dictator-rust 0.17.2

Rust language decree for Dictator structural linter
Documentation 
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//! File line counting (excluding comments and blank lines).

use dictator_decree_abi::{Diagnostic, Diagnostics, Span};
use memchr::memchr_iter;

/// Rule 1: File line count (ignoring comments and blank lines)
pub fn check_file_line_count(source: &str, max_lines: usize, diags: &mut Diagnostics) {
    let mut code_lines = 0;
    let bytes = source.as_bytes();
    let mut line_start = 0;

    for nl in memchr_iter(b'\n', bytes) {
        let line = &source[line_start..nl];
        let trimmed = line.trim();

        // Count line if it's not blank and not a comment-only line
        if !trimmed.is_empty() && !is_comment_only_line(trimmed) {
            code_lines += 1;
        }

        line_start = nl + 1;
    }

    // Handle last line without newline
    if line_start < bytes.len() {
        let line = &source[line_start..];
        let trimmed = line.trim();
        if !trimmed.is_empty() && !is_comment_only_line(trimmed) {
            code_lines += 1;
        }
    }

    if code_lines > max_lines {
        diags.push(Diagnostic {
            rule: "rust/file-too-long".to_string(),
            message: format!(
                "File has {code_lines} code lines (max {max_lines}, excl. comments/blanks)"
            ),
            enforced: false,
            span: Span::new(0, source.len().min(100)),
        });
    }
}

/// Check if a line is comment-only (// or /* */ style)
pub fn is_comment_only_line(trimmed: &str) -> bool {
    trimmed.starts_with("//") || trimmed.starts_with("/*") || trimmed.starts_with('*')
}

#[cfg(test)]
mod tests {
    use crate::lint_source;

    #[test]
    fn detects_file_too_long() {
        use std::fmt::Write;
        let mut src = String::new();
        for i in 0..410 {
            let _ = writeln!(src, "let x{i} = {i};");
        }
        let diags = lint_source(&src);
        assert!(
            diags.iter().any(|d| d.rule == "rust/file-too-long"),
            "Should detect file with >400 code lines"
        );
    }

    #[test]
    fn ignores_comments_in_line_count() {
        use std::fmt::Write;
        // 390 code lines + 60 comment lines = 450 total, but only 390 counted
        let mut src = String::new();
        for i in 0..390 {
            let _ = writeln!(src, "let x{i} = {i};");
        }
        for i in 0..60 {
            let _ = writeln!(src, "// Comment {i}");
        }
        let diags = lint_source(&src);
        assert!(
            !diags.iter().any(|d| d.rule == "rust/file-too-long"),
            "Should not count comment-only lines"
        );
    }

    #[test]
    fn ignores_blank_lines_in_count() {
        use std::fmt::Write;
        // 390 code lines + 60 blank lines = 450 total, but only 390 counted
        let mut src = String::new();
        for i in 0..390 {
            let _ = writeln!(src, "let x{i} = {i};");
        }
        for _ in 0..60 {
            src.push('\n');
        }
        let diags = lint_source(&src);
        assert!(
            !diags.iter().any(|d| d.rule == "rust/file-too-long"),
            "Should not count blank lines"
        );
    }

    #[test]
    fn handles_empty_file() {
        let src = "";
        let diags = lint_source(src);
        assert!(diags.is_empty(), "Empty file should have no violations");
    }

    #[test]
    fn handles_file_with_only_comments() {
        let src = "// Comment 1\n// Comment 2\n/* Block comment */\n";
        let diags = lint_source(src);
        assert!(
            !diags.iter().any(|d| d.rule == "rust/file-too-long"),
            "File with only comments should not trigger line count"
        );
    }
}