Implementing Language Extensions with Model Transformations

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Implementing Language Extensions with Model
Transformations Ivan Kurtev Software
Engineering Group University of Twente the
Netherlands
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Outline

• The Role of Languages in MDE
• Language Elements
• Language Extensions
• Examples
• Language composition
• Abstract syntax extension
• Conclusions

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Use of Languages in MDE

• Languages for expressing models

• Meta-modeling modeling of languages
• Transformation languages

Can we use MDE techniques to solve language
design problems?
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Language Elements

• Concrete Syntax
• Related to parsing
• Textual, visual
• Abstract Syntax (L)
• Defines the structures represented by the
  concrete syntax
• Semantics
• Semantic Domain (D)
• Semantic Mapping (M)
• M L -gt D

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Language Extensions

• Syntax Extensions
• Extensible grammars
• Extensible parsers
• Macro definitions
• Semantic Extensions
• Modular attribute grammars
• Monads
• Action semantics
• Language Composition
• Involves syntax and semantic extensions

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Language Elements in MDA Terms (1)

• Concrete Syntax ?
• Abstract Syntax (L)
• Defined as a meta-model
• Semantics
• Semantic Domain (D) a model
• Semantic Mapping (M) a model transformation
• M L -gt D

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Language Elements in MDA Terms (2)

• How can MDA techniques be used for language
  design tasks?
• What do we gain (do we do better than the current
  techniques) ?
• How are traditional problems solved in MDA?
• Language reuse
• Language composition
• Language extension

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Example 1 Composing XML Languages

• Application-specific XML processing

XMLDocument
DOM Parser
Processing Code
DOM Tree
Application Objects
Transformation

• Transformation from XML document to application
  objects
• XML Language Composition
• Concrete syntax composition is solved
• Semantic mapping composition of transformations
• Semantic domain software composition
• Application hybrid XML languages and compound
  documents

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Transformation Pattern for XML Processing

• Schema-less processing based on DOM
• Schema-based processing an XML schema and DOM
  are available

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Structure of XML Applications

• Separation of concerns
• Syntax (schema)
• Processing logic (transformation specification)
• Application classes (semantic domain)

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Example (1)

• Processing of a subset of SMIL timing module
• Source schema

ltattribute namebegin typestring/gt ltattribute
nameend typestring/gt ltattribute namedur
typestring/gt ltattribute nametimeContainer
typestring/gt

• Example of a timed document

lta timeContainerseq begin1 dur20gt ltb
timeContainerpar dur10gt ltc
timeContainernone dur10/gt ltd
timeContainernone dur10/gt lt/bgt lte
timeContainernone dur10/gt lt/agt
SMIL Synchronized Multimedia Integration
Language
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Example (2)

• Target Application Classes

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Composition of XML Languages

• A new language may be composed with the timing
  module

• New processor is obtained via
• Composing target application classes (software
  composition)
• Composing transformation definitions (based on
  the transformation language constructs)

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Example 2 Abstract Syntax Extensions

• Problem
• what if a transformation language does not
  support required compositional operators?

• Possible Solutions
• Compose transformation definitions by applying a
  transformation
• Extend the transformation language with new
  constructs
• Example
• Extending the abstract syntax of a language

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Example 2 Implementation

• Extended syntax is transformed to the initial
  syntax

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Sequential Composition of Extensions
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Conclusions

• Examples of applicability of MDA techniques
• Composition of XML languages
• Abstract syntax extension
• Open Questions
• Are model transformations suitable for defining
  semantic mappings?
• For which type of languages?
• Scalability in case of language composition?
• Comparison to other techniques (attribute
  grammars, action semantics,)