Function collect

libs/error-stack/src/fmt/mod.rs:734–757

Collect the current "stack", a stack are the current frames which only have a single source/parent. This searches until it finds a stack "split", where a frame has more than a single source.

(root: &'a Frame, prefix: &'a [&Frame])

/// source/parent.
/// This searches until it finds a stack "split", where a frame has more than a single source.
fn collect<'a>(root: &'a Frame, prefix: &'a [&Frame]) -> (Vec<&'a Frame>, &'a [Frame]) {
    let mut stack = vec![];
    stack.extend(prefix);
    stack.push(root);

    let mut ptr = Some(root);
    let mut next: &'a [_] = &[];

    while let Some(current) = ptr.take() {
        let sources = current.sources();

        match sources {
            [parent] => {
                stack.push(parent);
                ptr = Some(parent);
            }
            sources => {
                next = sources;
            }
        }
    }

    (stack, next)
}

/// Partition the tree, this looks for the first context frame,
/// then moves it up the chain and adds it to our results.