Datatype DSL

Purpose

The Datatype DSL is, beside the Entity DSL, one of the most basic DSL for the Software Factory. It provides you with the most common used basic (atomic) datatypes by mapping them. It also allows you to define new simple and complex datatypes, to be used in all your projects. You will find here a couple of informations to help you understand how to use it.

Overview

The main semantic elements of the Compex Datatype DSL are the following:

• "Import" declarations - used to import external Java classes.

• "Package" - the root element that contains all the other elements. A model can contain multiple packages.

• "Datatype" declarations - the way to define datatypes that can be used in entities and beans.

• "Enum" - the abstraction for Java enums.

The Datatype DSL as such is working under the hood of your application's entity model by providing acces to datatypes (Number, String, Boolean...). The figure below represents straightforward how the grammar was designed in order to make it possible for you to use and also create your own datatypes. This is the structural foundation, on which the Datatype DSL model is based on.

Figure 1: Grammar Definition

Figure 2: Grammar Definition - Detailed View 1

Figure 3: Grammar Definition - Detailed View 2

Datatypes Model Files

Datatype DSL model files end with the .datatype extension. Datatype models may be split into several .datatype files, as long as they have the same package declaration.

Reserved Keywords

In the following we will dive deeper into the description and the usage of datatype related and reserved keywords.

package

Datatype model files must start with a package declaration. Packages are the root element of the Datatype DSL grammar. Everything is contained in a package: Datatypes and Enums have to be defined inside the Package definition. One document can contain multiple packages with unique names.

  import importStatement;

  package name {
     datatype datatypeDefinition
     enums enumDefinition
  }

File:DatatypePackage.png

Figure 4 - Datatype model file

import

Although Import-Statements are located above the package declaration, they are optional as you may not necessarely need to reference any external Java Classes to extend the your datatype definitions. Using an import statement is a way to make these elements available in the current namespace without having to address them by their fully qualified name.

Import statements allow the use of the '*' wildcard.

	import importStatement

File:DatatypeImport.png

Figure 5: Items (Java Classes) contained in another package can be addressed if the package is imported using the import keyword and its fully qualified name.

datatype

The Datatype DSL allows the definition of datatypes. These are translated by the inferrer into their standard Java representation. The behavior of the generator can be controlled by the datatype definitions. Datatypes defined in an .datatype file are local to that file.

There are three types of datatype definitions:

jvmType

Datatype definitons that map types to jvmType take the basic syntax of

 datatype <name> jvmType <type> asPrimitive

Specifying datatypes in this manner uses an appropriate wrapper class in the generated Java code; adding the keywords asPrimitive enforces the use of primitive datatypes where applicable:

datatype foo jvmType Integer

compiles to an Integer whereas

datatype foo jvmType Integer asPrimitive

results in int.

Figure 6: The defined datatype is translated to a wrapper class

Figure 7: By adding the asPrimitive keywords, the datatype is translated to a primitive datatype

dateType

The datatypes for handling temporal information can be defined by the following statement:

datatype <name> dateType {date|time|timestamp}

Datatypes that have been defined in this manner can be used as property variables in entities and beans.

Figure 8: Defining datatypes for handling temporal information. Content assist is available.

asBlob

Binary blobs can be handled by defining a datatype with the asBlob keywords. The Java implementation of such a blob is a byte array. Appropriate persistence annotations are automatically added.

datatype <name> asBlob

File:DatatypeBlob.png

Figure 9: Including binary blobs by using a datatype with the asBlob keywords

After datatype definitions, the content of the .datatype file can be extended with enum definitions.

enum

Enumerations can be handled by defining a slightly different datatype with the enum keywords. The Java implementation of such a enum is exactly the same.

enum <name>  { <Value1> [, <Value2>]* }

File:DatatypeEnum.png

Figure 10: Defining an Enumeration with enum keyword.

Custom Datatypes

In this section you will find some informations about the available custom datatypes (OSBEE).

BlobMapping

This datatype allows the use of big data as a blob.

Disclaimer / Notice

A small notice/disclaimer about the how it is used in other DSLs...

How to use existing and newly created Datatypes? => The same way it is used in the Entity DSL, Entitymock DSL and the Function Library DSL with the import keyword.

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