Big Data Technologies and Applications by Borko Furht & Flavio Villanustre

Author:Borko Furht & Flavio Villanustre
Language: eng
Format: epub
Publisher: Springer International Publishing, Cham

Parsing

The sources for an ECL program can come from a local directory tree, an external repository, or a single-source archive. The ECL compiler reads the ECL source, parses it, and converts it into an abstract graph representation of the program. The representation is then normalized to resolve ambiguities and ensure is it is suitable for subsequent processing. All of the subsequent operations within the compiler work on, and create, this same abstract representation.

Optimizations

The design of the ECL language provides abundant scope for optimizations. When reusable attributes are combined it often creates the scope for optimizations that would be hard, if not impossible, to be spotted by a programmer. Its declarative design allows many optimizations without the concerns about side-effects associated with imperative languages. Many different optimizations are performed on the program, some of the key ones are: Constant folding. This includes simple purely constant expressions like 12 * 3 => 36, and more complex changes e.g. IF(a, ‘b’, ‘c’) IN [‘a’,‘c’] => NOT a

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