Source: transform.go in package golang.org/x/text/unicode/norm


package norm

import (
	"unicode/utf8"

	"golang.org/x/text/transform"
)

Reset implements the Reset method of the transform.Transformer interface.

func (Form) Reset() {}

Transform implements the Transform method of the transform.Transformer interface. It may need to write segments of up to MaxSegmentSize at once. Users should either catch ErrShortDst and allow dst to grow or have dst be at least of size MaxTransformChunkSize to be guaranteed of progress.

Cap the maximum number of src bytes to check.

	b := src
	eof := atEOF
	if ns := len(dst); ns < len(b) {
		err = transform.ErrShortDst
		eof = false
		b = b[:ns]
	}
	i, ok := formTable[f].quickSpan(inputBytes(b), 0, len(b), eof)
	n := copy(dst, b[:i])
	if !ok {
		nDst, nSrc, err = f.transform(dst[n:], src[n:], atEOF)
		return nDst + n, nSrc + n, err
	}

	if err == nil && n < len(src) && !atEOF {
		err = transform.ErrShortSrc
	}
	return n, n, err
}

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}

transform implements the transform.Transformer interface. It is only called when quickSpan does not pass for a given string.

TODO: get rid of reorderBuffer. See CL 23460044.

	rb := reorderBuffer{}
	rb.init(f, src)

Load segment into reorder buffer.

		rb.setFlusher(dst[nDst:], flushTransform)
		end := decomposeSegment(&rb, nSrc, atEOF)
		if end < 0 {
			return nDst, nSrc, errs[-end]
		}
		nDst = len(dst) - len(rb.out)
		nSrc = end

Next quickSpan.

		end = rb.nsrc
		eof := atEOF
		if n := nSrc + len(dst) - nDst; n < end {
			err = transform.ErrShortDst
			end = n
			eof = false
		}
		end, ok := rb.f.quickSpan(rb.src, nSrc, end, eof)
		n := copy(dst[nDst:], rb.src.bytes[nSrc:end])
		nSrc += n
		nDst += n
		if ok {
			if err == nil && n < rb.nsrc && !atEOF {
				err = transform.ErrShortSrc
			}
			return nDst, nSrc, err
		}
	}