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bpe.go
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bpe.go
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package bpe
import (
"bufio"
"encoding/json"
"errors"
"fmt"
"io/ioutil"
"os"
"path/filepath"
"regexp"
"sort"
// "strconv"
"log"
"strings"
"github.com/sugarme/tokenizer"
"github.com/sugarme/tokenizer/model"
"github.com/sugarme/tokenizer/util"
)
type Merges map[Pair]PairVal
type configFiles struct {
vocab string
merges string
}
type Config struct {
files *configFiles
vocab *model.Vocab
merges *Merges
cacheCapacity int
dropout *float32
unkToken *string
continuingSubwordPrefix *string
endOfWordSuffix *string
}
// BpeBuilder can be used to create a `BPE` model with
// a custom configuration
type BpeBuilder struct {
config Config
}
func NewBpeBuilder() *BpeBuilder {
var (
vocab model.Vocab = make(map[string]int)
merges Merges = make(map[Pair]PairVal)
)
return &BpeBuilder{
config: Config{
files: nil,
vocab: &vocab,
merges: &merges,
cacheCapacity: DefaultCacheCapacity,
dropout: nil,
unkToken: nil,
continuingSubwordPrefix: nil,
endOfWordSuffix: nil,
},
}
}
// Files sets input files for the model
func (bb *BpeBuilder) Files(vocab string, merges string) {
bb.config.files = &configFiles{vocab, merges}
}
// VocabAndMerges sets vocab and merges
func (bb *BpeBuilder) VocabAndMerges(vocab model.Vocab, merges Merges) {
bb.config.vocab = &vocab
bb.config.merges = &merges
}
// CacheCapacity sets the cache capacity. Disable cache by setting it to 0
func (bb *BpeBuilder) CacheCapacity(capacity int) {
bb.config.cacheCapacity = capacity
}
// Dropout set dropout for model
// Ref. https://arxiv.org/abs/1910.13267
func (bb *BpeBuilder) Dropout(dropout float32) {
bb.config.dropout = &dropout
}
// UnkToken set the `UNK` token for the vocab
func (bb *BpeBuilder) UnkToken(unkTok string) {
bb.config.unkToken = &unkTok
}
// ContinuingSubword set the `continuingSubwordPrefix` option.
func (bb *BpeBuilder) ContinuingSubwordPrefix(continuingSubwordPrefix string) {
bb.config.continuingSubwordPrefix = &continuingSubwordPrefix
}
// EndOfWordSuffix set the `endOfWordSuffix` option.
func (bb *BpeBuilder) EndOfWordSuffix(endOfWordSuffix string) {
bb.config.endOfWordSuffix = &endOfWordSuffix
}
// Build returns a `BPE` model that uses the BpeBuilder configuration
func (bb *BpeBuilder) Build() (*BPE, error) {
var (
err error
vocab *model.Vocab
merges *Merges
vocabR model.VocabR = make(map[int]string)
cache *Cache
bpe BPE
)
vocab = bb.config.vocab
merges = bb.config.merges
// validate dropout
if bb.config.dropout != nil {
var p float32
p = *bb.config.dropout
if p <= 0.0 || p > 1.0 {
err = errors.New("Error: Invalid dropout.")
return nil, err
}
}
// Read files if provided
if bb.config.files != nil {
vocab, merges, err = bpe.ReadFiles(bb.config.files.vocab, bb.config.files.merges)
if err != nil {
return nil, err
}
bb.config.vocab = vocab
bb.config.merges = merges
}
for k, v := range *vocab {
vocabR[v] = k
}
if bb.config.cacheCapacity != 0 {
cache = NewCache(bb.config.cacheCapacity)
} else {
cache = nil
}
bpe = BPE{
Vocab: vocab,
VocabR: &vocabR,
Merges: merges,
Cache: cache,
Dropout: bb.config.dropout,
UnkToken: bb.config.unkToken,
ContinuingSubwordPrefix: bb.config.continuingSubwordPrefix,
EndOfWordSuffix: bb.config.endOfWordSuffix,
}
return &bpe, nil
}
// BPE is a struct for byte pair encoding model
// Ref. https://www.aclweb.org/anthology/P16-1162/
type BPE struct {
// Vocab is the vocabulary assigns a number to each token.
Vocab *model.Vocab
// VocabR is Reversed vocabulary, to rebuild sentences.
VocabR *model.VocabR
// Merges contains the mapping between Pairs and their (rank, newId).
Merges *Merges
// Cache contains the cache for optimizing the encoding step.
// It is a `map[string]Word`
Cache *Cache
// Dropout probability for merges.
// 0 = no dropout is the default.
// At 1.0, tokenization will perform no merges, so the result will just be characters.
Dropout *float32
// UnkToken is the unknown token to be used when we encounter an unknown char
UnkToken *string
// ContinuingSubwordPrefix is an optional prefix
// to use on any subword that exist only behind another one
ContinuingSubwordPrefix *string
// EndOfWordSuffix is an optional suffix
// to caracterize and end-of-word subword
EndOfWordSuffix *string
}
func (b *BPE) builder() *BpeBuilder {
return NewBpeBuilder()
}
// new create a BPE with default values
func (b *BPE) new() {
var err error
b, err = b.builder().Build()
if err != nil {
log.Fatal(err)
}
}
// `Clone` can't be derive because it's not implemented for `Cache`.
// To keep things simple when we clone, the new BPE will start with a fresh cache.
func (b *BPE) clone() {
newBpe := b
newBpe.Cache.Fresh()
b = newBpe
}
// newBPE create a default BPE from sratch using its pbeBuilder
func newBPE() (*BPE, error) {
b := NewBpeBuilder()
return b.Build()
}
func DefaultBPE() (*BPE, error) {
return newBPE()
}
// NewBpeFromFiles create BPE model from vocab and merges files
func NewBpeFromFiles(vocab, merges string) (*BPE, error) {
b := NewBpeBuilder()
b.Files(vocab, merges)
return b.Build()
}
// NewBPE creates new BPE model with given vocab and merges
func NewBPE(vocab model.Vocab, merges Merges) *BPE {
b, err := newBPE()
if err != nil {
log.Fatal(err)
}
b.Vocab = &vocab
var vocabR model.VocabR = make(map[int]string)
for k, v := range vocab {
vocabR[v] = k
}
b.VocabR = &vocabR
b.Merges = &merges
return b
}
// FromFile creates `BpeBuilder` from vocab and merges files.
func (b *BPE) FromFiles(vocab string, merges string) *BpeBuilder {
builder := b.builder()
builder.Files(vocab, merges)
return builder
}
// ReadFiles read the given files to extract vocab and merges
func (b *BPE) ReadFiles(vocabF string, mergesF string) (*model.Vocab, *Merges, error) {
var err error
// read json file
vocabBytes, err := ioutil.ReadFile(vocabF)
if err != nil {
return nil, nil, err
}
var (
vocab model.Vocab
merges Merges = make(map[Pair]PairVal)
)
err = json.Unmarshal(vocabBytes, &vocab)
if err != nil {
return nil, nil, err
}
// Read merges file. Each line contains a Merges object(rank, )
// Recall: Merges is map[Pair]PairVal (rank int, newId int)
mFile, err := os.Open(mergesF)
if err != nil {
return nil, nil, err
}
defer mFile.Close()
s := bufio.NewScanner(mFile)
// `s.Scan()` advance scaning and return `false` if
// end of file or hit any error. The error will be
// access by s.Err. If error caused by EOF it's value is nil.
var lineNum = 0
for s.Scan() {
line := s.Text()
// Skip line with `#version`
re := regexp.MustCompile(`#version`)
if re.MatchString(line) {
continue
}
parts := strings.Split(line, " ")
if len(parts) != 2 {
err = fmt.Errorf("Read merge file error: invalid data at line %d\n", lineNum)
return nil, nil, err
}
a, ok := vocab[parts[0]]
if !ok {
// err = fmt.Errorf("Read merge file error: part a value for '%s' key not found.", parts[0])
continue
// return nil, nil, err
}
b, ok := vocab[parts[1]]
if !ok {
// err = fmt.Errorf("Read merge file error: part b value for '%s' key not found.", parts[1])
continue
// return nil, nil, err
}
pair := Pair{a, b}
// newToken := fmt.Sprintf("%v%v", parts[0], parts[1])
newToken := fmt.Sprintf("%v%v", parts[0], parts[1])
newId, ok := vocab[newToken]
if !ok {
err = fmt.Errorf("Read merge file error: key value for token: \"%s\" not found.", newToken)
return nil, nil, err
}
// newTokenInt, err := strconv.ParseInt(newToken, 10, 64)
err = util.TraceError(err)
if err != nil {
return nil, nil, err
}
pairVal := PairVal{lineNum, newId}
merges[pair] = pairVal
lineNum += 1
}
if s.Err() != nil {
return nil, nil, s.Err()
}
return &vocab, &merges, nil
}
// ClearCache reset the cache
func (b *BPE) ClearCache() {
if b.Cache != nil {
b.Cache.Clear()
}
}
// GetVocab returns BPE vocab
// func (b *BPE) GetVocab() *model.Vocab {
func (b BPE) GetVocab() map[string]int {
return *b.Vocab
}
// GetUnkToken returns `unk` token
func (b *BPE) GetUnkToken() *string {
return b.UnkToken
}
// GetContinuingSubwordPrefix returns continuing subword prefix
func (b *BPE) GetContinuingSubwordPrfix() *string {
return b.ContinuingSubwordPrefix
}
// MergeWord merges given word
func (b *BPE) MergeWord(w string) *Word {
word := NewWord()
var (
prefix, suffix string
)
if b.ContinuingSubwordPrefix != nil {
prefix = *b.ContinuingSubwordPrefix
} else {
prefix = ""
}
if b.EndOfWordSuffix != nil {
suffix = *b.EndOfWordSuffix
} else {
suffix = ""
}
chars := []rune(w)
currRuneIdx := 0
for byteIdx, r := range w {
var (
s string
byteLen int
)
byteLen = len(string(r))
// if first rune, add prefix
if byteIdx == 0 {
s = fmt.Sprintf("%v%v", prefix, string(r))
} else if currRuneIdx == len(chars) { // last rune, add suffix
s = fmt.Sprintf("%v%v", string(r), suffix)
} else { // the rest
s = string(r)
}
currRuneIdx++
// If `s` exists in vocab, add its id, otherwise add id of `unk`
vocab := *b.Vocab
if id, ok := vocab[s]; ok { // found
word.Add(id, byteLen)
} else { // not found, add `unk`
if b.UnkToken != nil {
// get `unk` id
unkId := (*b.Vocab)[*b.UnkToken]
// add `unk`
word.Add(unkId, byteLen)
} else {
fmt.Printf("cannot find '%s' in the vocab. \n", s)
panic("Can't find `unk` token in the vocab. Have you added one when initiating the model?")
}
}
}
if b.Dropout != nil {
word.MergeAll(*b.Merges, *b.Dropout)
} else {
word.MergeAll(*b.Merges)
}
return word
}
// WordToTokens slices word to tokens
func (b *BPE) WordToTokens(word Word) []tokenizer.Token {
var tokens []tokenizer.Token
chars := word.GetChars()
offsets := word.GetOffsets()
type zword struct { // zip id and offsets
Id int
Offsets []int
}
var zWord []zword
for i, char := range chars {
zWord = append(zWord, zword{
Id: char,
Offsets: offsets[i],
})
}
for _, z := range zWord {
tok := tokenizer.Token{
Id: z.Id,
Value: (*b.VocabR)[z.Id],
Offsets: z.Offsets,
}
tokens = append(tokens, tok)
}
return tokens
}
// Implement Model interface for BPE
// Model has the following methods:
// 1. Tokenize(sequence string) ([]Token, error)
// 2. TokenToId(token string) (id int, ok bool)
// 3. IdToToken(id int) (token string, ok bool)
// 4. GetVocab() map[string]int
// 5. GetVocabSize() int
// 6. Save(path string, prefixOpt ...string) error
// Tokenize tokenizes sentences into tokens
// NOTE: sentence is []PreToken struct{Value string, Offsets Offsets}
func (b BPE) Tokenize(sequence string) (retVal []tokenizer.Token, err error) {
if len(sequence) == 0 {
return []tokenizer.Token{}, nil
}
if b.Dropout == nil {
return b.TokenizeWithCache(sequence), nil
}
word := b.MergeWord(sequence)
return b.WordToTokens(*word), nil
}
func (b BPE) TokenizeWithCache(sequence string) (retVal []tokenizer.Token) {
if hit, ok := b.Cache.cmap[sequence]; ok {
return b.WordToTokens(hit)
} else {
word := b.MergeWord(sequence)
retVal = b.WordToTokens(*word)
if b.Cache != nil {
b.Cache.SetValues([]CacheItem{
{sequence, *word},
})
}
return retVal
}
}
func (b BPE) TokenToId(token string) (id int, ok bool) {
id, ok = (*b.Vocab)[token]
return id, ok
}
func (b BPE) IdToToken(id int) (token string, ok bool) {
token, ok = (*b.VocabR)[id]
return token, ok
}
func (b BPE) GetVocabSize() int {
return len(*b.Vocab)
}
func (b BPE) Save(dir string, nameOpt ...string) error {
var vfile string
var mfile string
var err error
if len(nameOpt) > 0 {
vfile = fmt.Sprintf("%v/%v-vocab.json", dir, nameOpt[0])
mfile = fmt.Sprintf("%v/%v-merges.txt", dir, nameOpt[0])
} else {
vfile = fmt.Sprintf("%v/vocab.json", dir)
mfile = fmt.Sprintf("%v/merges.txt", dir)
}
// make filepath
err = makeFilePath(vfile)
if err != nil {
return err
}
// Write vocab.json
var vocabData []byte
vocabData, err = json.Marshal(b.Vocab)
if err != nil {
return err
}
err = ioutil.WriteFile(vfile, vocabData, os.ModePerm)
if err != nil {
return err
}
// Write merges.txt
// each line is a pair separated by a space
var lines []string
type pairRank struct {
Pair Pair
Rank int
}
var pairRanks []pairRank
for pair, pairVal := range *b.Merges {
pairRanks = append(pairRanks, pairRank{
Pair: pair,
Rank: pairVal.Rank,
})
}
// sort pairRanks by `Rank` field in-place
sort.Slice(pairRanks, func(i, j int) bool {
return pairRanks[i].Rank < pairRanks[j].Rank
})
// Create lines of merges
for _, p := range pairRanks {
// line := fmt.Sprintf("%v %v", p.Pair.C1, p.Pair.C2)
c1, _ := b.IdToToken(p.Pair.C1)
c2, _ := b.IdToToken(p.Pair.C2)
line := fmt.Sprintf("%v %v", c1, c2)
lines = append(lines, line)
}
// write to file
file, err := os.Create(mfile)
if err != nil {
return err
}
defer file.Close()
w := bufio.NewWriter(file)
for _, line := range lines {
fmt.Fprintln(w, line)
}
return w.Flush()
}
func deleteWord(a []Word, i int) ([]Word, error) {
var err error
if i < 0 || i > len(a) {
err = errors.New("`i` index is out of bound.")
return nil, err
}
return append(a[:i], a[i+1:]...), nil
}
// makeFilePath creates a filePath. If dir not existing, create it
func makeFilePath(filename string) error {
var err error
dirName := filepath.Dir(filename)
if _, err = os.Stat(dirName); err != nil {
return err
}
return os.MkdirAll(dirName, os.ModePerm)
}