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jeremybenn |
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package gob
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import (
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"bytes"
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"math"
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"reflect"
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"unsafe"
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)
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const uint64Size = int(unsafe.Sizeof(uint64(0)))
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// encoderState is the global execution state of an instance of the encoder.
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// Field numbers are delta encoded and always increase. The field
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// number is initialized to -1 so 0 comes out as delta(1). A delta of
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// 0 terminates the structure.
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type encoderState struct {
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enc *Encoder
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b *bytes.Buffer
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sendZero bool // encoding an array element or map key/value pair; send zero values
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fieldnum int // the last field number written.
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buf [1 + uint64Size]byte // buffer used by the encoder; here to avoid allocation.
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next *encoderState // for free list
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}
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func (enc *Encoder) newEncoderState(b *bytes.Buffer) *encoderState {
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e := enc.freeList
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if e == nil {
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e = new(encoderState)
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e.enc = enc
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} else {
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enc.freeList = e.next
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}
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e.sendZero = false
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e.fieldnum = 0
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e.b = b
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return e
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}
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func (enc *Encoder) freeEncoderState(e *encoderState) {
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e.next = enc.freeList
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enc.freeList = e
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}
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// Unsigned integers have a two-state encoding. If the number is less
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// than 128 (0 through 0x7F), its value is written directly.
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// Otherwise the value is written in big-endian byte order preceded
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// by the byte length, negated.
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// encodeUint writes an encoded unsigned integer to state.b.
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func (state *encoderState) encodeUint(x uint64) {
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if x <= 0x7F {
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err := state.b.WriteByte(uint8(x))
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if err != nil {
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error_(err)
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}
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return
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}
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i := uint64Size
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for x > 0 {
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state.buf[i] = uint8(x)
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x >>= 8
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i--
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}
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state.buf[i] = uint8(i - uint64Size) // = loop count, negated
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_, err := state.b.Write(state.buf[i : uint64Size+1])
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if err != nil {
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error_(err)
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}
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}
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// encodeInt writes an encoded signed integer to state.w.
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// The low bit of the encoding says whether to bit complement the (other bits of the)
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// uint to recover the int.
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func (state *encoderState) encodeInt(i int64) {
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var x uint64
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if i < 0 {
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x = uint64(^i<<1) | 1
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} else {
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x = uint64(i << 1)
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}
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state.encodeUint(uint64(x))
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}
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// encOp is the signature of an encoding operator for a given type.
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type encOp func(i *encInstr, state *encoderState, p unsafe.Pointer)
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// The 'instructions' of the encoding machine
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type encInstr struct {
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op encOp
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field int // field number
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indir int // how many pointer indirections to reach the value in the struct
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offset uintptr // offset in the structure of the field to encode
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}
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// update emits a field number and updates the state to record its value for delta encoding.
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// If the instruction pointer is nil, it does nothing
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func (state *encoderState) update(instr *encInstr) {
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if instr != nil {
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state.encodeUint(uint64(instr.field - state.fieldnum))
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state.fieldnum = instr.field
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}
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}
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// Each encoder for a composite is responsible for handling any
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// indirections associated with the elements of the data structure.
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// If any pointer so reached is nil, no bytes are written. If the
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// data item is zero, no bytes are written. Single values - ints,
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// strings etc. - are indirected before calling their encoders.
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// Otherwise, the output (for a scalar) is the field number, as an
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// encoded integer, followed by the field data in its appropriate
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// format.
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// encIndirect dereferences p indir times and returns the result.
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func encIndirect(p unsafe.Pointer, indir int) unsafe.Pointer {
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for ; indir > 0; indir-- {
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p = *(*unsafe.Pointer)(p)
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if p == nil {
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return unsafe.Pointer(nil)
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}
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}
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return p
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}
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// encBool encodes the bool with address p as an unsigned 0 or 1.
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func encBool(i *encInstr, state *encoderState, p unsafe.Pointer) {
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b := *(*bool)(p)
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if b || state.sendZero {
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state.update(i)
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if b {
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state.encodeUint(1)
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} else {
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state.encodeUint(0)
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}
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}
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}
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// encInt encodes the int with address p.
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func encInt(i *encInstr, state *encoderState, p unsafe.Pointer) {
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v := int64(*(*int)(p))
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if v != 0 || state.sendZero {
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state.update(i)
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state.encodeInt(v)
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}
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}
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// encUint encodes the uint with address p.
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func encUint(i *encInstr, state *encoderState, p unsafe.Pointer) {
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v := uint64(*(*uint)(p))
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if v != 0 || state.sendZero {
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state.update(i)
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state.encodeUint(v)
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}
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}
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// encInt8 encodes the int8 with address p.
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func encInt8(i *encInstr, state *encoderState, p unsafe.Pointer) {
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v := int64(*(*int8)(p))
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if v != 0 || state.sendZero {
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state.update(i)
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state.encodeInt(v)
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}
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}
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// encUint8 encodes the uint8 with address p.
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func encUint8(i *encInstr, state *encoderState, p unsafe.Pointer) {
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v := uint64(*(*uint8)(p))
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if v != 0 || state.sendZero {
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state.update(i)
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state.encodeUint(v)
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}
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}
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// encInt16 encodes the int16 with address p.
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func encInt16(i *encInstr, state *encoderState, p unsafe.Pointer) {
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v := int64(*(*int16)(p))
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if v != 0 || state.sendZero {
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state.update(i)
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state.encodeInt(v)
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}
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}
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// encUint16 encodes the uint16 with address p.
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func encUint16(i *encInstr, state *encoderState, p unsafe.Pointer) {
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v := uint64(*(*uint16)(p))
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if v != 0 || state.sendZero {
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state.update(i)
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state.encodeUint(v)
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}
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}
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// encInt32 encodes the int32 with address p.
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func encInt32(i *encInstr, state *encoderState, p unsafe.Pointer) {
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v := int64(*(*int32)(p))
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if v != 0 || state.sendZero {
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state.update(i)
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state.encodeInt(v)
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}
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}
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// encUint encodes the uint32 with address p.
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func encUint32(i *encInstr, state *encoderState, p unsafe.Pointer) {
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v := uint64(*(*uint32)(p))
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if v != 0 || state.sendZero {
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state.update(i)
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state.encodeUint(v)
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}
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}
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// encInt64 encodes the int64 with address p.
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func encInt64(i *encInstr, state *encoderState, p unsafe.Pointer) {
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v := *(*int64)(p)
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if v != 0 || state.sendZero {
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state.update(i)
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state.encodeInt(v)
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}
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}
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// encInt64 encodes the uint64 with address p.
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func encUint64(i *encInstr, state *encoderState, p unsafe.Pointer) {
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v := *(*uint64)(p)
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if v != 0 || state.sendZero {
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state.update(i)
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state.encodeUint(v)
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}
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}
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// encUintptr encodes the uintptr with address p.
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func encUintptr(i *encInstr, state *encoderState, p unsafe.Pointer) {
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v := uint64(*(*uintptr)(p))
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if v != 0 || state.sendZero {
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state.update(i)
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state.encodeUint(v)
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}
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}
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// floatBits returns a uint64 holding the bits of a floating-point number.
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// Floating-point numbers are transmitted as uint64s holding the bits
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// of the underlying representation. They are sent byte-reversed, with
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// the exponent end coming out first, so integer floating point numbers
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// (for example) transmit more compactly. This routine does the
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// swizzling.
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func floatBits(f float64) uint64 {
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u := math.Float64bits(f)
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var v uint64
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for i := 0; i < 8; i++ {
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v <<= 8
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v |= u & 0xFF
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u >>= 8
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}
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return v
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}
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// encFloat32 encodes the float32 with address p.
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func encFloat32(i *encInstr, state *encoderState, p unsafe.Pointer) {
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f := *(*float32)(p)
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if f != 0 || state.sendZero {
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v := floatBits(float64(f))
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state.update(i)
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state.encodeUint(v)
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}
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}
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// encFloat64 encodes the float64 with address p.
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func encFloat64(i *encInstr, state *encoderState, p unsafe.Pointer) {
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f := *(*float64)(p)
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if f != 0 || state.sendZero {
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state.update(i)
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v := floatBits(f)
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state.encodeUint(v)
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}
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}
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// encComplex64 encodes the complex64 with address p.
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// Complex numbers are just a pair of floating-point numbers, real part first.
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func encComplex64(i *encInstr, state *encoderState, p unsafe.Pointer) {
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c := *(*complex64)(p)
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if c != 0+0i || state.sendZero {
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rpart := floatBits(float64(real(c)))
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ipart := floatBits(float64(imag(c)))
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state.update(i)
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state.encodeUint(rpart)
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state.encodeUint(ipart)
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}
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}
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// encComplex128 encodes the complex128 with address p.
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func encComplex128(i *encInstr, state *encoderState, p unsafe.Pointer) {
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c := *(*complex128)(p)
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if c != 0+0i || state.sendZero {
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rpart := floatBits(real(c))
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ipart := floatBits(imag(c))
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state.update(i)
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state.encodeUint(rpart)
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state.encodeUint(ipart)
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}
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}
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// encUint8Array encodes the byte slice whose header has address p.
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// Byte arrays are encoded as an unsigned count followed by the raw bytes.
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func encUint8Array(i *encInstr, state *encoderState, p unsafe.Pointer) {
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b := *(*[]byte)(p)
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if len(b) > 0 || state.sendZero {
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state.update(i)
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state.encodeUint(uint64(len(b)))
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state.b.Write(b)
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}
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}
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// encString encodes the string whose header has address p.
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// Strings are encoded as an unsigned count followed by the raw bytes.
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func encString(i *encInstr, state *encoderState, p unsafe.Pointer) {
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s := *(*string)(p)
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if len(s) > 0 || state.sendZero {
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state.update(i)
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state.encodeUint(uint64(len(s)))
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state.b.WriteString(s)
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}
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}
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// encStructTerminator encodes the end of an encoded struct
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// as delta field number of 0.
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func encStructTerminator(i *encInstr, state *encoderState, p unsafe.Pointer) {
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state.encodeUint(0)
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}
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// Execution engine
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// encEngine an array of instructions indexed by field number of the encoding
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// data, typically a struct. It is executed top to bottom, walking the struct.
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type encEngine struct {
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instr []encInstr
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}
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const singletonField = 0
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// encodeSingle encodes a single top-level non-struct value.
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func (enc *Encoder) encodeSingle(b *bytes.Buffer, engine *encEngine, basep uintptr) {
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state := enc.newEncoderState(b)
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state.fieldnum = singletonField
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// There is no surrounding struct to frame the transmission, so we must
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// generate data even if the item is zero. To do this, set sendZero.
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state.sendZero = true
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instr := &engine.instr[singletonField]
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p := unsafe.Pointer(basep) // offset will be zero
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if instr.indir > 0 {
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if p = encIndirect(p, instr.indir); p == nil {
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return
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}
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}
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instr.op(instr, state, p)
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enc.freeEncoderState(state)
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}
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// encodeStruct encodes a single struct value.
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func (enc *Encoder) encodeStruct(b *bytes.Buffer, engine *encEngine, basep uintptr) {
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state := enc.newEncoderState(b)
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state.fieldnum = -1
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for i := 0; i < len(engine.instr); i++ {
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instr := &engine.instr[i]
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364 |
|
|
p := unsafe.Pointer(basep + instr.offset)
|
365 |
|
|
if instr.indir > 0 {
|
366 |
|
|
if p = encIndirect(p, instr.indir); p == nil {
|
367 |
|
|
continue
|
368 |
|
|
}
|
369 |
|
|
}
|
370 |
|
|
instr.op(instr, state, p)
|
371 |
|
|
}
|
372 |
|
|
enc.freeEncoderState(state)
|
373 |
|
|
}
|
374 |
|
|
|
375 |
|
|
// encodeArray encodes the array whose 0th element is at p.
|
376 |
|
|
func (enc *Encoder) encodeArray(b *bytes.Buffer, p uintptr, op encOp, elemWid uintptr, elemIndir int, length int) {
|
377 |
|
|
state := enc.newEncoderState(b)
|
378 |
|
|
state.fieldnum = -1
|
379 |
|
|
state.sendZero = true
|
380 |
|
|
state.encodeUint(uint64(length))
|
381 |
|
|
for i := 0; i < length; i++ {
|
382 |
|
|
elemp := p
|
383 |
|
|
up := unsafe.Pointer(elemp)
|
384 |
|
|
if elemIndir > 0 {
|
385 |
|
|
if up = encIndirect(up, elemIndir); up == nil {
|
386 |
|
|
errorf("encodeArray: nil element")
|
387 |
|
|
}
|
388 |
|
|
elemp = uintptr(up)
|
389 |
|
|
}
|
390 |
|
|
op(nil, state, unsafe.Pointer(elemp))
|
391 |
|
|
p += uintptr(elemWid)
|
392 |
|
|
}
|
393 |
|
|
enc.freeEncoderState(state)
|
394 |
|
|
}
|
395 |
|
|
|
396 |
|
|
// encodeReflectValue is a helper for maps. It encodes the value v.
|
397 |
|
|
func encodeReflectValue(state *encoderState, v reflect.Value, op encOp, indir int) {
|
398 |
|
|
for i := 0; i < indir && v.IsValid(); i++ {
|
399 |
|
|
v = reflect.Indirect(v)
|
400 |
|
|
}
|
401 |
|
|
if !v.IsValid() {
|
402 |
|
|
errorf("encodeReflectValue: nil element")
|
403 |
|
|
}
|
404 |
|
|
op(nil, state, unsafe.Pointer(unsafeAddr(v)))
|
405 |
|
|
}
|
406 |
|
|
|
407 |
|
|
// encodeMap encodes a map as unsigned count followed by key:value pairs.
|
408 |
|
|
// Because map internals are not exposed, we must use reflection rather than
|
409 |
|
|
// addresses.
|
410 |
|
|
func (enc *Encoder) encodeMap(b *bytes.Buffer, mv reflect.Value, keyOp, elemOp encOp, keyIndir, elemIndir int) {
|
411 |
|
|
state := enc.newEncoderState(b)
|
412 |
|
|
state.fieldnum = -1
|
413 |
|
|
state.sendZero = true
|
414 |
|
|
keys := mv.MapKeys()
|
415 |
|
|
state.encodeUint(uint64(len(keys)))
|
416 |
|
|
for _, key := range keys {
|
417 |
|
|
encodeReflectValue(state, key, keyOp, keyIndir)
|
418 |
|
|
encodeReflectValue(state, mv.MapIndex(key), elemOp, elemIndir)
|
419 |
|
|
}
|
420 |
|
|
enc.freeEncoderState(state)
|
421 |
|
|
}
|
422 |
|
|
|
423 |
|
|
// encodeInterface encodes the interface value iv.
|
424 |
|
|
// To send an interface, we send a string identifying the concrete type, followed
|
425 |
|
|
// by the type identifier (which might require defining that type right now), followed
|
426 |
|
|
// by the concrete value. A nil value gets sent as the empty string for the name,
|
427 |
|
|
// followed by no value.
|
428 |
|
|
func (enc *Encoder) encodeInterface(b *bytes.Buffer, iv reflect.Value) {
|
429 |
|
|
state := enc.newEncoderState(b)
|
430 |
|
|
state.fieldnum = -1
|
431 |
|
|
state.sendZero = true
|
432 |
|
|
if iv.IsNil() {
|
433 |
|
|
state.encodeUint(0)
|
434 |
|
|
return
|
435 |
|
|
}
|
436 |
|
|
|
437 |
|
|
ut := userType(iv.Elem().Type())
|
438 |
|
|
name, ok := concreteTypeToName[ut.base]
|
439 |
|
|
if !ok {
|
440 |
|
|
errorf("type not registered for interface: %s", ut.base)
|
441 |
|
|
}
|
442 |
|
|
// Send the name.
|
443 |
|
|
state.encodeUint(uint64(len(name)))
|
444 |
|
|
_, err := state.b.WriteString(name)
|
445 |
|
|
if err != nil {
|
446 |
|
|
error_(err)
|
447 |
|
|
}
|
448 |
|
|
// Define the type id if necessary.
|
449 |
|
|
enc.sendTypeDescriptor(enc.writer(), state, ut)
|
450 |
|
|
// Send the type id.
|
451 |
|
|
enc.sendTypeId(state, ut)
|
452 |
|
|
// Encode the value into a new buffer. Any nested type definitions
|
453 |
|
|
// should be written to b, before the encoded value.
|
454 |
|
|
enc.pushWriter(b)
|
455 |
|
|
data := new(bytes.Buffer)
|
456 |
|
|
data.Write(spaceForLength)
|
457 |
|
|
enc.encode(data, iv.Elem(), ut)
|
458 |
|
|
if enc.err != nil {
|
459 |
|
|
error_(enc.err)
|
460 |
|
|
}
|
461 |
|
|
enc.popWriter()
|
462 |
|
|
enc.writeMessage(b, data)
|
463 |
|
|
if enc.err != nil {
|
464 |
|
|
error_(err)
|
465 |
|
|
}
|
466 |
|
|
enc.freeEncoderState(state)
|
467 |
|
|
}
|
468 |
|
|
|
469 |
|
|
// isZero returns whether the value is the zero of its type.
|
470 |
|
|
func isZero(val reflect.Value) bool {
|
471 |
|
|
switch val.Kind() {
|
472 |
|
|
case reflect.Array:
|
473 |
|
|
for i := 0; i < val.Len(); i++ {
|
474 |
|
|
if !isZero(val.Index(i)) {
|
475 |
|
|
return false
|
476 |
|
|
}
|
477 |
|
|
}
|
478 |
|
|
return true
|
479 |
|
|
case reflect.Map, reflect.Slice, reflect.String:
|
480 |
|
|
return val.Len() == 0
|
481 |
|
|
case reflect.Bool:
|
482 |
|
|
return !val.Bool()
|
483 |
|
|
case reflect.Complex64, reflect.Complex128:
|
484 |
|
|
return val.Complex() == 0
|
485 |
|
|
case reflect.Chan, reflect.Func, reflect.Ptr:
|
486 |
|
|
return val.IsNil()
|
487 |
|
|
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
|
488 |
|
|
return val.Int() == 0
|
489 |
|
|
case reflect.Float32, reflect.Float64:
|
490 |
|
|
return val.Float() == 0
|
491 |
|
|
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
|
492 |
|
|
return val.Uint() == 0
|
493 |
|
|
case reflect.Struct:
|
494 |
|
|
for i := 0; i < val.NumField(); i++ {
|
495 |
|
|
if !isZero(val.Field(i)) {
|
496 |
|
|
return false
|
497 |
|
|
}
|
498 |
|
|
}
|
499 |
|
|
return true
|
500 |
|
|
}
|
501 |
|
|
panic("unknown type in isZero " + val.Type().String())
|
502 |
|
|
}
|
503 |
|
|
|
504 |
|
|
// encGobEncoder encodes a value that implements the GobEncoder interface.
|
505 |
|
|
// The data is sent as a byte array.
|
506 |
|
|
func (enc *Encoder) encodeGobEncoder(b *bytes.Buffer, v reflect.Value) {
|
507 |
|
|
// TODO: should we catch panics from the called method?
|
508 |
|
|
// We know it's a GobEncoder, so just call the method directly.
|
509 |
|
|
data, err := v.Interface().(GobEncoder).GobEncode()
|
510 |
|
|
if err != nil {
|
511 |
|
|
error_(err)
|
512 |
|
|
}
|
513 |
|
|
state := enc.newEncoderState(b)
|
514 |
|
|
state.fieldnum = -1
|
515 |
|
|
state.encodeUint(uint64(len(data)))
|
516 |
|
|
state.b.Write(data)
|
517 |
|
|
enc.freeEncoderState(state)
|
518 |
|
|
}
|
519 |
|
|
|
520 |
|
|
var encOpTable = [...]encOp{
|
521 |
|
|
reflect.Bool: encBool,
|
522 |
|
|
reflect.Int: encInt,
|
523 |
|
|
reflect.Int8: encInt8,
|
524 |
|
|
reflect.Int16: encInt16,
|
525 |
|
|
reflect.Int32: encInt32,
|
526 |
|
|
reflect.Int64: encInt64,
|
527 |
|
|
reflect.Uint: encUint,
|
528 |
|
|
reflect.Uint8: encUint8,
|
529 |
|
|
reflect.Uint16: encUint16,
|
530 |
|
|
reflect.Uint32: encUint32,
|
531 |
|
|
reflect.Uint64: encUint64,
|
532 |
|
|
reflect.Uintptr: encUintptr,
|
533 |
|
|
reflect.Float32: encFloat32,
|
534 |
|
|
reflect.Float64: encFloat64,
|
535 |
|
|
reflect.Complex64: encComplex64,
|
536 |
|
|
reflect.Complex128: encComplex128,
|
537 |
|
|
reflect.String: encString,
|
538 |
|
|
}
|
539 |
|
|
|
540 |
|
|
// encOpFor returns (a pointer to) the encoding op for the base type under rt and
|
541 |
|
|
// the indirection count to reach it.
|
542 |
|
|
func (enc *Encoder) encOpFor(rt reflect.Type, inProgress map[reflect.Type]*encOp) (*encOp, int) {
|
543 |
|
|
ut := userType(rt)
|
544 |
|
|
// If the type implements GobEncoder, we handle it without further processing.
|
545 |
|
|
if ut.isGobEncoder {
|
546 |
|
|
return enc.gobEncodeOpFor(ut)
|
547 |
|
|
}
|
548 |
|
|
// If this type is already in progress, it's a recursive type (e.g. map[string]*T).
|
549 |
|
|
// Return the pointer to the op we're already building.
|
550 |
|
|
if opPtr := inProgress[rt]; opPtr != nil {
|
551 |
|
|
return opPtr, ut.indir
|
552 |
|
|
}
|
553 |
|
|
typ := ut.base
|
554 |
|
|
indir := ut.indir
|
555 |
|
|
k := typ.Kind()
|
556 |
|
|
var op encOp
|
557 |
|
|
if int(k) < len(encOpTable) {
|
558 |
|
|
op = encOpTable[k]
|
559 |
|
|
}
|
560 |
|
|
if op == nil {
|
561 |
|
|
inProgress[rt] = &op
|
562 |
|
|
// Special cases
|
563 |
|
|
switch t := typ; t.Kind() {
|
564 |
|
|
case reflect.Slice:
|
565 |
|
|
if t.Elem().Kind() == reflect.Uint8 {
|
566 |
|
|
op = encUint8Array
|
567 |
|
|
break
|
568 |
|
|
}
|
569 |
|
|
// Slices have a header; we decode it to find the underlying array.
|
570 |
|
|
elemOp, indir := enc.encOpFor(t.Elem(), inProgress)
|
571 |
|
|
op = func(i *encInstr, state *encoderState, p unsafe.Pointer) {
|
572 |
|
|
slice := (*reflect.SliceHeader)(p)
|
573 |
|
|
if !state.sendZero && slice.Len == 0 {
|
574 |
|
|
return
|
575 |
|
|
}
|
576 |
|
|
state.update(i)
|
577 |
|
|
state.enc.encodeArray(state.b, slice.Data, *elemOp, t.Elem().Size(), indir, int(slice.Len))
|
578 |
|
|
}
|
579 |
|
|
case reflect.Array:
|
580 |
|
|
// True arrays have size in the type.
|
581 |
|
|
elemOp, indir := enc.encOpFor(t.Elem(), inProgress)
|
582 |
|
|
op = func(i *encInstr, state *encoderState, p unsafe.Pointer) {
|
583 |
|
|
state.update(i)
|
584 |
|
|
state.enc.encodeArray(state.b, uintptr(p), *elemOp, t.Elem().Size(), indir, t.Len())
|
585 |
|
|
}
|
586 |
|
|
case reflect.Map:
|
587 |
|
|
keyOp, keyIndir := enc.encOpFor(t.Key(), inProgress)
|
588 |
|
|
elemOp, elemIndir := enc.encOpFor(t.Elem(), inProgress)
|
589 |
|
|
op = func(i *encInstr, state *encoderState, p unsafe.Pointer) {
|
590 |
|
|
// Maps cannot be accessed by moving addresses around the way
|
591 |
|
|
// that slices etc. can. We must recover a full reflection value for
|
592 |
|
|
// the iteration.
|
593 |
|
|
v := reflect.ValueOf(unsafe.Unreflect(t, unsafe.Pointer(p)))
|
594 |
|
|
mv := reflect.Indirect(v)
|
595 |
|
|
// We send zero-length (but non-nil) maps because the
|
596 |
|
|
// receiver might want to use the map. (Maps don't use append.)
|
597 |
|
|
if !state.sendZero && mv.IsNil() {
|
598 |
|
|
return
|
599 |
|
|
}
|
600 |
|
|
state.update(i)
|
601 |
|
|
state.enc.encodeMap(state.b, mv, *keyOp, *elemOp, keyIndir, elemIndir)
|
602 |
|
|
}
|
603 |
|
|
case reflect.Struct:
|
604 |
|
|
// Generate a closure that calls out to the engine for the nested type.
|
605 |
|
|
enc.getEncEngine(userType(typ))
|
606 |
|
|
info := mustGetTypeInfo(typ)
|
607 |
|
|
op = func(i *encInstr, state *encoderState, p unsafe.Pointer) {
|
608 |
|
|
state.update(i)
|
609 |
|
|
// indirect through info to delay evaluation for recursive structs
|
610 |
|
|
state.enc.encodeStruct(state.b, info.encoder, uintptr(p))
|
611 |
|
|
}
|
612 |
|
|
case reflect.Interface:
|
613 |
|
|
op = func(i *encInstr, state *encoderState, p unsafe.Pointer) {
|
614 |
|
|
// Interfaces transmit the name and contents of the concrete
|
615 |
|
|
// value they contain.
|
616 |
|
|
v := reflect.ValueOf(unsafe.Unreflect(t, unsafe.Pointer(p)))
|
617 |
|
|
iv := reflect.Indirect(v)
|
618 |
|
|
if !state.sendZero && (!iv.IsValid() || iv.IsNil()) {
|
619 |
|
|
return
|
620 |
|
|
}
|
621 |
|
|
state.update(i)
|
622 |
|
|
state.enc.encodeInterface(state.b, iv)
|
623 |
|
|
}
|
624 |
|
|
}
|
625 |
|
|
}
|
626 |
|
|
if op == nil {
|
627 |
|
|
errorf("can't happen: encode type %s", rt)
|
628 |
|
|
}
|
629 |
|
|
return &op, indir
|
630 |
|
|
}
|
631 |
|
|
|
632 |
|
|
// gobEncodeOpFor returns the op for a type that is known to implement
|
633 |
|
|
// GobEncoder.
|
634 |
|
|
func (enc *Encoder) gobEncodeOpFor(ut *userTypeInfo) (*encOp, int) {
|
635 |
|
|
rt := ut.user
|
636 |
|
|
if ut.encIndir == -1 {
|
637 |
|
|
rt = reflect.PtrTo(rt)
|
638 |
|
|
} else if ut.encIndir > 0 {
|
639 |
|
|
for i := int8(0); i < ut.encIndir; i++ {
|
640 |
|
|
rt = rt.Elem()
|
641 |
|
|
}
|
642 |
|
|
}
|
643 |
|
|
var op encOp
|
644 |
|
|
op = func(i *encInstr, state *encoderState, p unsafe.Pointer) {
|
645 |
|
|
var v reflect.Value
|
646 |
|
|
if ut.encIndir == -1 {
|
647 |
|
|
// Need to climb up one level to turn value into pointer.
|
648 |
|
|
v = reflect.ValueOf(unsafe.Unreflect(rt, unsafe.Pointer(&p)))
|
649 |
|
|
} else {
|
650 |
|
|
v = reflect.ValueOf(unsafe.Unreflect(rt, p))
|
651 |
|
|
}
|
652 |
|
|
if !state.sendZero && isZero(v) {
|
653 |
|
|
return
|
654 |
|
|
}
|
655 |
|
|
state.update(i)
|
656 |
|
|
state.enc.encodeGobEncoder(state.b, v)
|
657 |
|
|
}
|
658 |
|
|
return &op, int(ut.encIndir) // encIndir: op will get called with p == address of receiver.
|
659 |
|
|
}
|
660 |
|
|
|
661 |
|
|
// compileEnc returns the engine to compile the type.
|
662 |
|
|
func (enc *Encoder) compileEnc(ut *userTypeInfo) *encEngine {
|
663 |
|
|
srt := ut.base
|
664 |
|
|
engine := new(encEngine)
|
665 |
|
|
seen := make(map[reflect.Type]*encOp)
|
666 |
|
|
rt := ut.base
|
667 |
|
|
if ut.isGobEncoder {
|
668 |
|
|
rt = ut.user
|
669 |
|
|
}
|
670 |
|
|
if !ut.isGobEncoder &&
|
671 |
|
|
srt.Kind() == reflect.Struct {
|
672 |
|
|
for fieldNum, wireFieldNum := 0, 0; fieldNum < srt.NumField(); fieldNum++ {
|
673 |
|
|
f := srt.Field(fieldNum)
|
674 |
|
|
if !isExported(f.Name) {
|
675 |
|
|
continue
|
676 |
|
|
}
|
677 |
|
|
op, indir := enc.encOpFor(f.Type, seen)
|
678 |
|
|
engine.instr = append(engine.instr, encInstr{*op, wireFieldNum, indir, uintptr(f.Offset)})
|
679 |
|
|
wireFieldNum++
|
680 |
|
|
}
|
681 |
|
|
if srt.NumField() > 0 && len(engine.instr) == 0 {
|
682 |
|
|
errorf("type %s has no exported fields", rt)
|
683 |
|
|
}
|
684 |
|
|
engine.instr = append(engine.instr, encInstr{encStructTerminator, 0, 0, 0})
|
685 |
|
|
} else {
|
686 |
|
|
engine.instr = make([]encInstr, 1)
|
687 |
|
|
op, indir := enc.encOpFor(rt, seen)
|
688 |
|
|
engine.instr[0] = encInstr{*op, singletonField, indir, 0} // offset is zero
|
689 |
|
|
}
|
690 |
|
|
return engine
|
691 |
|
|
}
|
692 |
|
|
|
693 |
|
|
// getEncEngine returns the engine to compile the type.
|
694 |
|
|
// typeLock must be held (or we're in initialization and guaranteed single-threaded).
|
695 |
|
|
func (enc *Encoder) getEncEngine(ut *userTypeInfo) *encEngine {
|
696 |
|
|
info, err1 := getTypeInfo(ut)
|
697 |
|
|
if err1 != nil {
|
698 |
|
|
error_(err1)
|
699 |
|
|
}
|
700 |
|
|
if info.encoder == nil {
|
701 |
|
|
// mark this engine as underway before compiling to handle recursive types.
|
702 |
|
|
info.encoder = new(encEngine)
|
703 |
|
|
info.encoder = enc.compileEnc(ut)
|
704 |
|
|
}
|
705 |
|
|
return info.encoder
|
706 |
|
|
}
|
707 |
|
|
|
708 |
|
|
// lockAndGetEncEngine is a function that locks and compiles.
|
709 |
|
|
// This lets us hold the lock only while compiling, not when encoding.
|
710 |
|
|
func (enc *Encoder) lockAndGetEncEngine(ut *userTypeInfo) *encEngine {
|
711 |
|
|
typeLock.Lock()
|
712 |
|
|
defer typeLock.Unlock()
|
713 |
|
|
return enc.getEncEngine(ut)
|
714 |
|
|
}
|
715 |
|
|
|
716 |
|
|
func (enc *Encoder) encode(b *bytes.Buffer, value reflect.Value, ut *userTypeInfo) {
|
717 |
|
|
defer catchError(&enc.err)
|
718 |
|
|
engine := enc.lockAndGetEncEngine(ut)
|
719 |
|
|
indir := ut.indir
|
720 |
|
|
if ut.isGobEncoder {
|
721 |
|
|
indir = int(ut.encIndir)
|
722 |
|
|
}
|
723 |
|
|
for i := 0; i < indir; i++ {
|
724 |
|
|
value = reflect.Indirect(value)
|
725 |
|
|
}
|
726 |
|
|
if !ut.isGobEncoder && value.Type().Kind() == reflect.Struct {
|
727 |
|
|
enc.encodeStruct(b, engine, unsafeAddr(value))
|
728 |
|
|
} else {
|
729 |
|
|
enc.encodeSingle(b, engine, unsafeAddr(value))
|
730 |
|
|
}
|
731 |
|
|
}
|