Function is_preceded_by_use

src/classmap_scanner.rs:1592–1610

Check whether the keyword at position `i` is preceded by `use ` (with optional whitespace), indicating a `use function` or `use const` import statement rather than a declaration.

(content: &[u8], i: usize)

/// (with optional whitespace), indicating a `use function` or `use const`
/// import statement rather than a declaration.
fn is_preceded_by_use(content: &[u8], i: usize) -> bool {
    if i < 4 {
        return false;
    }
    // Walk backwards over whitespace.
    let mut j = i - 1;
    while j > 0 && content[j].is_ascii_whitespace() {
        j -= 1;
    }
    // Check for `use` (the 'e' is at j, 'u' at j-2).
    if j >= 2 && &content[j - 2..=j] == b"use" {
        // Make sure `use` itself is at a keyword boundary (not part
        // of a longer identifier like `reuse`).
        if j - 2 == 0 || is_boundary_char(content[j - 3]) {
            return true;
        }
    }
    false
}

/// Check whether a keyword can start at this offset.
///