1 files changed, 81 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/utils.rb b/activerecord/lib/active_record/connection_adapters/postgresql/utils.rb
new file mode 100644
index 0000000000..f2f4701500
--- /dev/null
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/utils.rb
@@ -0,0 +1,81 @@
+# frozen_string_literal: true
+
+module ActiveRecord
+  module ConnectionAdapters
+    module PostgreSQL
+      # Value Object to hold a schema qualified name.
+      # This is usually the name of a PostgreSQL relation but it can also represent
+      # schema qualified type names. +schema+ and +identifier+ are unquoted to prevent
+      # double quoting.
+      class Name # :nodoc:
+        SEPARATOR = "."
+        attr_reader :schema, :identifier
+
+        def initialize(schema, identifier)
+          @schema, @identifier = unquote(schema), unquote(identifier)
+        end
+
+        def to_s
+          parts.join SEPARATOR
+        end
+
+        def quoted
+          if schema
+            PG::Connection.quote_ident(schema) << SEPARATOR << PG::Connection.quote_ident(identifier)
+          else
+            PG::Connection.quote_ident(identifier)
+          end
+        end
+
+        def ==(o)
+          o.class == self.class && o.parts == parts
+        end
+        alias_method :eql?, :==
+
+        def hash
+          parts.hash
+        end
+
+        protected
+
+          def parts
+            @parts ||= [@schema, @identifier].compact
+          end
+
+        private
+          def unquote(part)
+            if part && part.start_with?('"')
+              part[1..-2]
+            else
+              part
+            end
+          end
+      end
+
+      module Utils # :nodoc:
+        extend self
+
+        # Returns an instance of <tt>ActiveRecord::ConnectionAdapters::PostgreSQL::Name</tt>
+        # extracted from +string+.
+        # +schema+ is +nil+ if not specified in +string+.
+        # +schema+ and +identifier+ exclude surrounding quotes (regardless of whether provided in +string+)
+        # +string+ supports the range of schema/table references understood by PostgreSQL, for example:
+        #
+        # * <tt>table_name</tt>
+        # * <tt>"table.name"</tt>
+        # * <tt>schema_name.table_name</tt>
+        # * <tt>schema_name."table.name"</tt>
+        # * <tt>"schema_name".table_name</tt>
+        # * <tt>"schema.name"."table name"</tt>
+        def extract_schema_qualified_name(string)
+          schema, table = string.scan(/[^".]+|"[^"]*"/)
+          if table.nil?
+            table = schema
+            schema = nil
+          end
+          PostgreSQL::Name.new(schema, table)
+        end
+      end
+    end
+  end
+end