1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147

use std::io::{self, IsTerminal};

use termcolor::{self, HyperlinkSpec};

/// A writer that supports coloring with either line or block buffering.
pub struct StandardStream(StandardStreamKind);

/// Returns a possibly buffered writer to stdout for the given color choice.
///
/// The writer returned is either line buffered or block buffered. The decision
/// between these two is made automatically based on whether a tty is attached
/// to stdout or not. If a tty is attached, then line buffering is used.
/// Otherwise, block buffering is used. In general, block buffering is more
/// efficient, but may increase the time it takes for the end user to see the
/// first bits of output.
///
/// If you need more fine grained control over the buffering mode, then use one
/// of `stdout_buffered_line` or `stdout_buffered_block`.
///
/// The color choice given is passed along to the underlying writer. To
/// completely disable colors in all cases, use `ColorChoice::Never`.
pub fn stdout(color_choice: termcolor::ColorChoice) -> StandardStream {
    if std::io::stdout().is_terminal() {
        stdout_buffered_line(color_choice)
    } else {
        stdout_buffered_block(color_choice)
    }
}

/// Returns a line buffered writer to stdout for the given color choice.
///
/// This writer is useful when printing results directly to a tty such that
/// users see output as soon as it's written. The downside of this approach
/// is that it can be slower, especially when there is a lot of output.
///
/// You might consider using [`stdout`] instead, which chooses the buffering
/// strategy automatically based on whether stdout is connected to a tty.
pub fn stdout_buffered_line(
    color_choice: termcolor::ColorChoice,
) -> StandardStream {
    let out = termcolor::StandardStream::stdout(color_choice);
    StandardStream(StandardStreamKind::LineBuffered(out))
}

/// Returns a block buffered writer to stdout for the given color choice.
///
/// This writer is useful when printing results to a file since it amortizes
/// the cost of writing data. The downside of this approach is that it can
/// increase the latency of display output when writing to a tty.
///
/// You might consider using [`stdout`] instead, which chooses the buffering
/// strategy automatically based on whether stdout is connected to a tty.
pub fn stdout_buffered_block(
    color_choice: termcolor::ColorChoice,
) -> StandardStream {
    let out = termcolor::BufferedStandardStream::stdout(color_choice);
    StandardStream(StandardStreamKind::BlockBuffered(out))
}

enum StandardStreamKind {
    LineBuffered(termcolor::StandardStream),
    BlockBuffered(termcolor::BufferedStandardStream),
}

impl io::Write for StandardStream {
    #[inline]
    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
        use self::StandardStreamKind::*;

        match self.0 {
            LineBuffered(ref mut w) => w.write(buf),
            BlockBuffered(ref mut w) => w.write(buf),
        }
    }

    #[inline]
    fn flush(&mut self) -> io::Result<()> {
        use self::StandardStreamKind::*;

        match self.0 {
            LineBuffered(ref mut w) => w.flush(),
            BlockBuffered(ref mut w) => w.flush(),
        }
    }
}

impl termcolor::WriteColor for StandardStream {
    #[inline]
    fn supports_color(&self) -> bool {
        use self::StandardStreamKind::*;

        match self.0 {
            LineBuffered(ref w) => w.supports_color(),
            BlockBuffered(ref w) => w.supports_color(),
        }
    }

    #[inline]
    fn supports_hyperlinks(&self) -> bool {
        use self::StandardStreamKind::*;

        match self.0 {
            LineBuffered(ref w) => w.supports_hyperlinks(),
            BlockBuffered(ref w) => w.supports_hyperlinks(),
        }
    }

    #[inline]
    fn set_color(&mut self, spec: &termcolor::ColorSpec) -> io::Result<()> {
        use self::StandardStreamKind::*;

        match self.0 {
            LineBuffered(ref mut w) => w.set_color(spec),
            BlockBuffered(ref mut w) => w.set_color(spec),
        }
    }

    #[inline]
    fn set_hyperlink(&mut self, link: &HyperlinkSpec) -> io::Result<()> {
        use self::StandardStreamKind::*;

        match self.0 {
            LineBuffered(ref mut w) => w.set_hyperlink(link),
            BlockBuffered(ref mut w) => w.set_hyperlink(link),
        }
    }

    #[inline]
    fn reset(&mut self) -> io::Result<()> {
        use self::StandardStreamKind::*;

        match self.0 {
            LineBuffered(ref mut w) => w.reset(),
            BlockBuffered(ref mut w) => w.reset(),
        }
    }

    #[inline]
    fn is_synchronous(&self) -> bool {
        use self::StandardStreamKind::*;

        match self.0 {
            LineBuffered(ref w) => w.is_synchronous(),
            BlockBuffered(ref w) => w.is_synchronous(),
        }
    }
}