Construct XlsxFile from zip.Reader (#28)

file.go

@@ -19,7 +19,7 @@ type XlsxFile struct {
 
 // XlsxFileCloser wraps XlsxFile to be able to close an open file
 type XlsxFileCloser struct {
-	zipReadCloser zip.ReadCloser
+	zipReadCloser *zip.ReadCloser
 	XlsxFile
 }
 
@@ -72,14 +72,32 @@ func OpenFile(filename string) (*XlsxFileCloser, error) {
 
 	x := new(XlsxFile)
 
-	if err := x.init(zipFile.Reader); err != nil {
+	if err := x.init(&zipFile.Reader); err != nil {
 		zipFile.Close()
 		return nil, err
 	}
 
 	return &XlsxFileCloser{
 		XlsxFile:      *x,
-		zipReadCloser: *zipFile,
+		zipReadCloser: zipFile,
+	}, nil
+}
+
+// OpenReaderZip takes the zip ReadCloser of an XLSX file and returns a populated XlsxFileCloser struct for it.
+// If the file cannot be found, or key parts of the files contents are missing, an error
+// is returned.
+// Note that the file must be Close()-d when you are finished with it.
+func OpenReaderZip(rc *zip.ReadCloser) (*XlsxFileCloser, error) {
+	x := new(XlsxFile)
+
+	if err := x.init(&rc.Reader); err != nil {
+		rc.Close()
+		return nil, err
+	}
+
+	return &XlsxFileCloser{
+		XlsxFile:      *x,
+		zipReadCloser: rc,
 	}, nil
 }
 
@@ -93,15 +111,28 @@ func NewReader(xlsxBytes []byte) (*XlsxFile, error) {
 	}
 
 	x := new(XlsxFile)
-	err = x.init(*r)
+	err = x.init(r)
 	if err != nil {
 		return nil, err
 	}
 
 	return x, nil
 }
 
-func (x *XlsxFile) init(zipReader zip.Reader) error {
+// NewReaderZip takes zip reader of Xlsx file and returns a populated XlsxFile struct for it.
+// If the file cannot be found, or key parts of the files contents are missing, an error
+// is returned.
+func NewReaderZip(r *zip.Reader) (*XlsxFile, error) {
+	x := new(XlsxFile)
+
+	if err := x.init(r); err != nil {
+		return nil, err
+	}
+
+	return x, nil
+}
+
+func (x *XlsxFile) init(zipReader *zip.Reader) error {
 	sharedStrings, err := getSharedStrings(zipReader.File)
 	if err != nil {
 		return err

file_test.go

@@ -53,6 +53,18 @@ func TestOpeningXlsxFile(t *testing.T) {
 	require.Equal(t, []string{"datarefinery_groundtruth_400000"}, f.Sheets)
 }
 
+func TestOpeningZipReadCloser(t *testing.T) {
+	zrc, err := zip.OpenReader("./test/test-small.xlsx")
+	require.NoError(t, err)
+	defer zrc.Close()
+
+	f, err := OpenReaderZip(zrc)
+	defer f.Close()
+
+	require.NoError(t, err)
+	require.Equal(t, []string{"datarefinery_groundtruth_400000"}, f.Sheets)
+}
+
 func TestClosingFile(t *testing.T) {
 	actual, err := OpenFile("./test/test-small.xlsx")
 	require.NoError(t, err)
@@ -72,6 +84,23 @@ func TestNewReaderFromXlsxBytes(t *testing.T) {
 	require.Equal(t, []string{"datarefinery_groundtruth_400000"}, actual.Sheets)
 }
 
+func TestNewZipReader(t *testing.T) {
+	f, err := os.Open("./test/test-small.xlsx")
+	require.NoError(t, err)
+
+	defer f.Close()
+
+	fstat, err := f.Stat()
+	require.NoError(t, err)
+
+	zr, err := zip.NewReader(f, fstat.Size())
+	require.NoError(t, err)
+
+	xlsx, err := NewReaderZip(zr)
+	require.NoError(t, err)
+	require.Equal(t, []string{"datarefinery_groundtruth_400000"}, xlsx.Sheets)
+}
+
 func TestDeletedSheet(t *testing.T) {
 	actual, err := OpenFile("./test/test-deleted-sheet.xlsx")