Use a single FacterDB.get_facts call

The major cost is FacterDB.get_facts. Instead of calling it once for
every OS version this instead calls it once with a complex filter. It
then uses JGrep to simulate another smaller DB and futher query that.

In my non-scientific test this reduces the load time of puppet-example
from 3.5 to 2.5 seconds.

lib/rspec-puppet-facts.rb

@@ -113,13 +113,20 @@ def on_supported_os_implementation(opts = {})
     loose_requirement = RspecPuppetFacts.facter_version_to_loose_requirement(facterversion)
     received_facts = []
 
+    db = FacterDB.get_facts(filter, symbolize_keys: false)
+    unless db.any?
+      RspecPuppetFacts.warning "No facts were found in the FacterDB for: #{filter.inspect}"
+      return {}
+    end
+
     # FacterDB may have newer versions of facter data for which it contains a subset of all possible
     # facter data (see FacterDB 0.5.2 for Facter releases 3.8 and 3.9). In this situation we need to
     # cycle through and downgrade Facter versions per platform type until we find matching Facter data.
-    facterversion_key = RSpec.configuration.facterdb_string_keys ? 'facterversion' : :facterversion
+    json_db = db.to_json
     filter.each do |filter_spec|
-      versions = FacterDB.get_facts(filter_spec, symbolize_keys: !RSpec.configuration.facterdb_string_keys).to_h do |facts|
-        [Gem::Version.new(facts[facterversion_key]), facts]
+      versions = JGrep.jgrep(json_db, FacterDB.generate_filter_str(filter_spec)).to_h do |facts|
+        result = RSpec.configuration.facterdb_string_keys ? facts : facts.transform_keys(&:to_sym)
+        [Gem::Version.new(facts['facterversion']), result]
       end
 
       version, facts = versions.select { |v, _f| strict_requirement =~ v }.max_by { |v, _f| v }

spec/rspec_puppet_facts_spec.rb

@@ -610,13 +610,13 @@
       end
 
       it 'escapes the parens in the filter' do
-        filter = {
+        filter = [{
           'os.name' => 'IOS',
           'os.release.full' => '/^12\\.2\\(25\\)EWA9/',
           'os.hardware' => 'x86_64',
-        }
+        }]
 
-        expect(FacterDB).to receive(:get_facts).with(filter, symbolize_keys: true).once
+        expect(FacterDB).to receive(:get_facts).with(filter, symbolize_keys: false).once.and_return([])
         subject
       end
 
@@ -742,11 +742,14 @@
       end
 
       before do
-        allow(FacterDB).to receive(:get_facts).and_call_original
         allow(FacterDB).to receive(:get_facts).with(
-          { 'os.name' => 'CentOS', 'os.release.full' => '/^9/', 'os.hardware' => 'x86_64' }, symbolize_keys: true
-        ).and_wrap_original do |m, *args|
-          m.call(*args).reject { |facts| facts[:facterversion].start_with?('4.6.') }
+          [
+            { 'os.name' => 'CentOS', 'os.release.full' => '/^9/', 'os.hardware' => 'x86_64' },
+            { 'os.name' => 'Debian', 'os.release.full' => '/^12/', 'os.hardware' => 'x86_64' },
+          ],
+          symbolize_keys: false,
+        ).and_wrap_original do |m, *args, **kwargs|
+          m.call(*args, **kwargs).reject { |facts| facts.dig('os', 'name') == 'CentOS' && facts['facterversion'].start_with?('4.6.') }
         end
       end