100 lines
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Go
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2019-04-26 21:32:20 +03:00
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
}