metadata: Introduce EsSub8 and EsSub32 tags.
They replace the existing `EsEnumVid`, `EsVecLen` and `EsMapLen` tags altogether; the meaning of them can be easily inferred from the enclosing tag. It also has an added benefit of encodings for smaller variant ids or lengths being more compact (5 bytes to 2 bytes).
This commit is contained in:
Kang Seonghoon
parent
35c798b3fc
commit
de00b858d1
@ -97,22 +97,21 @@ pub enum EbmlEncoderTag {
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EsChar = 0x0b, // + 4 bytes
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EsF64 = 0x0c, // + 8 bytes
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EsF32 = 0x0d, // + 4 bytes
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EsEnumVid = 0x0e, // + 4 bytes
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EsVecLen = 0x0f, // + 4 bytes
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EsMapLen = 0x10, // + 4 bytes
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EsSub8 = 0x0e, // + 1 byte
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EsSub32 = 0x0f, // + 4 bytes
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EsStr = 0x11,
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EsEnum = 0x12,
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EsVec = 0x13,
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EsVecElt = 0x14,
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EsMap = 0x15,
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EsMapKey = 0x16,
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EsMapVal = 0x17,
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EsOpaque = 0x18,
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EsStr = 0x10,
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EsEnum = 0x11, // encodes the variant id as the first EsSub*
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EsVec = 0x12, // encodes the # of elements as the first EsSub*
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EsVecElt = 0x13,
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EsMap = 0x14, // encodes the # of pairs as the first EsSub*
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EsMapKey = 0x15,
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EsMapVal = 0x16,
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EsOpaque = 0x17,
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}
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const NUM_TAGS: uint = 0x1000;
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const NUM_IMPLICIT_TAGS: uint = 0x11;
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const NUM_IMPLICIT_TAGS: uint = 0x10;
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static TAG_IMPLICIT_LEN: [i8; NUM_IMPLICIT_TAGS] = [
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8, 8, 4, 2, 1, // EsU*
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@ -120,9 +119,7 @@ static TAG_IMPLICIT_LEN: [i8; NUM_IMPLICIT_TAGS] = [
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1, // EsBool
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4, // EsChar
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8, 4, // EsF*
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4, // EsEnumVid
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4, // EsVecLen
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4, // EsMapLen
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1, 4, // EsSub*
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];
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#[derive(Debug)]
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@ -152,8 +149,8 @@ pub mod reader {
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use serialize;
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use super::{ ApplicationError, EsVec, EsMap, EsEnum, EsVecLen, EsVecElt,
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EsMapLen, EsMapKey, EsEnumVid, EsU64, EsU32, EsU16, EsU8, EsInt, EsI64,
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use super::{ ApplicationError, EsVec, EsMap, EsEnum, EsSub8, EsSub32,
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EsVecElt, EsMapKey, EsU64, EsU32, EsU16, EsU8, EsInt, EsI64,
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EsI32, EsI16, EsI8, EsBool, EsF64, EsF32, EsChar, EsStr, EsMapVal,
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EsUint, EsOpaque, EbmlEncoderTag, Doc, TaggedDoc,
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Error, IntTooBig, InvalidTag, Expected, NUM_IMPLICIT_TAGS, TAG_IMPLICIT_LEN };
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@ -419,6 +416,37 @@ pub mod reader {
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Ok(r_doc)
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}
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fn next_doc2(&mut self,
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exp_tag1: EbmlEncoderTag,
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exp_tag2: EbmlEncoderTag) -> DecodeResult<(bool, Doc<'doc>)> {
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assert!((exp_tag1 as uint) != (exp_tag2 as uint));
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debug!(". next_doc2(exp_tag1={:?}, exp_tag2={:?})", exp_tag1, exp_tag2);
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if self.pos >= self.parent.end {
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return Err(Expected(format!("no more documents in \
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current node!")));
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}
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let TaggedDoc { tag: r_tag, doc: r_doc } =
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try!(doc_at(self.parent.data, self.pos));
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debug!("self.parent={:?}-{:?} self.pos={:?} r_tag={:?} r_doc={:?}-{:?}",
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self.parent.start,
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self.parent.end,
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self.pos,
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r_tag,
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r_doc.start,
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r_doc.end);
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if r_tag != (exp_tag1 as uint) && r_tag != (exp_tag2 as uint) {
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return Err(Expected(format!("expected EBML doc with tag {:?} or {:?} but \
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found tag {:?}", exp_tag1, exp_tag2, r_tag)));
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}
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if r_doc.end > self.parent.end {
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return Err(Expected(format!("invalid EBML, child extends to \
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{:#x}, parent to {:#x}",
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r_doc.end, self.parent.end)));
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}
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self.pos = r_doc.end;
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Ok((r_tag == (exp_tag2 as uint), r_doc))
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}
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fn push_doc<T, F>(&mut self, exp_tag: EbmlEncoderTag, f: F) -> DecodeResult<T> where
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F: FnOnce(&mut Decoder<'doc>) -> DecodeResult<T>,
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{
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@ -433,10 +461,15 @@ pub mod reader {
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Ok(r)
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}
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fn _next_uint(&mut self, exp_tag: EbmlEncoderTag) -> DecodeResult<uint> {
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let r = doc_as_u32(try!(self.next_doc(exp_tag)));
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debug!("_next_uint exp_tag={:?} result={:?}", exp_tag, r);
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Ok(r as uint)
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fn _next_sub(&mut self) -> DecodeResult<uint> {
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let (big, doc) = try!(self.next_doc2(EsSub8, EsSub32));
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let r = if big {
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doc_as_u32(doc) as uint
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} else {
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doc_as_u8(doc) as uint
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};
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debug!("_next_sub result={:?}", r);
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Ok(r)
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}
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pub fn read_opaque<R, F>(&mut self, op: F) -> DecodeResult<R> where
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@ -538,7 +571,7 @@ pub mod reader {
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where F: FnMut(&mut Decoder<'doc>, uint) -> DecodeResult<T>,
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{
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debug!("read_enum_variant()");
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let idx = try!(self._next_uint(EsEnumVid));
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let idx = try!(self._next_sub());
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debug!(" idx={}", idx);
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f(self, idx)
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@ -556,7 +589,7 @@ pub mod reader {
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where F: FnMut(&mut Decoder<'doc>, uint) -> DecodeResult<T>,
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{
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debug!("read_enum_struct_variant()");
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let idx = try!(self._next_uint(EsEnumVid));
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let idx = try!(self._next_sub());
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debug!(" idx={}", idx);
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f(self, idx)
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@ -647,7 +680,7 @@ pub mod reader {
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{
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debug!("read_seq()");
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self.push_doc(EsVec, move |d| {
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let len = try!(d._next_uint(EsVecLen));
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let len = try!(d._next_sub());
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debug!(" len={}", len);
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f(d, len)
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})
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@ -665,7 +698,7 @@ pub mod reader {
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{
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debug!("read_map()");
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self.push_doc(EsMap, move |d| {
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let len = try!(d._next_uint(EsMapLen));
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let len = try!(d._next_sub());
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debug!(" len={}", len);
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f(d, len)
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})
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@ -697,10 +730,10 @@ pub mod writer {
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use std::old_io::{Writer, Seek};
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use std::old_io;
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use super::{ EsVec, EsMap, EsEnum, EsVecLen, EsVecElt, EsMapLen, EsMapKey,
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EsEnumVid, EsU64, EsU32, EsU16, EsU8, EsInt, EsI64, EsI32, EsI16, EsI8,
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use super::{ EsVec, EsMap, EsEnum, EsSub8, EsSub32, EsVecElt, EsMapKey,
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EsU64, EsU32, EsU16, EsU8, EsInt, EsI64, EsI32, EsI16, EsI8,
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EsBool, EsF64, EsF32, EsChar, EsStr, EsMapVal, EsUint,
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EsOpaque, EbmlEncoderTag, NUM_IMPLICIT_TAGS, NUM_TAGS };
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EsOpaque, NUM_IMPLICIT_TAGS, NUM_TAGS };
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use serialize;
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@ -907,9 +940,18 @@ pub mod writer {
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impl<'a, W: Writer + Seek> Encoder<'a, W> {
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// used internally to emit things like the vector length and so on
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fn _emit_tagged_uint(&mut self, t: EbmlEncoderTag, v: uint) -> EncodeResult {
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assert!(v <= 0xFFFF_FFFF);
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self.wr_tagged_raw_u32(t as uint, v as u32)
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fn _emit_tagged_sub(&mut self, v: uint) -> EncodeResult {
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if let Some(v) = v.to_u8() {
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self.wr_tagged_raw_u8(EsSub8 as uint, v)
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} else if let Some(v) = v.to_u32() {
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self.wr_tagged_raw_u32(EsSub32 as uint, v)
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} else {
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Err(old_io::IoError {
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kind: old_io::OtherIoError,
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desc: "length or variant id too big",
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detail: Some(format!("{}", v))
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})
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}
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}
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pub fn emit_opaque<F>(&mut self, f: F) -> EncodeResult where
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@ -995,7 +1037,7 @@ pub mod writer {
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f: F) -> EncodeResult where
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F: FnOnce(&mut Encoder<'a, W>) -> EncodeResult,
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{
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try!(self._emit_tagged_uint(EsEnumVid, v_id));
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try!(self._emit_tagged_sub(v_id));
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f(self)
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}
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@ -1078,7 +1120,7 @@ pub mod writer {
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{
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try!(self.start_tag(EsVec as uint));
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try!(self._emit_tagged_uint(EsVecLen, len));
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try!(self._emit_tagged_sub(len));
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try!(f(self));
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self.end_tag()
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}
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@ -1097,7 +1139,7 @@ pub mod writer {
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{
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try!(self.start_tag(EsMap as uint));
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try!(self._emit_tagged_uint(EsMapLen, len));
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try!(self._emit_tagged_sub(len));
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try!(f(self));
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self.end_tag()
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}
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