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string_numberer.go
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/
string_numberer.go
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// Copyright 2016 The Citar 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 model
import (
"bufio"
"bytes"
"encoding/gob"
"fmt"
"io"
"strings"
)
var _ gob.GobEncoder = &StringNumberer{}
var _ gob.GobDecoder = &StringNumberer{}
// A StringNumberer creates a bijection between (string-based) labels
// and numbers.
type StringNumberer struct {
labelNumbers map[string]uint
labels []string
}
// NewStringStringNumberer creates a new StringNumberer that is empty (it
// has no mappings yet).
func NewStringStringNumberer() *StringNumberer {
return &StringNumberer{make(map[string]uint), make([]string, 0)}
}
// Number returns the (unique) number for for a label (string).
func (l *StringNumberer) Number(label string) uint {
idx, ok := l.labelNumbers[label]
if !ok {
idx = uint(len(l.labelNumbers))
l.labelNumbers[label] = idx
l.labels = append(l.labels, label)
}
return idx
}
// Label returns the label (string) for a number.
func (l *StringNumberer) Label(number uint) string {
return l.labels[number]
}
// Size returns the number of labels known in the bijection.
func (l *StringNumberer) Size() int {
return len(l.labels)
}
// Read a label <-> number bijection from a Reader.
func (l *StringNumberer) Read(reader io.Reader) error {
var labels []string
bufReader := bufio.NewReader(reader)
eof := false
for !eof {
line, err := bufReader.ReadString('\n')
if err != nil {
if err != io.EOF {
return err
}
eof = true
}
line = strings.TrimSpace(line)
if line == "" {
continue
}
labels = append(labels, line)
}
numbers := make(map[string]uint)
for idx, label := range labels {
numbers[label] = uint(idx)
}
l.labels = labels
l.labelNumbers = numbers
return nil
}
// WriteStringStringNumberer writes the bijection in a StringNumberer to a file.
func (l *StringNumberer) WriteStringStringNumberer(writer io.Writer) error {
for _, s := range l.labels {
fmt.Fprintf(writer, "%s\n", s)
}
return nil
}
// GobDecode decodes a Model from a gob.
func (l *StringNumberer) GobDecode(data []byte) error {
var en encodedStringNumberer
buf := bytes.NewBuffer(data)
decoder := gob.NewDecoder(buf)
if err := decoder.Decode(&en); err != nil {
return err
}
l.labelNumbers = en.LabelNumbers
l.labels = en.Labels
return nil
}
// GobEncode encodes a StringNumberer as a gob.
func (l *StringNumberer) GobEncode() ([]byte, error) {
en := encodedStringNumberer{
LabelNumbers: l.labelNumbers,
Labels: l.labels,
}
var buf bytes.Buffer
encoder := gob.NewEncoder(&buf)
if err := encoder.Encode(en); err != nil {
return nil, err
}
return buf.Bytes(), nil
}
type encodedStringNumberer struct {
LabelNumbers map[string]uint
Labels []string
}