Only parse xml once when reading

We were parsing the whole sheet twice since the
sheet reader already reads in all the rows.

getTotalRowsCols function is unused after these changes
so it has been deleted as well.

Closes #439

rows.go

@@ -10,10 +10,8 @@
 package excelize
 
 import (
-	"bytes"
 	"encoding/xml"
 	"fmt"
-	"io"
 	"math"
 	"strconv"
 )
@@ -30,95 +28,35 @@ import (
 //    }
 //
 func (f *File) GetRows(sheet string) ([][]string, error) {
-	name, ok := f.sheetMap[trimSheetName(sheet)]
-	if !ok {
-		return nil, nil
-	}
-
-	xlsx, err := f.workSheetReader(sheet)
+	rows, err := f.Rows(sheet)
 	if err != nil {
 		return nil, err
 	}
-	if xlsx != nil {
-		output, _ := xml.Marshal(f.Sheet[name])
-		f.saveFileList(name, replaceWorkSheetsRelationshipsNameSpaceBytes(output))
-	}
-
-	xml.NewDecoder(bytes.NewReader(f.readXML(name)))
-	d := f.sharedStringsReader()
-	var (
-		inElement string
-		rowData   xlsxRow
-	)
-
-	rowCount, colCount, err := f.getTotalRowsCols(name)
-	if err != nil {
-		return nil, nil
-	}
-	rows := make([][]string, rowCount)
-	for i := range rows {
-		rows[i] = make([]string, colCount)
-	}
-
-	var row int
-	decoder := xml.NewDecoder(bytes.NewReader(f.readXML(name)))
-	for {
-		token, _ := decoder.Token()
-		if token == nil {
+	results := make([][]string, 0, 64)
+	for rows.Next() {
+		if rows.Error() != nil {
 			break
 		}
-		switch startElement := token.(type) {
-		case xml.StartElement:
-			inElement = startElement.Name.Local
-			if inElement == "row" {
-				rowData = xlsxRow{}
-				_ = decoder.DecodeElement(&rowData, &startElement)
-				cr := rowData.R - 1
-				for _, colCell := range rowData.C {
-					col, _, err := CellNameToCoordinates(colCell.R)
-					if err != nil {
-						return nil, err
-					}
-					val, _ := colCell.getValueFrom(f, d)
-					rows[cr][col-1] = val
-					if val != "" {
-						row = rowData.R
-					}
-				}
-			}
-		default:
+		row, err := rows.Columns()
+		if err != nil {
+			break
 		}
+		results = append(results, row)
 	}
-	return rows[:row], nil
+	return results, nil
 }
 
 // Rows defines an iterator to a sheet
 type Rows struct {
-	decoder *xml.Decoder
-	token   xml.Token
-	err     error
-	f       *File
+	err    error
+	f      *File
+	rows   []xlsxRow
+	curRow int
 }
 
 // Next will return true if find the next row element.
 func (rows *Rows) Next() bool {
-	for {
-		rows.token, rows.err = rows.decoder.Token()
-		if rows.err == io.EOF {
-			rows.err = nil
-		}
-		if rows.token == nil {
-			return false
-		}
-
-		switch startElement := rows.token.(type) {
-		case xml.StartElement:
-			inElement := startElement.Name.Local
-			if inElement == "row" {
-				return true
-			}
-		}
-	}
+	return rows.curRow < len(rows.rows)
 }
 
 // Error will return the error when the find next row element
@@ -128,15 +66,12 @@ func (rows *Rows) Error() error {
 
 // Columns return the current row's column values
 func (rows *Rows) Columns() ([]string, error) {
-	if rows.token == nil {
-		return []string{}, nil
-	}
-	startElement := rows.token.(xml.StartElement)
-	r := xlsxRow{}
-	_ = rows.decoder.DecodeElement(&r, &startElement)
+	curRow := rows.rows[rows.curRow]
+	rows.curRow++
+
+	columns := make([]string, len(curRow.C))
 	d := rows.f.sharedStringsReader()
-	columns := make([]string, len(r.C))
-	for _, colCell := range r.C {
+	for _, colCell := range curRow.C {
 		col, _, err := CellNameToCoordinates(colCell.R)
 		if err != nil {
 			return columns, err
@@ -181,46 +116,11 @@ func (f *File) Rows(sheet string) (*Rows, error) {
 		f.saveFileList(name, replaceWorkSheetsRelationshipsNameSpaceBytes(output))
 	}
 	return &Rows{
-		f:       f,
-		decoder: xml.NewDecoder(bytes.NewReader(f.readXML(name))),
+		f:    f,
+		rows: xlsx.SheetData.Row,
 	}, nil
 }
 
-// getTotalRowsCols provides a function to get total columns and rows in a
-// worksheet.
-func (f *File) getTotalRowsCols(name string) (int, int, error) {
-	decoder := xml.NewDecoder(bytes.NewReader(f.readXML(name)))
-	var inElement string
-	var r xlsxRow
-	var tr, tc int
-	for {
-		token, _ := decoder.Token()
-		if token == nil {
-			break
-		}
-		switch startElement := token.(type) {
-		case xml.StartElement:
-			inElement = startElement.Name.Local
-			if inElement == "row" {
-				r = xlsxRow{}
-				_ = decoder.DecodeElement(&r, &startElement)
-				tr = r.R
-				for _, colCell := range r.C {
-					col, _, err := CellNameToCoordinates(colCell.R)
-					if err != nil {
-						return tr, tc, err
-					}
-					if col > tc {
-						tc = col
-					}
-				}
-			}
-		default:
-		}
-	}
-	return tr, tc, nil
-}
-
 // SetRowHeight provides a function to set the height of a single row. For
 // example, set the height of the first row in Sheet1:
 //

rows_test.go

@@ -39,9 +39,6 @@ func TestRows(t *testing.T) {
 	if !assert.Equal(t, collectedRows, returnedRows) {
 		t.FailNow()
 	}
-
-	r := Rows{}
-	r.Columns()
 }
 
 func TestRowsError(t *testing.T) {
@@ -672,6 +669,21 @@ func TestDuplicateRowInvalidRownum(t *testing.T) {
 	}
 }
 
+func BenchmarkRows(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		f, _ := OpenFile(filepath.Join("test", "Book1.xlsx"))
+		rows, _ := f.Rows("Sheet2")
+		for rows.Next() {
+			row, _ := rows.Columns()
+			for i := range row {
+				if i >= 0 {
+					continue
+				}
+			}
+		}
+	}
+}
+
 func trimSliceSpace(s []string) []string {
 	for {
 		if len(s) > 0 && s[len(s)-1] == "" {