/
reader.go
222 lines (204 loc) · 4.89 KB
/
reader.go
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package dbf
import (
"bufio"
"fmt"
"io"
"time"
"golang.org/x/text/encoding"
)
// The Reader reads records from a DBF file.
type Reader struct {
header *header
fields *Fields
reader *bufio.Reader
buf []byte
recNo uint32
decoder *encoding.Decoder
err error
}
// NewReader returns a new Reader that reads from r.
func NewReader(rd io.Reader) (*Reader, error) {
r, err := newReader(rd)
if err != nil {
return nil, fmt.Errorf("dbf.NewReader: %w", err)
}
return r, nil
}
func newReader(rd io.Reader) (*Reader, error) {
if _, ok := rd.(io.Reader); !ok {
return nil, fmt.Errorf("parameter %v is not io.Reader", rd)
}
r := &Reader{
header: &header{},
fields: NewFields(),
reader: bufio.NewReader(rd),
}
if err := r.header.read(r.reader); err != nil {
return nil, err
}
if err := r.fields.read(r.reader, r.header.fieldCount()); err != nil {
return nil, err
}
// Skip byte header end
if _, err := r.reader.Discard(1); err != nil {
return nil, err
}
// Create buffer
r.buf = make([]byte, int(r.header.RecSize))
// Code page
if cp := r.header.codePage(); cp != 0 {
cm := charmapByPage(cp)
r.decoder = cm.NewDecoder()
}
return r, nil
}
// Err returns the first error that was encountered by the Reader.
func (r *Reader) Err() error {
if r.err != nil {
return fmt.Errorf("dbf.Reader: %w", r.err)
}
return nil
}
// SetCodePage sets the code page if no code page is set in the file header.
//
// Supported code pages:
// 437 - US MS-DOS
// 850 - International MS-DOS
// 1252 - Windows ANSI
// 10000 - Standard Macintosh
// 852 - Easern European MS-DOS
// 866 - Russian MS-DOS
// 865 - Nordic MS-DOS
// 1255 - Hebrew Windows
// 1256 - Arabic Windows
// 10007 - Russian Macintosh
// 1250 - Eastern European Windows
// 1251 - Russian Windows
// 1254 - Turkish Windows
// 1253 - Greek Windows
func (r *Reader) SetCodePage(cp int) {
if r.err != nil {
return
}
cm := charmapByPage(cp)
if cm == nil {
r.err = fmt.Errorf("SetCodePage: unsupported code page %d", cp)
return
}
r.decoder = cm.NewDecoder()
r.header.setCodePage(cp)
}
// CodePage returns the code page set in the file header.
func (r *Reader) CodePage() int {
if r.err != nil {
return 0
}
return r.header.codePage()
}
// ModDate returns the modified date in the file header.
func (r *Reader) ModDate() time.Time {
if r.err != nil {
var d time.Time
return d
}
return r.header.modDate()
}
// RecordCount returns the number of records in the DBF file.
func (r *Reader) RecordCount() uint32 {
if r.err != nil {
return 0
}
return r.header.RecCount
}
// Fields returns the file structure.
func (r *Reader) Fields() *Fields {
if r.err != nil {
return nil
}
return r.fields
}
// Read reads one record from r.
// Returns false if end of file is reached or an error occurs.
func (r *Reader) Read() bool {
if r.err != nil {
return false
}
r.recNo++
if _, err := io.ReadFull(r.reader, r.buf); err != nil {
if err != io.EOF && err != io.ErrUnexpectedEOF {
r.err = fmt.Errorf("Read: record %d: %w", r.recNo, err)
}
return false
}
return true
}
// Deleted returns deleted record flag.
func (r *Reader) Deleted() bool {
if r.err != nil {
return false
}
return r.buf[0] == '*'
}
// StringFieldValue returns the value of the field by index.
// Field type must be Character.
func (r *Reader) StringFieldValue(index int) string {
if r.err != nil {
return ""
}
value, err := r.fields.stringFieldValue(index, r.buf, r.decoder)
if err != nil {
r.err = fmt.Errorf("StringFieldValue: %w", err)
}
return value
}
// BoolFieldValue returns the value of the field by index.
// Field type must be Logical.
func (r *Reader) BoolFieldValue(index int) bool {
if r.err != nil {
return false
}
value, err := r.fields.boolFieldValue(index, r.buf)
if err != nil {
r.err = fmt.Errorf("BoolFieldValue: %w", err)
}
return value
}
// DateFieldValue returns the value of the field by index.
// Field type must be Date.
func (r *Reader) DateFieldValue(index int) time.Time {
var d time.Time
if r.err != nil {
return d
}
value, err := r.fields.dateFieldValue(index, r.buf)
if err != nil {
r.err = fmt.Errorf("DateFieldValue: %w", err)
}
return value
}
// IntFieldValue returns the value of the field by index.
// Field type must be Numeric.
// If field decimal places is not zero,
// then it returns the integer part of the number.
func (r *Reader) IntFieldValue(index int) int64 {
if r.err != nil {
return 0
}
value, err := r.fields.intFieldValue(index, r.buf)
if err != nil {
r.err = fmt.Errorf("IntFieldValue: %w", err)
}
return value
}
// FloatFieldValue returns the value of the field by index.
// Field type must be Numeric.
func (r *Reader) FloatFieldValue(index int) float64 {
if r.err != nil {
return 0
}
value, err := r.fields.floatFieldValue(index, r.buf)
if err != nil {
r.err = fmt.Errorf("FloatFieldValue: %w", err)
}
return value
}