forked from gitea/gitea
380 lines
8.4 KiB
Go
380 lines
8.4 KiB
Go
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// 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 gitdiff
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import (
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"encoding/csv"
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"errors"
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"io"
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"code.gitea.io/gitea/modules/util"
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)
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const unmappedColumn = -1
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const maxRowsToInspect int = 10
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const minRatioToMatch float32 = 0.8
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// TableDiffCellType represents the type of a TableDiffCell.
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type TableDiffCellType uint8
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// TableDiffCellType possible values.
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const (
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TableDiffCellEqual TableDiffCellType = iota + 1
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TableDiffCellChanged
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TableDiffCellAdd
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TableDiffCellDel
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)
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// TableDiffCell represents a cell of a TableDiffRow
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type TableDiffCell struct {
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LeftCell string
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RightCell string
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Type TableDiffCellType
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}
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// TableDiffRow represents a row of a TableDiffSection.
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type TableDiffRow struct {
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RowIdx int
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Cells []*TableDiffCell
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}
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// TableDiffSection represents a section of a DiffFile.
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type TableDiffSection struct {
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Rows []*TableDiffRow
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}
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// csvReader wraps a csv.Reader which buffers the first rows.
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type csvReader struct {
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reader *csv.Reader
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buffer [][]string
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line int
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eof bool
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}
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// createCsvReader creates a csvReader and fills the buffer
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func createCsvReader(reader *csv.Reader, bufferRowCount int) (*csvReader, error) {
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csv := &csvReader{reader: reader}
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csv.buffer = make([][]string, bufferRowCount)
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for i := 0; i < bufferRowCount && !csv.eof; i++ {
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row, err := csv.readNextRow()
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if err != nil {
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return nil, err
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}
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csv.buffer[i] = row
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}
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csv.line = bufferRowCount
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return csv, nil
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}
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// GetRow gets a row from the buffer if present or advances the reader to the requested row. On the end of the file only nil gets returned.
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func (csv *csvReader) GetRow(row int) ([]string, error) {
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if row < len(csv.buffer) {
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return csv.buffer[row], nil
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}
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if csv.eof {
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return nil, nil
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}
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for {
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fields, err := csv.readNextRow()
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if err != nil {
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return nil, err
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}
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if csv.eof {
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return nil, nil
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}
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csv.line++
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if csv.line-1 == row {
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return fields, nil
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}
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}
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}
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func (csv *csvReader) readNextRow() ([]string, error) {
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if csv.eof {
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return nil, nil
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}
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row, err := csv.reader.Read()
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if err != nil {
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if err != io.EOF {
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return nil, err
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}
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csv.eof = true
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}
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return row, nil
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}
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// CreateCsvDiff creates a tabular diff based on two CSV readers.
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func CreateCsvDiff(diffFile *DiffFile, baseReader *csv.Reader, headReader *csv.Reader) ([]*TableDiffSection, error) {
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if baseReader != nil && headReader != nil {
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return createCsvDiff(diffFile, baseReader, headReader)
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}
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if baseReader != nil {
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return createCsvDiffSingle(baseReader, TableDiffCellDel)
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}
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return createCsvDiffSingle(headReader, TableDiffCellAdd)
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}
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// createCsvDiffSingle creates a tabular diff based on a single CSV reader. All cells are added or deleted.
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func createCsvDiffSingle(reader *csv.Reader, celltype TableDiffCellType) ([]*TableDiffSection, error) {
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var rows []*TableDiffRow
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i := 1
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for {
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row, err := reader.Read()
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if err != nil {
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if err == io.EOF {
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break
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}
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return nil, err
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}
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cells := make([]*TableDiffCell, len(row))
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for j := 0; j < len(row); j++ {
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cells[j] = &TableDiffCell{LeftCell: row[j], Type: celltype}
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}
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rows = append(rows, &TableDiffRow{RowIdx: i, Cells: cells})
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i++
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}
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return []*TableDiffSection{{Rows: rows}}, nil
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}
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func createCsvDiff(diffFile *DiffFile, baseReader *csv.Reader, headReader *csv.Reader) ([]*TableDiffSection, error) {
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a, err := createCsvReader(baseReader, maxRowsToInspect)
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if err != nil {
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return nil, err
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}
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b, err := createCsvReader(headReader, maxRowsToInspect)
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if err != nil {
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return nil, err
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}
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a2b, b2a := getColumnMapping(a, b)
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columns := len(a2b) + countUnmappedColumns(b2a)
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if len(a2b) < len(b2a) {
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columns = len(b2a) + countUnmappedColumns(a2b)
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}
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createDiffRow := func(aline int, bline int) (*TableDiffRow, error) {
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cells := make([]*TableDiffCell, columns)
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if aline == 0 || bline == 0 {
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var (
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row []string
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celltype TableDiffCellType
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err error
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)
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if bline == 0 {
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row, err = a.GetRow(aline - 1)
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celltype = TableDiffCellDel
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} else {
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row, err = b.GetRow(bline - 1)
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celltype = TableDiffCellAdd
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}
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if err != nil {
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return nil, err
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}
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if row == nil {
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return nil, nil
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}
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for i := 0; i < len(row); i++ {
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cells[i] = &TableDiffCell{LeftCell: row[i], Type: celltype}
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}
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return &TableDiffRow{RowIdx: bline, Cells: cells}, nil
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}
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arow, err := a.GetRow(aline - 1)
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if err != nil {
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return nil, err
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}
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brow, err := b.GetRow(bline - 1)
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if err != nil {
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return nil, err
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}
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if len(arow) == 0 && len(brow) == 0 {
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return nil, nil
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}
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for i := 0; i < len(a2b); i++ {
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acell, _ := getCell(arow, i)
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if a2b[i] == unmappedColumn {
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cells[i] = &TableDiffCell{LeftCell: acell, Type: TableDiffCellDel}
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} else {
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bcell, _ := getCell(brow, a2b[i])
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celltype := TableDiffCellChanged
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if acell == bcell {
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celltype = TableDiffCellEqual
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}
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cells[i] = &TableDiffCell{LeftCell: acell, RightCell: bcell, Type: celltype}
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}
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}
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for i := 0; i < len(b2a); i++ {
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if b2a[i] == unmappedColumn {
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bcell, _ := getCell(brow, i)
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cells[i] = &TableDiffCell{LeftCell: bcell, Type: TableDiffCellAdd}
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}
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}
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return &TableDiffRow{RowIdx: bline, Cells: cells}, nil
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}
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var sections []*TableDiffSection
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for i, section := range diffFile.Sections {
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var rows []*TableDiffRow
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lines := tryMergeLines(section.Lines)
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for j, line := range lines {
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if i == 0 && j == 0 && (line[0] != 1 || line[1] != 1) {
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diffRow, err := createDiffRow(1, 1)
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if err != nil {
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return nil, err
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}
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if diffRow != nil {
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rows = append(rows, diffRow)
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}
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}
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diffRow, err := createDiffRow(line[0], line[1])
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if err != nil {
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return nil, err
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}
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if diffRow != nil {
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rows = append(rows, diffRow)
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}
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}
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if len(rows) > 0 {
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sections = append(sections, &TableDiffSection{Rows: rows})
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}
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}
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return sections, nil
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}
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// getColumnMapping creates a mapping of columns between a and b
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func getColumnMapping(a *csvReader, b *csvReader) ([]int, []int) {
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arow, _ := a.GetRow(0)
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brow, _ := b.GetRow(0)
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a2b := []int{}
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b2a := []int{}
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if arow != nil {
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a2b = make([]int, len(arow))
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}
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if brow != nil {
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b2a = make([]int, len(brow))
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}
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for i := 0; i < len(b2a); i++ {
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b2a[i] = unmappedColumn
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}
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bcol := 0
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for i := 0; i < len(a2b); i++ {
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a2b[i] = unmappedColumn
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acell, ea := getCell(arow, i)
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if ea == nil {
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for j := bcol; j < len(b2a); j++ {
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bcell, eb := getCell(brow, j)
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if eb == nil && acell == bcell {
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a2b[i] = j
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b2a[j] = i
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bcol = j + 1
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break
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}
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}
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}
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}
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tryMapColumnsByContent(a, a2b, b, b2a)
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tryMapColumnsByContent(b, b2a, a, a2b)
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return a2b, b2a
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}
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// tryMapColumnsByContent tries to map missing columns by the content of the first lines.
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func tryMapColumnsByContent(a *csvReader, a2b []int, b *csvReader, b2a []int) {
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start := 0
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for i := 0; i < len(a2b); i++ {
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if a2b[i] == unmappedColumn {
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if b2a[start] == unmappedColumn {
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rows := util.Min(maxRowsToInspect, util.Max(0, util.Min(len(a.buffer), len(b.buffer))-1))
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same := 0
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for j := 1; j <= rows; j++ {
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acell, ea := getCell(a.buffer[j], i)
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bcell, eb := getCell(b.buffer[j], start+1)
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if ea == nil && eb == nil && acell == bcell {
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same++
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}
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}
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if (float32(same) / float32(rows)) > minRatioToMatch {
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a2b[i] = start + 1
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b2a[start+1] = i
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}
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}
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}
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start = a2b[i]
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}
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}
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// getCell returns the specific cell or nil if not present.
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func getCell(row []string, column int) (string, error) {
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if column < len(row) {
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return row[column], nil
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}
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return "", errors.New("Undefined column")
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}
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// countUnmappedColumns returns the count of unmapped columns.
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func countUnmappedColumns(mapping []int) int {
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count := 0
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for i := 0; i < len(mapping); i++ {
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if mapping[i] == unmappedColumn {
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count++
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}
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}
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return count
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}
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// tryMergeLines maps the separated line numbers of a git diff. The result is assumed to be ordered.
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func tryMergeLines(lines []*DiffLine) [][2]int {
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ids := make([][2]int, len(lines))
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i := 0
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for _, line := range lines {
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if line.Type != DiffLineSection {
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ids[i][0] = line.LeftIdx
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ids[i][1] = line.RightIdx
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i++
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}
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}
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ids = ids[:i]
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result := make([][2]int, len(ids))
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j := 0
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for i = 0; i < len(ids); i++ {
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if ids[i][0] == 0 {
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if j > 0 && result[j-1][1] == 0 {
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temp := j
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for temp > 0 && result[temp-1][1] == 0 {
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temp--
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}
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result[temp][1] = ids[i][1]
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continue
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}
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}
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result[j] = ids[i]
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j++
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}
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return result[:j]
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}
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