forked from gitea/gitea
102 lines
2.6 KiB
Go
102 lines
2.6 KiB
Go
// Copyright 2021 The Gitea Authors. All rights reserved.
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// Use of this source code is governed by a MIT-style
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// license that can be found in the LICENSE file.
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package csv
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import (
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"bytes"
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"encoding/csv"
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stdcsv "encoding/csv"
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"errors"
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"io"
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"regexp"
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"strings"
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"code.gitea.io/gitea/modules/translation"
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"code.gitea.io/gitea/modules/util"
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)
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var quoteRegexp = regexp.MustCompile(`["'][\s\S]+?["']`)
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// CreateReader creates a csv.Reader with the given delimiter.
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func CreateReader(input io.Reader, delimiter rune) *stdcsv.Reader {
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rd := stdcsv.NewReader(input)
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rd.Comma = delimiter
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rd.TrimLeadingSpace = true
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return rd
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}
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// CreateReaderAndGuessDelimiter tries to guess the field delimiter from the content and creates a csv.Reader.
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// Reads at most 10k bytes.
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func CreateReaderAndGuessDelimiter(rd io.Reader) (*stdcsv.Reader, error) {
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var data = make([]byte, 1e4)
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size, err := util.ReadAtMost(rd, data)
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if err != nil {
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return nil, err
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}
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return CreateReader(
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io.MultiReader(bytes.NewReader(data[:size]), rd),
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guessDelimiter(data[:size]),
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), nil
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}
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// guessDelimiter scores the input CSV data against delimiters, and returns the best match.
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func guessDelimiter(data []byte) rune {
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maxLines := 10
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text := quoteRegexp.ReplaceAllLiteralString(string(data), "")
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lines := strings.SplitN(text, "\n", maxLines+1)
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lines = lines[:util.Min(maxLines, len(lines))]
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delimiters := []rune{',', ';', '\t', '|', '@'}
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bestDelim := delimiters[0]
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bestScore := 0.0
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for _, delim := range delimiters {
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score := scoreDelimiter(lines, delim)
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if score > bestScore {
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bestScore = score
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bestDelim = delim
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}
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}
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return bestDelim
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}
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// scoreDelimiter uses a count & regularity metric to evaluate a delimiter against lines of CSV.
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func scoreDelimiter(lines []string, delim rune) float64 {
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countTotal := 0
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countLineMax := 0
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linesNotEqual := 0
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for _, line := range lines {
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if len(line) == 0 {
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continue
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}
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countLine := strings.Count(line, string(delim))
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countTotal += countLine
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if countLine != countLineMax {
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if countLineMax != 0 {
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linesNotEqual++
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}
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countLineMax = util.Max(countLine, countLineMax)
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}
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}
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return float64(countTotal) * (1 - float64(linesNotEqual)/float64(len(lines)))
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}
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// FormatError converts csv errors into readable messages.
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func FormatError(err error, locale translation.Locale) (string, error) {
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var perr *csv.ParseError
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if errors.As(err, &perr) {
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if perr.Err == csv.ErrFieldCount {
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return locale.Tr("repo.error.csv.invalid_field_count", perr.Line), nil
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}
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return locale.Tr("repo.error.csv.unexpected", perr.Line, perr.Column), nil
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}
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return "", err
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}
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