+
+
+
+### ``style_italic``
+
+Style enumerator representing an italic escape code.
+
+
+
+### ``style_underline``
+
+Style enumerator representing an underline escape code.
+
+
+### ``style_blink``
+
+Style enumerator representing a blink escape code.
+
+
+### ``style_blink_fast``
+
+Style enumerator representing a (fast) blink escape code.
+
+
+### ``style_reverse``
+
+Style enumerator representing a reverse escape code.
+
+
+### ``style_hidden``
+
+Style enumerator representing a hidden escape code.
+
+
+### ``style_strikethrough
+
+Style enumerator representing a strike-through escape code.
+
+
+### ``fg_color_black``
+
+Foreground color enumerator representing a foreground black color escape code.
+
+
+### ``fg_color_red``
+
+Foreground color enumerator representing a foreground red color escape code.
+
+
+### ``fg_color_green``
+
+Foreground color enumerator representing a foreground green color escape code.
+
+
+### ``fg_color_yellow``
+
+Foreground color enumerator representing a foreground yellow color escape code.
+
+
+### ``fg_color_blue
+
+Foreground color enumerator representing a foreground blue color escape code.
+
+
+### ``fg_color_magenta``
+
+Foreground color enumerator representing a foreground magenta color escape code.
+
+
+### ``fg_color_cyan``
+
+Foreground color enumerator representing a foreground cyan color escape code.
+
+
+### ``fg_color_white``
+
+Foreground color enumerator representing a foreground white color escape code.
+
+
+### ``fg_color_default
+
+Foreground color enumerator representing a foreground default color escape code.
+
+
+### ``bg_color_black``
+
+Background color enumerator representing a background black color escape code.
+
+
+### ``bg_color_red``
+
+Background color enumerator representing a background red color escape code.
+
+
+### ``bg_color_green``
+
+Background color enumerator representing a background green color escape code.
+
+
+### ``bg_color_yellow``
+
+Background color enumerator representing a background yellow color escape code.
+
+
+### ``bg_color_blue
+
+Background color enumerator representing a background blue color escape code.
+
+
+### ``bg_color_magenta``
+
+Background color enumerator representing a background magenta color escape code.
+
+
+### ``bg_color_cyan``
+
+Background color enumerator representing a background cyan color escape code.
+
+
+### ``bg_color_white``
+
+Background color enumerator representing a background white color escape code.
+
+
+### ``bg_color_default``
+
+Background color enumerator representing a background default color escape code.
+
+
+## Procedures and methods provided
+
+### ``to_string``
+
+Generic interface to turn a style, foreground or background enumerator into an actual escape code string for printout.
+
+#### Syntax
+
+`string = [[stdlib_string_colors(module):to_string(interface)]] (enum)`
+
+#### Class
+
+Pure function.
+
+#### Argument
+
+``enum``: Style, foreground or background enumerator, this argument is ``intent(in)``.
+
+#### Result value
+
+The result is a default character string.
+
+#### Status
+
+Experimental
+
+
+### ``to_string``
+
+Generic interface to turn a foreground or background true color type into an actual escape code string for printout.
+
+#### Syntax
+
+`string = [[stdlib_string_colors(module):to_string(interface)]] (color24)`
+
+#### Class
+
+Pure function.
+
+#### Argument
+
+``color24``: Foreground or background true color instance, this argument is ``intent(in)``.
+
+#### Result value
+
+The result is a default character string.
+
+#### Status
+
+Experimental

src/CMakeLists.txt

@@ -60,6 +60,8 @@ list(
 fypp_f90("${fyppFlags}" "${fppFiles}" outFiles)
 
 set(SRC
+    stdlib_colors.f90
+    stdlib_colors_to_string.f90
     stdlib_error.f90
     stdlib_logger.f90
     stdlib_system.F90

src/Makefile.manual

@@ -38,6 +38,8 @@ SRCFYPP = \
         stdlib_strings_to_string.fypp
 
 SRC = f18estop.f90 \
+      stdlib_colors.f90 \
+      stdlib_colors_to_string.f90 \
       stdlib_error.f90 \
       stdlib_specialfunctions.f90 \
       stdlib_specialfunctions_legendre.f90 \
@@ -175,3 +177,6 @@ stdlib_linalg_outer_product.o: stdlib_linalg.o
 stdlib_stringlist_type.o: stdlib_string_type.o \
     stdlib_math.o \
 	stdlib_optval.o
+stdlib_colors_to_string.o: \
+    stdlib_strings.o \
+    stdlib_colors.o