Merge pull request #481 from lautis/lateral

Lateral expressions for PostgreSQL

2 files changed, 19 insertions, 0 deletions

diff --git a/lib/arel/visitors/depth_first.rb b/lib/arel/visitors/depth_first.rb
index 5416a285f5..b3bbc9bd40 100644
--- a/lib/arel/visitors/depth_first.rb
+++ b/lib/arel/visitors/depth_first.rb
@@ -25,6 +25,7 @@ module Arel
       alias :visit_Arel_Nodes_GroupingElement   :unary
       alias :visit_Arel_Nodes_Grouping          :unary
       alias :visit_Arel_Nodes_Having            :unary
+      alias :visit_Arel_Nodes_Lateral           :unary
       alias :visit_Arel_Nodes_Limit             :unary
       alias :visit_Arel_Nodes_Not               :unary
       alias :visit_Arel_Nodes_Offset            :unary
diff --git a/lib/arel/visitors/postgresql.rb b/lib/arel/visitors/postgresql.rb
index 2a935e4318..047f71aaa6 100644
--- a/lib/arel/visitors/postgresql.rb
+++ b/lib/arel/visitors/postgresql.rb
@@ -5,6 +5,7 @@ module Arel
       CUBE = 'CUBE'
       ROLLUP = 'ROLLUP'
       GROUPING_SET = 'GROUPING SET'
+      LATERAL = 'LATERAL'
 
       private
 
@@ -69,6 +70,23 @@ module Arel
         grouping_array_or_grouping_element o, collector
       end
 
+      def visit_Arel_Nodes_Lateral o, collector
+        collector << LATERAL
+        collector << SPACE
+        grouping_parentheses o, 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