go-chart/file_util.go

51 lines
954 B
Go

package chart
import (
"bufio"
"io"
"os"
)
var (
// File contains file utility functions
File = fileUtil{}
)
type fileUtil struct{}
// ReadByLines reads a file and calls the handler for each line.
func (fu fileUtil) ReadByLines(filePath string, handler func(line string)) error {
if f, err := os.Open(filePath); err == nil {
defer f.Close()
scanner := bufio.NewScanner(f)
for scanner.Scan() {
line := scanner.Text()
handler(line)
}
} else {
return err
}
return nil
}
// ReadByChunks reads a file in `chunkSize` pieces, dispatched to the handler.
func (fu fileUtil) ReadByChunks(filePath string, chunkSize int, handler func(line []byte)) error {
if f, err := os.Open(filePath); err == nil {
defer f.Close()
chunk := make([]byte, chunkSize)
for {
readBytes, err := f.Read(chunk)
if err == io.EOF {
break
}
readData := chunk[:readBytes]
handler(readData)
}
} else {
return err
}
return nil
}