map.zig

const std = @import("std");


/// Can return error.OutOfMemory
/// Caller owns the returned memory
fn map(allocator: &std.mem.Allocator, comptime T: type, items: []const T, func: fn(T)->T) -> %[]T {
    const new_items = try allocator.alloc(T, items.len);
    %defer allocator.free(new_items);

    for (items) |item, i| {
        new_items[i] = func(item);
    }

    return new_items;
}

fn addOne(x: i32) -> i32 { return x + 1; }

test "basic usage of map" {
    var data = []i32{1, 2, 3};

    const new_data = try map(std.debug.global_allocator, i32, data[0..], addOne);

    std.debug.assert(new_data[0] == 2);
    std.debug.assert(new_data[1] == 3);
    std.debug.assert(new_data[2] == 4);
}