OCL21 — Issue: Abstract syntax tree

Description: Some of the elements presented in 3.3.10 (e.g. EnumLiteralExp, children of ModelPropertyCallExp) cannot be constructed without using semantic information (e.g. the type of the expression determines if a name denotes an attribute, an association end, or an operation).
Rationale: Usually a parser produces an AST. The semantic analyser augments the AST by computing for each node from AST the values of the attached attributes. The semantic analysis also checks if there are static semantics errors and reports them. Using other terms in the AST and hence other non-terminals in 4.5 (e.g. dot-selection-expression, arrow-selection-expression, call-expression etc.) will solve this problem.

The exposition of the OCL grammar is poor, but it is possible to resolve context pursuing a left to right analysis of an expression. It is also possible to perform a syntactic parse and then resolve semantics in a tree walk.The 'problems' have not prevented OCL tool being built.
Users would not be well-served by a major resyntaxing to introduce new operators that required the user to have greater understanding of the metamodels.
Disposition: Closed, no change