reducer.go

package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
	"strings"
)

type Score struct {
	DomainScore int
	PageScore   int
	TokenScore  int
}

func addScore(score *Score, id string, val int) (*Score, bool) {
	switch id {
	case "tokens":
		score.TokenScore += val
	case "pages":
		score.PageScore += val
	case "score":
		score.DomainScore += val
	default:
		return score, false
	}
	return score, true
}

func main() {
	// Wrapping the unbuffered `os.Stdin` with a buffered
	// scanner gives us a convenient `Scan` method that
	// advances the scanner to the next token; which is
	// the next line in the default scanner.

	scanner := bufio.NewScanner(os.Stdin)
	results := make(map[string]*Score)

	for scanner.Scan() {
		// `Text` returns the current token, here the next line,
		// from the input.
		var err error
		var scoreInt int

		text := strings.Split(strings.TrimSpace(scanner.Text()), "\t")
		token, scoreStr := text[0], text[1]
		token = strings.Replace(token, `"`, "", -1)
		parts := strings.Split(token, ":")
		domain := parts[0]
		id := parts[1]

		if scoreInt, err = strconv.Atoi(scoreStr); err != nil {
			continue
		}

		if score, ok := results[domain]; ok {
			addScore(score, id, scoreInt)
		} else {
			score = &Score{}
			addScore(score, id, scoreInt)
			results[domain] = score
		}
	}

	fmt.Printf("domain\tscore\tpages\ttokens\n")
	for k, v := range results {
		fmt.Printf("%s\t%v\t%v\t%v\n", k, v.DomainScore, v.PageScore, v.TokenScore)
	}

	if err := scanner.Err(); err != nil {
		fmt.Fprintln(os.Stderr, "error:", err)
		os.Exit(1)
	}
}