110 lines
2.6 KiB
Go
110 lines
2.6 KiB
Go
|
package main
|
||
|
|
|
||
|
|
import (
|
||
|
|
"fmt"
|
||
|
|
"strconv"
|
||
|
|
"strings"
|
||
|
|
)
|
||
|
|
|
||
|
|
// domain represents a 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
|
||
|
|
total int // total visits to all domains
|
||
|
|
lines int // number of parsed lines (for the error messages)
|
||
|
|
err error // saves the last error occurred
|
||
|
|
}
|
||
|
|
|
||
|
|
// newParser creates and returns a new parser.
|
||
|
|
func newParser() *parser {
|
||
|
|
return &parser{sum: make(map[string]int)}
|
||
|
|
}
|
||
|
|
|
||
|
|
// 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.err != nil {
|
||
|
|
return
|
||
|
|
}
|
||
|
|
|
||
|
|
dom, err := parse(p, line)
|
||
|
|
|
||
|
|
// store only the last error
|
||
|
|
if err != nil {
|
||
|
|
p.err = err
|
||
|
|
return
|
||
|
|
}
|
||
|
|
|
||
|
|
push(p, dom)
|
||
|
|
}
|
||
|
|
|
||
|
|
// iterator returns two functions for iterating over domains.
|
||
|
|
// next = returns true when there are more domains to iterate on.
|
||
|
|
// cur = returns the current domain
|
||
|
|
func iterator(p *parser) (next func() bool, cur func() domain) {
|
||
|
|
// remember the last received line
|
||
|
|
var last int
|
||
|
|
|
||
|
|
next = func() bool {
|
||
|
|
defer func() { last++ }()
|
||
|
|
return len(p.domains) > last
|
||
|
|
}
|
||
|
|
|
||
|
|
cur = func() domain {
|
||
|
|
d := p.domains[last-1]
|
||
|
|
vis := p.sum[d.name]
|
||
|
|
|
||
|
|
// return a copy so the caller cannot change it
|
||
|
|
return domain{name: d.name, visits: vis}
|
||
|
|
}
|
||
|
|
|
||
|
|
return
|
||
|
|
}
|
||
|
|
|
||
|
|
// error returns the last error occurred
|
||
|
|
func err(p *parser) error {
|
||
|
|
return p.err
|
||
|
|
}
|
||
|
|
|
||
|
|
// parse parses the given text and returns a domain struct
|
||
|
|
func parse(p *parser, line string) (dom domain, err error) {
|
||
|
|
p.lines++ // increase the parsed line counter (only write is here)
|
||
|
|
|
||
|
|
fields := strings.Fields(line)
|
||
|
|
if len(fields) != 2 {
|
||
|
|
err = fmt.Errorf("wrong input: %v (line #%d)", fields, p.lines)
|
||
|
|
return
|
||
|
|
}
|
||
|
|
|
||
|
|
name, visits := fields[0], fields[1]
|
||
|
|
|
||
|
|
n, err := strconv.Atoi(visits)
|
||
|
|
if n < 0 || err != nil {
|
||
|
|
err = fmt.Errorf("wrong input: %q (line #%d)", visits, p.lines)
|
||
|
|
return
|
||
|
|
}
|
||
|
|
|
||
|
|
return domain{name: name, visits: n}, nil
|
||
|
|
}
|
||
|
|
|
||
|
|
// 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) {
|
||
|
|
// collect the unique domains
|
||
|
|
if _, ok := p.sum[d.name]; !ok {
|
||
|
|
p.domains = append(p.domains, d)
|
||
|
|
}
|
||
|
|
|
||
|
|
p.sum[d.name] += d.visits
|
||
|
|
p.total += d.visits
|
||
|
|
}
|