Color output

src/output/shell.rs

@@ -0,0 +1,126 @@
+pub struct Shell
+{
+	output: ShellOutput,
+}
+
+enum ShellOutput
+{
+	Basic(Box<dyn std::io::Write>),
+	WithColorSupport
+	{
+		stream: termcolor::StandardStream,
+		color_choice: ColorChoice,
+		is_a_tty: bool,
+	},
+}
+
+#[derive(Clone, Copy, Eq, PartialEq)]
+pub enum ColorChoice
+{
+	Always,
+	Never,
+	Auto,
+}
+
+impl Shell
+{
+	pub fn from_stdout() -> Self
+	{
+		Self
+		{
+			output: ShellOutput::WithColorSupport
+			{
+				stream:
+					termcolor::StandardStream::stdout(ColorChoice::Auto.to_termcolor_color_choice()),
+				color_choice: ColorChoice::Auto,
+				is_a_tty: atty::is(atty::Stream::Stdout),
+			},
+		}
+	}
+
+	pub fn print(&mut self, text: &dyn std::fmt::Display, color: &termcolor::ColorSpec)
+		-> std::io::Result<()>
+	{
+		self.output.print(text, color)
+	}
+
+	pub fn println(&mut self, text: &dyn std::fmt::Display, color: &termcolor::ColorSpec)
+		-> std::io::Result<()>
+	{
+		self.output.println(text, color)
+	}
+
+	pub fn erase_line(&mut self)
+	{
+		self.output.erase_line();
+	}
+}
+
+impl ShellOutput
+{
+	fn print(&mut self, text: &dyn std::fmt::Display, color: &termcolor::ColorSpec)
+		-> std::io::Result<()>
+	{
+		use std::io::Write as _;
+		use termcolor::WriteColor as _;
+
+		match *self
+		{
+			Self::Basic(ref mut write) => write!(write, "{}", text),
+			Self::WithColorSupport{ref mut stream, ..} =>
+			{
+				stream.reset()?;
+				stream.set_color(color)?;
+
+				write!(stream, "{}", text)?;
+
+				stream.reset()
+			},
+		}
+	}
+
+	fn println(&mut self, text: &dyn std::fmt::Display, color: &termcolor::ColorSpec)
+		-> std::io::Result<()>
+	{
+		self.print(text, color)?;
+
+		use std::io::Write as _;
+
+		match *self
+		{
+			Self::Basic(ref mut write) => writeln!(write, ""),
+			Self::WithColorSupport{ref mut stream, ..} => writeln!(stream, ""),
+		}
+	}
+
+	#[cfg(unix)]
+	pub fn erase_line(&mut self)
+	{
+		let erase_sequence = b"\x1b[2K";
+
+		use std::io::Write as _;
+
+		let _ = match *self
+		{
+			Self::Basic(ref mut write) => write.write_all(erase_sequence),
+			Self::WithColorSupport{ref mut stream, ..} => stream.write_all(erase_sequence),
+		};
+	}
+}
+
+impl ColorChoice
+{
+	fn to_termcolor_color_choice(self) -> termcolor::ColorChoice
+	{
+		match self
+		{
+			Self::Always => termcolor::ColorChoice::Always,
+			Self::Never => termcolor::ColorChoice::Never,
+			Self::Auto => match atty::is(atty::Stream::Stdout)
+			{
+				true => termcolor::ColorChoice::Auto,
+				false => termcolor::ColorChoice::Never,
+			},
+		}
+	}
+}