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head.go
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head.go
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// Copyright © 2016 Wei Shen <shenwei356@gmail.com>
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package cmd
import (
"encoding/csv"
"fmt"
"runtime"
"github.com/shenwei356/xopen"
"github.com/spf13/cobra"
)
// headCmd represents the seq command
var headCmd = &cobra.Command{
Use: "head",
Short: "print first N records",
Long: `print first N records
`,
Run: func(cmd *cobra.Command, args []string) {
config := getConfigs(cmd)
files := getFileList(args)
runtime.GOMAXPROCS(config.NumCPUs)
number := getFlagPositiveInt(cmd, "number")
outfh, err := xopen.Wopen(config.OutFile)
checkError(err)
defer outfh.Close()
writer := csv.NewWriter(outfh)
if config.OutTabs || config.Tabs {
writer.Comma = '\t'
} else {
writer.Comma = config.OutDelimiter
}
for _, file := range files {
csvReader, err := newCSVReaderByConfig(config, file)
checkError(err)
csvReader.Run()
isHeaderLine := !config.NoHeaderRow
i := 0
printMetaLine := true
LOOP:
for chunk := range csvReader.Ch {
checkError(chunk.Err)
if printMetaLine && len(csvReader.Reader.MetaLine) > 0 {
outfh.WriteString(fmt.Sprintf("sep=%s\n", string(writer.Comma)))
printMetaLine = false
}
for _, record := range chunk.Data {
checkError(writer.Write(record))
if isHeaderLine {
isHeaderLine = false
} else {
i++
}
if number == i {
break LOOP
}
}
}
}
writer.Flush()
checkError(writer.Error())
},
}
func init() {
RootCmd.AddCommand(headCmd)
headCmd.Flags().IntP("number", "n", 10, "print first N records")
}