cha_core/plugins/
switch_statement.rs

1use crate::{AnalysisContext, Finding, Location, Plugin, Severity, SmellCategory};
2
3/// Detect functions with excessive switch/match arms.
4pub struct SwitchStatementAnalyzer {
5    pub max_arms: usize,
6}
7
8impl Default for SwitchStatementAnalyzer {
9    fn default() -> Self {
10        Self { max_arms: 8 }
11    }
12}
13
14impl Plugin for SwitchStatementAnalyzer {
15    fn name(&self) -> &str {
16        "switch_statement"
17    }
18
19    fn smells(&self) -> Vec<String> {
20        vec!["switch_statement".into()]
21    }
22
23    fn description(&self) -> &str {
24        "Excessive switch/match arms"
25    }
26
27    fn analyze(&self, ctx: &AnalysisContext) -> Vec<Finding> {
28        let lines: Vec<&str> = ctx.file.content.lines().collect();
29        ctx.model
30            .functions
31            .iter()
32            .filter(|f| f.switch_arms > self.max_arms)
33            .map(|f| {
34                let loc = find_switch_keyword(&lines, f.start_line, f.end_line).unwrap_or((
35                    f.start_line,
36                    f.name_col,
37                    f.name_end_col,
38                ));
39                Finding {
40                    smell_name: "switch_statement".into(),
41                    category: SmellCategory::OoAbusers,
42                    severity: Severity::Warning,
43                    location: Location {
44                        path: ctx.file.path.clone(),
45                        start_line: loc.0,
46                        start_col: loc.1,
47                        end_line: loc.0,
48                        end_col: loc.2,
49                        name: Some(f.name.clone()),
50                    },
51                    message: format!(
52                        "Function `{}` has {} switch/match arms (threshold: {})",
53                        f.name, f.switch_arms, self.max_arms
54                    ),
55                    suggested_refactorings: vec!["Replace Conditional with Polymorphism".into()],
56                    actual_value: Some(f.switch_arms as f64),
57                    threshold: Some(self.max_arms as f64),
58                }
59            })
60            .collect()
61    }
62}
63
64/// Scan the function body for the first `switch`/`match` keyword and return
65/// `(line, start_col, end_col)` of the keyword token. Returns None if not
66/// found (fallback to function name location).
67fn find_switch_keyword(lines: &[&str], start: usize, end: usize) -> Option<(usize, usize, usize)> {
68    let keywords = ["switch", "match"];
69    for (idx, line) in lines
70        .iter()
71        .enumerate()
72        .take(end.min(lines.len()))
73        .skip(start.saturating_sub(1))
74    {
75        for kw in &keywords {
76            if let Some(col) = find_keyword(line, kw) {
77                return Some((idx + 1, col, col + kw.len()));
78            }
79        }
80    }
81    None
82}
83
84/// Find `keyword` in `line` but only where it stands as a word (whitespace /
85/// line start before, non-alphanumeric after). Skips occurrences inside
86/// comments starting at line start (`//`, `#`, `/*`).
87fn find_keyword(line: &str, keyword: &str) -> Option<usize> {
88    let trimmed = line.trim_start();
89    if trimmed.starts_with("//") || trimmed.starts_with('#') || trimmed.starts_with("/*") {
90        return None;
91    }
92    let bytes = line.as_bytes();
93    let klen = keyword.len();
94    let mut i = 0;
95    while i + klen <= bytes.len() {
96        if &bytes[i..i + klen] == keyword.as_bytes() {
97            let before_ok = i == 0 || !is_ident_byte(bytes[i - 1]);
98            let after_ok = i + klen == bytes.len() || !is_ident_byte(bytes[i + klen]);
99            if before_ok && after_ok {
100                return Some(i);
101            }
102        }
103        i += 1;
104    }
105    None
106}
107
108fn is_ident_byte(b: u8) -> bool {
109    b.is_ascii_alphanumeric() || b == b'_'
110}
cha_core/plugins/switch_statement.rs

cha_core/plugins/
switch_statement.rs
