forgejo/modules/csv/csv.go
KN4CK3R 0c6137617f
Add Tabular Diff for CSV files (#14661)
Implements request #14320 The rendering of CSV files does match the diff style.

* Moved CSV logic into base package.

* Added method to create a tabular diff.

* Added CSV compare context.

* Added CSV diff template.

* Use new table style in CSV markup.

* Added file size limit for CSV rendering.

* Display CSV parser errors in diff.

* Lazy read single file.

* Lazy read rows for full diff.

* Added unit tests for various CSV changes.
2021-03-29 22:44:28 +02:00

93 lines
2.5 KiB
Go

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