Language Implementation Patterns

Pattern 19

Symbol Table for Classes

Purpose

This pattern tracks symbols and builds a scope tree for non-nested classes with single inheritance.

Discussion

Classes are data aggregates that allow method members and that can inherit members from superclasses. Methods within classes can see global variables in the object-oriented version of our Cymbol language (since Cymbol is a subset of C++). To support these language semantics, we need to tweak the scope trees we used for structs in Pattern 18, ​Symbol Table for Data Aggregates​. We’ll replace StructSymbol nodes with ClassSymbol nodes and have them point at their superclasses as well as their enclosing scopes (recall Figure 17, ​Scope tree for classes A and B​). All the symbol table objects this ...