|
... imperative type-based dispatch
|
... facility of the C++ language
|
void expr_generate_code(struct expr *e);
void
expr_generate_code(expr *e)
{
switch(e->e_op)
{
|
class expression
{
public:
virtual void generate_code() const = 0;
};
|
case PLUS:
expr_generate_code(e->e_lhs);
expr_generate_code(e->e_rhs);
emit(OP_ADI);
break;
|
class expression_add:
public expression
{
public:
virtual void generate_code() const {
lhs->generate_code();
rhs->generate_code();
gen_emit_byte(OP_ADI);
}
private:
expression *lhs;
expression *rhs;
}
|
case INT_CONST:
gen_emit_byte(OP_SLDC);
gen_emit_int(e->e_int);
break;
|
class expression_int_const:
public expression
{
public:
virtual void generate_code() const {
gen_emit_byte(OP_SLDC);
gen_emit_int(e->value);
break;
}
private:
short value;
}
|
etc etc
}
}
|
etc etc
|