diff --git a/LICENSE b/LICENSE
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--- /dev/null
+++ b/LICENSE
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+ GNU GENERAL PUBLIC LICENSE
+ Version 3, 29 June 2007
+
+ Copyright (C) 2007 Free Software Foundation, Inc.
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+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+ END OF TERMS AND CONDITIONS
+
+ How to Apply These Terms to Your New Programs
+
+ If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+ To do so, attach the following notices to the program. It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+
+ Copyright (C)
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see .
+
+Also add information on how to contact you by electronic and paper mail.
+
+ If the program does terminal interaction, make it output a short
+notice like this when it starts in an interactive mode:
+
+ Copyright (C)
+ This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+ This is free software, and you are welcome to redistribute it
+ under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License. Of course, your program's commands
+might be different; for a GUI interface, you would use an "about box".
+
+ You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU GPL, see
+.
+
+ The GNU General Public License does not permit incorporating your program
+into proprietary programs. If your program is a subroutine library, you
+may consider it more useful to permit linking proprietary applications with
+the library. If this is what you want to do, use the GNU Lesser General
+Public License instead of this License. But first, please read
+.
diff --git a/ebml/README.md b/ebml/README.md
new file mode 100644
index 0000000..f063143
--- /dev/null
+++ b/ebml/README.md
@@ -0,0 +1,89 @@
+Go-EBML
+=======
+A marshaler/unmarshaler for [EBML](http://ebml.sourceforge.net/).
+
+It's quite simple to use:
+```go
+
+func ExampleMarshal() {
+ DoDad := new(struct {
+ EbmlId ebml.Id `ebml:"3f0000"`
+ DoHickey uint `ebml:"4242"`
+ ThingaMabob string `ebml:"4243"`
+ HumDinger int `ebml:"4244"`
+ })
+
+ DoDad.DoHickey = 70000
+ DoDad.ThingaMabob = "huzah"
+ DoDad.HumDinger = -92387
+
+ b, _ := ebml.Marshal(*DoDad)
+ fmt.Printf("0x%x\n", b)
+
+ // Output:
+ // 0x3f00009442428301117042438568757a6168424483fe971d
+}
+
+func ExampleUnmarshal() {
+ data := []byte{
+ 0x3f, 0x00, 0x00, 0x94,
+ 0x42, 0x42, 0x83, 0x01, 0x11, 0x70,
+ 0x42, 0x43, 0x85, 0x68, 0x75, 0x7a, 0x61, 0x68,
+ 0x42, 0x44, 0x83, 0xfe, 0x97, 0x1d,
+ }
+
+ DoDad := new(struct {
+ EbmlId ebml.Id `ebml:"3f0000"`
+ DoHickey uint `ebml:"4242"`
+ ThingaMabob string `ebml:"4243"`
+ HumDinger int `ebml:"4244"`
+ })
+
+ ebml.Unmarshal(data, DoDad)
+ fmt.Printf("%v\n", DoDad)
+ // Output:
+ // &{0 70000 huzah -92387}
+}
+
+```
+
+
+Caveats
+-------
+If an EBML DTD specifies a value as an unsigned integer, you must use a uint
+type. For example: the uint32 8388608 and int -8388608 may encode to identical
+0x800000 24 bit arrays in an EBML stream.
+
+EBML does not have a boolean type, but booleans are commonly defined in DTDs
+as zero or non-zero usigned integers.
+
+
+Not Implemented
+---------------
+* Default values.
+> Every non-container MAY be assigned a default value. If so, its
+> value will be added to the interpretation of the EBML data if no
+> element with another value exists in the data.
+>
+> As an example, consider this EBML DTD:
+>
+> Weight := 4101 {
+> WeightValue := 41a1 uint;
+> WeightUnit := 41a2 string [ def:"kilogram" ];
+> }
+>
+> If the Weight element only contains the WeightValue element, the
+> WeightUnit element with value "kilogram" will be added when the
+> information is semantically processed. A WeightUnit element with
+> another value would of course override the default.
+>
+> The default value can also be a symbol referring back to a
+> previously seen symbol. If however no such symbol has been seen,
+> i.e. it has not been encoded into the EBML data and has no default
+> value, the element will not be added as a child on the semantic
+> level.
+>
+> Weight := 4101 {
+> WeightValue := 41a1 uint;
+> WeightUnit := 41a2 string [ def:WeightUnit ];
+> }
diff --git a/ebml/cache.go b/ebml/cache.go
new file mode 100644
index 0000000..dc74b91
--- /dev/null
+++ b/ebml/cache.go
@@ -0,0 +1,110 @@
+// Copyright © 2013 Emery Hemingway
+// Released under the terms of the GNU Public License version 3
+
+package ebml
+
+import (
+ "reflect"
+ "sync"
+)
+
+var (
+ fieldIdMap = make(map[reflect.Type]map[Id]int)
+ fieldIdMutex sync.RWMutex
+ //fieldDecoderMap = make(map[reflect.Type][]decoderFunc)
+ //fieldDecoderMutex sync.RWMutex
+)
+
+// cachedFieldIdMap returns a map that contains Id to field number
+// mappings for typ
+func cachedFieldIdMap(typ reflect.Type) map[Id]int {
+ fieldIdMutex.RLock()
+ m, ok := fieldIdMap[typ]
+ fieldIdMutex.RUnlock()
+ if ok {
+ return m
+ }
+
+ // Didn't get a map, lock down the map
+ fieldIdMutex.Lock()
+ defer fieldIdMutex.Unlock()
+ m, ok = fieldIdMap[typ]
+ if ok { // the work is already done
+ return m
+ }
+
+ m = make(map[Id]int)
+ // look over the fields
+ for i := 0; i < typ.NumField(); i++ {
+ f := typ.Field(i)
+ if f.Name == "EbmlId" {
+ continue
+ }
+ tag := f.Tag.Get("ebml")
+ if tag == "" || tag == "-" {
+ continue
+ }
+ id, err := NewIdFromString(tag)
+ if err != nil {
+ panic(ebmlError("ebml: could not parse Id from struct " + typ.String() + " field " + f.Name + ", " + err.Error()))
+ }
+ m[id] = i
+ }
+ fieldIdMap[typ] = m
+ return m
+}
+
+/*
+
+// cachedFieldIpDecoderTable returns a slice that contains decoder functions
+// indexed by field number
+func cachedFieldDecoderTable(typ reflect.Type) []decoderFunc {
+ fieldDecoderMutex.RLock()
+ s, ok := fieldDecoderMap[typ]
+ fieldDecoderMutex.RUnlock()
+ if ok {
+ return s
+ }
+
+ // Didn't get a slice, lock down the map
+ fieldDecoderMutex.Lock()
+ defer fieldDecoderMutex.Unlock()
+ s, ok = fieldDecoderMap[typ]
+ if ok { // the work is already done
+ return s
+ }
+
+ // a struct should have its fields parsed by cachedFieldIdMap already,
+ // so this shouldn't be too sloppy to just pull it
+ m := fieldIdMap[typ]
+
+ // create a map with pre-nil'ed functions for typ
+ s = make([]decoderFunc, typ.NumField())
+ // look over the fields that could be decoded into
+ for _, i := range m {
+ f := typ.Field(i)
+ k := f.Type.Kind()
+ for k == reflect.Ptr {
+ k = f.Type.Elem().Kind()
+ }
+ switch k {
+ case reflect.Int, reflect.Int8, reflect.Int32, reflect.Int64:
+ s[i] = decodeInt
+ case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+ s[i] = decodeUinta
+ case reflect.Slice:
+ s[i] = decodeSlice
+ case reflect.String:
+ s[i] = decodeString
+ case reflect.Struct:
+ s[i] = decodeStruct
+ default:
+ decError(fmt.Sprintf("cannot decode to %s.%s, %s decoding is unsupported ",
+ typ, f.Name, f.Type.Kind()))
+ }
+ }
+ fieldDecoderMap[typ] = s
+ return s
+}
+
+*/
diff --git a/ebml/decode.go b/ebml/decode.go
new file mode 100644
index 0000000..dbde475
--- /dev/null
+++ b/ebml/decode.go
@@ -0,0 +1,339 @@
+// Copyright © 2013 Emery Hemingway
+// Released under the terms of the GNU Public License version 3
+
+package ebml
+
+import (
+ "bytes"
+ "encoding/binary"
+ "fmt"
+ "io"
+ "reflect"
+ "time"
+)
+
+// readIdFrom reads an Id from a Reader and returns the number of bytes read and the Id
+func (d *Decoder) readId() (int, Id) {
+ n, err := d.r.Read(d.buf[:1])
+ if err != nil {
+ decError(err.Error())
+ }
+
+ id := Id(d.buf[0])
+ var buf []byte
+ switch {
+ case id >= 0x80:
+ return n, id
+ case id >= 0x40:
+ buf = d.buf[:1]
+ case id >= 0x20:
+ buf = d.buf[:2]
+ case id >= 0x10:
+ buf = d.buf[:3]
+ default:
+ p, err := d.r.Seek(-1, 1)
+ if err != nil {
+ decError(err.Error())
+ }
+ d.r.Read(buf)
+ decError(fmt.Sprintf("invalid Id at reader position 0x%x or EBMLMaxIDLength > 4, next 8 bytes 0x%0.2x", p, buf))
+ }
+ var nn int
+ nn, err = d.r.Read(buf)
+ n += nn
+ if err != nil {
+ decError(err.Error())
+ }
+ for _, c := range buf {
+ id <<= 8
+ id += Id(c)
+ }
+ return n, id
+}
+
+// readSizeFrom reads a size from a Reader and returns the number of bytes read and the size
+func (d *Decoder) readSize() (int, int64) {
+ n, err := d.r.Read(d.buf[:1])
+ if err != nil {
+ decError(err.Error())
+ }
+ size := int64(d.buf[0])
+ var buf []byte
+ switch {
+ case size >= 0x80:
+ size -= 0x80
+ return n, size
+ case size >= 0x40:
+ size -= 0x40
+ buf = d.buf[:1]
+ case size >= 0x20:
+ size -= 0x20
+ buf = d.buf[:2]
+ case size >= 0x10:
+ size -= 0x10
+ buf = d.buf[:3]
+ case size >= 0x08:
+ size -= 0x08
+ buf = d.buf[:4]
+ case size >= 0x04:
+ size -= 0x04
+ buf = d.buf[:5]
+ case size >= 0x02:
+ size -= 0x02
+ buf = d.buf[:6]
+ case size >= 0x01:
+ size -= 0x01
+ buf = d.buf[:7]
+ }
+ var nn int
+ nn, err = d.r.Read(buf)
+ n += nn
+ if err != nil {
+ decError(err.Error())
+ }
+ for _, c := range buf {
+ size <<= 8
+ size += int64(c)
+ }
+ return n, size
+}
+
+type decoderFunc func(d *Decoder, id Id, size int64, v reflect.Value)
+
+/* Sadly this using this table results in 'initialization loops' during building
+var decoderFuncTable = [...]decoderFunc{
+ reflect.Uint: decodeUint,
+ reflect.Uint8: decodeUint,
+ reflect.Uint16: decodeUint,
+ reflect.Uint32: decodeUint,
+ reflect.Uint64: decodeUint,
+ reflect.Float32: decodeFloat,
+ reflect.Float64: decodeFloat,
+ reflect.Slice: decodeSlice,
+ reflect.String: decodeString,
+ reflect.Struct: decodeStruct,
+}
+*/
+
+func decodeValue(d *Decoder, id Id, size int64, v reflect.Value) {
+ if um, ok := v.Interface().(Unmarshaler); ok {
+ if v.Kind() == reflect.Ptr && v.IsNil() {
+ v.Set(reflect.New(v.Type().Elem()))
+ um = v.Interface().(Unmarshaler)
+ }
+
+ rf := um.UnmarshalEBML(size)
+ r := io.LimitReader(d.r, size)
+ rf.ReadFrom(r)
+ return
+ }
+
+ // If we got an interface or a pointer, dereference it.
+ for v.Kind() == reflect.Ptr || v.Kind() == reflect.Interface {
+ if v.IsNil() {
+ v.Set(reflect.New(v.Type().Elem()))
+ }
+ v = v.Elem()
+ }
+
+ // look up the function to decode to value v
+ var fn decoderFunc
+ // I wanted to use an array of functions indexed by reflect.Kind,
+ // but kept getting initialization loop build errors
+ switch v.Kind() {
+ case reflect.Int, reflect.Int8, reflect.Int32, reflect.Int64:
+ fn = decodeInt
+ case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+ fn = decodeUint
+ case reflect.Float32:
+ fn = decodeFloat32
+ case reflect.Float64:
+ fn = decodeFloat64
+ case reflect.Slice:
+ fn = decodeSlice
+ case reflect.String:
+ fn = decodeString
+ case reflect.Struct:
+ if _, ok := v.Interface().(time.Time); ok {
+ fn = decodeTime
+ } else {
+ fn = decodeStruct
+ }
+ default:
+ decError(fmt.Sprintf("unsupported type %v", v.Type()))
+ }
+ fn(d, id, size, v)
+}
+
+func decodeInt(d *Decoder, id Id, size int64, v reflect.Value) {
+ _, err := d.r.Read(d.buf[:size])
+ x := int64(int8(d.buf[0]))
+ for _, c := range d.buf[1:size] {
+ x <<= 8
+ x += int64(c)
+ }
+ if x == 0 {
+ return
+ }
+ if v.OverflowInt(x) {
+ decError(fmt.Sprintf("element %s value %d overflows %s", id, x, v.Type()))
+ }
+ v.SetInt(x)
+ if err != nil {
+ decError(err.Error())
+ }
+}
+
+func decodeUint(d *Decoder, id Id, size int64, v reflect.Value) {
+ _, err := d.r.Read(d.buf[:size])
+ x := uint64(d.buf[0])
+ for _, c := range d.buf[1:size] {
+ x <<= 8
+ x += uint64(c)
+ }
+ if x == 0 {
+ return
+ }
+ if v.OverflowUint(x) {
+ decError(fmt.Sprintf("element %s value %d overflows %s", id, x, v.Type()))
+ }
+ v.SetUint(x)
+ if err != nil {
+ decError(err.Error())
+ }
+}
+
+func decodeFloat32(d *Decoder, id Id, size int64, v reflect.Value) {
+ var x float32
+ if size != 4 {
+ decError(fmt.Sprintf("cannot decode a float of len %d to a float32", size))
+ }
+
+ buf := d.buf[:size]
+ _, err := d.r.Read(buf)
+ if err != nil && err != io.EOF {
+ decError(err.Error())
+ }
+ err = binary.Read(bytes.NewReader(buf), binary.BigEndian, &x)
+ if err != nil {
+ println(fmt.Sprintf("%x", buf))
+ decError(err.Error())
+ }
+ v.SetFloat(float64(x))
+}
+
+func decodeFloat64(d *Decoder, id Id, size int64, v reflect.Value) {
+ var x float64
+ if size != 8 {
+ decError(fmt.Sprintf("cannot decode a float of len %d to a float64", size))
+ }
+
+ buf := d.buf[:size]
+ _, err := d.r.Read(buf)
+ if err != nil && err != io.EOF {
+ decError(err.Error())
+ }
+ err = binary.Read(bytes.NewReader(buf), binary.BigEndian, &x)
+ if err != nil {
+ println(fmt.Sprintf("%x", buf))
+ decError(err.Error())
+ }
+ v.SetFloat(x)
+}
+
+func decodeSlice(d *Decoder, id Id, size int64, v reflect.Value) {
+ if _, ok := v.Interface().([]byte); ok {
+ var buf []byte
+ if size <= 8 {
+ buf = d.buf[:size]
+ } else {
+ buf = make([]byte, int(size))
+ }
+ _, err := d.r.Read(buf)
+ v.Set(reflect.ValueOf(buf))
+ if err != nil {
+ decError(err.Error())
+ }
+ return
+ }
+
+ // TODO(Emery): would be nice to use reflect.Append()
+ n := v.Len()
+ if n >= v.Cap() {
+ newcap := v.Cap() + v.Cap()/2
+ if newcap < 4 {
+ newcap = 4
+ }
+ newv := reflect.MakeSlice(v.Type(), n+1, newcap)
+ reflect.Copy(newv, v)
+ v.Set(newv)
+ } else {
+ v.SetLen(n + 1)
+ }
+ decodeValue(d, id, size, v.Index(n))
+}
+
+func decodeString(d *Decoder, id Id, size int64, v reflect.Value) {
+ buf := make([]byte, size)
+ _, err := d.r.Read(buf)
+ v.SetString(string(buf))
+ if err != nil {
+ decError(err.Error())
+ }
+}
+
+func decodeStruct(d *Decoder, id Id, size int64, v reflect.Value) {
+ t := v.Type()
+ // get Id to field mappings
+ idField := cachedFieldIdMap(t)
+ // BUG(Emery): not caching decoder funtions for struct fields is suboptimal
+ //fieldFunc := cachedFieldDecoderTable(t)
+
+ var n int
+ var subId Id
+ var subSize int64
+ var ok bool
+ for size > 0 {
+ // read and and size
+ n, subId = d.readId()
+ size -= int64(n)
+ n, subSize = d.readSize()
+ size -= int64(n)
+
+ // look up if the subId should decode into a field
+ if n, ok = idField[subId]; ok {
+ decodeValue(d, subId, subSize, v.Field(n))
+ /*
+ subV = v.Field(n)
+ // Derefence pointer
+ for subV.Kind() == reflect.Ptr {
+ subV = subV.Elem()
+ }
+
+ // use the cached decoder funtion for field
+ fieldFunc[n]
+ */
+ } else {
+ d.r.Seek(size, 0)
+ }
+ size -= subSize
+ }
+}
+
+func decodeTime(d *Decoder, id Id, size int64, v reflect.Value) {
+ if size != 8 {
+ decError(fmt.Sprintf("%d is an invalid length for a date value", size))
+ }
+ _, err := d.r.Read(d.buf)
+
+ date := time.Duration(int8(d.buf[0]))
+ for _, c := range d.buf[1:] {
+ date <<= 8
+ date += time.Duration(c)
+ }
+ v.Set(reflect.ValueOf(epoch.Add(date))) // epoch defined in ebml.go
+
+ if err != nil {
+ decError(err.Error())
+ }
+}
diff --git a/ebml/ebml.go b/ebml/ebml.go
new file mode 100644
index 0000000..273b34b
--- /dev/null
+++ b/ebml/ebml.go
@@ -0,0 +1,128 @@
+// Copyright © 2013 Emery Hemingway
+// Released under the terms of the GNU Public License version 3
+
+/*
+Package ebml marshals and unmarshals Go structs to and from
+the Exensible Binary Markup Langauge.
+*/
+package ebml
+
+import (
+ "errors"
+ "fmt"
+ "reflect"
+ "strconv"
+ "time"
+)
+
+// Header is a struct for encoding and decoding EBML streams.
+//
+// The following could be a valid top-level struct for
+// representing Matroska streams:
+// type Matroska struct {
+// ebml.Header
+// Segment []Segment `ebml:"18538067"`
+// }
+//
+// You will however need to populate field values in Header
+// to form a valid EBML document.
+type Header struct {
+ // BUG(Emery): Setting default and fallback values in
+ // struct field tags is not supported.
+ EbmlId Id `ebml:"1a45dfa3"`
+ EBMLVersion uint8 `ebml:"4286"`
+ EBMLReadVersion uint8 `ebml:"42f7"`
+ EBMLMaxIDLength uint8 `ebml:"42f2"`
+ EBMLMaxSizeLength uint8 `ebml:"42f3"`
+ DocType string `ebml:"4282"`
+ DocTypeVersion uint8 `ebml:"4287"`
+ DocTypeReadVersion uint8 `ebml:"4285"`
+}
+
+// Id is a type that identifies an ebml element.
+type Id uint64
+
+func (id Id) len() (l int64) {
+ switch {
+ case id > 0x80 && id < 0xFF:
+ l = 1
+ case id > 0x4000 && id < 0x7FFF:
+ l = 2
+ case id > 0x200000 && id < 0x3FFFFF:
+ l = 3
+ case id > 0x10000000 && id < 0x3FFFFFFF:
+ l = 4
+ }
+ return
+}
+
+// Bytes returns an Id in byte slice form
+func (id Id) bytes() []byte {
+ var l int
+ switch {
+ case id > 0x80 && id < 0xFF:
+ l = 1
+
+ case id > 0x4000 && id < 0x7FFF:
+ l = 2
+
+ case id > 0x200000 && id < 0x3FFFFF:
+ l = 3
+
+ case id > 0x10000000 && id < 0x3FFFFFFF:
+ l = 4
+
+ default:
+ panic(fmt.Errorf("invalid element ID %s", id))
+ }
+ b := make([]byte, l)
+ for l > 1 {
+ l--
+ b[l] = byte(id)
+ id >>= 8
+ }
+ b[0] = byte(id)
+ return b
+}
+
+// NewIdFromString is a convience fuction that returns an Id
+// for a string of hexadecimal.
+func NewIdFromString(s string) (Id, error) {
+ x, err := strconv.ParseUint(s, 16, 64)
+ if err != nil {
+ return 0, err
+ }
+ return Id(x), nil
+}
+
+// String implements the Stringer interface, returning Id in
+// hexadecimal form.
+func (id Id) String() string {
+ return strconv.FormatUint(uint64(id), 16)
+}
+
+// getId parses a struct for "EbmlId"
+func getId(v reflect.Value) (id Id) {
+ v = reflect.Indirect(v)
+ t := v.Type()
+ if f, ok := t.FieldByName("EbmlId"); ok {
+ id = v.FieldByIndex(f.Index).Interface().(Id)
+ if id == 0 {
+ var err error
+ id, err = NewIdFromString(f.Tag.Get("ebml"))
+ if err != nil {
+ panic(errors.New("cannot resolve EBML Id for " + t.Name() + ", " + err.Error()))
+ }
+ }
+ } else {
+ if n := t.Name(); n == "" {
+ panic(errors.New("cannot resolve EBML Id for anonymous struct"))
+ } else {
+ panic(errors.New("cannot resolve EBML Id for " + n))
+ }
+ }
+ return
+}
+
+// EBML epoch is the beginning of this millennium
+var epoch = time.Date(2001, time.January, 1, 0, 0, 0, 0, time.UTC)
diff --git a/ebml/ebml_test.go b/ebml/ebml_test.go
new file mode 100644
index 0000000..e730caa
--- /dev/null
+++ b/ebml/ebml_test.go
@@ -0,0 +1,370 @@
+// Copyright © 2013 Emery Hemingway
+// Released under the terms of the GNU Public License version 3
+
+package ebml
+
+import (
+ "bytes"
+ "io"
+ "io/ioutil"
+ "math/rand"
+ "reflect"
+ "testing"
+ "time"
+)
+
+func init() {
+ rand.Seed(time.Now().UnixNano())
+}
+
+/*
+func ExampleHeader() {
+ var headerA, headerB Header
+ headerA.EBMLVersion = 1
+ headerA.EBMLReadVersion = 1
+ headerA.EBMLMaxIDLength = 1
+ headerA.EBMLMaxSizeLength = 1
+ headerA.DocType = "matroska"
+ headerA.DocTypeVersion = 1
+ headerA.DocTypeReadVersion = 1
+
+ b, _ := Marshal(headerA)
+
+ src := bytes.NewReader(b)
+ dec := NewDecoder(src)
+
+ dec.Decode(&headerB)
+
+ fmt.Printf("0x%x DeepEqual: %v", b, reflect.DeepEqual(headerA, headerB))
+ // Output:
+ // 0x1a45dfa3a34286810142f7810142f2810142f381014282886d6174726f736b614287810142858101 DeepEqual: true
+}
+
+func ExampleMarshal() {
+ DoDad := new(struct {
+ EbmlId Id `ebml:"3f0000"`
+ DoHickey uint `ebml:"4242"`
+ ThingaMabob string `ebml:"4243"`
+ HumDinger int `ebml:"4244"`
+ })
+
+ DoDad.DoHickey = 70000
+ DoDad.ThingaMabob = "huzah"
+ DoDad.HumDinger = -92387
+
+ b, err := Marshal(*DoDad)
+ if err != nil {
+ fmt.Println(err)
+ }
+ fmt.Printf("0x%x\n", b)
+
+ // Output:
+ // 0x3f00009442428301117042438568757a6168424483fe971d
+}
+
+func ExampleUnmarshal() {
+ data := []byte{
+ 0x3f, 0x00, 0x00, 0x94,
+ 0x42, 0x42, 0x83, 0x01, 0x11, 0x70,
+ 0x42, 0x43, 0x85, 0x68, 0x75, 0x7a, 0x61, 0x68,
+ 0x42, 0x44, 0x83, 0xfe, 0x97, 0x1d,
+ }
+
+ DoDad := new(struct {
+ EbmlId Id `ebml:"3f0000"`
+ DoHickey uint `ebml:"4242"`
+ ThingaMabob string `ebml:"4243"`
+ HumDinger int `ebml:"4244"`
+ })
+
+ err := Unmarshal(data, DoDad)
+ if err != nil {
+ fmt.Println(err)
+ }
+ fmt.Printf("%v\n", DoDad)
+ // Output:
+ // &{0 70000 huzah -92387}
+}
+*/
+
+type intTestStruct struct {
+ EbmlId Id `ebml:"81"`
+ I int `ebml:"88"`
+}
+
+func TestInt(t *testing.T) {
+ var in, out intTestStruct
+ in.I = rand.Int()
+
+ buf, err := Marshal(in)
+ if err != nil {
+ t.Fatalf("marshal int %d: %s\n buf: %x", in.I, err, buf)
+ return
+ }
+
+ err = Unmarshal(buf, &out)
+ if err != nil && err != io.EOF {
+ t.Fatalf("unmarshal int %d: %s\n buf: %x", in.I, err, buf)
+ return
+ }
+ if !reflect.DeepEqual(in, out) {
+ t.Fatalf("marshal and unmarshal int: in=%0.2x out=%0.2x", in.I, out.I)
+ return
+ }
+
+}
+
+func BenchmarkMarshalInt(b *testing.B) {
+ var (
+ in intTestStruct
+ buf []byte
+ err error
+ )
+ in.I = rand.Int()
+ for i := 0; i < b.N; i++ {
+ _, err = Marshal(in)
+ if err != nil {
+ b.Fatalf("marshal int %d: %s\n buf: %x", in.I, err, buf)
+ }
+ }
+}
+
+func BenchmarkUnmarshalInt(b *testing.B) {
+ var (
+ in, out intTestStruct
+ buf []byte
+ err error
+ )
+ in.I = rand.Int()
+ buf, err = Marshal(in)
+ if err != nil {
+ b.Fatalf("marshal int %d: %s\n buf: %x", in.I, err, buf)
+ return
+ }
+ for i := 0; i < b.N; i++ {
+ err = Unmarshal(buf, &out)
+ if err != nil && err != io.EOF {
+ b.Fatalf("unmarshal int %d: %s\n buf: %x", in.I, err, buf)
+ return
+ }
+ }
+}
+
+type uintTestStruct struct {
+ EbmlId Id `ebml:"81"`
+ I uint `ebml:"88"`
+}
+
+func TestUint(t *testing.T) {
+ var in, out uintTestStruct
+
+ in.I = uint(rand.Int63())
+ buf, err := Marshal(in)
+ if err != nil {
+ t.Fatalf("marshal uint %d: %s\n buf: %x", in.I, err, buf)
+ }
+
+ err = Unmarshal(buf, &out)
+ if err != nil && err != io.EOF {
+ t.Fatalf("unmarshal uint %d: %s\n buf: %x", in.I, err, buf)
+ }
+
+ if !reflect.DeepEqual(in, out) {
+ t.Fatalf("marshal and unmarshal uint: in=%0.2x out=%0.2x", in.I, out.I)
+ }
+}
+
+func BenchmarkMarshalUint(b *testing.B) {
+ var (
+ in uintTestStruct
+ err error
+ )
+
+ in.I = uint(rand.Int63())
+ for i := 0; i < b.N; i++ {
+ if _, err = Marshal(in); err != nil {
+ b.Fatalf("marshal uint %d: %s\n buf: %x", in.I, err)
+ }
+ }
+}
+
+func BenchmarkUnmarshalUint(b *testing.B) {
+ var (
+ in, out uintTestStruct
+ buf []byte
+ err error
+ )
+
+ in.I = uint(rand.Int63())
+ buf, err = Marshal(in)
+ if err != nil {
+ b.Fatalf("marshal uint %d: %s\n buf: %x", in.I, err, buf)
+ }
+ for i := 0; i < b.N; i++ {
+ if err = Unmarshal(buf, &out); err != nil && err != io.EOF {
+ b.Fatalf("unmarshal uint %d: %s\n buf: %x", in.I, err, buf)
+ }
+ }
+}
+
+type floatTestStruct struct {
+ EbmlId Id `ebml:"81"`
+ F float32 `ebml:"88"`
+ FF float64 `ebml:"89"`
+}
+
+func TestFloat(t *testing.T) {
+ var in, out floatTestStruct
+
+ in.F, in.FF = rand.Float32(), rand.Float64()
+ buf, err := Marshal(in)
+ if err != nil {
+ t.Fatalf("encode floats %f %f: %s\nbuf: %x", in.F, in.FF, err, buf)
+ return
+ }
+ if err = Unmarshal(buf, &out); err != nil {
+ t.Fatalf("decode floats %f %f: %s\nbuf: %x", in.FF, in.FF, err, buf)
+ return
+ }
+ if !reflect.DeepEqual(in, out) {
+ t.Errorf("encode/decode float mismatch: in=%f,%f out=%f,%f\n%x", in.F, in.FF, out.F, out.FF, buf)
+ return
+ }
+}
+
+func BenchmarkMarshalFloat(b *testing.B) {
+ var (
+ in floatTestStruct
+ err error
+ )
+ in.F, in.FF = rand.Float32(), rand.Float64()
+
+ for i := 0; i < b.N; i++ {
+ if _, err = Marshal(in); err != nil {
+ b.Fatalf("encode floats %f %f: %s\nbuf: %x", in.F, in.FF, err)
+ }
+ }
+}
+
+func BenchmarkUnmarshalFloat(b *testing.B) {
+ var (
+ in, out floatTestStruct
+ buf []byte
+ err error
+ )
+ in.F, in.FF = rand.Float32(), rand.Float64()
+ if buf, err = Marshal(in); err != nil {
+ b.Fatalf("encode floats %f %f: %s\nbuf: %x", in.F, in.FF, err, buf)
+ return
+ }
+ for i := 0; i < b.N; i++ {
+ if err = Unmarshal(buf, &out); err != nil {
+ b.Fatalf("decode floats %f %f: %s", in.F, in.FF, err)
+ }
+ }
+}
+
+type dateTestStruct struct {
+ EbmlId Id `ebml:"81"`
+ D time.Time `ebml:"82"`
+}
+
+func TestDate(t *testing.T) {
+ now := time.Now()
+ I := rand.Int63n(1 << 62)
+
+ var in, out dateTestStruct
+
+ for i := 0; i < 32; i++ {
+ date := now.Add(time.Duration(I))
+
+ in.D = date
+ buf, err := Marshal(in)
+ if err != nil {
+ t.Fatalf("marshal time.Time %v: %s\n buf: %x", date, err, buf)
+ }
+
+ err = Unmarshal(buf, &out)
+ if err != nil && err != io.EOF {
+ t.Fatalf("unmarshal time.Time %v: %s\n buf: %x", date, err, buf)
+ }
+
+ if !in.D.Equal(out.D) {
+ t.Fatalf("marshal and unmarshal time.Time: in=%v out=%v", in.D, out.D)
+ }
+ }
+}
+
+type stringTest struct {
+ EbmlId Id `ebml:"81"`
+ S string `ebml:"82"`
+}
+
+func TestString(t *testing.T) {
+ var in, out stringTest
+ in.S = "wrong me not good sister, nor wrong yourself"
+ buf, err := Marshal(in)
+ if err != nil {
+ t.Fatal("marshal string failed:", err)
+ }
+ if err = Unmarshal(buf, &out); err != nil {
+ t.Fatalf("unmarshal string failed: %s\n %x", err, buf)
+ }
+
+ if in.S != out.S {
+ t.Fatalf("%s != %s\n%x", in.S, out.S, buf)
+ }
+}
+
+type benchTestStruct struct {
+ EbmlId Id `ebml:"81"`
+ A uint `ebml:"4011"`
+ B int64 `ebml:"200011"`
+ C float64 `ebml:"10000011"`
+ D string `ebml:"3FFFFFFE"`
+}
+
+func BenchmarkEncoding(b *testing.B) {
+ var test benchTestStruct
+ test.A = uint(rand.Int63())
+ test.B = rand.Int63()
+ test.C = rand.Float64()
+ test.D = "of ships and sails and whether pigs have wings"
+
+ var err error
+ b.ResetTimer()
+ enc := NewEncoder(ioutil.Discard)
+ for i := 0; i < b.N; i++ {
+ err = enc.Encode(test)
+ if err != nil {
+ b.Fatal(err.Error())
+ }
+ }
+}
+
+func BenchmarkDecoding(b *testing.B) {
+ control := new(benchTestStruct)
+
+ control.A = uint(rand.Int63())
+ control.B = rand.Int63()
+ control.C = rand.Float64()
+ control.D = "of ships and sails and whether pigs have wings"
+
+ buf, err := Marshal(control)
+ r := bytes.NewReader(buf)
+ b.ResetTimer()
+
+ dec := NewDecoder(r)
+ for i := 0; i < b.N; i++ {
+ var test benchTestStruct
+ err = dec.Decode(&test)
+ if err != nil {
+ b.Fatal(err.Error())
+ }
+
+ if !reflect.DeepEqual(control, test) {
+ b.Fatalf("not equal\n%v\n%v", control, test)
+ }
+ r.Seek(0, 0)
+ }
+}
diff --git a/ebml/encode.go b/ebml/encode.go
new file mode 100644
index 0000000..03d761a
--- /dev/null
+++ b/ebml/encode.go
@@ -0,0 +1,421 @@
+// Copyright © 2013 Emery Hemingway
+// Released under the terms of the GNU Public License version 3
+
+package ebml
+
+import (
+ "encoding/binary"
+ "fmt"
+ "io"
+ "reflect"
+ "time"
+)
+
+var indent string
+
+type encoder interface {
+ io.WriterTo
+ Size() int64
+}
+
+type containerElement struct {
+ // These []bytes can probably be merged
+ id Id
+ size int64
+ header []byte
+ elements []encoder
+}
+
+func (ce *containerElement) Append(e encoder) {
+ ce.elements = append(ce.elements, e)
+ ce.size += e.Size()
+}
+
+func (ce *containerElement) Size() (n int64) {
+ ce.header = append(ce.id.bytes(), marshalSize(ce.size)...)
+ return int64(len(ce.header)) + ce.size
+}
+
+func (ce *containerElement) WriteTo(w io.Writer) (n int64, err error) {
+ if len(ce.header) == 0 {
+ ce.Size() // top level elements don't get Size called
+ }
+ var N int
+ var nn int64
+ N, err = w.Write(ce.header)
+ if err != nil {
+ return
+ }
+ n += int64(N)
+
+ for _, e := range ce.elements {
+ nn, err = e.WriteTo(w)
+ n += nn
+ if err != nil {
+ break
+ }
+ }
+ return
+}
+
+type simpleElement []byte
+
+func (b simpleElement) Size() int64 { return int64(len(b)) }
+func (b simpleElement) WriteTo(w io.Writer) (int64, error) {
+ n, err := w.Write(b)
+ return int64(n), err
+}
+
+// sliceElement is a encoder for holding groups of elements, such as a group
+// elements of the same type that occur more than once in a container.
+type sliceElement []encoder
+
+func (se sliceElement) Size() (n int64) {
+ for _, e := range se {
+ n += e.Size()
+ }
+ return
+}
+
+func (se sliceElement) WriteTo(w io.Writer) (n int64, err error) {
+ var nn int64
+ for _, e := range se {
+ nn, err = e.WriteTo(w)
+ n += nn
+ if err != nil {
+ break
+ }
+ }
+ return
+}
+
+type marshalerElement struct {
+ id Id
+ size int64
+ header []byte
+ wt io.WriterTo
+}
+
+func (me *marshalerElement) Size() int64 { return me.size }
+
+func (me *marshalerElement) WriteTo(w io.Writer) (n int64, err error) {
+ var N int
+ var nn int64
+ N, err = w.Write(me.header)
+ n = int64(N)
+ if err != nil {
+ return
+ }
+ nn, err = me.wt.WriteTo(w)
+ n += nn
+ return
+}
+
+func unsupportedTypeError(typ reflect.Type) {
+ encError("unsupported type: " + typ.String())
+}
+
+func isEmptyValue(v reflect.Value) bool {
+ switch v.Kind() {
+ case reflect.Array, reflect.Slice, reflect.String:
+ return v.Len() == 0
+ case reflect.Interface, reflect.Ptr:
+ return v.IsNil()
+ }
+ return false
+}
+
+func encode(id Id, v reflect.Value) encoder {
+ if m, ok := v.Interface().(Marshaler); ok {
+ size, wt := m.MarshalEBML()
+ header := append(id.bytes(), marshalSize(size)...)
+ return &marshalerElement{id, size, header, wt}
+ }
+
+ if t, ok := v.Interface().(time.Time); ok {
+ return encodeTime(id, t)
+ }
+
+ for v.Kind() == reflect.Ptr || v.Kind() == reflect.Interface {
+ v = v.Elem()
+ }
+
+ switch v.Kind() {
+ case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+ x := v.Int()
+ return marshalInt(id, x)
+
+ case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+ x := v.Uint()
+ return marshalUint(id, x)
+
+ case reflect.Float32:
+ return float32Element{id, v.Interface().(float32)}
+
+ case reflect.Float64:
+ return float64Element{id, v.Interface().(float64)}
+
+ case reflect.String:
+ return encodeString(id, v)
+
+ case reflect.Slice:
+ return encodeSlice(id, v)
+
+ case reflect.Struct:
+ return encodeStruct(id, v)
+ }
+ unsupportedTypeError(v.Type())
+ return nil
+}
+
+const (
+ o1 = 1<<7 - 2
+ o2 = 1<<14 - 2
+ o3 = 1<<21 - 2
+ o4 = 1<<28 - 2
+ o5 = 1<<35 - 2
+ o6 = 1<<42 - 2
+ o7 = 1<<49 - 2
+ o8 = 1<<56 - 2
+)
+
+// MarshalSize returns the EBML variable width representation
+// of an element's size
+func marshalSize(x int64) []byte {
+ var s int
+ var m byte
+
+ switch {
+ case x == 0:
+ return []byte{byte(0x80)}
+ case x < o1:
+ return []byte{byte(0x80) | byte(x)}
+ case x < o2:
+ s = 2
+ m = 0x40
+ case x < o3:
+ s = 3
+ m = 0x20
+ case x < o4:
+ s = 4
+ m = 0x10
+ case x < o5:
+ s = 5
+ m = 0x08
+ case x < o6:
+ s = 6
+ m = 0x04
+ case x < o7:
+ s = 7
+ m = 0x02
+ case x < o8:
+ s = 8
+ m = 0x01
+ default:
+ encError(fmt.Sprintf("element size %d overflows", x))
+ }
+ b := make([]byte, s)
+ s--
+ for s > 0 {
+ b[s] = byte(x)
+ x >>= 8
+ s--
+ }
+ b[0] = byte(x) | m
+ return b
+}
+
+func marshalInt(id Id, x int64) encoder {
+ var xl int
+ if x > 0 {
+ switch {
+ case x < 0x80:
+ xl = 1
+ case x < 0x8000:
+ xl = 2
+ case x < 0x800000:
+ xl = 3
+ case x < 0x80000000:
+ xl = 4
+ case x < 0x8000000000:
+ xl = 5
+ case x < 0x800000000000:
+ xl = 6
+ case x < 0x80000000000000:
+ xl = 7
+ default:
+ xl = 8
+ }
+ } else {
+ switch {
+ case x > -0x7F:
+ xl = 1
+ case x > -0x7FFF:
+ xl = 2
+ case x > -0x7FFFFF:
+ xl = 3
+ case x > -0x7FFFFFFF:
+ xl = 4
+ case x > -0x7FFFFFFFFF:
+ xl = 5
+ case x > -0x7FFFFFFFFFFF:
+ xl = 6
+ case x > -0x7FFFFFFFFFFFFF:
+ xl = 7
+ default:
+ xl = 8
+ }
+ }
+
+ idBuf := id.bytes()
+ l := len(idBuf) + 1 + xl
+ b := make(simpleElement, l)
+ p := copy(b, idBuf)
+ b[p] = 0x80 | byte(xl)
+ p++
+
+ l--
+ b[l] = byte(x)
+ for l > p {
+ l--
+ x >>= 8
+ b[l] = byte(x)
+ }
+ return b
+}
+
+func marshalUint(id Id, x uint64) encoder {
+ var xl int
+ switch {
+ case x < 0xFF:
+ xl = 1
+ case x < 0xFFFF:
+ xl = 2
+ case x < 0xFFFFFF:
+ xl = 3
+ case x < 0xFFFFFFFF:
+ xl = 4
+ case x < 0xFFFFFFFFFF:
+ xl = 5
+ case x < 0xFFFFFFFFFFFF:
+ xl = 6
+ case x < 0xFFFFFFFFFFFFFF:
+ xl = 7
+ default:
+ xl = 8
+ }
+ idBuf := id.bytes()
+
+ l := len(idBuf) + 1 + xl
+ b := make(simpleElement, l)
+ p := copy(b, idBuf)
+ b[p] = 0x80 | byte(xl)
+ p++
+
+ l--
+ b[l] = byte(x)
+ for l > p {
+ l--
+ x >>= 8
+ b[l] = byte(x)
+ }
+ return b
+}
+
+type float32Element struct {
+ id Id
+ f float32
+}
+
+func (e float32Element) Size() int64 { return e.id.len() + 5 }
+func (e float32Element) WriteTo(w io.Writer) (int64, error) {
+ n, err := w.Write(e.id.bytes())
+ if err == nil {
+ _, err = w.Write([]byte{0x84})
+ if err == nil {
+ err = binary.Write(w, binary.BigEndian, e.f)
+ n += 5
+ }
+ }
+ return int64(n), err
+}
+
+type float64Element struct {
+ id Id
+ f float64
+}
+
+func (e float64Element) Size() int64 { return e.id.len() + 9 }
+func (e float64Element) WriteTo(w io.Writer) (int64, error) {
+ n, err := w.Write(e.id.bytes())
+ if err == nil {
+ _, err = w.Write([]byte{0x88})
+ if err == nil {
+ n++
+ err = binary.Write(w, binary.BigEndian, e.f)
+ } else {
+ n += 8
+ }
+ }
+ return int64(n), err
+}
+
+func encodeSlice(id Id, v reflect.Value) encoder {
+ if bs, ok := v.Interface().([]byte); ok {
+ idBuf := id.bytes()
+ sizeBuf := marshalSize(int64(len(bs)))
+ buf := make(simpleElement, len(idBuf)+len(sizeBuf)+len(bs))
+ n := copy(buf, idBuf)
+ n += copy(buf[n:], sizeBuf)
+ copy(buf[n:], bs)
+ return buf
+ }
+
+ l := v.Len()
+ s := make(sliceElement, l)
+ for i := 0; i < l; i++ {
+ s[i] = encode(id, v.Index(i))
+ }
+ return s
+}
+
+func encodeString(id Id, v reflect.Value) encoder {
+ sb := []byte(v.String())
+ l := len(sb)
+ sz := marshalSize(int64(l))
+ idBuf := id.bytes()
+ b := make(simpleElement, len(idBuf)+len(sz)+l)
+ n := copy(b, idBuf)
+ n += copy(b[n:], sz)
+ copy(b[n:], sb)
+ return b
+}
+
+func encodeStruct(id Id, v reflect.Value) encoder {
+ e := &containerElement{id: id}
+ for fid, i := range cachedFieldIdMap(v.Type()) {
+ fv := v.Field(i)
+ if !fv.IsValid() || isEmptyValue(fv) {
+ continue
+ }
+ fe := encode(fid, fv)
+ if e != nil {
+ e.Append(fe)
+ }
+ }
+ return e
+}
+
+func encodeTime(id Id, t time.Time) encoder {
+ d := t.Sub(epoch) // epoch defined in ebml.go
+
+ idb := id.bytes()
+ b := make(simpleElement, len(idb)+9)
+ n := copy(b, idb)
+ b[n] = 0x88 // length will be 8
+ for i := len(b) - 1; i > n; i-- {
+ b[i] = byte(d)
+ d >>= 8
+ }
+ return b
+}
diff --git a/ebml/error.go b/ebml/error.go
new file mode 100644
index 0000000..130d405
--- /dev/null
+++ b/ebml/error.go
@@ -0,0 +1,17 @@
+// Copyright © 2013 Emery Hemingway
+// Released under the terms of the GNU Public License version 3
+
+package ebml
+
+// A ebmlError is used to distinguish errors (panics) generated in this package.
+type ebmlError string
+
+func (e ebmlError) Error() string { return string(e) }
+
+func encError(s string) {
+ panic(ebmlError("ebml encoder: " + s))
+}
+
+func decError(s string) {
+ panic(ebmlError("ebml decoder: " + s))
+}
diff --git a/ebml/file.go b/ebml/file.go
new file mode 100644
index 0000000..9979b7d
--- /dev/null
+++ b/ebml/file.go
@@ -0,0 +1,94 @@
+// Copyright © 2013 Emery Hemingway
+// Released under the terms of the GNU Public License version 3
+
+package ebml
+
+import (
+ "bufio"
+ "io"
+ "os"
+)
+
+type fileAbstraction struct {
+ filename string
+ info os.FileInfo
+}
+
+// NewFileMarshaler returns a Marshaler that reads from a file
+// during encoding.
+func NewFileMarshaler(filename string) (Marshaler, error) {
+ info, err := os.Stat(filename)
+ if err != nil {
+ return nil, err
+ }
+ return &fileAbstraction{filename, info}, nil
+}
+
+func (f *fileAbstraction) MarshalEBML() (size int64, wt io.WriterTo) {
+ return f.info.Size(), f
+}
+
+func (f *fileAbstraction) WriteTo(w io.Writer) (written int64, err error) {
+ var file *os.File
+ file, err = os.Open(f.filename)
+ if err != nil {
+ return
+ }
+ defer file.Close()
+ // let bufio handle the details
+ return bufio.NewReader(file).WriteTo(w)
+}
+
+// NewFileUnmarshaler returns an Unmarshaler that writes to a file
+// during decoding.
+func NewFileUnmarshaler(filename string) (Unmarshaler, error) {
+ info, err := os.Stat(filename)
+ if err == nil {
+ return &fileAbstraction{filename, info}, nil
+ }
+
+ // create the file to check write permission before decoding.
+ if !os.IsNotExist(err) {
+ return nil, err
+ }
+
+ var file *os.File
+ file, err = os.OpenFile(filename, os.O_CREATE|os.O_EXCL, 0666)
+ if err != nil {
+ return nil, err
+ }
+ defer file.Close()
+
+ // try again
+ info, err = os.Stat(filename)
+ if err != nil {
+ return nil, err
+ }
+ return &fileAbstraction{filename, info}, nil
+}
+
+func (f *fileAbstraction) UnmarshalEBML(n int64) io.ReaderFrom {
+ if f.info.Size() != n {
+ err := os.Truncate(f.filename, n)
+ if err != nil {
+ panic(err)
+ }
+ }
+ return f
+}
+
+func (f *fileAbstraction) ReadFrom(r io.Reader) (readed int64, err error) {
+ var file *os.File
+ file, err = os.OpenFile(f.filename, os.O_WRONLY, 0)
+ if err != nil {
+ return
+ }
+ defer file.Close()
+ // let bufio handle the details
+ return bufio.NewWriter(file).ReadFrom(r)
+}
+
+var (
+ _ Marshaler = (*fileAbstraction)(nil)
+ _ Unmarshaler = (*fileAbstraction)(nil)
+)
diff --git a/ebml/file_test.go b/ebml/file_test.go
new file mode 100644
index 0000000..929c71a
--- /dev/null
+++ b/ebml/file_test.go
@@ -0,0 +1,35 @@
+// +build file
+// This test is only run with the "file" build tag,
+// as it touches the filesystem and needs a test file.
+
+package ebml
+
+import "testing"
+
+func TestFile(t *testing.T) {
+ fm, err := NewFileMarshaler("/tmp/test.in")
+ if err != nil {
+ t.Fatal("NewFileMarshaler:", err)
+ }
+ x := &struct {
+ EbmlId Id `ebml:"81"`
+ F Marshaler `ebml:"82"`
+ }{F: fm}
+ b, err := Marshal(x)
+ if err != nil {
+ t.Fatal("Marshal:", err)
+ }
+
+ fu, err := NewFileUnmarshaler("/tmp/test.out")
+ if err != nil {
+ t.Fatal("NewFileUnmarshaler:", err)
+ }
+ y := &struct {
+ EbmlId Id `ebml:"81"`
+ F Unmarshaler `ebml:"82"`
+ }{F: fu}
+ err = Unmarshal(b, y)
+ if err != nil {
+ t.Fatal("Unmarshal:", err)
+ }
+}
diff --git a/ebml/idtest/idtest.go b/ebml/idtest/idtest.go
new file mode 100644
index 0000000..99e040e
--- /dev/null
+++ b/ebml/idtest/idtest.go
@@ -0,0 +1,43 @@
+// idtest is a utility for checking the validity of EBML ids
+package main
+
+import (
+ "fmt"
+ "github.com/ehmry/encoding/ebml"
+ "os"
+)
+
+func main() {
+ for _, s := range os.Args[1:] {
+ id, err := ebml.NewIdFromString(s)
+ if err != nil {
+ fmt.Println(err)
+ continue
+ }
+
+ b := id.Bytes()
+ c := b[0]
+ var good bool
+ switch l := len(b); l {
+ case 1:
+ good = c <= 0xff && c > 0x80
+ case 2:
+ good = c <= 0x7f && c > 0x40
+ case 3:
+ good = c <= 0x3f && c > 0x20
+ case 4:
+ good = c <= 0x1f && c > 0x10
+ }
+
+ if good {
+ fmt.Print("Id is good: ")
+ } else {
+ fmt.Print("Id is bad: ")
+ }
+ fmt.Printf("% 11s ", id)
+ for _, c := range b {
+ fmt.Printf(".%08b", c)
+ }
+ fmt.Println()
+ }
+}
diff --git a/ebml/stream.go b/ebml/stream.go
new file mode 100644
index 0000000..aa7f3a8
--- /dev/null
+++ b/ebml/stream.go
@@ -0,0 +1,155 @@
+// Copyright © 2013 Emery Hemingway
+// Released under the terms of the GNU Public License version 3
+
+package ebml
+
+import (
+ "bytes"
+ "fmt"
+ "io"
+ "reflect"
+ "runtime"
+)
+
+// An Encoder writes EBML data to an output stream.
+type Encoder struct {
+ w io.Writer
+ err error
+}
+
+// NewEncoder returns a new Encoder that writes to w.
+func NewEncoder(w io.Writer) *Encoder {
+ return &Encoder{w: w}
+}
+
+// Encode writes the EBML binary encoding of element to an Encoder stream.
+func (enc *Encoder) Encode(element interface{}) (err error) {
+ if enc.err != nil {
+ return enc.err
+ }
+
+ // encoding doesn't use error internally, but panics if there is a
+ // problem and then unwinds up to here.
+ defer func() {
+ if r := recover(); r != nil {
+ if _, ok := r.(runtime.Error); ok {
+ panic(r)
+ }
+ err = r.(error)
+ }
+ }()
+
+ v := reflect.ValueOf(element)
+ id := getId(v)
+
+ elem := encode(id, v)
+ if elem != nil {
+ _, err = elem.WriteTo(enc.w)
+ }
+ return
+}
+
+// A Decoder decodes EBML data from a ReadSeeker
+type Decoder struct {
+ r io.ReadSeeker
+ buf []byte // this is a resuable buffer for decoding
+ err error
+}
+
+// NewDecoder returns a new decoder that decodes from r.
+func NewDecoder(r io.ReadSeeker) *Decoder {
+ // TODO(Emery): just ask for a io.Reader and try and make it
+ // an io.ReadSeeker
+ return &Decoder{r: r, buf: make([]byte, 8)}
+}
+
+// Decode decodes a EBML stream into v.
+func (d *Decoder) Decode(element interface{}) (err error) {
+ if d.err != nil {
+ return d.err
+ }
+
+ // decoding doesn't use error internally, but panics if there is a
+ // problem and then unwinds up to here.
+ defer func() {
+ if r := recover(); r != nil {
+ if _, ok := r.(runtime.Error); ok {
+ panic(r)
+ }
+ err = r.(error)
+ }
+ }()
+
+ v := reflect.ValueOf(element)
+ for v.Kind() == reflect.Ptr || v.Kind() == reflect.Interface {
+ v = v.Elem()
+ }
+
+ id := getId(v)
+ if n, curId := d.readId(); id != curId {
+ d.r.Seek(int64(-n), 0)
+ return fmt.Errorf("ebml: read stream positioned at element %s not %s", curId, id)
+ }
+ _, size := d.readSize()
+
+ decodeValue(d, id, size, v)
+ return
+}
+
+// Marshal returns an EBML representation of element.
+//
+// Marshal first determines the Id of element from the field named 'EbmlId',
+// then recursively traverses element. Any exported struct field of element
+// with an `ebml` tag will be including in marshalling, with the exception
+// of fields tagged with `ebml:"-"`.
+//
+// The ebml tag should contain a valid EBML id, see the EBML documention for
+// what constitutes a valid id.
+func Marshal(element interface{}) ([]byte, error) {
+ buf := new(bytes.Buffer)
+ encoder := NewEncoder(buf)
+ err := encoder.Encode(element)
+ return buf.Bytes(), err
+}
+
+// Unmarshal unmarshals EBML data into element.
+//
+// Unmarshal first determines the Id of element from the field named 'EbmlId',
+// then recursively traverses element. Any exported struct field of element
+// with an `ebml` tag will be including in unmarshalling, with the exception
+// of fields tagged with `ebml:"-"`.
+//
+// The ebml tag should contain a valid EBML id, see the EBML documention for
+// what constitutes a valid id.
+func Unmarshal(data []byte, element interface{}) error {
+ return NewDecoder(bytes.NewReader(data)).Decode(element)
+}
+
+// Marshaler is the interface implemented by objects that
+// can marshal themselves into an EBML stream. The WriterTo
+// should only Write element data, and not the id and size
+// header of the element. size is the length of the data that
+// shall be written and is used to build the element header
+// and compute the size of the parent element before it is
+// writen to an EBML stream.
+type Marshaler interface {
+ // BUG(Emery): an embedded Marshaler will trample on a struct
+ MarshalEBML() (size int64, wt io.WriterTo)
+}
+
+// Unmarshaler is the interface implemented by objects that
+// can unmarshal themselves from an EBML stream. The data
+// read into ReaderFrom will contain the data for the element
+// being unmarshaled, and not an id or size header.
+//
+// n shall be the size of the element data, and it is not the
+// resposibility of an Unmarshaler to limit reading to n.
+//
+// An Unmarshaler is usually sent to the decoding engine as a nil pointer
+// in a struct and created when a tagged element is encountered, for this
+// reason the UnmarshalEBML method should behave as if the Unmarshaler is
+// at a zero value state.
+type Unmarshaler interface {
+ // BUG(Emery): an embedded Unmarshaler will trample on a struct
+ UnmarshalEBML(n int64) io.ReaderFrom
+}