func nextDecomposed()

in unicode/norm/iter.go [225:339]

• 104 lines of code
• 25 McCabe index (conditional complexity)

func nextDecomposed(i *Iter) (next []byte) {
	outp := 0
	inCopyStart, outCopyStart := i.p, 0
	for {
		if sz := int(i.info.size); sz <= 1 {
			i.rb.ss = 0
			p := i.p
			i.p++ // ASCII or illegal byte.  Either way, advance by 1.
			if i.p >= i.rb.nsrc {
				i.setDone()
				return i.returnSlice(p, i.p)
			} else if i.rb.src._byte(i.p) < utf8.RuneSelf {
				i.next = i.asciiF
				return i.returnSlice(p, i.p)
			}
			outp++
		} else if d := i.info.Decomposition(); d != nil {
			// Note: If leading CCC != 0, then len(d) == 2 and last is also non-zero.
			// Case 1: there is a leftover to copy.  In this case the decomposition
			// must begin with a modifier and should always be appended.
			// Case 2: no leftover. Simply return d if followed by a ccc == 0 value.
			p := outp + len(d)
			if outp > 0 {
				i.rb.src.copySlice(i.buf[outCopyStart:], inCopyStart, i.p)
				// TODO: this condition should not be possible, but we leave it
				// in for defensive purposes.
				if p > len(i.buf) {
					return i.buf[:outp]
				}
			} else if i.info.multiSegment() {
				// outp must be 0 as multi-segment decompositions always
				// start a new segment.
				if i.multiSeg == nil {
					i.multiSeg = d
					i.next = nextMulti
					return nextMulti(i)
				}
				// We are in the last segment.  Treat as normal decomposition.
				d = i.multiSeg
				i.multiSeg = nil
				p = len(d)
			}
			prevCC := i.info.tccc
			if i.p += sz; i.p >= i.rb.nsrc {
				i.setDone()
				i.info = Properties{} // Force BoundaryBefore to succeed.
			} else {
				i.info = i.rb.f.info(i.rb.src, i.p)
			}
			switch i.rb.ss.next(i.info) {
			case ssOverflow:
				i.next = nextCGJDecompose
				fallthrough
			case ssStarter:
				if outp > 0 {
					copy(i.buf[outp:], d)
					return i.buf[:p]
				}
				return d
			}
			copy(i.buf[outp:], d)
			outp = p
			inCopyStart, outCopyStart = i.p, outp
			if i.info.ccc < prevCC {
				goto doNorm
			}
			continue
		} else if r := i.rb.src.hangul(i.p); r != 0 {
			outp = decomposeHangul(i.buf[:], r)
			i.p += hangulUTF8Size
			inCopyStart, outCopyStart = i.p, outp
			if i.p >= i.rb.nsrc {
				i.setDone()
				break
			} else if i.rb.src.hangul(i.p) != 0 {
				i.next = nextHangul
				return i.buf[:outp]
			}
		} else {
			p := outp + sz
			if p > len(i.buf) {
				break
			}
			outp = p
			i.p += sz
		}
		if i.p >= i.rb.nsrc {
			i.setDone()
			break
		}
		prevCC := i.info.tccc
		i.info = i.rb.f.info(i.rb.src, i.p)
		if v := i.rb.ss.next(i.info); v == ssStarter {
			break
		} else if v == ssOverflow {
			i.next = nextCGJDecompose
			break
		}
		if i.info.ccc < prevCC {
			goto doNorm
		}
	}
	if outCopyStart == 0 {
		return i.returnSlice(inCopyStart, i.p)
	} else if inCopyStart < i.p {
		i.rb.src.copySlice(i.buf[outCopyStart:], inCopyStart, i.p)
	}
	return i.buf[:outp]
doNorm:
	// Insert what we have decomposed so far in the reorderBuffer.
	// As we will only reorder, there will always be enough room.
	i.rb.src.copySlice(i.buf[outCopyStart:], inCopyStart, i.p)
	i.rb.insertDecomposed(i.buf[0:outp])
	return doNormDecomposed(i)
}