Write an attribute grammar whose BNF basis is that of Example 3.6 in Section 3.4.5 but whose language rules are as follows: Data types cannot be mixed in expressions, but assignment statements need not have the same types on both sides of the assignment operator.

Data from Example 3.6:

1. Syntax rule: Semantic rule: .expected_type .actual_type 2. Syntax rule: [2] + [3] Semantic rule: .actual_type - = if ( [2].actual_type = int) and ( [3].actual_type = int) then int else real end if Predicate: .actual_type %33D .expected_type 3. Syntax rule: Semantic rule: .actual_type .actual_type Predicate: .actual_ty %3D3D .expected_type A | BIC 4. Syntax rule: Semantic rule: .actual_type look-up ( .string)