os_info/
matcher.rs

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
/// An implementation to match on simple strings.
#[derive(Debug, Clone)]
#[allow(dead_code)]
pub enum Matcher {
    /// Considers the entire string (trimmed) to be the match.
    AllTrimmed,

    /// After finding the `prefix` followed by one or more spaces, returns the following word.
    PrefixedWord { prefix: &'static str },

    /// Similar to `PrefixedWord`, but only if the word is a valid version.
    PrefixedVersion { prefix: &'static str },

    /// Takes a set of lines (separated by `\n`) and searches for the value in a key/value pair
    /// separated by the `=` character. For example `VERSION_ID="8.1"`.
    KeyValue { key: &'static str },
}

impl Matcher {
    /// Find the match on the input `string`.
    pub fn find(&self, string: &str) -> Option<String> {
        match *self {
            Self::AllTrimmed => Some(string.trim().to_string()),
            Self::PrefixedWord { prefix } => find_prefixed_word(string, prefix).map(str::to_owned),
            Self::PrefixedVersion { prefix } => find_prefixed_word(string, prefix)
                .filter(|&v| is_valid_version(v))
                .map(str::to_owned),
            Self::KeyValue { key } => find_by_key(string, key).map(str::to_owned),
        }
    }
}

fn find_by_key<'a>(string: &'a str, key: &str) -> Option<&'a str> {
    let key = [key, "="].concat();
    for line in string.lines() {
        if line.starts_with(&key) {
            return Some(line[key.len()..].trim_matches(|c: char| c == '"' || c.is_whitespace()));
        }
    }

    None
}

fn find_prefixed_word<'a>(string: &'a str, prefix: &str) -> Option<&'a str> {
    if let Some(prefix_start) = string.find(prefix) {
        // Ignore prefix and leading whitespace
        let string = &string[prefix_start + prefix.len()..].trim_start();

        // Find where the word boundary ends
        let word_end = string
            .find(|c: char| c.is_whitespace())
            .unwrap_or(string.len());
        let string = &string[..word_end];

        Some(string)
    } else {
        None
    }
}

fn is_valid_version(word: &str) -> bool {
    !word.starts_with('.') && !word.ends_with('.')
}

#[cfg(test)]
mod tests {
    use super::*;
    use pretty_assertions::assert_eq;

    #[test]
    fn trimmed() {
        let data = [
            ("", Some("")),
            ("test", Some("test")),
            (" 		 test", Some("test")),
            ("test  	   ", Some("test")),
            ("  test 	", Some("test")),
        ];

        let matcher = Matcher::AllTrimmed;

        for (input, expected) in &data {
            let result = matcher.find(input);
            assert_eq!(result.as_deref(), *expected);
        }
    }

    #[test]
    fn prefixed_word() {
        let data = [
            ("", None),
            ("test", Some("")),
            ("test1", Some("1")),
            ("test 1", Some("1")),
            (" test 1", Some("1")),
            ("test 1.2.3", Some("1.2.3")),
            (" 		test 1.2.3", Some("1.2.3")),
        ];

        let matcher = Matcher::PrefixedWord { prefix: "test" };

        for (input, expected) in &data {
            let result = matcher.find(input);
            assert_eq!(result.as_deref(), *expected);
        }
    }

    #[test]
    fn prefixed_version() {
        let data = [
            ("", None),
            ("test", Some("")),
            ("test 1", Some("1")),
            ("test .1", None),
            ("test 1.", None),
            ("test .1.", None),
            (" test 1", Some("1")),
            ("test 1.2.3", Some("1.2.3")),
            (" 		test 1.2.3", Some("1.2.3")),
        ];

        let matcher = Matcher::PrefixedVersion { prefix: "test" };

        for (input, expected) in &data {
            let result = matcher.find(input);
            assert_eq!(result.as_deref(), *expected);
        }
    }

    #[test]
    fn key_value() {
        let data = [
            ("", None),
            ("key", None),
            ("key=value", Some("value")),
            ("key=1", Some("1")),
            ("key=\"1\"", Some("1")),
            ("key=\"CentOS Linux\"", Some("CentOS Linux")),
        ];

        let matcher = Matcher::KeyValue { key: "key" };

        for (input, expected) in &data {
            let result = matcher.find(input);
            assert_eq!(result.as_deref(), *expected);
        }
    }
}