68 lines
1.2 KiB
Go
68 lines
1.2 KiB
Go
// For more tutorials: https://blog.learngoprogramming.com
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//
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// Copyright © 2018 Inanc Gumus
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// Learn Go Programming Course
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// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
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//
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package main
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import (
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"bufio"
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"bytes"
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"fmt"
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"io"
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"strings"
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)
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func textReader(r io.Reader) inputFunc {
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return func() ([]result, error) {
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// first: count the lines, so the parseText can create
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// enough buffer.
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var buf bytes.Buffer
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lines, err := countLines(io.TeeReader(r, &buf))
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if err != nil {
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return nil, err
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}
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return parseText(bufio.NewScanner(&buf), lines)
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}
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}
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// TODO: custom error type for line information
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func parseText(in *bufio.Scanner, nlines int) ([]result, error) {
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res := make([]result, 0, nlines)
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for l := 1; in.Scan(); l++ {
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fields := strings.Fields(in.Text())
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r, err := parseFields(fields)
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if err != nil {
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return nil, fmt.Errorf("line %d: %v", l, err)
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}
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res = append(res, r)
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}
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return res, in.Err()
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}
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func countLines(r io.Reader) (int, error) {
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var (
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lines int
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buf = make([]byte, 1024<<4) // read via 16 KB blocks
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)
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for {
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n, err := r.Read(buf)
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lines += bytes.Count(buf[:n], []byte{'\n'})
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if err == io.EOF {
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return lines, nil
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}
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if err != nil {
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return lines, err
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}
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}
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}
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