1 // 2 // Copyright (c) SAS Institute Inc. 3 // 4 // Licensed under the Apache License, Version 2.0 (the "License"); 5 // you may not use this file except in compliance with the License. 6 // You may obtain a copy of the License at 7 // 8 // http://www.apache.org/licenses/LICENSE-2.0 9 // 10 // Unless required by applicable law or agreed to in writing, software 11 // distributed under the License is distributed on an "AS IS" BASIS, 12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 // See the License for the specific language governing permissions and 14 // limitations under the License. 15 // 16 17 package readercounter 18 19 import "io" 20 21 // Wraps a Reader and counts how many bytes are read from it 22 type ReaderCounter struct { 23 R io.Reader // underlying Reader 24 N int64 // number of bytes read 25 } 26 27 func New(r io.Reader) *ReaderCounter { 28 return &ReaderCounter{R: r} 29 } 30 31 func (c *ReaderCounter) Read(d []byte) (int, error) { 32 n, err := c.R.Read(d) 33 c.N += int64(n) 34 return n, err 35 } 36