1 // Copyright 2022 Google LLC
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 //      http://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14 
15 package com.google.api.generator.gapic.protoparser;
16 
17 import com.google.api.pathtemplate.PathTemplate;
18 import com.google.common.collect.ImmutableSortedSet;
19 import java.util.Set;
20 
21 public class PatternParser {
22 
23   // This method tries to parse all named segments from pattern and sort in natual order
24   // e.g. /v1beta1/{table_name=tests/*}/{routing_id=instances/*}/** -> (routing_id, table_name)
getPatternBindings(String pattern)25   public static Set<String> getPatternBindings(String pattern) {
26     ImmutableSortedSet.Builder<String> bindings = ImmutableSortedSet.naturalOrder();
27     if (pattern.isEmpty()) {
28       return bindings.build();
29     }
30 
31     PathTemplate template = PathTemplate.create(pattern);
32     // Filter out any unbound variable like "$0, $1, etc.
33     template.vars().stream().filter(s -> !s.contains("$")).forEach(bindings::add);
34     return bindings.build();
35   }
36 }
37