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package xio
import (
"bufio"
"fmt"
"io"
"os"
"strings"
"sync"
)
type Encoder interface {
Encode(interface{}) error
}
type SafeEncoder struct {
sync.Mutex
enc Encoder
}
func NewSafeEncoder(enc Encoder) *SafeEncoder {
return &SafeEncoder{enc: enc}
}
func (s *SafeEncoder) Encode(v interface{}) error {
s.Lock()
defer s.Unlock()
return s.enc.Encode(v)
}
// SingleWriter makes any writer thread safe.
type SingleWriter struct {
sync.Mutex
w io.Writer
}
// NewSingleWriter returns an io.Writer that can be safely accessed by multiple
// goroutines.
func NewSingleWriter(w io.Writer) *SingleWriter {
return &SingleWriter{w: w}
}
// Write wraps the underlying writer and gives exclusive access.
func (w *SingleWriter) Write(p []byte) (n int, err error) {
w.Lock()
defer w.Unlock()
return w.w.Write(p)
}
// OpenTwo opens two files. The caller needs to check for a single error only.
func OpenTwo(f0, f1 string) (g0, g1 *os.File, err error) {
if g0, err = os.Open(f0); err != nil {
return nil, nil, err
}
if g1, err = os.Open(f1); err != nil {
return nil, nil, err
}
return g0, g1, nil
}
// TabsToMapFile turns two columns from a tabular file into a map.
func TabsToMapFile(filename, sep string, kCol, vCol int) (map[string]string, error) {
f, err := os.Open(filename)
if err != nil {
return nil, err
}
defer f.Close()
return TabsToMap(f, sep, kCol, vCol)
}
// TabsToMap read from a reader and turns values from kCol, vCol columns
// (1-indexed) into a map.
func TabsToMap(r io.Reader, sep string, kCol, vCol int) (map[string]string, error) {
var (
br = bufio.NewReader(r)
m = make(map[string]string)
line, k, v string
fields []string
err error
)
for {
line, err = br.ReadString('\n')
if err == io.EOF {
return m, nil
}
if err != nil {
return nil, err
}
fields = strings.Split(line, sep)
if len(fields) > kCol-1 && len(fields) > vCol-1 {
k = strings.TrimSpace(fields[kCol-1])
v = strings.TrimSpace(fields[vCol-1])
m[k] = v
} else {
return nil, fmt.Errorf("invalid line: %v (%v fields, %v, %v)", line, len(fields), kCol, vCol)
}
}
return m, nil
}
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