nushell/crates/nu-ansi-term/src/lib.rs

//! This is a library for controlling colors and formatting, such as
//! red bold text or blue underlined text, on ANSI terminals.
//!
//!
//! ## Basic usage
//!
//! There are three main types in this crate that you need to be
//! concerned with: [`ANSIString`], [`Style`], and [`Color`].
//!
//! A `Style` holds stylistic information: foreground and background colors,
//! whether the text should be bold, or blinking, or other properties. The
//! [`Color`] enum represents the available colors. And an [`ANSIString`] is a
//! string paired with a [`Style`].
//!
//! [`Color`] is also available as an alias to `Color`.
//!
//! To format a string, call the `paint` method on a `Style` or a `Color`,
//! passing in the string you want to format as the argument. For example,
//! here’s how to get some red text:
//!
//! ```
//! use nu_ansi_term::Color::Red;
//!
//! println!("This is in red: {}", Red.paint("a red string"));
//! ```
//!
//! It’s important to note that the `paint` method does *not* actually return a
//! string with the ANSI control characters surrounding it. Instead, it returns
//! an [`ANSIString`] value that has a [`Display`] implementation that, when
//! formatted, returns the characters. This allows strings to be printed with a
//! minimum of [`String`] allocations being performed behind the scenes.
//!
//! If you *do* want to get at the escape codes, then you can convert the
//! [`ANSIString`] to a string as you would any other `Display` value:
//!
//! ```
//! use nu_ansi_term::Color::Red;
//!
//! let red_string = Red.paint("a red string").to_string();
//! ```
//!
//!
//! ## Bold, underline, background, and other styles
//!
//! For anything more complex than plain foreground color changes, you need to
//! construct `Style` values themselves, rather than beginning with a `Color`.
//! You can do this by chaining methods based on a new `Style`, created with
//! [`Style::new()`]. Each method creates a new style that has that specific
//! property set. For example:
//!
//! ```
//! use nu_ansi_term::Style;
//!
//! println!("How about some {} and {}?",
//!          Style::new().bold().paint("bold"),
//!          Style::new().underline().paint("underline"));
//! ```
//!
//! For brevity, these methods have also been implemented for `Color` values,
//! so you can give your styles a foreground color without having to begin with
//! an empty `Style` value:
//!
//! ```
//! use nu_ansi_term::Color::{Blue, Yellow};
//!
//! println!("Demonstrating {} and {}!",
//!          Blue.bold().paint("blue bold"),
//!          Yellow.underline().paint("yellow underline"));
//!
//! println!("Yellow on blue: {}", Yellow.on(Blue).paint("wow!"));
//! ```
//!
//! The complete list of styles you can use are: [`bold`], [`dimmed`], [`italic`],
//! [`underline`], [`blink`], [`reverse`], [`hidden`], [`strikethrough`], and [`on`] for
//! background colors.
//!
//! In some cases, you may find it easier to change the foreground on an
//! existing `Style` rather than starting from the appropriate `Color`.
//! You can do this using the [`fg`] method:
//!
//! ```
//! use nu_ansi_term::Style;
//! use nu_ansi_term::Color::{Blue, Cyan, Yellow};
//!
//! println!("Yellow on blue: {}", Style::new().on(Blue).fg(Yellow).paint("yow!"));
//! println!("Also yellow on blue: {}", Cyan.on(Blue).fg(Yellow).paint("zow!"));
//! ```
//!
//! You can turn a `Color` into a `Style` with the [`normal`] method.
//! This will produce the exact same `ANSIString` as if you just used the
//! `paint` method on the `Color` directly, but it’s useful in certain cases:
//! for example, you may have a method that returns `Styles`, and need to
//! represent both the “red bold” and “red, but not bold” styles with values of
//! the same type. The `Style` struct also has a [`Default`] implementation if you
//! want to have a style with *nothing* set.
//!
//! ```
//! use nu_ansi_term::Style;
//! use nu_ansi_term::Color::Red;
//!
//! Red.normal().paint("yet another red string");
//! Style::default().paint("a completely regular string");
//! ```
//!
//!
//! ## Extended colors
//!
//! You can access the extended range of 256 colors by using the `Color::Fixed`
//! variant, which takes an argument of the color number to use. This can be
//! included wherever you would use a `Color`:
//!
//! ```
//! use nu_ansi_term::Color::Fixed;
//!
//! Fixed(134).paint("A sort of light purple");
//! Fixed(221).on(Fixed(124)).paint("Mustard in the ketchup");
//! ```
//!
//! The first sixteen of these values are the same as the normal and bold
//! standard color variants. There’s nothing stopping you from using these as
//! `Fixed` colors instead, but there’s nothing to be gained by doing so
//! either.
//!
//! You can also access full 24-bit color by using the `Color::Rgb` variant,
//! which takes separate `u8` arguments for red, green, and blue:
//!
//! ```
//! use nu_ansi_term::Color::Rgb;
//!
//! Rgb(70, 130, 180).paint("Steel blue");
//! ```
//!
//! ## Combining successive colored strings
//!
//! The benefit of writing ANSI escape codes to the terminal is that they
//! *stack*: you do not need to end every colored string with a reset code if
//! the text that follows it is of a similar style. For example, if you want to
//! have some blue text followed by some blue bold text, it’s possible to send
//! the ANSI code for blue, followed by the ANSI code for bold, and finishing
//! with a reset code without having to have an extra one between the two
//! strings.
//!
//! This crate can optimise the ANSI codes that get printed in situations like
//! this, making life easier for your terminal renderer. The [`ANSIStrings`]
//! type takes a slice of several [`ANSIString`] values, and will iterate over
//! each of them, printing only the codes for the styles that need to be updated
//! as part of its formatting routine.
//!
//! The following code snippet uses this to enclose a binary number displayed in
//! red bold text inside some red, but not bold, brackets:
//!
//! ```
//! use nu_ansi_term::Color::Red;
//! use nu_ansi_term::{ANSIString, ANSIStrings};
//!
//! let some_value = format!("{:b}", 42);
//! let strings: &[ANSIString<'static>] = &[
//!     Red.paint("["),
//!     Red.bold().paint(some_value),
//!     Red.paint("]"),
//! ];
//!
//! println!("Value: {}", ANSIStrings(strings));
//! ```
//!
//! There are several things to note here. Firstly, the [`paint`] method can take
//! *either* an owned [`String`] or a borrowed [`&str`]. Internally, an [`ANSIString`]
//! holds a copy-on-write ([`Cow`]) string value to deal with both owned and
//! borrowed strings at the same time. This is used here to display a `String`,
//! the result of the `format!` call, using the same mechanism as some
//! statically-available `&str` slices. Secondly, that the [`ANSIStrings`] value
//! works in the same way as its singular counterpart, with a [`Display`]
//! implementation that only performs the formatting when required.
//!
//! ## Byte strings
//!
//! This library also supports formatting `\[u8]` byte strings; this supports
//! applications working with text in an unknown encoding.  [`Style`] and
//! [`Color`] support painting `\[u8]` values, resulting in an [`ANSIByteString`].
//! This type does not implement [`Display`], as it may not contain UTF-8, but
//! it does provide a method [`write_to`] to write the result to any value that
//! implements [`Write`]:
//!
//! ```
//! use nu_ansi_term::Color::Green;
//!
//! Green.paint("user data".as_bytes()).write_to(&mut std::io::stdout()).unwrap();
//! ```
//!
//! Similarly, the type [`ANSIByteStrings`] supports writing a list of
//! [`ANSIByteString`] values with minimal escape sequences:
//!
//! ```
//! use nu_ansi_term::Color::Green;
//! use nu_ansi_term::ANSIByteStrings;
//!
//! ANSIByteStrings(&[
//!     Green.paint("user data 1\n".as_bytes()),
//!     Green.bold().paint("user data 2\n".as_bytes()),
//! ]).write_to(&mut std::io::stdout()).unwrap();
//! ```
//!
//! [`Cow`]: https://doc.rust-lang.org/std/borrow/enum.Cow.html
//! [`Display`]: https://doc.rust-lang.org/std/fmt/trait.Display.html
//! [`Default`]: https://doc.rust-lang.org/std/default/trait.Default.html
//! [`String`]: https://doc.rust-lang.org/std/string/struct.String.html
//! [`&str`]: https://doc.rust-lang.org/std/primitive.str.html
//! [`Write`]: https://doc.rust-lang.org/std/io/trait.Write.html
//! [`Style`]: struct.Style.html
//! [`Style::new()`]: struct.Style.html#method.new
//! [`Color`]: enum.Color.html
//! [`Color`]: enum.Color.html
//! [`ANSIString`]: type.ANSIString.html
//! [`ANSIStrings`]: type.ANSIStrings.html
//! [`ANSIByteString`]: type.ANSIByteString.html
//! [`ANSIByteStrings`]: type.ANSIByteStrings.html
//! [`write_to`]: type.ANSIByteString.html#method.write_to
//! [`paint`]: type.ANSIByteString.html#method.write_to
//! [`normal`]: enum.Color.html#method.normal
//!
//! [`bold`]: struct.Style.html#method.bold
//! [`dimmed`]: struct.Style.html#method.dimmed
//! [`italic`]: struct.Style.html#method.italic
//! [`underline`]: struct.Style.html#method.underline
//! [`blink`]: struct.Style.html#method.blink
//! [`reverse`]: struct.Style.html#method.reverse
//! [`hidden`]: struct.Style.html#method.hidden
//! [`strikethrough`]: struct.Style.html#method.strikethrough
//! [`fg`]: struct.Style.html#method.fg
//! [`on`]: struct.Style.html#method.on

#![crate_name = "nu_ansi_term"]
#![crate_type = "rlib"]
#![crate_type = "dylib"]
#![warn(missing_copy_implementations)]
// #![warn(missing_docs)]
#![warn(trivial_casts, trivial_numeric_casts)]
// #![warn(unused_extern_crates, unused_qualifications)]

#[cfg(target_os = "windows")]
extern crate winapi;
#[cfg(test)]
#[macro_use]
extern crate doc_comment;

#[cfg(test)]
doctest!("../README.md");

pub mod ansi;
pub use ansi::{Infix, Prefix, Suffix};

mod style;
pub use style::{Color, Style};

mod difference;
mod display;
pub use display::*;

mod write;

mod windows;
pub use windows::*;

mod util;
pub use util::*;

mod debug;

pub mod gradient;
pub use gradient::*;

mod rgb;
pub use rgb::*;