std/colour

=encoding utf8

=head1 NAME

std/colour - Colour parsing helpers.

=head1 SYNOPSIS

  from std/colour import parse_colour;

  say( parse_colour("red") );  # #ff0000
  say( parse_colour("#abc") ); # #aabbcc

=head1 IMPLEMENTATION SUPPORT

This module is supported by all implementations of ZuzuScript.

=head1 DESCRIPTION

C<parse_colour> accepts three- and six-digit hexadecimal colours and the
CSS3 extended colour keywords. It returns a lowercase six-digit
hexadecimal colour string.

=head1 EXPORTS

=head2 Functions

=over

=item C<< parse_colour(String x) >>

Parameters: C<x> is a CSS colour keyword or a three- or six-digit
hexadecimal colour string. Returns: C<String>. Returns the normalized
lowercase C<#rrggbb> colour string, or throws if C<x> is not recognised.

=back

=head1 COPYRIGHT AND LICENCE

B<< std/colour >> is copyright Toby Inkster.

It is free software; you may redistribute it and/or modify it under
the terms of either the Artistic License 1.0 or the GNU General Public
License version 2.

=cut

from std/string import trim;

const _COLOUR_KEYWORDS := {
	aliceblue: "#f0f8ff",
	antiquewhite: "#faebd7",
	aqua: "#00ffff",
	aquamarine: "#7fffd4",
	azure: "#f0ffff",
	beige: "#f5f5dc",
	bisque: "#ffe4c4",
	black: "#000000",
	blanchedalmond: "#ffebcd",
	blue: "#0000ff",
	blueviolet: "#8a2be2",
	brown: "#a52a2a",
	burlywood: "#deb887",
	cadetblue: "#5f9ea0",
	chartreuse: "#7fff00",
	chocolate: "#d2691e",
	coral: "#ff7f50",
	cornflowerblue: "#6495ed",
	cornsilk: "#fff8dc",
	crimson: "#dc143c",
	cyan: "#00ffff",
	darkblue: "#00008b",
	darkcyan: "#008b8b",
	darkgoldenrod: "#b8860b",
	darkgray: "#a9a9a9",
	darkgreen: "#006400",
	darkgrey: "#a9a9a9",
	darkkhaki: "#bdb76b",
	darkmagenta: "#8b008b",
	darkolivegreen: "#556b2f",
	darkorange: "#ff8c00",
	darkorchid: "#9932cc",
	darkred: "#8b0000",
	darksalmon: "#e9967a",
	darkseagreen: "#8fbc8f",
	darkslateblue: "#483d8b",
	darkslategray: "#2f4f4f",
	darkslategrey: "#2f4f4f",
	darkturquoise: "#00ced1",
	darkviolet: "#9400d3",
	deeppink: "#ff1493",
	deepskyblue: "#00bfff",
	dimgray: "#696969",
	dimgrey: "#696969",
	dodgerblue: "#1e90ff",
	firebrick: "#b22222",
	floralwhite: "#fffaf0",
	forestgreen: "#228b22",
	fuchsia: "#ff00ff",
	gainsboro: "#dcdcdc",
	ghostwhite: "#f8f8ff",
	gold: "#ffd700",
	goldenrod: "#daa520",
	gray: "#808080",
	green: "#008000",
	greenyellow: "#adff2f",
	grey: "#808080",
	honeydew: "#f0fff0",
	hotpink: "#ff69b4",
	indianred: "#cd5c5c",
	indigo: "#4b0082",
	ivory: "#fffff0",
	khaki: "#f0e68c",
	lavender: "#e6e6fa",
	lavenderblush: "#fff0f5",
	lawngreen: "#7cfc00",
	lemonchiffon: "#fffacd",
	lightblue: "#add8e6",
	lightcoral: "#f08080",
	lightcyan: "#e0ffff",
	lightgoldenrodyellow: "#fafad2",
	lightgray: "#d3d3d3",
	lightgreen: "#90ee90",
	lightgrey: "#d3d3d3",
	lightpink: "#ffb6c1",
	lightsalmon: "#ffa07a",
	lightseagreen: "#20b2aa",
	lightskyblue: "#87cefa",
	lightslategray: "#778899",
	lightslategrey: "#778899",
	lightsteelblue: "#b0c4de",
	lightyellow: "#ffffe0",
	lime: "#00ff00",
	limegreen: "#32cd32",
	linen: "#faf0e6",
	magenta: "#ff00ff",
	maroon: "#800000",
	mediumaquamarine: "#66cdaa",
	mediumblue: "#0000cd",
	mediumorchid: "#ba55d3",
	mediumpurple: "#9370db",
	mediumseagreen: "#3cb371",
	mediumslateblue: "#7b68ee",
	mediumspringgreen: "#00fa9a",
	mediumturquoise: "#48d1cc",
	mediumvioletred: "#c71585",
	midnightblue: "#191970",
	mintcream: "#f5fffa",
	mistyrose: "#ffe4e1",
	moccasin: "#ffe4b5",
	navajowhite: "#ffdead",
	navy: "#000080",
	oldlace: "#fdf5e6",
	olive: "#808000",
	olivedrab: "#6b8e23",
	orange: "#ffa500",
	orangered: "#ff4500",
	orchid: "#da70d6",
	palegoldenrod: "#eee8aa",
	palegreen: "#98fb98",
	paleturquoise: "#afeeee",
	palevioletred: "#db7093",
	papayawhip: "#ffefd5",
	peachpuff: "#ffdab9",
	peru: "#cd853f",
	pink: "#ffc0cb",
	plum: "#dda0dd",
	powderblue: "#b0e0e6",
	purple: "#800080",
	red: "#ff0000",
	rosybrown: "#bc8f8f",
	royalblue: "#4169e1",
	saddlebrown: "#8b4513",
	salmon: "#fa8072",
	sandybrown: "#f4a460",
	seagreen: "#2e8b57",
	seashell: "#fff5ee",
	sienna: "#a0522d",
	silver: "#c0c0c0",
	skyblue: "#87ceeb",
	slateblue: "#6a5acd",
	slategray: "#708090",
	slategrey: "#708090",
	snow: "#fffafa",
	springgreen: "#00ff7f",
	steelblue: "#4682b4",
	tan: "#d2b48c",
	teal: "#008080",
	thistle: "#d8bfd8",
	tomato: "#ff6347",
	turquoise: "#40e0d0",
	violet: "#ee82ee",
	wheat: "#f5deb3",
	white: "#ffffff",
	whitesmoke: "#f5f5f5",
	yellow: "#ffff00",
	yellowgreen: "#9acd32",
};

function parse_colour ( String x ) {
	let text := lc( trim(x) );

	if ( text ~ /^#[0-9a-f]{6}$/ ) {
		return text;
	}

	let short := text ~ /^#([0-9a-f])([0-9a-f])([0-9a-f])$/;
	if ( short ) {
		return "#"
			_ short[1] _ short[1]
			_ short[2] _ short[2]
			_ short[3] _ short[3];
	}

	if ( _COLOUR_KEYWORDS.exists(text) ) {
		return _COLOUR_KEYWORDS.get(text);
	}

	die `Invalid colour: ${x}`;
}
Module
