Zig 0.17.0-dev (Split by item)

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joinSepMaybeZ

This is different from mem.join in that the separator will not be repeated if it is found at the end or beginning of a pair of consecutive paths.

path.joinSepMaybeZ

fn joinSepMaybeZ(allocator: Allocator, separator: u8, comptime sepPredicate: fn (u8) bool, paths: []const []const u8, zero: bool) ![]u8

File

lib/std/fs/path.zig:71

Code

fn joinSepMaybeZ(allocator: Allocator, separator: u8, comptime sepPredicate: fn (u8) bool, paths: []const []const u8, zero: bool) ![]u8 {
    if (paths.len == 0) return if (zero) try allocator.dupe(u8, &[1]u8{0}) else &[0]u8{};

    // Find first non-empty path index.
    const first_path_index = blk: {
        for (paths, 0..) |path, index| {
            if (path.len == 0) continue else break :blk index;
        }

        // All paths provided were empty, so return early.
        return if (zero) try allocator.dupe(u8, &[1]u8{0}) else &[0]u8{};
    };

    // Calculate length needed for resulting joined path buffer.
    const total_len = blk: {
        var sum: usize = paths[first_path_index].len;
        var prev_path = paths[first_path_index];
        assert(prev_path.len > 0);
        var i: usize = first_path_index + 1;
        while (i < paths.len) : (i += 1) {
            const this_path = paths[i];
            if (this_path.len == 0) continue;
            const prev_sep = sepPredicate(prev_path[prev_path.len - 1]);
            const this_sep = sepPredicate(this_path[0]);
            sum += @intFromBool(!prev_sep and !this_sep);
            sum += if (prev_sep and this_sep) this_path.len - 1 else this_path.len;
            prev_path = this_path;
        }

        if (zero) sum += 1;
        break :blk sum;
    };

    const buf = try allocator.alloc(u8, total_len);
    errdefer allocator.free(buf);

    @memcpy(buf[0..paths[first_path_index].len], paths[first_path_index]);
    var buf_index: usize = paths[first_path_index].len;
    var prev_path = paths[first_path_index];
    assert(prev_path.len > 0);
    var i: usize = first_path_index + 1;
    while (i < paths.len) : (i += 1) {
        const this_path = paths[i];
        if (this_path.len == 0) continue;
        const prev_sep = sepPredicate(prev_path[prev_path.len - 1]);
        const this_sep = sepPredicate(this_path[0]);
        if (!prev_sep and !this_sep) {
            buf[buf_index] = separator;
            buf_index += 1;
        }
        const adjusted_path = if (prev_sep and this_sep) this_path[1..] else this_path;
        @memcpy(buf[buf_index..][0..adjusted_path.len], adjusted_path);
        buf_index += adjusted_path.len;
        prev_path = this_path;
    }

    if (zero) buf[buf.len - 1] = 0;

    // No need for shrink since buf is exactly the correct size.
    return buf;
}