| // 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 |
| } |