Chapter 4, Problem 25E

Explanation of Solution

Modified pseudo-code of Figure 4.14:

macro declare_name (id, cur_item, next_item : syntax_tree_node; t : type)

  if (id.name, ?) ϵ cur_item.symtab

  next_item.errors_in := cur_item.errors_in

  + [“redefinition of” id.name “at” cur_item.location]

  next_item.symtab := prepend ((id.name, error), cur_item.symtab)

  else

  next_item.errors_in := cur_item.errors_in

  next_item.symtab := prepend (id.name, t), cur_item.symtab)

Explanation:

• The key idea is to represent the symbol table as a stack particularly, a linked list onto which the programmer push new elements at the front...