first-commit
This commit is contained in:
469
services/gitdiff/csv.go
Normal file
469
services/gitdiff/csv.go
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@@ -0,0 +1,469 @@
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// Copyright 2021 The Gitea Authors. All rights reserved.
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// SPDX-License-Identifier: MIT
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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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)
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const (
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unmappedColumn = -1
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maxRowsToInspect int = 10
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minRatioToMatch float32 = 0.8
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)
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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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TableDiffCellUnchanged TableDiffCellType = iota + 1
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TableDiffCellChanged
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TableDiffCellAdd
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TableDiffCellDel
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TableDiffCellMovedUnchanged
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TableDiffCellMovedChanged
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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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// ErrorUndefinedCell is for when a row, column coordinates do not exist in the CSV
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var ErrorUndefinedCell = errors.New("undefined cell")
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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) && row >= 0 {
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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, 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 := range row {
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if celltype == TableDiffCellDel {
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cells[j] = &TableDiffCell{LeftCell: row[j], Type: celltype}
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} else {
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cells[j] = &TableDiffCell{RightCell: row[j], Type: celltype}
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}
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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, headReader *csv.Reader) ([]*TableDiffSection, error) {
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// Given the baseReader and headReader, we are going to create CSV Reader for each, baseCSVReader and b respectively
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baseCSVReader, 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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headCSVReader, 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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// Initializing the mappings of base to head (a2bColMap) and head to base (b2aColMap) columns
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a2bColMap, b2aColMap := getColumnMapping(baseCSVReader, headCSVReader)
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// Determines how many cols there will be in the diff table, which includes deleted columns from base and added columns to base
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numDiffTableCols := len(a2bColMap) + countUnmappedColumns(b2aColMap)
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if len(a2bColMap) < len(b2aColMap) {
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numDiffTableCols = len(b2aColMap) + countUnmappedColumns(a2bColMap)
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}
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// createDiffTableRow takes the row # of the `a` line and `b` line of a diff (starting from 1), 0 if the line doesn't exist (undefined)
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// in the base or head respectively.
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// Returns a TableDiffRow which has the row index
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createDiffTableRow := func(aLineNum, bLineNum int) (*TableDiffRow, error) {
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// diffTableCells is a row of the diff table. It will have a cells for added, deleted, changed, and unchanged content, thus either
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// the same size as the head table or bigger
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diffTableCells := make([]*TableDiffCell, numDiffTableCols)
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var bRow *[]string
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if bLineNum > 0 {
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row, err := headCSVReader.GetRow(bLineNum - 1)
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if err != nil {
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return nil, err
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}
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bRow = &row
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}
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var aRow *[]string
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if aLineNum > 0 {
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row, err := baseCSVReader.GetRow(aLineNum - 1)
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if err != nil {
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return nil, err
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}
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aRow = &row
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}
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if aRow == nil && bRow == nil {
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// No content
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return nil, nil
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}
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aIndex := 0 // tracks where we are in the a2bColMap
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bIndex := 0 // tracks where we are in the b2aColMap
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colsAdded := 0 // incremented whenever we found a column was added
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colsDeleted := 0 // incrememted whenever a column was deleted
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// We loop until both the aIndex and bIndex are greater than their col map, which then we are done
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for aIndex < len(a2bColMap) || bIndex < len(b2aColMap) {
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// Starting from where aIndex is currently pointing, we see if the map is -1 (dleeted) and if is, create column to note that, increment, and look at the next aIndex
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for aIndex < len(a2bColMap) && a2bColMap[aIndex] == -1 && (bIndex >= len(b2aColMap) || aIndex <= bIndex) {
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var aCell string
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if aRow != nil {
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if cell, err := getCell(*aRow, aIndex); err != nil {
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if err != ErrorUndefinedCell {
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return nil, err
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}
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} else {
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aCell = cell
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}
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}
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diffTableCells[bIndex+colsDeleted] = &TableDiffCell{LeftCell: aCell, Type: TableDiffCellDel}
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aIndex++
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colsDeleted++
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}
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// aIndex is now pointing to a column that also exists in b, or is at the end of a2bColMap. If the former,
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// we can just increment aIndex until it points to a -1 column or one greater than the current bIndex
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for aIndex < len(a2bColMap) && a2bColMap[aIndex] != -1 {
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aIndex++
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}
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// Starting from where bIndex is currently pointing, we see if the map is -1 (added) and if is, create column to note that, increment, and look at the next aIndex
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for bIndex < len(b2aColMap) && b2aColMap[bIndex] == -1 && (aIndex >= len(a2bColMap) || bIndex < aIndex) {
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var bCell string
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cellType := TableDiffCellAdd
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if bRow != nil {
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if cell, err := getCell(*bRow, bIndex); err != nil {
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if err != ErrorUndefinedCell {
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return nil, err
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}
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} else {
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bCell = cell
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}
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} else {
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cellType = TableDiffCellDel
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}
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diffTableCells[bIndex+colsDeleted] = &TableDiffCell{RightCell: bCell, Type: cellType}
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bIndex++
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colsAdded++
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}
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// aIndex is now pointing to a column that also exists in a, or is at the end of b2aColMap. If the former,
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// we get the a col and b col values (if they exist), figure out if they are the same or not, and if the column moved, and add it to the diff table
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for bIndex < len(b2aColMap) && b2aColMap[bIndex] != -1 && (aIndex >= len(a2bColMap) || bIndex < aIndex) {
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var diffTableCell TableDiffCell
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var aCell *string
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// get the aCell value if the aRow exists
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if aRow != nil {
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if cell, err := getCell(*aRow, b2aColMap[bIndex]); err != nil {
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if err != ErrorUndefinedCell {
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return nil, err
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}
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} else {
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aCell = &cell
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diffTableCell.LeftCell = cell
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}
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} else {
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diffTableCell.Type = TableDiffCellAdd
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}
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var bCell *string
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// get the bCell value if the bRow exists
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if bRow != nil {
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if cell, err := getCell(*bRow, bIndex); err != nil {
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if err != ErrorUndefinedCell {
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return nil, err
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}
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} else {
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bCell = &cell
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diffTableCell.RightCell = cell
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}
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} else {
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diffTableCell.Type = TableDiffCellDel
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}
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// if both a and b have a row that exists, compare the value and determine if the row has moved
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if aCell != nil && bCell != nil {
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moved := ((bIndex + colsDeleted) != (b2aColMap[bIndex] + colsAdded))
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if *aCell != *bCell {
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if moved {
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diffTableCell.Type = TableDiffCellMovedChanged
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} else {
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diffTableCell.Type = TableDiffCellChanged
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}
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} else {
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if moved {
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diffTableCell.Type = TableDiffCellMovedUnchanged
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} else {
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diffTableCell.Type = TableDiffCellUnchanged
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}
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diffTableCell.LeftCell = ""
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}
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}
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// Add the diff column to the diff row
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diffTableCells[bIndex+colsDeleted] = &diffTableCell
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bIndex++
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}
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}
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return &TableDiffRow{RowIdx: bLineNum, Cells: diffTableCells}, nil
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}
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// diffTableSections are TableDiffSections which represent the diffTableSections we get when doing a diff, each will be its own table in the view
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var diffTableSections []*TableDiffSection
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for i, section := range diffFile.Sections {
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// Each section has multiple diffTableRows
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var diffTableRows []*TableDiffRow
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lines := tryMergeLines(section.Lines)
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// Loop through the merged lines to get each row of the CSV diff table for this section
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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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diffTableRow, err := createDiffTableRow(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 diffTableRow != nil {
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diffTableRows = append(diffTableRows, diffTableRow)
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}
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}
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diffTableRow, err := createDiffTableRow(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 diffTableRow != nil {
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diffTableRows = append(diffTableRows, diffTableRow)
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}
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}
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if len(diffTableRows) > 0 {
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diffTableSections = append(diffTableSections, &TableDiffSection{Rows: diffTableRows})
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}
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}
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return diffTableSections, 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(baseCSVReader, headCSVReader *csvReader) ([]int, []int) {
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baseRow, _ := baseCSVReader.GetRow(0)
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headRow, _ := headCSVReader.GetRow(0)
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base2HeadColMap := []int{}
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head2BaseColMap := []int{}
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if baseRow != nil {
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base2HeadColMap = make([]int, len(baseRow))
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}
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if headRow != nil {
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head2BaseColMap = make([]int, len(headRow))
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}
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// Initializes all head2base mappings to be unmappedColumn (-1)
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for i := 0; i < len(head2BaseColMap); i++ {
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head2BaseColMap[i] = unmappedColumn
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}
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// Loops through the baseRow and see if there is a match in the head row
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for i := range baseRow {
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base2HeadColMap[i] = unmappedColumn
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baseCell, err := getCell(baseRow, i)
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if err == nil {
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for j := range headRow {
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if head2BaseColMap[j] == -1 {
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headCell, err := getCell(headRow, j)
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if err == nil && baseCell == headCell {
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base2HeadColMap[i] = j
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head2BaseColMap[j] = i
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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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}
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tryMapColumnsByContent(baseCSVReader, base2HeadColMap, headCSVReader, head2BaseColMap)
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tryMapColumnsByContent(headCSVReader, head2BaseColMap, baseCSVReader, base2HeadColMap)
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return base2HeadColMap, head2BaseColMap
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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(baseCSVReader *csvReader, base2HeadColMap []int, headCSVReader *csvReader, head2BaseColMap []int) {
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for i := range base2HeadColMap {
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headStart := 0
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for base2HeadColMap[i] == unmappedColumn && headStart < len(head2BaseColMap) {
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if head2BaseColMap[headStart] == unmappedColumn {
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rows := min(maxRowsToInspect, max(0, min(len(baseCSVReader.buffer), len(headCSVReader.buffer))-1))
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same := 0
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for j := 1; j <= rows; j++ {
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baseCell, baseErr := getCell(baseCSVReader.buffer[j], i)
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headCell, headErr := getCell(headCSVReader.buffer[j], headStart)
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if baseErr == nil && headErr == nil && baseCell == headCell {
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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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base2HeadColMap[i] = headStart
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head2BaseColMap[headStart] = i
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}
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}
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headStart++
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}
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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 "", ErrorUndefinedCell
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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 := range mapping {
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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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Reference in New Issue
Block a user