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A Simple Example

Assume that a copmiler pass needs to create a statement that adds two given variables. Builder will perform this task in a simple and elegant manner.

tree_node_list * b_gets_a_plus_b(tree_proc * proc,
                                 var_sym * a, 
                                 var_sym * b)

        block A(a);
        block B(b);
        block result(B = A + B);
        return result.make_tree_node_list()

The function b_gets_a_plus_b() takes the current SUIF procedure and two variables and produce a tree_node_list containing the resulting statement.

Before using any builder commands, the current procedure must be set using set_proc(). Two blocks were created for the variables and a result block was obtained by composing these two blocks. Overloaded = and + operators were used to perform the composition. Finally, the tree_node_list was generated for the result block.

There are many possible ways to calculate the block with the correct statement. Following are a few possibilities.

Example: In a Single Line

        block result(block(b) = block(a) + block(b));

Since a complete set of operator overloading is given, any C++ syntax and semantics will work.

Example: A Single Composition at Each Step

        block A(a);
        block B(b);
        block add2(A + B);
        block result(B = add2);

Example: No Operator Overloading

Instead of operator overloading, explicit composition functions can be used to perform composition. Control flow and other constructs are handled in this manner.

        block A(a);
        block B(b);
        block add2(block::op(A, bop_add, B));
        block result(block::op(B, aop_eq, add2));

Example: Using Operator Symbols

When using explicit composition functions, instead of providing an enumeration value specifying the operation (see section Operators), an ASCII string representing the operation can be used.

        block A(a);
        block B(b);
        block add2(block::op(A, "+", B));
        block result(block::op(B, "=", add2));

Example: Yet Another Method

        block A(a);
        block B(b);
        block add2(A.dobinop(bop_add, B));
        block result(B.doasignop(aop_eq, add2));

There are many different possibilities for creating expressions and statements (see section Creating Expressions and Statements).

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