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stringutf8.go
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/
stringutf8.go
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// Licensed to the Apache Software Foundation (ASF) under one or more
// contributor license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright ownership.
// The ASF licenses this file to You under the Apache License, Version 2.0
// (the "License"); you may not use this file except in compliance with
// the License. You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package coder
import (
"io"
"strings"
"github.com/apache/beam/sdks/go/pkg/beam/core/util/ioutilx"
)
const bufCap = 64
// EncodeStringUTF8 encodes a UTF8 string with a length prefix.
func EncodeStringUTF8(s string, w io.Writer) error {
if err := EncodeVarInt(int64(len(s)), w); err != nil {
return err
}
return encodeStringUTF8(s, w)
}
// encodeStringUTF8 encodes a string.
func encodeStringUTF8(s string, w io.Writer) error {
l := len(s)
var b [bufCap]byte
i := 0
for l-i > bufCap {
n := i + bufCap
copy(b[:], s[i:n])
if _, err := ioutilx.WriteUnsafe(w, b[:]); err != nil {
return err
}
i = n
}
n := l - i
copy(b[:n], s[i:])
ioutilx.WriteUnsafe(w, b[:n])
return nil
}
// decodeStringUTF8 reads l bytes and produces a string.
func decodeStringUTF8(l int64, r io.Reader) (string, error) {
var builder strings.Builder
var b [bufCap]byte
i := l
for i > bufCap {
err := ioutilx.ReadNBufUnsafe(r, b[:])
if err != nil {
return "", err
}
i -= bufCap
builder.Write(b[:])
}
err := ioutilx.ReadNBufUnsafe(r, b[:i])
if err != nil {
return "", err
}
builder.Write(b[:i])
return builder.String(), nil
}
// DecodeStringUTF8 decodes a length prefixed UTF8 string.
func DecodeStringUTF8(r io.Reader) (string, error) {
l, err := DecodeVarInt(r)
if err != nil {
return "", err
}
return decodeStringUTF8(l, r)
}