move: struct log parser into the structs folder

24-structs/05-project-log-parser-structs/main.go

@@ -0,0 +1,89 @@
+// For more tutorials: https://blog.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"
+	"os"
+	"sort"
+	"strconv"
+	"strings"
+)
+
+// visit stores metrics for a domain
+type visit struct {
+	domain string
+	count  int
+	// add more metrics if needed
+}
+
+// parser keep tracks of the parsing
+type parser struct {
+	sum     map[string]visit // metrics per domain
+	domains []string         // unique domain names
+	total   int              // total visits for all domains
+	lines   int              // number of parsed lines (for the error messages)
+}
+
+func main() {
+	p := parser{sum: make(map[string]visit)}
+
+	// Scan the standard-in line by line
+	in := bufio.NewScanner(os.Stdin)
+	for in.Scan() {
+		p.lines++
+
+		// Parse the fields
+		fields := strings.Fields(in.Text())
+		if len(fields) != 2 {
+			fmt.Printf("wrong input: %v (line #%d)\n", fields, p.lines)
+			return
+		}
+
+		// Sum the total visits per domain
+		visits, err := strconv.Atoi(fields[1])
+		if visits < 0 || err != nil {
+			fmt.Printf("wrong input: %q (line #%d)\n", fields[1], p.lines)
+			return
+		}
+
+		name := fields[0]
+
+		// Collect the unique domains
+		if _, ok := p.sum[name]; !ok {
+			p.domains = append(p.domains, name)
+		}
+
+		// Keep track of total and per domain visits
+		p.total += visits
+
+		// You cannot assign to composite values
+		// p.sum[name].count += visits
+
+		// create and assign a new copy of `visit`
+		p.sum[name] = visit{
+			domain: name,
+			count:  visits + p.sum[name].count,
+		}
+	}
+
+	// Print the visits per domain
+	sort.Strings(p.domains)
+
+	fmt.Printf("%-30s %10s\n", "DOMAIN", "VISITS")
+	fmt.Println(strings.Repeat("-", 45))
+
+	for _, name := range p.domains {
+		visits := p.sum[name]
+		fmt.Printf("%-30s %10d\n", name, visits.count)
+	}
+
+	// Print the total visits for all domains
+	fmt.Printf("\n%-30s %10d\n", "TOTAL", p.total)
+}