Function streamExactPreserve [src]

"Pump" exactly n bytes from the reader to the writer. When draining w, ensures that at least preserve_len bytes remain buffered. Asserts Writer.buffer capacity exceeds preserve_len.

Prototype

pub fn streamExactPreserve(r: *Reader, w: *Writer, preserve_len: usize, n: usize) StreamError!void

Parameters

r: *Readerw: *Writerpreserve_len: usizen: usize

Possible Errors

EndOfStream

End of stream indicated from the Reader. This error cannot originate from the Writer.

ReadFailed

See the Reader implementation for detailed diagnostics.

WriteFailed

See the Writer implementation for detailed diagnostics.

Source

  pub fn streamExactPreserve(r: *Reader, w: *Writer, preserve_len: usize, n: usize) StreamError!void {
    if (w.end + n <= w.buffer.len) {
        @branchHint(.likely);
        return streamExact(r, w, n);
    }
    // If `n` is large, we can ignore `preserve_len` up to a point.
    var remaining = n;
    while (remaining > preserve_len) {
        assert(remaining != 0);
        remaining -= try r.stream(w, .limited(remaining - preserve_len));
        if (w.end + remaining <= w.buffer.len) return streamExact(r, w, remaining);
    }
    // All the next bytes received must be preserved.
    if (preserve_len < w.end) {
        @memmove(w.buffer[0..preserve_len], w.buffer[w.end - preserve_len ..][0..preserve_len]);
        w.end = preserve_len;
    }
    return streamExact(r, w, remaining);
}  