Filter entity lists

factorio-rs lowers a small iterator subset to Lua. Use it when you already have a Vec (or a numeric range) and want a new table without writing nested for loops by hand.

Ordered loops

Bindings typed as Vec<_> (or .iter()) use ipairs - order is preserved:

type Entities = Vec<LuaEntity>;

fn count_inserters(entities: Entities) -> i64 {
    let mut n = 0;
    for entity in entities {
        if entity.name() == "inserter" {
            n += 1;
        }
    }
    n
}

Ranges become Lua numeric for:

for i in 0..n {
    // i is 0 .. n-1
}
for i in 0..=n {
    // inclusive end
}

map / filter / collect

Supported chain: range or Vec + .map and/or .filter + .collect (including .collect::<Vec<_>>()). Other adapters (enumerate, zip, …) are rejected.

fn double_positive(values: Vec<i64>) -> Vec<i64> {
    values
        .iter()
        .map(|n| n * 2)
        .filter(|n| *n > 0)
        .collect::<Vec<_>>()
}

fn indices(n: i64) -> Vec<i64> {
    (0..n).map(|i| i + 1).collect::<Vec<_>>()
}

That lowers to an immediately invoked Lua function that builds a table.

With a type alias

type Scores = Vec<i64>;

fn top_half(scores: Scores) -> Scores {
    scores.iter().filter(|s| *s >= 50).collect::<Vec<_>>()
}

Aliases are transparent - see Type aliases.

Limits

Supported	Not yet
for on Vec / .iter() / ranges	enumerate, zip, flat_map
.map / .filter / .collect on that subset	Standing .iter() without collect
type Name = Vec<_> for ipairs detection	Arbitrary Iterator trait objects

Full table: Collections and iterators.