map.nula

// Nulang standard library — Map operations.
// Language version: 2.0.0-alpha
// Import: `import stdlib::map`
//
// Maps are arrays of {key, value} records.
// Key lookup is O(n). get() returns -1 for missing keys.

/// An empty map.
pub fn empty() { [] }

/// Insert or update a key-value pair. Returns a new map.
pub fn insert(k, v, m) {
    var found = false;
    var result = [];
    for r in m {
        if r.key == k then {
            result = perform Array.push(result, {key: k, value: v});
            found = true
        } else {
            result = perform Array.push(result, r)
        }
    };
    if found then result else { perform Array.push(result, {key: k, value: v}) }
}

/// Look up a key. Returns the value, or -1 if not found.
pub fn get(k, m) {
    for r in m {
        if r.key == k then { return r.value } else {}
    };
    -1
}

/// True when the key is present.
pub fn contains_key(k, m) {
    for r in m {
        if r.key == k then { return true } else {}
    };
    false
}

/// Remove a key. Returns a new map.
pub fn remove(k, m) {
    var result = [];
    for r in m {
        if r.key != k then { result = perform Array.push(result, r) } else {}
    };
    result
}

/// Number of key-value pairs.
pub fn size(m) { perform Array.length(m) }

/// True when the map is empty.
pub fn is_empty(m) { perform Array.length(m) == 0 }

/// Return an array of all keys.
pub fn keys(m) {
    var result = [];
    for r in m {
        result = perform Array.push(result, r.key)
    };
    result
}

/// Return an array of all values.
pub fn values(m) {
    var result = [];
    for r in m {
        result = perform Array.push(result, r.value)
    };
    result
}