bc 0.1.16

Use `bc` in the Rust Programming Language.
Documentation 
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
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179

/*!
# bc (An arbitrary precision calculator language)

Use `bc` in the Rust Programming Language.

## Examples

```rust
let result = bc::bc!("2 + 6");

assert_eq!("8", result.unwrap());
```

```rust
let result = bc::bc!("2.5 + 6");

assert_eq!("8.5", result.unwrap());
```

```rust
let result = bc::bc_timeout!("99^99");

assert_eq!("369729637649726772657187905628805440595668764281741102430259972423552570455277523421410650010128232727940978889548326540119429996769494359451621570193644014418071060667659301384999779999159200499899", result.unwrap());
```

```rust
let result = bc::bc_timeout!(20, "99^99");

assert_eq!("369729637649726772657187905628805440595668764281741102430259972423552570455277523421410650010128232727940978889548326540119429996769494359451621570193644014418071060667659301384999779999159200499899", result.unwrap());
```
*/

use std::{
    error::Error,
    fmt::{Display, Error as FmtError, Formatter},
    io,
    path::Path,
    process::Stdio,
};

use execute::{command_args, Execute};

#[derive(Debug)]
pub enum BCError {
    IOError(io::Error),
    NoResult,
    Timeout,
    /// Maybe it is a syntax error.
    Error(String),
}

impl From<io::Error> for BCError {
    #[inline]
    fn from(err: io::Error) -> Self {
        BCError::IOError(err)
    }
}

impl From<String> for BCError {
    #[inline]
    fn from(err: String) -> Self {
        BCError::Error(err)
    }
}

impl Display for BCError {
    #[inline]
    fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), FmtError> {
        match self {
            BCError::IOError(err) => Display::fmt(err, f),
            BCError::NoResult => f.write_str("There is no result of BC."),
            BCError::Timeout => f.write_str("The BC calculation has timed out."),
            BCError::Error(text) => f.write_str(text.as_str()),
        }
    }
}

impl Error for BCError {}

/// Call `bc`.
pub fn bc<P: AsRef<Path>, S: AsRef<str>>(bc_path: P, statement: S) -> Result<String, BCError> {
    let mut command = command_args!(bc_path.as_ref(), "-l", "-q");

    command.stdout(Stdio::piped());
    command.stderr(Stdio::piped());

    let output = command.execute_input_output(format!("{}\n", statement.as_ref()).as_bytes())?;

    if output.stderr.is_empty() {
        if output.stdout.is_empty() {
            Err(BCError::NoResult)
        } else {
            Ok(handle_output(unsafe { String::from_utf8_unchecked(output.stdout) }))
        }
    } else {
        Err(BCError::Error(handle_output(unsafe { String::from_utf8_unchecked(output.stderr) })))
    }
}

/// Call `bc` with `timeout`.
pub fn bc_timeout<PT: AsRef<Path>, P: AsRef<Path>, S: AsRef<str>>(
    timeout_path: PT,
    timeout_secs: u32,
    bc_path: P,
    statement: S,
) -> Result<String, BCError> {
    let mut command = command_args!(
        timeout_path.as_ref(),
        format!("{}s", timeout_secs),
        bc_path.as_ref(),
        "-l",
        "-q"
    );

    command.stdout(Stdio::piped());
    command.stderr(Stdio::piped());

    let output = command.execute_input_output(format!("{}\n", statement.as_ref()).as_bytes())?;

    if let Some(code) = output.status.code() {
        if code == 124 {
            return Err(BCError::Timeout);
        }
    }

    if output.stderr.is_empty() {
        if output.stdout.is_empty() {
            Err(BCError::NoResult)
        } else {
            Ok(handle_output(unsafe { String::from_utf8_unchecked(output.stdout) }))
        }
    } else {
        Err(BCError::Error(handle_output(unsafe { String::from_utf8_unchecked(output.stderr) })))
    }
}

fn handle_output(mut output: String) -> String {
    let length = output.len();

    unsafe {
        output.as_mut_vec().set_len(length - 1);
    }

    match output.find("\\\n") {
        Some(index) => {
            let mut s = String::from(&output[..index]);

            s.push_str(&output[(index + 2)..].replace("\\\n", ""));

            s
        },
        None => output,
    }
}

/// Call `bc`.
#[macro_export]
macro_rules! bc {
    ($statement:expr) => {
        $crate::bc("bc", $statement)
    };
    ($bc_path:expr, $statement:expr) => {
        $crate::bc($bc_path, $statement)
    };
}

/// Call `bc` with `timeout`.
#[macro_export]
macro_rules! bc_timeout {
    ($statement:expr) => {
        $crate::bc_timeout("timeout", 15, "bc", $statement)
    };
    ($timeout:expr, $statement:expr) => {
        $crate::bc_timeout("timeout", $timeout, "bc", $statement)
    };
    ($timeout_path:expr, $timeout:expr, $bc_path:expr, $statement:expr) => {
        $crate::bc_timeout($timeout_path, $timeout, $bc_path, $statement)
    };
}