// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package pkgbits

import (
	
	
	
	
	
	
	
	
)

// A PkgEncoder provides methods for encoding a package's Unified IR
// export data.
type PkgEncoder struct {
	// version of the bitstream.
	version Version

	// elems holds the bitstream for previously encoded elements.
	elems [numRelocs][]string

	// stringsIdx maps previously encoded strings to their index within
	// the RelocString section, to allow deduplication. That is,
	// elems[RelocString][stringsIdx[s]] == s (if present).
	stringsIdx map[string]Index

	// syncFrames is the number of frames to write at each sync
	// marker. A negative value means sync markers are omitted.
	syncFrames int
}

// SyncMarkers reports whether pw uses sync markers.
func ( *PkgEncoder) () bool { return .syncFrames >= 0 }

// NewPkgEncoder returns an initialized PkgEncoder.
//
// syncFrames is the number of caller frames that should be serialized
// at Sync points. Serializing additional frames results in larger
// export data files, but can help diagnosing desync errors in
// higher-level Unified IR reader/writer code. If syncFrames is
// negative, then sync markers are omitted entirely.
func ( Version,  int) PkgEncoder {
	return PkgEncoder{
		version:    ,
		stringsIdx: make(map[string]Index),
		syncFrames: ,
	}
}

// DumpTo writes the package's encoded data to out0 and returns the
// package fingerprint.
func ( *PkgEncoder) ( io.Writer) ( [8]byte) {
	 := md5.New()
	 := io.MultiWriter(, )

	 := func( uint32) {
		assert(binary.Write(, binary.LittleEndian, ) == nil)
	}

	(uint32(.version))

	if .version.Has(Flags) {
		var  uint32
		if .SyncMarkers() {
			 |= flagSyncMarkers
		}
		()
	}

	// Write elemEndsEnds.
	var  uint32
	for ,  := range &.elems {
		 += uint32(len())
		()
	}

	// Write elemEnds.
	 = 0
	for ,  := range &.elems {
		for ,  := range  {
			 += uint32(len())
			()
		}
	}

	// Write elemData.
	for ,  := range &.elems {
		for ,  := range  {
			,  := io.WriteString(, )
			assert( == nil)
		}
	}

	// Write fingerprint.
	copy([:], .Sum(nil))
	,  := .Write([:])
	assert( == nil)

	return
}

// StringIdx adds a string value to the strings section, if not
// already present, and returns its index.
func ( *PkgEncoder) ( string) Index {
	if ,  := .stringsIdx[];  {
		assert(.elems[RelocString][] == )
		return 
	}

	 := Index(len(.elems[RelocString]))
	.elems[RelocString] = append(.elems[RelocString], )
	.stringsIdx[] = 
	return 
}

// NewEncoder returns an Encoder for a new element within the given
// section, and encodes the given SyncMarker as the start of the
// element bitstream.
func ( *PkgEncoder) ( RelocKind,  SyncMarker) Encoder {
	 := .NewEncoderRaw()
	.Sync()
	return 
}

// NewEncoderRaw returns an Encoder for a new element within the given
// section.
//
// Most callers should use NewEncoder instead.
func ( *PkgEncoder) ( RelocKind) Encoder {
	 := Index(len(.elems[]))
	.elems[] = append(.elems[], "") // placeholder

	return Encoder{
		p:   ,
		k:   ,
		Idx: ,
	}
}

// An Encoder provides methods for encoding an individual element's
// bitstream data.
type Encoder struct {
	p *PkgEncoder

	Relocs   []RelocEnt
	RelocMap map[RelocEnt]uint32
	Data     bytes.Buffer // accumulated element bitstream data

	encodingRelocHeader bool

	k   RelocKind
	Idx Index // index within relocation section
}

// Flush finalizes the element's bitstream and returns its Index.
func ( *Encoder) () Index {
	var  strings.Builder

	// Backup the data so we write the relocations at the front.
	var  bytes.Buffer
	io.Copy(&, &.Data)

	// TODO(mdempsky): Consider writing these out separately so they're
	// easier to strip, along with function bodies, so that we can prune
	// down to just the data that's relevant to go/types.
	if .encodingRelocHeader {
		panic("encodingRelocHeader already true; recursive flush?")
	}
	.encodingRelocHeader = true
	.Sync(SyncRelocs)
	.Len(len(.Relocs))
	for ,  := range .Relocs {
		.Sync(SyncReloc)
		.Len(int(.Kind))
		.Len(int(.Idx))
	}

	io.Copy(&, &.Data)
	io.Copy(&, &)
	.p.elems[.k][.Idx] = .String()

	return .Idx
}

func ( *Encoder) ( error) {
	if  != nil {
		panicf("unexpected encoding error: %v", )
	}
}

func ( *Encoder) ( uint64) {
	var  [binary.MaxVarintLen64]byte
	 := binary.PutUvarint([:], )
	,  := .Data.Write([:])
	.checkErr()
}

func ( *Encoder) ( int64) {
	// Zig-zag encode.
	 := uint64() << 1
	if  < 0 {
		 = ^
	}

	.rawUvarint()
}

func ( *Encoder) ( RelocKind,  Index) int {
	 := RelocEnt{, }
	if .RelocMap != nil {
		if ,  := .RelocMap[];  {
			return int()
		}
	} else {
		.RelocMap = make(map[RelocEnt]uint32)
	}

	 := len(.Relocs)
	.RelocMap[] = uint32()
	.Relocs = append(.Relocs, )
	return 
}

func ( *Encoder) ( SyncMarker) {
	if !.p.SyncMarkers() {
		return
	}

	// Writing out stack frame string references requires working
	// relocations, but writing out the relocations themselves involves
	// sync markers. To prevent infinite recursion, we simply trim the
	// stack frame for sync markers within the relocation header.
	var  []string
	if !.encodingRelocHeader && .p.syncFrames > 0 {
		 := make([]uintptr, .p.syncFrames)
		 := runtime.Callers(2, )
		 = fmtFrames([:]...)
	}

	// TODO(mdempsky): Save space by writing out stack frames as a
	// linked list so we can share common stack frames.
	.rawUvarint(uint64())
	.rawUvarint(uint64(len()))
	for ,  := range  {
		.rawUvarint(uint64(.rawReloc(RelocString, .p.StringIdx())))
	}
}

// Bool encodes and writes a bool value into the element bitstream,
// and then returns the bool value.
//
// For simple, 2-alternative encodings, the idiomatic way to call Bool
// is something like:
//
//	if w.Bool(x != 0) {
//		// alternative #1
//	} else {
//		// alternative #2
//	}
//
// For multi-alternative encodings, use Code instead.
func ( *Encoder) ( bool) bool {
	.Sync(SyncBool)
	var  byte
	if  {
		 = 1
	}
	 := .Data.WriteByte()
	.checkErr()
	return 
}

// Int64 encodes and writes an int64 value into the element bitstream.
func ( *Encoder) ( int64) {
	.Sync(SyncInt64)
	.rawVarint()
}

// Uint64 encodes and writes a uint64 value into the element bitstream.
func ( *Encoder) ( uint64) {
	.Sync(SyncUint64)
	.rawUvarint()
}

// Len encodes and writes a non-negative int value into the element bitstream.
func ( *Encoder) ( int) { assert( >= 0); .Uint64(uint64()) }

// Int encodes and writes an int value into the element bitstream.
func ( *Encoder) ( int) { .Int64(int64()) }

// Uint encodes and writes a uint value into the element bitstream.
func ( *Encoder) ( uint) { .Uint64(uint64()) }

// Reloc encodes and writes a relocation for the given (section,
// index) pair into the element bitstream.
//
// Note: Only the index is formally written into the element
// bitstream, so bitstream decoders must know from context which
// section an encoded relocation refers to.
func ( *Encoder) ( RelocKind,  Index) {
	.Sync(SyncUseReloc)
	.Len(.rawReloc(, ))
}

// Code encodes and writes a Code value into the element bitstream.
func ( *Encoder) ( Code) {
	.Sync(.Marker())
	.Len(.Value())
}

// String encodes and writes a string value into the element
// bitstream.
//
// Internally, strings are deduplicated by adding them to the strings
// section (if not already present), and then writing a relocation
// into the element bitstream.
func ( *Encoder) ( string) {
	.StringRef(.p.StringIdx())
}

// StringRef writes a reference to the given index, which must be a
// previously encoded string value.
func ( *Encoder) ( Index) {
	.Sync(SyncString)
	.Reloc(RelocString, )
}

// Strings encodes and writes a variable-length slice of strings into
// the element bitstream.
func ( *Encoder) ( []string) {
	.Len(len())
	for ,  := range  {
		.String()
	}
}

// Value encodes and writes a constant.Value into the element
// bitstream.
func ( *Encoder) ( constant.Value) {
	.Sync(SyncValue)
	if .Bool(.Kind() == constant.Complex) {
		.scalar(constant.Real())
		.scalar(constant.Imag())
	} else {
		.scalar()
	}
}

func ( *Encoder) ( constant.Value) {
	switch v := constant.Val().(type) {
	default:
		panicf("unhandled %v (%v)", , .Kind())
	case bool:
		.Code(ValBool)
		.Bool()
	case string:
		.Code(ValString)
		.String()
	case int64:
		.Code(ValInt64)
		.Int64()
	case *big.Int:
		.Code(ValBigInt)
		.bigInt()
	case *big.Rat:
		.Code(ValBigRat)
		.bigInt(.Num())
		.bigInt(.Denom())
	case *big.Float:
		.Code(ValBigFloat)
		.bigFloat()
	}
}

func ( *Encoder) ( *big.Int) {
	 := .Bytes()
	.String(string()) // TODO: More efficient encoding.
	.Bool(.Sign() < 0)
}

func ( *Encoder) ( *big.Float) {
	 := .Append(nil, 'p', -1)
	.String(string()) // TODO: More efficient encoding.
}

// Version reports the version of the bitstream.
func ( *Encoder) () Version { return .p.version }