Update example for checking uniqueness of repeated fields (#227)

This also adds an example of `map`. Adding it into the same example file
because I think a large percentage `map` usage in protovalidate is for
checking uniqueness.

WORKSPACE

@@ -36,7 +36,7 @@ load("@rules_buf//buf:repositories.bzl", "rules_buf_dependencies", "rules_buf_to
 
 rules_buf_dependencies()
 
-rules_buf_toolchains(version = "v1.33.0")
+rules_buf_toolchains(version = "v1.35.0")
 
 load("@rules_proto//proto:repositories.bzl", "rules_proto_dependencies", "rules_proto_toolchains")
 

examples/BUILD.bazel

@@ -43,7 +43,7 @@ proto_library(
         "cel_repeated_field_all.proto",
         "cel_repeated_field_exists_one.proto",
         "cel_repeated_field_filter_and_count.proto",
-        "cel_repeated_field_unique.proto",
+        "cel_repeated_field_transform_and_unique.proto",
         "cel_string_concatenation.proto",
         "cel_string_contains.proto",
         "cel_string_is_email.proto",

examples/buf.lock

@@ -4,10 +4,10 @@ deps:
   - remote: buf.build
     owner: bufbuild
     repository: protovalidate
-    commit: b9b8148056b94f6898cc669574bae125
-    digest: shake256:5660d7a38dd2ff9a7b8a6304bca6fe798dc6bcd7ecb06c4ce8ebdc0649c2fe969356b90a445a391195fdeae461fbbd9a917dab7687e090465addcb2dbb285b36
+    commit: a6c49f84cc0f4e038680d390392e2ab0
+    digest: shake256:3deb629c655e469d87c58babcfbed403275a741fb4a269366c4fd6ea9db012cf562a1e64819508d73670c506f96d01f724c43bc97b44e2e02aa6e8bbdd160ab2
   - remote: buf.build
     owner: googleapis
     repository: googleapis
-    commit: 28151c0d0a1641bf938a7672c500e01d
-    digest: shake256:49215edf8ef57f7863004539deff8834cfb2195113f0b890dd1f67815d9353e28e668019165b9d872395871eeafcbab3ccfdb2b5f11734d3cca95be9e8d139de
+    commit: 2bbd25900cb34c79bae97d85c948d3cf
+    digest: shake256:a6446e23f4408160217c22738a0c8c370ff3ff966f601d678960b803829cf53b5cf5998d20fcb3f9c9be944b24337843e7beb6e681ddbf9d036fb6491c0e47e7

examples/cel_repeated_field_transform_and_unique.proto

@@ -0,0 +1,44 @@
+// Copyright 2023 Buf Technologies, Inc.
+//
+// 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.
+
+syntax = "proto3";
+
+import "buf/validate/validate.proto";
+
+message Author {
+  string name = 1;
+}
+
+message Book {
+  repeated string genres = 1 [(buf.validate.field).cel = {
+    id: "book_unique_genre"
+    message: "a genre cannot appear twice in the same book"
+    // `unique()` evaluates to whether each element in a list is unique.
+    //
+    // In this case, the expression validates that genres are unique.
+    expression: "this.unique()"
+  }];
+
+  repeated Author authors = 2 [(buf.validate.field).cel = {
+    id: "book_unique_authors"
+    message: "a name cannot appear twice in authors"
+    // `some_list.map(x, expression_x)` transforms list [x1, x2, ...] into [expression-x1, expression-x2, ...].
+    // In this case, the list of authors is transformed into the list of author names.
+    //
+    // `unique()` evaluates to whether each element in a list is unique.
+    //
+    // In this case, the expression validates that names in the list of authors are unique.
+    expression: "this.map(author, author.name).unique()"
+  }];
+}