func processSubSequence(puid string, ss mappings.SubSequence, eof, vry bool) (frames.Signature, error) {
sig, _, _, err := process(puid, ss.Sequence, eof)
if err != nil {
return nil, err
}
if len(ss.LeftFragments) > 0 {
sig, err = appendFragments(puid, sig, ss.LeftFragments, true, eof)
if err != nil {
return nil, err
}
}
if len(ss.RightFragments) > 0 {
sig, err = appendFragments(puid, sig, ss.RightFragments, false, eof)
if err != nil {
return nil, err
}
}
if ss.Position > 1 {
vry = true
}
calcOffset := func(minS, maxS string, vry bool) (int, int, error) {
min, err := decodeNum(minS)
if err != nil {
return 0, 0, err
}
if maxS == "" {
if vry {
return min, -1, nil
}
return min, 0, nil
}
max, err := decodeNum(maxS)
if err != nil {
return 0, 0, err
}
return min, max, nil
}
min, max, err := calcOffset(ss.SubSeqMinOffset, ss.SubSeqMaxOffset, vry)
if err != nil {
return nil, err
}
if eof {
if ss.Position == 1 {
sig[len(sig)-1] = frames.NewFrame(frames.EOF, sig[len(sig)-1].Pat(), min, max)
} else {
sig[len(sig)-1] = frames.NewFrame(frames.SUCC, sig[len(sig)-1].Pat(), min, max)
}
} else {
if ss.Position == 1 {
sig[0] = frames.NewFrame(frames.BOF, sig[0].Pat(), min, max)
} else {
sig[0] = frames.NewFrame(frames.PREV, sig[0].Pat(), min, max)
}
}
return sig, nil
}
func process(puid, seq string, eof bool) (frames.Signature, int, int, error) {
typ := frames.PREV
if eof {
typ = frames.SUCC
}
var min, max int
l := lexPRONOM(puid, seq)
sig := frames.Signature{}
for i := l.nextItem(); i.typ != itemEOF; i = l.nextItem() {
switch i.typ {
case itemError:
return nil, 0, 0, errors.New("parse error " + puid + ": " + i.String())
case itemWildSingle:
min++
max++
case itemWildStart:
min, _ = decodeNum(i.val)
case itemCurlyRight: //detect {n} wildcards by checking if the max value has been set
if max == 0 {
max = min
}
case itemWildEnd:
if i.val == "*" {
max = -1
} else {
max, _ = decodeNum(i.val)
}
case itemWild:
max = -1
case itemEnterGroup:
pat, err := processGroup(l)
if err != nil {
return nil, 0, 0, errors.New("parse error " + puid + ": " + err.Error())
}
sig = append(sig, frames.NewFrame(typ, pat, min, max))
min, max = 0, 0
case itemUnprocessedText:
sig = append(sig, frames.NewFrame(typ, patterns.Sequence(processText(i.val)), min, max))
min, max = 0, 0
}
}
return sig, min, max, nil
}
// PRONOM
func processPRONOM(puid string, s mappings.Signature) (frames.Signature, error) {
sig := make(frames.Signature, 0, 1)
for _, bs := range s.ByteSequences {
// check if <Offset> or <MaxOffset> elements are present
min, err := decodeNum(bs.Offset)
if err != nil {
return nil, err
}
max, err := decodeNum(bs.MaxOffset)
if err != nil {
return nil, err
}
// lack of a max offset implies a fixed offset for BOF and EOF seqs (not VAR)
if max == 0 {
max = min
} else {
max = max + min // the max offset in a PRONOM report is relative to the "offset" value, not to the BOF/EOF
}
var eof bool
if bs.Position == pronomeof {
eof = true
}
// parse the hexstring
seg, lmin, lmax, err := process(puid, bs.Hex, eof)
if err != nil {
return nil, err
}
// check position and add patterns to signature
switch bs.Position {
case pronombof:
if seg[0].Min() != 0 || seg[0].Max() != 0 {
min, max = seg[0].Min(), seg[0].Max()
}
seg[0] = frames.NewFrame(frames.BOF, seg[0].Pat(), min, max)
case pronomvry:
if max == 0 {
max = -1
}
if seg[0].Min() != 0 || seg[0].Max() != 0 {
min, max = seg[0].Min(), seg[0].Max()
}
if min == max {
max = -1
}
seg[0] = frames.NewFrame(frames.BOF, seg[0].Pat(), min, max)
case pronomeof:
if len(seg) > 1 {
for i, f := range seg[:len(seg)-1] {
seg[i] = frames.NewFrame(frames.SUCC, f.Pat(), seg[i+1].Min(), seg[i+1].Max())
}
}
// handle edge case where there is a {x-y} at end of EOF seq e.g. x-fmt/263
if lmin != 0 || lmax != 0 {
min, max = lmin, lmax
}
seg[len(seg)-1] = frames.NewFrame(frames.EOF, seg[len(seg)-1].Pat(), min, max)
default:
return nil, errors.New("Pronom parse error: invalid ByteSequence position " + bs.Position)
}
// add the segment to the complete signature
sig = appendSig(sig, seg, bs.Position)
}
return sig, nil
}
// append a slice of fragments (left or right) to the central droid sequence
func appendFragments(puid string, sig frames.Signature, frags []mappings.Fragment, left, eof bool) (frames.Signature, error) {
// First off, group the fragments:
// droid fragments (right or left) can share positions. If such fragments have same offsets, they are a patterns.Choice. If not, then err.
var maxPos int
for _, f := range frags {
if f.Position == 0 {
return nil, errors.New("Pronom: encountered fragment without a position, puid " + puid)
}
if f.Position > maxPos {
maxPos = f.Position
}
}
fs := make([][]mappings.Fragment, maxPos)
for _, f := range frags {
fs[f.Position-1] = append(fs[f.Position-1], f)
}
for _, r := range fs {
max, min := r[0].MaxOffset, r[0].MinOffset
for _, v := range r {
if v.MaxOffset != max || v.MinOffset != min {
return nil, errors.New("Pronom: encountered fragments at same positions with different offsets, puid " + puid)
}
}
}
typ := frames.PREV
if eof {
typ = frames.SUCC
}
var choice patterns.Choice
offs := make([][2]int, len(fs))
ns := make([]frames.Signature, len(fs))
//l := len(sig)
// iterate over the grouped fragments
for i, v := range fs {
if len(v) > 1 {
choice = patterns.Choice{}
for _, c := range v {
pats, _, _, err := process(puid, c.Value, eof)
if err != nil {
return nil, err
}
if len(pats) > 1 {
list := make(patterns.List, len(pats))
for i, v := range pats {
list[i] = v.Pat()
}
choice = append(choice, list)
} else {
choice = append(choice, pats[0].Pat())
}
}
ns[i] = frames.Signature{frames.NewFrame(typ, choice, 0, 0)}
} else {
pats, _, _, err := process(puid, v[0].Value, eof)
if err != nil {
return nil, err
}
ns[i] = pats
}
min, err := decodeNum(v[0].MinOffset)
if err != nil {
return nil, err
}
var max int
if v[0].MaxOffset == "" {
max = -1
} else {
max, err = decodeNum(v[0].MaxOffset)
if err != nil {
return nil, err
}
}
offs[i] = [2]int{min, max}
}
// Now make the frames by adding in offset information (if left fragments, this needs to be taken from their neighbour)
if left {
if eof {
for i, v := range ns {
v[len(v)-1] = frames.NewFrame(frames.SUCC, v[len(v)-1].Pat(), offs[i][0], offs[i][1])
sig = append(v, sig...)
}
} else {
for i, v := range ns {
sig[0] = frames.NewFrame(frames.PREV, sig[0].Pat(), offs[i][0], offs[i][1])
sig = append(v, sig...)
}
}
} else {
if eof {
for i, v := range ns {
sig[len(sig)-1] = frames.NewFrame(frames.SUCC, sig[len(sig)-1].Pat(), offs[i][0], offs[i][1])
sig = append(sig, v...)
}
} else {
for i, v := range ns {
v[0] = frames.NewFrame(frames.PREV, v[0].Pat(), offs[i][0], offs[i][1])
sig = append(sig, v...)
}
}
}
return sig, nil
}
