PgQuery.parse: Support complex queries with deeply nested ASTs

Requires at least google-protobuf v3.20.0, if using older releases this
change has no effect. To avoid complex dependency updates, we do not
require google-protobuf to be current when you use this library, so you
may want to pin it to the newer version if you depend on this behaviour.

Fixes #209

Gemfile.lock

@@ -9,7 +9,7 @@ GEM
   specs:
     ast (2.4.1)
     diff-lcs (1.3)
-    google-protobuf (3.19.4)
+    google-protobuf (3.20.0)
     parallel (1.20.1)
     parser (2.7.2.0)
       ast (~> 2.4.1)

lib/pg_query/parse.rb

@@ -3,7 +3,13 @@ def self.parse(query)
     result, stderr = parse_protobuf(query)
 
     begin
-      result = PgQuery::ParseResult.decode(result)
+      result = if PgQuery::ParseResult.method(:decode).arity == 1
+                 PgQuery::ParseResult.decode(result)
+               elsif PgQuery::ParseResult.method(:decode).arity == -1
+                 PgQuery::ParseResult.decode(result, recursion_limit: 1_000)
+               else
+                 raise ArgumentError, 'Unsupported protobuf Ruby API'
+               end
     rescue Google::Protobuf::ParseError => e
       raise PgQuery::ParseError.new(format('Failed to parse tree: %s', e.message), __FILE__, __LINE__, -1)
     end

spec/lib/parse_spec.rb

@@ -71,20 +71,15 @@
     end)
   end
 
-  it 'returns parser error due to too much nesting' do
+  it 'parses really deep queries' do
     # Old JSON test that was kept for Protobuf version (queries like this have not been seen in the real world)
     query_text = 'SELECT a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(a(b))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))'
-    expect { described_class.parse(query_text) }.to(raise_error do |error|
-      expect(error).to be_a(PgQuery::ParseError)
-      expect(error.message).to start_with 'Failed to parse tree'
-    end)
+    query = described_class.parse(query_text)
+    expect(query.tree).not_to be_nil
+    expect(query.tables).to eq []
   end
 
-  it 'returns parser error due to too much nesting (2)' do
-    # Protobuf Ruby supports a maximum message depth of 64 by default, and the
-    # ability to increase this is currently not exposed in the Ruby API:
-    # https://github.com/protocolbuffers/protobuf/issues/1493
-    #
+  it 'parses really deep queries (2)' do
     # Queries like this are uncommon, but have been seen in the real world.
     query_text = 'SELECT * FROM "t0"
     JOIN "t1" ON (1) JOIN "t2" ON (1) JOIN "t3" ON (1) JOIN "t4" ON (1) JOIN "t5" ON (1)
@@ -93,10 +88,16 @@
     JOIN "t16" ON (1) JOIN "t17" ON (1) JOIN "t18" ON (1) JOIN "t19" ON (1) JOIN "t20" ON (1)
     JOIN "t21" ON (1) JOIN "t22" ON (1) JOIN "t23" ON (1) JOIN "t24" ON (1) JOIN "t25" ON (1)
     JOIN "t26" ON (1) JOIN "t27" ON (1) JOIN "t28" ON (1) JOIN "t29" ON (1)'
-    expect { described_class.parse(query_text) }.to(raise_error do |error|
-      expect(error).to be_a(PgQuery::ParseError)
-      expect(error.message).to start_with 'Failed to parse tree'
-    end)
+    query = described_class.parse(query_text)
+    expect(query.tree).not_to be_nil
+    expect(query.tables).to eq (2..29).to_a.map {|i| "t#{i}" }.reverse + ['t0', 't1']
+  end
+
+  it 'parses really deep queries (3)' do
+    query_text = 'SELECT * FROM foo ' + (1..100).to_a.map { |i| "JOIN foo_#{i} ON foo.id = foo_#{i}.foo_id" }.join(' ')
+    query = described_class.parse(query_text)
+    expect(query.tree).not_to be_nil
+    expect(query.tables).to eq (2..100).to_a.map {|i| "foo_#{i}" }.reverse + ['foo', 'foo_1']
   end
 
   it "parses real queries" do