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- // Copyright 2018 Google LLC
- //
- // 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.
-
- // +build !go1.7
-
- package spanner
-
- import (
- "reflect"
- "strconv"
- )
-
- func structTagLookup(tag reflect.StructTag, key string) (string, bool) {
- // from go1.10.2 implementation of StructTag.Lookup.
- for tag != "" {
- // Skip leading space.
- i := 0
- for i < len(tag) && tag[i] == ' ' {
- i++
- }
- tag = tag[i:]
- if tag == "" {
- break
- }
-
- // Scan to colon. A space, a quote or a control character is a syntax error.
- // Strictly speaking, control chars include the range [0x7f, 0x9f], not just
- // [0x00, 0x1f], but in practice, we ignore the multi-byte control characters
- // as it is simpler to inspect the tag's bytes than the tag's runes.
- i = 0
- for i < len(tag) && tag[i] > ' ' && tag[i] != ':' && tag[i] != '"' && tag[i] != 0x7f {
- i++
- }
- if i == 0 || i+1 >= len(tag) || tag[i] != ':' || tag[i+1] != '"' {
- break
- }
- name := string(tag[:i])
- tag = tag[i+1:]
-
- // Scan quoted string to find value.
- i = 1
- for i < len(tag) && tag[i] != '"' {
- if tag[i] == '\\' {
- i++
- }
- i++
- }
- if i >= len(tag) {
- break
- }
- qvalue := string(tag[:i+1])
- tag = tag[i+1:]
-
- if key == name {
- value, err := strconv.Unquote(qvalue)
- if err != nil {
- break
- }
- return value, true
- }
- }
- return "", false
- }
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