mirror of https://github.com/minio/minio.git
88 lines
2.6 KiB
Go
88 lines
2.6 KiB
Go
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/*
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* Minio Cloud Storage, (C) 2018 Minio, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package ioutil
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import (
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"bufio"
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"io"
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)
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var (
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nByte byte = 10 // the byte that corresponds to the '\n' rune.
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rByte byte = 13 // the byte that corresponds to the '\r' rune.
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)
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// DelimitedReader reduces the custom delimiter to `\n`.
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type DelimitedReader struct {
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r *bufio.Reader
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delimiter []rune // Select can have upto 2 characters as delimiter.
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assignEmpty bool // Decides whether the next read byte should be discarded.
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}
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// NewDelimitedReader detects the custom delimiter and replaces with `\n`.
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func NewDelimitedReader(r io.Reader, delimiter []rune) *DelimitedReader {
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return &DelimitedReader{r: bufio.NewReader(r), delimiter: delimiter, assignEmpty: false}
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}
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// Reads and replaces the custom delimiter with `\n`.
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func (r *DelimitedReader) Read(p []byte) (n int, err error) {
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n, err = r.r.Read(p)
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if err != nil {
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return
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}
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for i, b := range p {
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if r.assignEmpty {
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swapAndNullify(p, i)
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r.assignEmpty = false
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continue
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}
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if b == rByte && rune(b) != r.delimiter[0] {
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// Replace the carriage returns with `\n`.
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// Mac styled csv will have `\r` as their record delimiter.
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p[i] = nByte
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} else if rune(b) == r.delimiter[0] { // Eg, `\r\n`,`ab`,`a` are valid delimiters
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if i+1 == len(p) && len(r.delimiter) > 1 {
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// If the first delimiter match falls on the boundary,
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// Peek the next byte and if it matches, discard it in the next byte read.
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if nextByte, nerr := r.r.Peek(1); nerr == nil {
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if rune(nextByte[0]) == r.delimiter[1] {
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p[i] = nByte
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// To Discard in the next read.
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r.assignEmpty = true
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}
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}
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} else if len(r.delimiter) > 1 && rune(p[i+1]) == r.delimiter[1] {
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// The second delimiter falls in the same chunk.
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p[i] = nByte
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r.assignEmpty = true
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} else if len(r.delimiter) == 1 {
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// Replace with `\n` incase of single charecter delimiter match.
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p[i] = nByte
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}
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}
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}
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return
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}
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// Occupy the first byte space and nullify the last byte.
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func swapAndNullify(p []byte, n int) {
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for i := n; i < len(p)-1; i++ {
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p[i] = p[i+1]
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}
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p[len(p)-1] = 0
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}
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