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reader.go
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reader.go
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package m3u8
import (
"bytes"
"fmt"
"io"
"io/ioutil"
"strings"
)
type state struct {
open bool
currentItem Item
master bool
}
// ReadString parses a text string and returns a playlist
func ReadString(text string) (*Playlist, error) {
return Read(strings.NewReader(text))
}
// ReadFile reads text from a file and returns a playlist
func ReadFile(path string) (*Playlist, error) {
f, err := ioutil.ReadFile(path)
if err != nil {
return nil, err
}
return Read(bytes.NewReader(f))
}
// Read reads text from an io.Reader and returns a playlist
func Read(reader io.Reader) (*Playlist, error) {
var buf bytes.Buffer
_, err := buf.ReadFrom(reader)
if err != nil {
return nil, err
}
pl := NewPlaylist()
st := &state{}
eof := false
header := true
for !eof {
line, err := buf.ReadString('\n')
if err == io.EOF {
eof = true
} else if err != nil {
return nil, err
}
value := strings.TrimSpace(line)
if header && value != HeaderTag {
return nil, ErrPlaylistInvalid
}
if err := parseLine(value, pl, st); err != nil {
return nil, err
}
header = false
}
return pl, nil
}
func parseLine(line string, pl *Playlist, st *state) error {
var err error
switch {
// basic tags
case matchTag(line, VersionTag):
pl.Version, err = parseIntPtr(line, VersionTag)
// media segment tags
case matchTag(line, SegmentItemTag):
st.currentItem, err = NewSegmentItem(line)
st.master = false
st.open = true
case matchTag(line, DiscontinuityItemTag):
st.master = false
st.open = false
item, err := NewDiscontinuityItem()
if err != nil {
return parseError(line, err)
}
pl.Items = append(pl.Items, item)
case matchTag(line, ByteRangeItemTag):
value := strings.Replace(line, ByteRangeItemTag+":", "", -1)
value = strings.Replace(value, "\n", "", -1)
br, err := NewByteRange(value)
if err != nil {
return parseError(line, err)
}
mit, ok := st.currentItem.(*MapItem)
if ok {
mit.ByteRange = br
st.currentItem = mit
} else {
sit, ok := st.currentItem.(*SegmentItem)
if ok {
sit.ByteRange = br
st.currentItem = sit
}
}
case matchTag(line, KeyItemTag):
item, err := NewKeyItem(line)
if err != nil {
return parseError(line, err)
}
pl.Items = append(pl.Items, item)
case matchTag(line, MapItemTag):
item, err := NewMapItem(line)
if err != nil {
return parseError(line, err)
}
pl.Items = append(pl.Items, item)
case matchTag(line, TimeItemTag):
pdt, err := NewTimeItem(line)
if err != nil {
return parseError(line, err)
}
if st.open {
item, ok := st.currentItem.(*SegmentItem)
if !ok {
return parseError(line, ErrSegmentItemInvalid)
}
item.ProgramDateTime = pdt
} else {
pl.Items = append(pl.Items, pdt)
}
case matchTag(line, DateRangeItemTag):
dri, err := NewDateRangeItem(line)
if err != nil {
return parseError(line, err)
}
pl.Items = append(pl.Items, dri)
// media playlist tags
case matchTag(line, MediaSequenceTag):
pl.Sequence, err = parseIntValue(line, MediaSequenceTag)
case matchTag(line, DiscontinuitySequenceTag):
pl.DiscontinuitySequence, err = parseIntPtr(line, DiscontinuitySequenceTag)
case matchTag(line, CacheTag):
ptr := parseYesNoPtr(line, CacheTag)
pl.Cache = ptr
case matchTag(line, TargetDurationTag):
pl.Target, err = parseIntValue(line, TargetDurationTag)
case matchTag(line, IFramesOnlyTag):
pl.IFramesOnly = true
case matchTag(line, PlaylistTypeTag):
pl.Type = parseStringPtr(line, PlaylistTypeTag)
// master playlist tags
case matchTag(line, MediaItemTag):
st.open = false
mi, err := NewMediaItem(line)
if err != nil {
return parseError(line, err)
}
pl.Items = append(pl.Items, mi)
case matchTag(line, SessionDataItemTag):
sdi, err := NewSessionDataItem(line)
if err != nil {
return parseError(line, err)
}
pl.Items = append(pl.Items, sdi)
case matchTag(line, SessionKeyItemTag):
ski, err := NewSessionKeyItem(line)
if err != nil {
return parseError(line, err)
}
pl.Items = append(pl.Items, ski)
case matchTag(line, PlaylistItemTag):
st.master = true
st.open = true
pi, err := NewPlaylistItem(line)
if err != nil {
return parseError(line, err)
}
st.currentItem = pi
case matchTag(line, PlaylistIframeTag):
st.master = true
st.open = false
pi, err := NewPlaylistItem(line)
if err != nil {
return parseError(line, err)
}
pi.IFrame = true
pl.Items = append(pl.Items, pi)
st.currentItem = pi
// universal tags
case matchTag(line, PlaybackStartTag):
ps, err := NewPlaybackStart(line)
if err != nil {
return parseError(line, err)
}
pl.Items = append(pl.Items, ps)
case matchTag(line, IndependentSegmentsTag):
pl.IndependentSegments = true
case matchTag(line, FooterTag):
pl.Live = false
default:
if st.currentItem != nil && st.open {
return parseNextLine(line, pl, st)
}
}
return parseError(line, err)
}
func parseNextLine(line string, pl *Playlist, st *state) error {
value := strings.Replace(line, "\n", "", -1)
value = strings.Replace(value, "\r", "", -1)
if st.master {
// PlaylistItem
it, ok := st.currentItem.(*PlaylistItem)
if !ok {
return parseError(line, ErrPlaylistItemInvalid)
}
it.URI = value
pl.Items = append(pl.Items, it)
} else {
// SegmentItem
it, ok := st.currentItem.(*SegmentItem)
if !ok {
return parseError(line, ErrSegmentItemInvalid)
}
it.Segment = value
pl.Items = append(pl.Items, it)
}
st.open = false
return nil
}
func matchTag(line, tag string) bool {
return strings.HasPrefix(line, tag) && !strings.HasPrefix(line, tag+"-")
}
func parseIntValue(line string, tag string) (int, error) {
var v int
_, err := fmt.Sscanf(line, tag+":%d", &v)
return v, err
}
func parseIntPtr(line string, tag string) (*int, error) {
var ptr int
_, err := fmt.Sscanf(line, tag+":%d", &ptr)
return &ptr, err
}
func parseStringPtr(line string, tag string) *string {
value := strings.Replace(line, tag+":", "", -1)
if value == "" {
return nil
}
return &value
}
func parseYesNoPtr(line string, tag string) *bool {
value := strings.Replace(line, tag+":", "", -1)
var b bool
if value == YesValue {
b = true
} else {
b = false
}
return &b
}
func parseError(line string, err error) error {
if err == nil {
return nil
}
return fmt.Errorf("error: %v when parsing playlist error for line: %s", err, line)
}