d2o 0.1.1

Help to Options - Parse help or manpage texts and generate shell completion scripts
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

use crate::types::Subcommand;
use bstr::ByteSlice;
use ecow::{EcoString, EcoVec};
use std::collections::BTreeSet;

pub struct SubcommandParser;

impl SubcommandParser {
    pub fn parse(content: &str) -> EcoVec<Subcommand> {
        // Use bstr for SIMD-accelerated line iteration
        let bytes = content.as_bytes();
        let lines: Vec<&str> = bytes
            .lines()
            .filter_map(|line| std::str::from_utf8(line).ok())
            .collect();
        let mut subcommands = BTreeSet::new();

        for window in lines.windows(2) {
            if let Some(subcommand) = Self::parse_line_pair(window[0], window[1]) {
                subcommands.insert(subcommand);
            }
        }

        for line in &lines {
            if let Some(subcommand) = Self::parse_single_line(line) {
                subcommands.insert(subcommand);
            }
        }

        subcommands.into_iter().collect()
    }

    fn parse_line_pair(first: &str, second: &str) -> Option<Subcommand> {
        let trimmed_first = first.trim();
        let trimmed_bytes = trimmed_first.as_bytes();

        // Fast path: skip empty or option lines using byte check
        if trimmed_bytes.is_empty() || trimmed_bytes[0] == b'-' {
            return None;
        }

        let first_word = trimmed_first.split_whitespace().next()?;

        if !Self::is_valid_subcommand_name(first_word) {
            return None;
        }

        let desc = second.trim();
        let desc_bytes = desc.as_bytes();

        // Fast path: skip empty or option descriptions
        if desc_bytes.is_empty() || desc_bytes[0] == b'-' {
            return None;
        }

        // Use memchr to find newline if present
        let desc_line = match memchr::memchr(b'\n', desc_bytes) {
            Some(pos) => &desc[..pos],
            None => desc,
        };

        Some(Subcommand {
            cmd: EcoString::from(first_word),
            desc: EcoString::from(desc_line),
        })
    }

    fn parse_single_line(line: &str) -> Option<Subcommand> {
        let trimmed = line.trim();
        let trimmed_bytes = trimmed.as_bytes();

        // Fast path: skip empty or option lines using byte check
        if trimmed_bytes.is_empty() || trimmed_bytes[0] == b'-' {
            return None;
        }

        // Count whitespace-separated parts without allocating
        let mut parts = trimmed.split_whitespace();
        let name = parts.next()?;

        // Need at least 2 more words for description (total 3+)
        let second = parts.next()?;
        let third = parts.next();

        third?;

        if !Self::is_valid_subcommand_name(name) {
            return None;
        }

        // Build description from remaining parts
        let mut desc = EcoString::from(second);
        desc.push(' ');
        desc.push_str(third.unwrap());
        for part in parts {
            desc.push(' ');
            desc.push_str(part);
        }

        Some(Subcommand {
            cmd: EcoString::from(name),
            desc,
        })
    }

    #[inline]
    fn is_valid_subcommand_name(name: &str) -> bool {
        let bytes = name.as_bytes();

        // Fast path: check first byte
        if bytes.is_empty() || bytes[0] == b'-' {
            return false;
        }

        // SIMD-friendly byte iteration
        bytes
            .iter()
            .all(|&b| b.is_ascii_alphanumeric() || b == b'-' || b == b'_')
    }
}

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

    #[test]
    fn test_parse_subcommands() {
        let content = "run       Run a command\nbuild     Build a project";
        let subs = SubcommandParser::parse(content);
        assert!(subs.iter().any(|s| s.cmd.as_str() == "run"));
        assert!(subs.iter().any(|s| s.cmd.as_str() == "build"));
    }

    #[test]
    fn test_is_valid_subcommand_name() {
        assert!(SubcommandParser::is_valid_subcommand_name("run"));
        assert!(SubcommandParser::is_valid_subcommand_name("sub-cmd"));
        assert!(!SubcommandParser::is_valid_subcommand_name("-v"));
        assert!(!SubcommandParser::is_valid_subcommand_name(""));
    }
}