64 lines
2.1 KiB
Go
64 lines
2.1 KiB
Go
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// Licensed to Elasticsearch B.V. under one or more contributor
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// license agreements. See the NOTICE file distributed with
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// this work for additional information regarding copyright
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// ownership. Elasticsearch B.V. licenses this file to you under
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// the Apache License, Version 2.0 (the "License"); you may
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// 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,
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// software distributed under the License is distributed on an
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// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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// KIND, either express or implied. See the License for the
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// specific language governing permissions and limitations
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// under the License.
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package sys
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// ByteBuffer is an expandable buffer backed by a byte slice.
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type ByteBuffer struct {
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buf []byte
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offset int
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}
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// NewByteBuffer creates a new ByteBuffer with an initial capacity of
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// initialSize.
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func NewByteBuffer(initialSize int) *ByteBuffer {
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return &ByteBuffer{buf: make([]byte, initialSize)}
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}
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// Write appends the contents of p to the buffer, growing the buffer as needed.
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// The return value is the length of p; err is always nil.
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func (b *ByteBuffer) Write(p []byte) (int, error) {
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if len(b.buf) < b.offset+len(p) {
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// Create a buffer larger than needed so we don't spend lots of time
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// allocating and copying.
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spaceNeeded := len(b.buf) - b.offset + len(p)
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largerBuf := make([]byte, 2*len(b.buf)+spaceNeeded)
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copy(largerBuf, b.buf[:b.offset])
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b.buf = largerBuf
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}
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n := copy(b.buf[b.offset:], p)
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b.offset += n
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return n, nil
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}
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// Reset resets the buffer to be empty. It retains the same underlying storage.
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func (b *ByteBuffer) Reset() {
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b.offset = 0
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b.buf = b.buf[:cap(b.buf)]
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}
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// Bytes returns a slice of length b.Len() holding the bytes that have been
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// written to the buffer.
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func (b *ByteBuffer) Bytes() []byte {
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return b.buf[:b.offset]
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}
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// Len returns the number of bytes that have been written to the buffer.
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func (b *ByteBuffer) Len() int {
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return b.offset
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}
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