/
string.go
66 lines (56 loc) · 1.53 KB
/
string.go
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/*
* Copyright 2018-2020 the original author or authors.
*
* Licensed 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
*
* https://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 count
import (
"encoding/binary"
"fmt"
"io"
)
type StringReader interface {
io.Reader
io.ReaderAt
io.Seeker
}
type Strings struct {
Offset int32
Size int32
Reader StringReader
}
func (s Strings) Get(offset int32) (string, error) {
if _, err := s.Reader.Seek(int64(s.Offset)+int64(offset), io.SeekStart); err != nil {
return "", fmt.Errorf("unable to seek to beginning of string\n%w", err)
}
length := 0
for {
var c byte
if err := binary.Read(s.Reader, binary.LittleEndian, &c); err != nil {
return "", fmt.Errorf("unable to determine string length\n%w", err)
}
if c == 0 {
break
}
if (c & 0xC0) != 0x80 {
length++
}
}
b := make([]byte, length)
if n, err := s.Reader.ReadAt(b, int64(s.Offset)+int64(offset)); err != nil {
return "", fmt.Errorf("unable to read string\n%w", err)
} else if n != length {
return "", fmt.Errorf("unable to read full string")
}
return string(b), nil
}