| // Copyright 2016 The LUCI 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 |
| // |
| // 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 errors |
| |
| // Filter examines a supplied error and removes instances of excluded errors |
| // from it. If the entire supplied error is excluded, Filter will return nil. |
| // |
| // If a MultiError is supplied to Filter, it will be recursively traversed, and |
| // its child errors will be turned into nil if they match the supplied filter. |
| // If a MultiError has all of its children converted to nil as a result of the |
| // filter, it will itself be reduced to nil. |
| func Filter(err error, exclude error, others ...error) error { |
| return FilterFunc(err, func(e error) bool { |
| if e == exclude { |
| return true |
| } |
| for _, v := range others { |
| if e == v { |
| return true |
| } |
| } |
| return false |
| }) |
| } |
| |
| // FilterFunc examines a supplied error and removes instances of errors that |
| // match the supplied filter function. If the entire supplied error is removed, |
| // FilterFunc will return nil. |
| // |
| // If a MultiError is supplied to FilterFunc, it will be recursively traversed, |
| // and its child errors will be turned into nil if they match the supplied |
| // filter function. If a MultiError has all of its children converted to nil as |
| // a result of the filter, it will itself be reduced to nil. |
| // |
| // Consqeuently, if err is a MultiError, shouldFilter will be called once with |
| // err as its value and once for every non-nil error that it contains. |
| func FilterFunc(err error, shouldFilter func(error) bool) error { |
| switch { |
| case shouldFilter == nil: |
| return err |
| case err == nil: |
| return nil |
| case shouldFilter(err): |
| return nil |
| } |
| |
| if merr, ok := err.(MultiError); ok { |
| var lme MultiError |
| for i, e := range merr { |
| if e != nil { |
| e = FilterFunc(e, shouldFilter) |
| if e != nil { |
| if lme == nil { |
| lme = make(MultiError, len(merr)) |
| } |
| lme[i] = e |
| } |
| } |
| } |
| if lme == nil { |
| return nil |
| } |
| return lme |
| } |
| |
| return err |
| } |