go-chart/file_util.go

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2016-10-21 21:44:44 +02:00
package chart
import (
"bufio"
"io"
"os"
exception "github.com/blendlabs/go-exception"
)
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 exception.Wrap(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 exception.Wrap(err)
}
return nil
}