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stringvalue.go
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/
stringvalue.go
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/*
http://www.apache.org/licenses/LICENSE-2.0.txt
Copyright 2015 Intel Corporation
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
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 opentsdb
import (
"bytes"
"fmt"
)
//StringValue implements Json interface to
//replece invalid characters.
type StringValue string
func (sv StringValue) MarshalJSON() ([]byte, error) {
length := len(sv)
result := bytes.NewBuffer(make([]byte, 0, length+2))
result.WriteByte('"')
for i := 0; i < length; i++ {
b := sv[i]
switch {
case (b >= '-' && b <= '9') || // '-', '.', '/', 0-9
(b >= 'A' && b <= 'Z') ||
(b >= 'a' && b <= 'z'):
result.WriteByte(b)
case b == '_':
result.WriteString("__")
case b == ':':
result.WriteString("_.")
default:
result.WriteString(fmt.Sprintf("_%X", b))
}
}
result.WriteByte('"')
return result.Bytes(), nil
}
func (sv *StringValue) UnmarshalJSON(json []byte) error {
escapeLevel := 0
var parsedByte byte
result := bytes.NewBuffer(make([]byte, 0, len(json)-2))
for i, b := range json {
if i == 0 {
if b != '"' {
return fmt.Errorf("expected '\"', got %q", b)
}
continue
}
if i == len(json)-1 {
if b != '"' {
return fmt.Errorf("expected '\"', got %q", b)
}
break
}
switch escapeLevel {
case 0:
if b == '_' {
escapeLevel = 1
continue
}
result.WriteByte(b)
case 1:
switch {
case b == '_':
result.WriteByte('_')
escapeLevel = 0
case b == '.':
result.WriteByte(':')
escapeLevel = 0
case b >= '0' && b <= '9':
parsedByte = (b - 48) << 4
escapeLevel = 2
case b >= 'A' && b <= 'F': // A-F
parsedByte = (b - 55) << 4
escapeLevel = 2
default:
return fmt.Errorf(
"illegal escape sequence at byte %d (%c)",
i, b,
)
}
case 2:
switch {
case b >= '0' && b <= '9':
parsedByte += b - 48
case b >= 'A' && b <= 'F': // A-F
parsedByte += b - 55
default:
return fmt.Errorf(
"illegal escape sequence at byte %d (%c)",
i, b,
)
}
result.WriteByte(parsedByte)
escapeLevel = 0
default:
panic("unexpected escape level")
}
}
*sv = StringValue(result.String())
return nil
}