CSV/TSV データの読み書き

//CsvTable is CSV/TSV table class
type CsvTable struct {
    header []string
    col    map[string]int
    body   [][]string
}

//New returns new CsvTable instance
func New(r *csv.Reader) (*CsvTable, error) {
    ct := &CsvTable{}
    err := ct.readAll(r)
    return ct, err
}

func (ct *CsvTable) readAll(r *csv.Reader) error {
    if ct == nil {
        ct = &CsvTable{}
    }
    ct.col = map[string]int{}

    dt, err := r.ReadAll()
    if err != nil {
        return err
    }
    l := len(dt)
    if l > 0 {
        ct.header = dt[0]
        for i, e := range ct.header {
            ct.col[e] = i
        }

        if l > 1 {
            ct.body = dt[1:]
        }
    }
    return nil
}

package main

import (
    "encoding/csv"
    "flag"
    "fmt"
    "io"
    "os"
    "strings"

    "github.com/spiegel-im-spiegel/csvtable"
)

func main() {
    flag.Parse()
    if flag.NArg() > 1 {
        fmt.Fprintln(os.Stderr, os.ErrInvalid)
        return
    }
    var r io.Reader
    if flag.NArg() == 0 {
        r = os.Stdin
    } else {
        f, err := os.Open(flag.Arg(0)) //maybe file path
        if err != nil {
            fmt.Fprintln(os.Stderr, err)
            return
        }
        defer f.Close()
        r = f
    }

    cr := csv.NewReader(r)
    cr.Comma = '\t'
    cr.LazyQuotes = true       // a quote may appear in an unquoted field and a non-doubled quote may appear in a quoted field.
    cr.TrimLeadingSpace = true // leading white space in a field is ignored.

    ct, err := csvtable.New(cr)
    if err != nil {
        fmt.Fprintln(os.Stderr, err)
        return
    }
    //fmt.Println("cols :", ct.Cols())
    //fmt.Println("rows :", ct.Rows())
    w := csv.NewWriter(os.Stdout)
    w.Comma = cr.Comma
    //w.UseCRLF = true
    //header, body := ct.OutputAll()
    header, body := ct.Output(strings.Split("city/temperature", "/"))
    w.Write(header)
    w.WriteAll(body)
}