Moves column dump specific code to a module included in AbstractAdapter

Having column related schema dumper code in the AbstractAdapter. The
code remains the same, but by placing it in the AbstractAdapter, we can
then overwrite it with Adapter specific methods that will help with
Adapter specific data types.

The goal of moving this code here is to create a new migration key for
PostgreSQL's array type. Since any datatype can be an array, the goal is
to have ':array => true' as a migration option, turning the datatype
into an array. I've implemented this in postgres_ext, the syntax is
shown here: https://github.com/dockyard/postgres_ext#arrays

Adds array migration support

Adds array_test.rb outlining the test cases for array data type
Adds pg_array_parser to Gemfile for testing
Adds pg_array_parser to postgresql_adapter (unused in this commit)

Adds schema dump support for arrays

Adds postgres array type casting support

Updates changelog, adds note for inet and cidr support, which I forgot to add before

Removing debugger, Adds pg_array_parser to JRuby platform

Removes pg_array_parser requirement, creates ArrayParser module used by
PostgreSQLAdapter

1 files changed, 97 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/array_parser.rb b/activerecord/lib/active_record/connection_adapters/postgresql/array_parser.rb
new file mode 100644
index 0000000000..b7d24f2bb3
--- /dev/null
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/array_parser.rb
@@ -0,0 +1,97 @@
+module ActiveRecord
+  module ConnectionAdapters
+    class PostgreSQLColumn < Column
+      module ArrayParser
+        private
+          # Loads pg_array_parser if available. String parsing can be
+          # performed quicker by a native extension, which will not create
+          # a large amount of Ruby objects that will need to be garbage
+          # collected. pg_array_parser has a C and Java extension
+          begin
+            require 'pg_array_parser'
+            include PgArrayParser
+          rescue LoadError
+            def parse_pg_array(string)
+              parse_data(string, 0)
+            end
+          end
+
+          def parse_data(string, index)
+            local_index = index
+            array = []
+            while(local_index < string.length)
+              case string[local_index]
+              when '{'
+                local_index,array = parse_array_contents(array, string, local_index + 1)
+              when '}'
+                return array
+              end
+              local_index += 1
+            end
+
+            array
+          end
+
+          def parse_array_contents(array, string, index)
+            is_escaping = false
+            is_quoted = false
+            was_quoted = false
+            current_item = ''
+
+            local_index = index
+            while local_index
+              token = string[local_index]
+              if is_escaping
+                current_item << token
+                is_escaping = false
+              else
+                if is_quoted
+                  case token
+                  when '"'
+                    is_quoted = false
+                    was_quoted = true
+                  when "\\"
+                    is_escaping = true
+                  else
+                    current_item << token
+                  end
+                else
+                  case token
+                  when "\\"
+                    is_escaping = true
+                  when ','
+                    add_item_to_array(array, current_item, was_quoted)
+                    current_item = ''
+                    was_quoted = false
+                  when '"'
+                    is_quoted = true
+                  when '{'
+                    internal_items = []
+                    local_index,internal_items = parse_array_contents(internal_items, string, local_index + 1)
+                    array.push(internal_items)
+                  when '}'
+                    add_item_to_array(array, current_item, was_quoted)
+                    return local_index,array
+                  else
+                    current_item << token
+                  end
+                end
+              end
+
+              local_index += 1
+            end
+            return local_index,array
+          end
+
+          def add_item_to_array(array, current_item, quoted)
+            if current_item.length == 0
+            elsif !quoted && current_item == 'NULL'
+              array.push nil
+            else
+              array.push current_item
+            end
+          end
+      end
+    end
+  end
+end