interfaces: refactor

interfaces/05-log-parser/oop/textparser.go

@@ -0,0 +1,86 @@
+// For more tutorials: https://bp.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"os"
+	"strconv"
+	"strings"
+)
+
+const fieldsLength = 4
+
+type textParser struct {
+	r      io.Reader
+	update func(r result)
+}
+
+func newTextParser(r io.Reader) *textParser {
+	return &textParser{
+		r:      r,
+		update: func(result) {},
+	}
+}
+
+func parseTextFile(path string) (*textParser, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		return nil, err
+	}
+
+	return newTextParser(f), nil
+}
+
+func (p *textParser) notify(f func(r result)) {
+	p.update = f
+}
+
+func (p *textParser) parse() error {
+	defer readClose(p.r)
+
+	var (
+		l  = 1
+		in = bufio.NewScanner(p.r)
+	)
+
+	for in.Scan() {
+		r, err := p.parseFields(in.Text())
+		if err != nil {
+			return fmt.Errorf("line %d: %v", l, err)
+		}
+
+		p.update(r)
+		l++
+	}
+
+	return in.Err()
+}
+
+func (p *textParser) parseFields(s string) (r result, err error) {
+	fields := strings.Fields(s)
+	if len(fields) != fieldsLength {
+		return r, fmt.Errorf("wrong number of fields %q", fields)
+	}
+
+	r.domain, r.page = fields[0], fields[1]
+
+	r.visits, err = strconv.Atoi(fields[2])
+	if err != nil || r.visits < 0 {
+		return r, fmt.Errorf("wrong input %q", fields[2])
+	}
+
+	r.uniques, err = strconv.Atoi(fields[3])
+	if err != nil || r.uniques < 0 {
+		return r, fmt.Errorf("wrong input %q", fields[3])
+	}
+
+	return r, nil
+}