Improve deparsing of OVERLAY keyword function (#161)

lib/pg_query/deparse.rb

@@ -413,11 +413,17 @@ def deparse_funccall(node)
       # COUNT(*)
       args << '*' if node['agg_star']
 
-      name = (node['funcname'].map { |n| deparse_item(n, FUNC_CALL) } - ['pg_catalog']).join('.')
-      distinct = node['agg_distinct'] ? 'DISTINCT ' : ''
-      output << format('%s(%s%s)', name, distinct, args.join(', '))
-      output << format('FILTER (WHERE %s)', deparse_item(node['agg_filter'])) if node['agg_filter']
-      output << format('OVER %s', deparse_item(node['over'])) if node['over']
+      name = (node['funcname'].map { |n| deparse_item(n, FUNC_CALL) }).join('.')
+      if name == 'pg_catalog.overlay'
+        # Note that this is a bit odd, but "OVERLAY" is a keyword on its own merit, and only accepts the
+        # keyword parameter style when its called as a keyword, not as a regular function (i.e. pg_catalog.overlay)
+        output << format('OVERLAY(%s PLACING %s FROM %s FOR %s)', args[0], args[1], args[2], args[3])
+      else
+        distinct = node['agg_distinct'] ? 'DISTINCT ' : ''
+        output << format('%s(%s%s)', name, distinct, args.join(', '))
+        output << format('FILTER (WHERE %s)', deparse_item(node['agg_filter'])) if node['agg_filter']
+        output << format('OVER %s', deparse_item(node['over'])) if node['over']
+      end
 
       output.join(' ')
     end

spec/lib/pg_query/deparse_spec.rb

@@ -169,6 +169,12 @@
         it { is_expected.to eq oneline_query }
       end
 
+      context 'OVERLAY' do
+        let(:query) { 'SELECT OVERLAY("m"."name" PLACING \'******\' FROM 3 FOR 6) AS tc_kimlik FROM "tb_test" m' }
+
+        it { is_expected.to eq query }
+      end
+
       context 'SUM' do
         let(:query) { 'SELECT sum("price_cents") FROM "products"' }