Data Transformation - Transformational Languages

Transformational Languages

There are numerous languages available for performing data transformation. Many transformation languages require a grammar to be provided. In many cases the grammar is structured using something closely resembling Backus–Naur Form (BNF). There are numerous languages available for such purposes varying in their accessibility (cost) and general usefulness. Examples of such languages include:

• AWK - one of the oldest and popular TXT data transform language;
• Perl - a high-level language with both procedural and object-oriented syntax capable of powerful operations on binary or text data.
• Template languages - specialized for transform data into documents (see also template processor);
• TXL - prototyping language-based descriptions, used for source code or data transformation.
• XSLT - the standard XML data transformation language (suitable by XQuery in many applications);

Although transformational languages are typically best suited for transformation, something as simple as regular expressions can be used to achieve useful transformation. A text editor like emacs or Textpad supports the use of regular expressions with arguments. This would allow all instances of a particular pattern to be replaced with another pattern using parts of the original pattern. For example:

foo ("some string", 42, gCommon); bar (someObj, anotherObj); foo ("another string", 24, gCommon); bar (myObj, myOtherObj);

could both be transformed into a more compact form like:

foobar("some string", 42, someObj, anotherObj); foobar("another string", 24, myObj, myOtherObj);

In other words, all instances of a function invocation of foo with three arguments, followed by a function invocation with two invocations would be replaced with a single function invocation using some or all of the original set of arguments.

Another advantage to using regular expressions is that they will not fail the null transform test. That is, using your transformational language of choice, run a sample program through a transformation that doesn't perform any transformations. Many transformational languages will fail this test.