Go record parsing example

gotest.go

package main

import (
	"bufio"
	"fmt"
	"io"
	"log"
	"os"
	"strings"
	"time"
)

type Record struct {
	Words []string
}

func NewRecord() *Record {
	return &Record{Words: make([]string, 0)}
}

func ParseRecord(s string) *Record {
	// return NewRecord()
	return &Record{Words: strings.Fields(s)}
}

type Table struct {
	Records []*Record
}

func NewTable() *Table {
	return &Table{Records: make([]*Record, 0)}
}

func ParseTable(r io.Reader) (*Table, error) {
	tbl := NewTable()

	//needed to deal with  large lines
	const maxCapacity = 512 * 1024
	buf := make([]byte, maxCapacity)
	scanner := bufio.NewScanner(r)
	scanner.Buffer(buf, maxCapacity)

	for scanner.Scan() {
		line := scanner.Text()
		rec := ParseRecord(line)
		tbl.Records = append(tbl.Records, rec)
	}

	err := scanner.Err()
	return tbl, err

}

func main() {
	var f io.Reader

	if len(os.Args) < 2 {
		log.Fatalln("Must specify file argument")
	}
	fname := os.Args[1]
	f, err := os.Open(fname)
	if err != nil {
		log.Fatalln("problem opening file")
	}

	t0 := time.Now()
	tbl, err := ParseTable(f)
	if err != nil {
		log.Panicln(err)
	}
	t1 := time.Now()

	fmt.Printf("Time elapsed to parse records: %v\n", t1.Sub(t0))
	fmt.Printf("Number of records: %d \n", len(tbl.Records))
}