add: new interfaces

interfaces/refactor-notes/refactor-00/parser.go

@@ -0,0 +1,74 @@
+// 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 (
+	"fmt"
+)
+
+// parser keeps track of the parsing
+type parser struct {
+	sum     map[string]result // metrics per domain
+	domains []string          // unique domain names
+	lines   int               // number of parsed lines (for the error messages)
+	lerr    error             // the last error occurred
+
+	// totalVisits  int               // total visits for all domains
+	// totalUniques int               // total uniques for all domains
+}
+
+// newParser constructs, initializes and returns a new parser
+func newParser() *parser {
+	return &parser{sum: make(map[string]result)}
+}
+
+// parse a log line and return the result
+func parse(p *parser, line string) (r result) {
+	if p.lerr != nil {
+		return
+	}
+
+	p.lines++
+
+	r, err := parseResult(line)
+	if err != nil {
+		p.lerr = fmt.Errorf("line %d: %v", p.lines, err)
+	}
+
+	return r
+}
+
+// update the parsing results
+func update(p *parser, r result) {
+	if p.lerr != nil {
+		return
+	}
+
+	// Collect the unique domains
+	cur, ok := p.sum[r.domain]
+	if !ok {
+		p.domains = append(p.domains, r.domain)
+	}
+
+	// Keep track of total and per domain visits
+	// p.totalVisits += r.visits
+	// p.totalUniques += r.uniques
+
+	// create and assign a new copy of `visit`
+	// p.sum[r.domain] = result{
+	// 	domain:  r.domain,
+	// 	visits:  r.visits + cur.visits,
+	// 	uniques: r.uniques + cur.uniques,
+	// }
+	p.sum[r.domain] = addResult(r, cur)
+}
+
+// err returns the last error encountered
+func err(p *parser) error {
+	return p.lerr
+}