Stack Symbol Table[adapted from slide by John Werth.]

During compilation, the compiler performs a depth-first traversal of the tree of procedures.

Since a procedure can access its symbols and the symbols of its ancestors, the symbol table could be structured as a stack.

Searching backwards through the stack implements shadowing , i.e. the closest definition of a symbol with a given name takes precedence.

When parsing of a procedure is finished, its local symbol table can be popped off the stack.

Alternatively, the whole tree of symbol tables can be maintained, with each node having a pointer to its parent.