Awesome

zignite

A lazy stream (iterator) library for Zig.

Example Code

The following code does not generate an intermediate collection.
The following code compiles to a single loop.
However, removing the sum method only produces the initial state of the iterator, not a loop.

const zignite = @import("src/zignite.zig");
const std = @import("std");

fn even(x: usize) bool {
    return @mod(x, 2) == 0;
}

const RepeatTake = zignite.Repeat(usize).Take();
fn repeatTake(x: usize) RepeatTake {
    return zignite.repeat(usize, x).take(x);
}

test "Example Code 1" {
    const x = zignite
        .range(usize, 0, 100) //            { 0, 1, ..., 99 }
        .filter(even) //                    { 0, 2, ..., 98 }
        .flatMap(RepeatTake, repeatTake) // { 2, 2, 4, 4, 4, 4, ..., 98 }
        .sum();

    try std.testing.expect(x == 161700);
}

The lazy in the following code can be reused without resetting.
However, in this case lazy is calculated twice.
This is because no collection is created to store intermediate results.

test "Example Code 2" {
    const lazy = zignite
        .range(usize, 1, 10) // { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 }
        .filter(even); //       { 2, 4, 6, 8, 10 }

    try std.testing.expect(lazy.sum() == 30);
    try std.testing.expect(lazy.product() == 3840);
}

You can convert between some standard collections like the following code.

test "Example Code 3" {
    const allocator = std.testing.allocator;
    const slice = "Example Code 3";

    // []const u8 -> BoundedArray(u8, 50)
    const bounded_array = try zignite.fromSlice(u8, slice).toBoundedArray(50);

    // BoundedArray(u8, 50) -> ArrayList(u8)
    var array_list = try zignite.fromBoundedArray(u8, 50, &bounded_array).toArrayList(allocator);
    defer array_list.deinit();

    // ArrayList(u8) -> []const u8
    var buffer: [50]u8 = undefined;
    const slice2 = zignite.fromArrayList(u8, &array_list).toSlice(&buffer).?;

    try std.testing.expect(std.mem.eql(u8, slice, slice2));
}

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zignite

Example Code

Test code and implementation

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