// Return a fatal error as this transformation can never complete.
			c.fatalError(i, errShortInternal)
		case ErrShortSrc:
			if i == 0 {
				// Save ErrShortSrc in err. All other errors take precedence.
				err = ErrShortSrc
				break
			}
			// Source bytes were depleted before filling up the destination buffer.

		err = transform.ErrShortSrc
	}
	return n, n, err
}

func flushTransform(rb *reorderBuffer) bool {
	// Write out (must fully fit in dst, or else it is an ErrShortDst).
	if len(rb.out) < rb.nrune*utf8.UTFMax {
		return false
	}
	rb.out = rb.out[rb.flushCopy(rb.out):]
	return true
}

var errs = []error{nil, transform.ErrShortDst, transform.ErrShortSrc}

		err = transform.ErrShortSrc
	}
	return n, n, err
}

func flushTransform(rb *reorderBuffer) bool {
	// Write out (must fully fit in dst, or else it is an ErrShortDst).
	if len(rb.out) < rb.nrune*utf8.UTFMax {
		return false
	}
	rb.out = rb.out[rb.flushCopy(rb.out):]
	return true
}

var errs = []error{nil, transform.ErrShortDst, transform.ErrShortSrc}

			// Return a fatal error as this transformation can never complete.
			c.fatalError(i, errShortInternal)
		case ErrShortSrc:
			if i == 0 {
				// Save ErrShortSrc in err. All other errors take precedence.
				err = ErrShortSrc
				break
			}
			// Source bytes were depleted before filling up the destination buffer.

	if len(dst) < len(src) {
		src = src[:len(dst)]
		atEOF = false
		err = transform.ErrShortDst
	}
	n, err1 := t.Span(src, atEOF)
	copy(dst, src[:n])
	if err == nil || err1 != nil && err1 != transform.ErrShortSrc {
		err = err1
	}
	return n, n, err
}

// Span returns the first n bytes of src that conform to the Bidi rule.
func (t *Transformer) Span(src []byte, atEOF bool) (n int, err error) {

	// buffer. This means that the source buffer was exhausted and that c.sz was
	// set to 0 by next.
	if c.atEOF && c.pSrc == len(c.src) {
		return c.pDst, c.pSrc, nil
	}
	return c.nDst, c.nSrc, transform.ErrShortSrc
}

// retSpan returns the return values for the Span method. It checks whether
// there were insufficient bytes in src to complete and introduces an error
// accordingly, if necessary.

func (f Form) Span(b []byte, atEOF bool) (n int, err error) {
	n, ok := formTable[f].quickSpan(inputBytes(b), 0, len(b), atEOF)
	if n < len(b) {
		if !ok {
			err = transform.ErrEndOfSpan
		} else {
			err = transform.ErrShortSrc
		}
	}
	return n, err
}

// SpanString returns a boundary n such that s[0:n] == f(s[0:n]).
// It is not guaranteed to return the largest such n.

func (f Form) Span(b []byte, atEOF bool) (n int, err error) {
	n, ok := formTable[f].quickSpan(inputBytes(b), 0, len(b), atEOF)
	if n < len(b) {
		if !ok {
			err = transform.ErrEndOfSpan
		} else {
			err = transform.ErrShortSrc
		}
	}
	return n, err
}

// SpanString returns a boundary n such that s[0:n] == f(s[0:n]).
// It is not guaranteed to return the largest such n.