func skipComment(f fancy.Reader) {
for {
c, err := f.ReadByte()
if err != nil || c == 13 || c == 10 {
break
}
}
}
// xrefStart() queries the start of the xref-table in a PDF file.
func xrefStart(f fancy.Reader) int {
s := int(f.Size())
pdf := make([]byte, min(s, 1024))
f.ReadAt(pdf, int64(max(0, s-1024)))
ps := xref.AllMatches(pdf, 0)
if ps == nil {
return -1
}
return num(xref.MatchSlices(ps[len(ps)-1])[2])
}
func skipSpaces(f fancy.Reader) byte {
for {
c, err := f.ReadByte()
if err != nil {
break
}
if c > 32 {
return c
}
}
return 0
}
func skipString(f fancy.Reader) {
for depth := 1; depth > 0; {
c, err := f.ReadByte()
if err != nil {
break
}
switch c {
case '(':
depth++
case ')':
depth--
case '\\':
f.ReadByte()
}
}
}
func skipToDelim(f fancy.Reader) byte {
for {
c, err := f.ReadByte()
if err != nil {
break
}
if c < 33 {
return c
}
switch c {
case '<', '>', '(', ')', '[', ']', '/', '%', '{', '}':
return c
}
}
return 255
}
// xrefSkip() queries the start of the trailer for a (partial) xref-table.
func xrefSkip(f fancy.Reader, xref int) int {
f.Seek(int64(xref), 0)
t, p := ps.Token(f)
if string(t) != "xref" {
return -1
}
for {
t, p = ps.Token(f)
if t[0] < '0' || t[0] > '9' {
f.Seek(p, 0)
break
}
t, _ = ps.Token(f)
ps.SkipLE(f)
f.Seek(int64(num(t)*20), 1)
}
r, _ := f.Seek(0, 1)
return int(r)
}
func refToken(f fancy.Reader) ([]byte, int64) {
tok, p := ps.Token(f)
if len(tok) > 0 && tok[0] >= '0' && tok[0] <= '9' {
ps.Token(f)
r, q := ps.Token(f)
if string(r) == "R" {
f.Seek(p, 0)
tok = f.Slice(int(1 + q - p))
} else {
f.Seek(p+int64(len(tok)), 0)
}
}
return tok, p
}
func SkipLE(f fancy.Reader) {
for {
c, err := f.ReadByte()
if err != nil {
return
}
if c > 32 {
f.UnreadByte()
return
}
if c == 13 {
c, err = f.ReadByte()
if err == nil && c != 10 {
f.UnreadByte()
}
return
}
if c == 10 {
return
}
}
}
// xrefRead() reads the xref table(s) of a PDF file. This is not recursive
// in favour of not to have to keep track of already used starting points
// for xrefs.
func xrefRead(f fancy.Reader, p int) map[int]int {
var back [MAX_PDF_UPDATES]int
b := 0
s := _Bytes
for ok := true; ok; {
back[b] = p
b++
p = xrefSkip(f, p)
f.Seek(int64(p), 0)
s, _ = ps.Token(f)
if string(s) != "trailer" {
return nil
}
s, _ = ps.Token(f)
s, ok = Dictionary(s)["/Prev"]
p = num(s)
}
r := make(map[int]int)
for b != 0 {
b--
f.Seek(int64(back[b]), 0)
ps.Token(f) // skip "xref"
for {
m := tupel(f, 2)
if string(m[0]) == "trailer" {
break
}
ps.SkipLE(f)
o := num(m[0])
dat := f.Slice(num(m[1]) * 20)
for i := 0; i < len(dat); i += 20 {
if dat[i+17] != 'n' {
r[o] = 0, false
} else {
r[o] = num(dat[i : i+10])
}
o++
}
}
}
return r
}
func Token(f fancy.Reader) ([]byte, int64) {
again:
c := skipSpaces(f)
if c == 0 {
return []byte{}, -1
}
p := fpos(f) - 1
switch c {
case '%':
skipComment(f)
goto again
case '<', '[', '{':
skipComposite(f)
case '(':
skipString(f)
default:
if skipToDelim(f) != 255 {
f.UnreadByte()
}
}
n := int(fpos(f) - p)
f.Seek(p, 0)
return f.Slice(n), p
}
func fpos(f fancy.Reader) int64 {
r, _ := f.Seek(0, 1)
return r
}
