1 files changed, 116 insertions, 0 deletions
diff --git a/activerecord/lib/arel/visitors/postgresql.rb b/activerecord/lib/arel/visitors/postgresql.rb
new file mode 100644
index 0000000000..920776b4dc
--- /dev/null
+++ b/activerecord/lib/arel/visitors/postgresql.rb
@@ -0,0 +1,116 @@
+# frozen_string_literal: true
+
+module Arel # :nodoc: all
+  module Visitors
+    class PostgreSQL < Arel::Visitors::ToSql
+      CUBE = "CUBE"
+      ROLLUP = "ROLLUP"
+      GROUPING_SETS = "GROUPING SETS"
+      LATERAL = "LATERAL"
+
+      private
+
+        def visit_Arel_Nodes_Matches(o, collector)
+          op = o.case_sensitive ? " LIKE " : " ILIKE "
+          collector = infix_value o, collector, op
+          if o.escape
+            collector << " ESCAPE "
+            visit o.escape, collector
+          else
+            collector
+          end
+        end
+
+        def visit_Arel_Nodes_DoesNotMatch(o, collector)
+          op = o.case_sensitive ? " NOT LIKE " : " NOT ILIKE "
+          collector = infix_value o, collector, op
+          if o.escape
+            collector << " ESCAPE "
+            visit o.escape, collector
+          else
+            collector
+          end
+        end
+
+        def visit_Arel_Nodes_Regexp(o, collector)
+          op = o.case_sensitive ? " ~ " : " ~* "
+          infix_value o, collector, op
+        end
+
+        def visit_Arel_Nodes_NotRegexp(o, collector)
+          op = o.case_sensitive ? " !~ " : " !~* "
+          infix_value o, collector, op
+        end
+
+        def visit_Arel_Nodes_DistinctOn(o, collector)
+          collector << "DISTINCT ON ( "
+          visit(o.expr, collector) << " )"
+        end
+
+        def visit_Arel_Nodes_BindParam(o, collector)
+          collector.add_bind(o.value) { |i| "$#{i}" }
+        end
+
+        def visit_Arel_Nodes_GroupingElement(o, collector)
+          collector << "( "
+          visit(o.expr, collector) << " )"
+        end
+
+        def visit_Arel_Nodes_Cube(o, collector)
+          collector << CUBE
+          grouping_array_or_grouping_element o, collector
+        end
+
+        def visit_Arel_Nodes_RollUp(o, collector)
+          collector << ROLLUP
+          grouping_array_or_grouping_element o, collector
+        end
+
+        def visit_Arel_Nodes_GroupingSet(o, collector)
+          collector << GROUPING_SETS
+          grouping_array_or_grouping_element o, collector
+        end
+
+        def visit_Arel_Nodes_Lateral(o, collector)
+          collector << LATERAL
+          collector << SPACE
+          grouping_parentheses o, collector
+        end
+
+        def visit_Arel_Nodes_IsNotDistinctFrom(o, collector)
+          collector = visit o.left, collector
+          collector << " IS NOT DISTINCT FROM "
+          visit o.right, collector
+        end
+
+        def visit_Arel_Nodes_IsDistinctFrom(o, collector)
+          collector = visit o.left, collector
+          collector << " IS DISTINCT FROM "
+          visit o.right, collector
+        end
+
+        # Used by Lateral visitor to enclose select queries in parentheses
+        def grouping_parentheses(o, collector)
+          if o.expr.is_a? Nodes::SelectStatement
+            collector << "("
+            visit o.expr, collector
+            collector << ")"
+          else
+            visit o.expr, collector
+          end
+        end
+
+        # Utilized by GroupingSet, Cube & RollUp visitors to
+        # handle grouping aggregation semantics
+        def grouping_array_or_grouping_element(o, collector)
+          if o.expr.is_a? Array
+            collector << "( "
+            visit o.expr, collector
+            collector << " )"
+          else
+            visit o.expr, collector
+          end
+        end
+    end
+  end
+end