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/
csv.go
198 lines (160 loc) · 3.79 KB
/
csv.go
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package csv
import (
"encoding/csv"
"fmt"
"io"
"reflect"
"strconv"
"strings"
)
type Scanner struct {
closer io.ReadCloser
reader *csv.Reader
columnNames []string
init bool
}
func NewScanner(in io.ReadCloser) (*Scanner, error) {
rdr := &Scanner{}
rdr.closer = in
rdr.reader = csv.NewReader(in)
rdr.reader.Comment = '#'
return rdr, nil
}
func (rd *Scanner) Scan(v interface{}) error {
value := reflect.ValueOf(v)
if value.Kind() == reflect.Ptr {
value = value.Elem()
}
valueType := value.Type()
if !rd.init {
var err error
// we still haven't read the header record yet.
// NOTE: As Gophercraft continues in its development, new fields will be added.
// it should be acceptable to omit certain fields from your CSV, however not to include unknown fields.
rd.columnNames, err = rd.reader.Read()
if err != nil {
return err
}
for _, ct := range rd.columnNames {
_, found := valueType.FieldByName(ct)
if !found {
return fmt.Errorf("could not find field %s in field %s", ct, valueType.String())
}
}
rd.init = true
}
switch value.Kind() {
case reflect.Struct:
default:
return fmt.Errorf("csv: cannot scan to non-struct type")
}
rec, err := rd.reader.Read()
if err != nil {
return err
}
if len(rec) != len(rd.columnNames) {
return fmt.Errorf("record length mismatch in line: %s", strings.Join(rec, ","))
}
for i, cname := range rd.columnNames {
recd := rec[i]
field := value.FieldByName(cname)
err := parseField(field, recd)
if err != nil {
return err
}
}
return nil
}
func (rd *Scanner) Close() error {
return rd.closer.Close()
}
func parseUint(rec reflect.Value, bitSize int, value string) error {
i, err := strconv.ParseUint(value, 0, bitSize)
if err != nil {
return err
}
rec.SetUint(i)
return nil
}
func parseInt(rec reflect.Value, bitSize int, value string) error {
i, err := strconv.ParseInt(value, 0, bitSize)
if err != nil {
return err
}
rec.SetInt(i)
return nil
}
func parseFloat(rec reflect.Value, bitSize int, value string) error {
f, err := strconv.ParseFloat(value, bitSize)
if err != nil {
return err
}
rec.SetFloat(f)
return nil
}
func parseStruct(strct reflect.Value, value string) error {
if value == "" {
return nil
}
split := strings.Split(value, ";")
for _, spl := range split {
keys := strings.Split(spl, ":")
if len(keys) != 2 {
return fmt.Errorf("invalid number of elements in %s", split)
}
_, ok := strct.Type().FieldByName(keys[0])
if !ok {
return fmt.Errorf("no field by name %d", value)
}
if err := parseField(strct.FieldByName(keys[0]), keys[1]); err != nil {
return err
}
}
return nil
}
func parseField(field reflect.Value, recd string) error {
var err error
switch field.Kind() {
case reflect.Uint8:
err = parseUint(field, 8, recd)
case reflect.Uint16:
err = parseUint(field, 16, recd)
case reflect.Uint32:
err = parseUint(field, 32, recd)
case reflect.Uint64:
err = parseUint(field, 64, recd)
case reflect.Int8:
err = parseInt(field, 8, recd)
case reflect.Int16:
err = parseInt(field, 16, recd)
case reflect.Int32:
err = parseInt(field, 32, recd)
case reflect.Int64:
err = parseInt(field, 64, recd)
case reflect.String:
field.SetString(recd)
case reflect.Float32:
err = parseFloat(field, 32, recd)
case reflect.Float64:
err = parseFloat(field, 64, recd)
case reflect.Bool:
field.SetBool(recd == "true")
case reflect.Slice:
strs := strings.Split(recd, ",")
sli := reflect.MakeSlice(field.Type(), len(strs), len(strs))
for i, v := range strs {
err = parseField(sli.Index(i), v)
if err != nil {
break
}
}
if err == nil {
field.Set(sli)
}
case reflect.Struct:
err = parseStruct(field, recd)
default:
err = fmt.Errorf("unhandled field kind %s", field.Kind().String())
}
return err
}