Refactor `SchemaDumper` to make it possible to adapter specific customization

Currently `SchemaDumper` is only customizable for column options. But
3rd party connection adapters (oracle-enhanced etc) need to customizable
for table or index dumping also. To make it possible, I introduced
adapter specific `SchemaDumper` classes for that.

2 files changed, 16 insertions, 9 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/mysql/schema_dumper.rb b/activerecord/lib/active_record/connection_adapters/mysql/schema_dumper.rb
index d5198a6dba..95eb77aea4 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql/schema_dumper.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql/schema_dumper.rb
@@ -3,13 +3,13 @@
 module ActiveRecord
   module ConnectionAdapters
     module MySQL
-      module ColumnDumper # :nodoc:
+      class SchemaDumper < ConnectionAdapters::SchemaDumper # :nodoc:
         private
           def prepare_column_options(column)
             spec = super
             spec[:unsigned] = "true" if column.unsigned?
 
-            if supports_virtual_columns? && column.virtual?
+            if @connection.supports_virtual_columns? && column.virtual?
               spec[:as] = extract_expression_for_virtual_column(column)
               spec[:stored] = "true" if /\b(?:STORED|PERSISTENT)\b/.match?(column.extra)
               spec = { type: schema_type(column).inspect }.merge!(spec)
@@ -44,24 +44,27 @@ module ActiveRecord
           def schema_collation(column)
             if column.collation && table_name = column.table_name
               @table_collation_cache ||= {}
-              @table_collation_cache[table_name] ||= exec_query("SHOW TABLE STATUS LIKE #{quote(table_name)}", "SCHEMA").first["Collation"]
+              @table_collation_cache[table_name] ||=
+                @connection.exec_query("SHOW TABLE STATUS LIKE #{@connection.quote(table_name)}", "SCHEMA").first["Collation"]
               column.collation.inspect if column.collation != @table_collation_cache[table_name]
             end
           end
 
           def extract_expression_for_virtual_column(column)
-            if mariadb? && version < "10.2.5"
-              create_table_info = create_table_info(column.table_name)
-              if %r/#{quote_column_name(column.name)} #{Regexp.quote(column.sql_type)}(?: COLLATE \w+)? AS \((?<expression>.+?)\) #{column.extra}/ =~ create_table_info
+            if @connection.mariadb? && @connection.version < "10.2.5"
+              create_table_info = @connection.send(:create_table_info, column.table_name)
+              column_name = @connection.quote_column_name(column.name)
+              if %r/#{column_name} #{Regexp.quote(column.sql_type)}(?: COLLATE \w+)? AS \((?<expression>.+?)\) #{column.extra}/ =~ create_table_info
                 $~[:expression].inspect
               end
             else
-              scope = quoted_scope(column.table_name)
+              scope = @connection.send(:quoted_scope, column.table_name)
+              column_name = @connection.quote(column.name)
               sql = "SELECT generation_expression FROM information_schema.columns" \
                     " WHERE table_schema = #{scope[:schema]}" \
                     "   AND table_name = #{scope[:name]}" \
-                    "   AND column_name = #{quote(column.name)}"
-              query_value(sql, "SCHEMA").inspect
+                    "   AND column_name = #{column_name}"
+              @connection.query_value(sql, "SCHEMA").inspect
             end
           end
       end
diff --git a/activerecord/lib/active_record/connection_adapters/mysql/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/mysql/schema_statements.rb
index 7bebe82065..759493e3bd 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql/schema_statements.rb
@@ -66,6 +66,10 @@ module ActiveRecord
           MySQL::Table.new(table_name, base)
         end
 
+        def create_schema_dumper(options)
+          MySQL::SchemaDumper.create(self, options)
+        end
+
         private
           CHARSETS_OF_4BYTES_MAXLEN = ["utf8mb4", "utf16", "utf16le", "utf32"]