| // Copyright 2024 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| // Package filter implements https://google.aip.dev/160. |
| // This is used to filter a collection using a "structured |
| // syntax accessible to a non-technical audience." |
| // |
| // A filter expression may use a field name to be found in a struct. |
| // If there is no exact match of the field name, |
| // the filter code will look for a camel case match, |
| // in which underscores will be skipped and characters following |
| // an underscore will match case-insensitively. |
| // For example, Field_name will match FieldName. |
| // The filter code will also look for a json struct field tag, |
| // and compare against the JSON name if there is one, |
| // again doing a camel case match. |
| // This approach makes it easier to use the same filter expression |
| // across languages when filtering protobuf types. |
| // If a struct field is a pointer type, |
| // it will be dereferenced before being used in any filter comparison. |
| // |
| // When a filter expression fails to find a field name, |
| // it will fall back to looking for an exported method with the name, |
| // again doing a camel case lookup. |
| // If there is a matching method, and the method takes no arguments |
| // and returns either a single value or a single value and an error, |
| // the filter code will call the method to get the value |
| // to search for. If the method returns an error, |
| // the value will simply be ignored; |
| // the error will not be returned or logged. |
| // If the method returns a pointer result, it will be dereferenced |
| // before being used in any filter comparison. |
| package filter |
