ruby: add CEL example

Gemfile

@@ -2,10 +2,12 @@
 
 source 'https://rubygems.org'
 
+gem 'cel', '~> 0.2.3'
 gem 'erb', '~> 4.0'
+gem 'google-protobuf', '~> 4.27'
 gem 'haml', '~> 5.2'
-gem 'rspec-its'
 gem 'rspec', '~> 3.13.0'
+gem 'rspec-its'
 gem 'slim', '~> 5.0'
 
 gem 'rubocop', require: false

Gemfile.lock

@@ -2,10 +2,21 @@ GEM
   remote: https://rubygems.org/
   specs:
     ast (2.4.2)
+    bigdecimal (3.1.8)
+    cel (0.2.3)
     cgi (0.3.6)
     diff-lcs (1.5.1)
     erb (4.0.4)
       cgi (>= 0.3.3)
+    google-protobuf (4.27.1-arm64-darwin)
+      bigdecimal
+      rake (>= 13)
+    google-protobuf (4.27.1-x86_64-darwin)
+      bigdecimal
+      rake (>= 13)
+    google-protobuf (4.27.1-x86_64-linux)
+      bigdecimal
+      rake (>= 13)
     haml (5.2.2)
       temple (>= 0.8.0)
       tilt
@@ -17,6 +28,7 @@ GEM
       racc
     racc (1.8.0)
     rainbow (3.1.1)
+    rake (13.2.1)
     regexp_parser (2.9.2)
     rexml (3.3.0)
       strscan
@@ -69,7 +81,9 @@ PLATFORMS
   x86_64-linux
 
 DEPENDENCIES
+  cel (~> 0.2.3)
   erb (~> 4.0)
+  google-protobuf (~> 4.27)
   haml (~> 5.2)
   rspec (~> 3.13.0)
   rspec-its
@@ -78,4 +92,4 @@ DEPENDENCIES
   slim (~> 5.0)
 
 BUNDLED WITH
-   2.5.3
+   2.5.11

src/ruby/cel/BUILD.bazel

@@ -0,0 +1,10 @@
+load("@rules_ruby//ruby:defs.bzl", "rb_binary", "rb_test")
+
+rb_binary(
+    name = "cel",
+    srcs = ["cel.rb"],
+    main = "cel.rb",
+    deps = [
+        "@bundle",
+    ],
+)

src/ruby/cel/cel.rb

@@ -0,0 +1,19 @@
+require "cel"
+
+env = Cel::Environment.new(name: :string, group: :string)
+
+begin
+  ast = env.compile('name.startsWith("/groups/" + group)') #=> Cel::Types[:bool], which is == :bool
+rescue Cel::Error => e
+  STDERR.puts("type-check error: #{e.message}")
+  raise e
+end
+
+prg = env.program(ast)
+
+return_value = prg.evaluate(
+  name: Cel::String.new("/groups/acme.co/documents/secret-stuff"),
+  group: Cel::String.new("acme.co"),
+)
+
+puts return_value #=> true