massive: move a lot of things

25-functions-and-pointers/08-log-parser-pointers/log.txt

@@ -0,0 +1,6 @@
+learngoprogramming.com 10
+learngoprogramming.com 10
+golang.org 4
+golang.org 6
+blog.golang.org 20
+blog.golang.org 10

25-functions-and-pointers/08-log-parser-pointers/log_err_missing.txt

@@ -0,0 +1,6 @@
+learngoprogramming.com 10
+learngoprogramming.com 10
+golang.org
+golang.org 6
+blog.golang.org 20
+blog.golang.org 10

25-functions-and-pointers/08-log-parser-pointers/log_err_negative.txt

@@ -0,0 +1,6 @@
+learngoprogramming.com 10
+learngoprogramming.com 10
+golang.org -100
+golang.org 6
+blog.golang.org 20
+blog.golang.org 10

25-functions-and-pointers/08-log-parser-pointers/log_err_str.txt

@@ -0,0 +1,6 @@
+learngoprogramming.com 10
+learngoprogramming.com 10
+golang.org FOUR
+golang.org 6
+blog.golang.org 20
+blog.golang.org 10

25-functions-and-pointers/08-log-parser-pointers/main.go

@@ -0,0 +1,36 @@
+// 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"
+)
+
+func main() {
+	in := bufio.NewScanner(os.Stdin)
+
+	p := newParser()
+
+	for in.Scan() {
+		add(p, in.Text())
+	}
+
+	for _, name := range p.domains {
+		// vis := p.sum[d.name]
+		d := p.sum[name]
+
+		fmt.Printf("%-25s -> %d\n", d.name, d.visits)
+	}
+	fmt.Printf("\n%-25s -> %d\n", "TOTAL", p.total)
+
+	if p.lerr != nil {
+		fmt.Printf("> Err: %s\n", p.lerr)
+	}
+}

25-functions-and-pointers/08-log-parser-pointers/parser.go

@@ -0,0 +1,99 @@
+package main
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+// TODO: add add() func
+// TODO: add error handling (variadics)
+// TODO: add iterator func values
+// TODO: add summarizer to main()
+
+// domain represents a single domain log record
+type domain struct {
+	name   string
+	visits int
+}
+
+// parser parses a log file and provides an iterator to iterate upon the domains
+//
+// the parser struct is carefully crafted to be usable using its zero values except the map field
+type parser struct {
+	// sum     map[string]int // visits per unique domain
+	// domains []domain       // unique domain names
+	sum     map[string]domain // visits per unique domain
+	domains []string          // unique domain names
+
+	total int   // total visits to all domains
+	lines int   // number of parsed lines (for the error messages)
+	lerr  error // saves the last error occurred
+}
+
+// newParser creates and returns a new parser.
+func newParser() *parser {
+	// return &parser{sum: make(map[string]int)}
+	return &parser{sum: make(map[string]domain)}
+}
+
+// add parses the given line and saves the result to the internal list of
+// domains. it doesn't add the record when the parsing fails.
+func add(p *parser, line string) {
+	// if there was a previous error do not add
+	if p.lerr != nil {
+		return
+	}
+
+	dom, err := parse(p, line)
+
+	// store only the last error
+	if err != nil {
+		p.lerr = err
+		return
+	}
+
+	push(p, dom)
+}
+
+// parse parses the given text and returns a domain struct
+func parse(p *parser, line string) (dom domain, err error) {
+	p.lines++
+
+	fields := strings.Fields(line)
+	if len(fields) != 2 {
+		err = fmt.Errorf("wrong input: %v (line #%d)", fields, p.lines)
+		return
+	}
+
+	dom.name = fields[0]
+
+	dom.visits, err = strconv.Atoi(fields[1])
+	if dom.visits < 0 || err != nil {
+		err = fmt.Errorf("wrong input: %q (line #%d)", fields[1], p.lines)
+	}
+
+	return
+}
+
+// push pushes the given domain to the internal list of domains.
+// it also increases the total visits for all the domains.
+func push(p *parser, d domain) {
+	// TODO:
+	// if _, ok := p.sum[d.name]; !ok {
+	// 	p.domains = append(p.domains, d)
+	// }
+
+	// p.sum[d.name] += d.visits
+	// p.total += d.visits
+	name := d.name
+
+	// collect the unique domains
+	if _, ok := p.sum[name]; !ok {
+		p.domains = append(p.domains, name)
+	}
+
+	p.total += d.visits
+	d.visits += p.sum[name].visits
+	p.sum[name] = d
+}