Synopsis a symbolic representation for abstract syntax trees of programming languages.
Usage
import analysis::m3::AST;
Description We provide a general set of data types for the syntactic constructs of programming languages:
The idea is that parsers for different languages will map to common abstract syntax elements, when this can be done meaningfully. If not, then these front-ends will extend the existing types with new constructor definitions, or even new kinds of types will be added. The shared representation limits the element of surprise when working with different languages, and perhaps may make some downstream analyses reusable.
The concept of a source [Location] is important for abstract syntax trees. The annotation
The concept of declaration is also relevant. A
Finally, the concept of a type is relevant for ASTs. In particular an
Expression, Statement, Declaration and Type.
Also, very common syntactic constructs are added to this, such as if, while, etc.
The idea is that parsers for different languages will map to common abstract syntax elements, when this can be done meaningfully. If not, then these front-ends will extend the existing types with new constructor definitions, or even new kinds of types will be added. The shared representation limits the element of surprise when working with different languages, and perhaps may make some downstream analyses reusable.
The concept of a source [Location] is important for abstract syntax trees. The annotation
src will always point to value of type loc,
pointing to the physical location of the construct in the source code.
The concept of declaration is also relevant. A
decl annotation points from a use of a concept to its definition, but always
via an indirection (i.e. fully qualified name). The decl annotation is also of type loc, where each Expressions/Values/Location is a fully qualified name of the
definition that is used.
Finally, the concept of a type is relevant for ASTs. In particular an
Expression may have a typ annotation, or
a variable declaration, etc.
Benefits
- Symbolic abstract syntax trees can be analyzed and transformed easily using Rascal primitives such as Patterns, Comprehensions, and Visit.
Pitfalls
- Even though different languages may map to the same syntactic construct, this does not mean that the semantics is the same. Downstream metrics or other analysis tools should still take semantic differences between programming languages into account.