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vcfReader.go
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vcfReader.go
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package vcfio
import (
"bufio"
"bytes"
"fmt"
"io"
"log"
"os"
"strconv"
"strings"
"unsafe"
)
// used for the quality score which is 0 to 255, but allows "."
const MISSING_VAL = 256
// Reader holds information about the current line number (for errors) and
// The VCF header that indicates the structure of records.
type VcfReader struct {
buf *bufio.Reader
Header *Header
verr *VCFError
LineNumber int64
r io.Reader
}
// NewVcfReader returns a Reader.
func NewVcfReader(r io.Reader) (*VcfReader, error) {
buffered := bufio.NewReaderSize(r, 32768*2)
var verr = NewVCFError()
var LineNumber int64
h := NewHeader()
for {
LineNumber++
line, err := buffered.ReadString('\n')
if err != nil && err != io.EOF {
verr.Add(err, LineNumber)
}
if len(line) > 1 && line[len(line)-1] == '\n' {
line = line[:len(line)-1]
}
if LineNumber == 1 {
v, err := parseHeaderFileVersion(line)
verr.Add(err, LineNumber)
h.FileFormat = v
} else if strings.HasPrefix(line, "##FORMAT") {
format, err := parseHeaderFormat(line)
verr.Add(err, LineNumber)
if format != nil {
h.SampleFormats[format.Id] = format
}
} else if strings.HasPrefix(line, "##INFO") {
info, err := parseHeaderInfo(line)
verr.Add(err, LineNumber)
if info != nil {
h.Infos[info.Id] = info
}
} else if strings.HasPrefix(line, "##FILTER") {
filter, err := parseHeaderFilter(line)
verr.Add(err, LineNumber)
if len(filter) == 2 {
h.Filters[filter[0]] = filter[1]
}
} else if strings.HasPrefix(line, "##contig") {
contig, err := parseHeaderContig(line)
verr.Add(err, LineNumber)
if contig != nil {
if _, ok := contig["ID"]; ok {
h.Contigs = append(h.Contigs, contig)
} else {
verr.Add(fmt.Errorf("bad contig: %v", line), LineNumber)
}
}
} else if strings.HasPrefix(line, "##SAMPLE") {
sample, err := parseHeaderSample(line)
verr.Add(err, LineNumber)
if sample != "" {
h.Samples[sample] = line
} else {
verr.Add(fmt.Errorf("bad sample: %v", line), LineNumber)
}
} else if strings.HasPrefix(line, "##PEDIGREE") {
h.Pedigrees = append(h.Pedigrees, line)
} else if strings.HasPrefix(line, "##") {
kv, err := parseHeaderExtraKV(line)
verr.Add(err, LineNumber)
if len(kv) == 2 {
h.Extras = append(h.Extras, line)
}
} else if strings.HasPrefix(line, "#CHROM") {
var err error
h.SampleNames, err = parseSampleLine(line)
verr.Add(err, LineNumber)
//h.Validate(verr)
break
} else {
e := fmt.Errorf("unexpected header line: %s", line)
return nil, e
}
}
reader := &VcfReader{buffered, h, verr, LineNumber, r}
return reader, reader.Error()
}
func makeVcfFields(line []byte) [][]byte {
fields := bytes.SplitN(line, []byte{'\t'}, 9)
s := 0
for i, f := range fields {
if i == 7 {
break
}
s += len(f) + 1
}
if s >= len(line) {
fmt.Fprintf(os.Stderr, "XXXXX: bad VCF line '%s'", line)
return fields
}
e := bytes.IndexByte(line[s:], '\t')
if e == -1 {
e = len(line)
} else {
e += s
}
fields[7] = line[s:e]
return fields
}
// Read returns a pointer to a Variant. Upon reading the caller is assumed
// to check Reader.Err()
func (vr *VcfReader) Read() *VariantVcf {
line, err := vr.buf.ReadBytes('\n')
if err != nil {
if len(line) == 0 && err == io.EOF {
return nil
} else if err != io.EOF {
vr.verr.Add(err, vr.LineNumber)
}
}
vr.LineNumber++
if line[len(line)-1] == '\n' {
line = line[:len(line)-1]
}
fields := makeVcfFields(line)
return vr.Parse(fields)
}
func (vr *VcfReader) Parse(fields [][]byte) *VariantVcf {
if len(fields) < 7 {
s := make([]string, 0)
for _, b := range fields {
s = append(s, string(b))
}
log.Printf("error at line %d: not enough fields for a VCF. Content was: '%s'\n", vr.LineNumber, strings.Join(s, "\t"))
}
pos, err := strconv.ParseUint(unsafeString(fields[1]), 10, 64)
vr.verr.Add(err, vr.LineNumber)
var qual float64
if len(fields[5]) == 1 && fields[5][0] == '.' {
qual = MISSING_VAL
} else {
qual, err = strconv.ParseFloat(unsafeString(fields[5]), 32)
vr.verr.Add(err, vr.LineNumber)
}
v := &VariantVcf{
Chromosome: string(fields[0]),
Pos: pos,
// Id_: string(fields[2]),
Reference: string(fields[3]),
Alternate: strings.Split(string(fields[4]), ","),
Quality: float32(qual),
Filter: string(fields[6]),
Header: vr.Header,
}
if len(fields) > 8 {
sample_fields := bytes.SplitN(fields[8], []byte{'\t'}, 2)
v.Format = strings.Split(string(sample_fields[0]), ":")
v.sampleString = string(sample_fields[1])
}
v.LineNumber = vr.LineNumber
v.Info_ = NewInfoByte(fields[7], vr.Header)
return v
}
// AddInfoToHeader adds a INFO field to the header.
func (vr *VcfReader) AddInfoToHeader(id string, num string, stype string, desc string) {
h := vr.Header
h.Infos[id] = &InfoVcf{Id: id, Number: num, Type: stype, Description: desc}
}
// AddFormatToHeader adds a FORMAT field to the header.
func (vr *VcfReader) AddFormatToHeader(id string, num string, stype string, desc string) {
h := vr.Header
h.SampleFormats[id] = &SampleFormat{Id: id, Number: num, Type: stype, Description: desc}
}
func (vr *VcfReader) GetHeaderType(field string) string {
if h, ok := vr.Header.Infos[field]; ok {
return h.Type
}
return ""
}
// Error() aggregates the multiple errors that can occur into a single object.
func (vr *VcfReader) Error() error {
if vr.verr.IsEmpty() {
return nil
}
return vr.verr
}
// Clear empties the cache of errors.
func (vr *VcfReader) Clear() {
vr.verr.Clear()
}
func (vr *VcfReader) Close() error {
if rc, ok := vr.r.(io.ReadCloser); ok {
return rc.Close()
}
return nil
}
func unsafeString(b []byte) string {
return *(*string)(unsafe.Pointer(&b))
}