Files
dolt/samples/go/csv/csv_reader.go
2016-06-05 02:37:28 -07:00

43 lines
1.2 KiB
Go

// Copyright 2016 The Noms Authors. All rights reserved.
// Licensed under the Apache License, version 2.0:
// http://www.apache.org/licenses/LICENSE-2.0
package csv
import (
"bufio"
"encoding/csv"
"io"
)
var (
rByte byte = 13 // the byte that corresponds to the '\r' rune.
nByte byte = 10 // the byte that corresponds to the '\n' rune.
)
type reader struct {
r *bufio.Reader
}
// Read replaces CR line endings in the source reader with LF line endings if the CR is not followed by a LF.
func (r reader) Read(p []byte) (n int, err error) {
n, err = r.r.Read(p)
bn, err := r.r.Peek(1)
for i, b := range p {
// if the current byte is a CR and the next byte is NOT a LF then replace the current byte with a LF
if j := i + 1; b == rByte && ((j < len(p) && p[j] != nByte) || (len(bn) > 0 && bn[0] != nByte)) {
p[i] = nByte
}
}
return
}
// NewCSVReader returns a new csv.Reader that splits on comma and asserts that all rows contain the same number of fields as the first.
func NewCSVReader(res io.Reader, comma rune) *csv.Reader {
bufRes := bufio.NewReader(res)
r := csv.NewReader(reader{r: bufRes})
r.Comma = comma
r.FieldsPerRecord = -1 // Don't enforce number of fields.
return r
}