Create utils for colorful and stylish terminal output

Cargo.toml

@@ -23,6 +23,10 @@ rust-version = "1.70.0"
 name = "pls"
 
 [dependencies]
+colored = "2.0.0"
+lazy_static = "1.4.0"
+regex = { version = "1.8.4", default-features = false, features = ["std", "perf"] }
+unicode-segmentation = "1.10.1"
 
 [profile.release]
 # Reference: https://github.com/johnthagen/min-sized-rust

src/fmt.rs

@@ -0,0 +1,21 @@
+//! This module contains code for working with markup strings.
+//!
+//! Markup strings are a more convenient way to represent ANSI-formatted text.
+//! They use an HTML-like syntax instead of arcane escape sequences.
+//!
+//! For example, to render the string "Hello, World!" in bold, you would write
+//! `<bold>Hello, World!</>`.
+//!
+//! The tag consists of space separated directives. See [`fmt`](format::fmt) for
+//! a list of supported directives. Tags can be nested, with inner tags capable
+//! of overwriting directives from outer tags.
+//!
+//! The public interface of the module consists of two functions:
+//!
+//! * [`len`]
+//! * [`render`]
+
+mod format;
+mod markup;
+
+pub use markup::{len, render};

src/fmt/format.rs

@@ -0,0 +1,140 @@
+use colored::{Color, ColoredString, Colorize};
+use lazy_static::lazy_static;
+use regex::Regex;
+
+lazy_static! {
+	static ref TRUE_COLOR: Regex = Regex::new(
+		r"(?x)(?-u)^
+        rgb\(
+            (?P<red>\d{1,3}),\s?
+            (?P<green>\d{1,3}),\s?
+            (?P<blue>\d{1,3})
+        \)
+    $",
+	)
+	.unwrap();
+}
+
+/// Format the given string using the given list of directives.
+///
+/// Each of these directives can be a style or a color.
+///
+/// Styles can be one of a predefined list, namely 'blink', 'bold', 'dimmed',
+/// 'hidden', 'italic', 'reversed', 'strikethrough', 'underline', or 'clear'.
+/// Using the 'clear' style removes all existing styles from the string.
+///
+/// Colors can be one of the following:
+///
+/// * 8 ANSI colors
+/// * 8 bright versions of the ANSI colors (with the 'bright_' prefix)
+/// * true RGB colors (using the 'rgb(<red>,<green>,<blue>)' notation)
+///
+/// These colors are applied to the foreground text by default, but can be
+/// applied to the background instead (using the 'bg:' prefix).
+///
+/// For more information, refer to the documentation for the
+/// [colored](https://docs.rs/colored) crate.
+///
+/// # Arguments
+///
+/// * `text` - the string to format according to the style directives
+/// * `directives` - the formatting directives to apply to the string
+pub fn fmt<S, T>(text: S, directives: &[T]) -> String
+where
+	S: AsRef<str>,
+	T: AsRef<str>,
+{
+	let mut string = ColoredString::from(text.as_ref());
+	for directive in directives {
+		string = apply_directive(string, directive.as_ref())
+	}
+	string.to_string()
+}
+
+/// Apply a single directive to a `ColoredString` instance, consuming it and
+/// returning a new `ColoredString` instance with that directive applied.
+fn apply_directive(string: ColoredString, directive: &str) -> ColoredString {
+	let is_bg = directive.starts_with("bg:");
+	let directive = directive.replace("bg:", "").replace("bright_", "bright ");
+
+	let string = match directive.as_str() {
+		"clear" => return string.clear(), // no style
+		"blink" => return string.blink(),
+		"bold" => return string.bold(),
+		"dimmed" => return string.dimmed(),
+		"hidden" => return string.hidden(),
+		"italic" => return string.italic(),
+		"reversed" => return string.reversed(),
+		"strikethrough" => return string.strikethrough(),
+		"underline" => return string.underline(),
+		_ => string,
+	};
+
+	let mut color: Option<Color> = None;
+	if let Some(caps) = TRUE_COLOR.captures(&directive) {
+		// RGB true colors
+		let channels: Vec<_> = vec!["red", "green", "blue"]
+			.into_iter()
+			.filter_map(|x| caps[x].parse::<u8>().ok())
+			.collect();
+		if channels.len() == 3 {
+			color = Some(Color::TrueColor {
+				r: channels[0],
+				g: channels[1],
+				b: channels[2],
+			});
+		}
+	} else {
+		// Named ANSI colors
+		color = directive.parse().ok()
+	}
+
+	match color {
+		Some(col) if is_bg => string.on_color(col),
+		Some(col) => string.color(col),
+		None => string,
+	}
+}
+
+/// You can see the comprehensive list of escape codes for
+/// [ANSI colours on Wikipedia](https://en.wikipedia.org/wiki/ANSI_escape_code#Colors).
+#[cfg(test)]
+mod tests {
+	use super::fmt;
+
+	macro_rules! make_test {
+		( $($name:ident: $styles:expr => $prefix:expr, $suffix:expr,)* ) => {
+			$(
+				#[test]
+				fn $name() {
+					colored::control::set_override(true); // needed when running tests in CLion
+					let text = fmt("Hello, World!", $styles);
+					assert_eq!(text, format!("{}{}{}", $prefix, "Hello, World!", $suffix));
+				}
+			)*
+		};
+	}
+
+	make_test!(
+		test_fmt_applies_ansi_code_for_single_style: &["bold"] => "\x1b[1m", "\x1b[0m",
+		test_fmt_applies_ansi_code_for_multiple_styles: &["bold", "italic"] => "\x1b[1;3m", "\x1b[0m",
+
+		test_fmt_handles_reversed_colors: &["reversed"] => "\x1b[7m", "\x1b[0m",
+
+		test_fmt_applies_regular_text_color: &["blue"] => "\x1b[34m", "\x1b[0m",
+		test_fmt_applies_bright_text_color: &["bright_blue"] => "\x1b[94m", "\x1b[0m",
+		test_fmt_ignores_invalid_text_color: &["invalid"] => "", "",
+
+		test_fmt_applies_rgb_text_color: &["rgb(77,77,77)"] => "\x1b[38;2;77;77;77m", "\x1b[0m",
+		test_fmt_ignores_out_of_bounds_rgb_text_color: &["rgb(256,256,256)"] => "", "",
+
+		test_fmt_applies_regular_background_color: &["bg:blue"] => "\x1b[44m", "\x1b[0m",
+		test_fmt_applies_bright_background_color: &["bg:bright_blue"] => "\x1b[104m", "\x1b[0m",
+		test_fmt_ignores_invalid_background_color: &["bg:invalid"] => "", "",
+
+		test_fmt_applies_rgb_background_color: &["bg:rgb(77,77,77)"] => "\x1b[48;2;77;77;77m", "\x1b[0m",
+		test_fmt_ignores_out_of_bounds_rgb_background_color: &["bg:rgb(256,256,256)"] => "", "",
+
+		test_fmt_handles_clear_directive: &["bold", "italic", "clear"] => "", "", // no prefix, no suffix
+	);
+}