Value * visit(Or const * e) { return eval_or(e->left->accept(*this), e->right->accept(*this)); }
ast_t* eval_expression(env_t* env, ast_t* ast) {
switch(ast->type) {
/* valid */
case at_call: return eval_call(env,ast);
case at_identifier: return get_ast_by_id(env, ast->data.id);
case at_expression: {
ast_t* result = NULL;
ast_t* left = eval_expression(env, ast->data.expression.left);
ast_t* right = eval_expression(env, ast->data.expression.right);
inc_ref(left);
inc_ref(right);
switch(ast->data.expression.op) {
case op_add: result = eval_add(env, left, right); break;
case op_mul: result = eval_mul(env, left, right); break;
case op_div: result = eval_div(env, left, right); break;
case op_sub: result = eval_sub(env, left, right); break;
case op_mod: result = eval_mod(env, left, right); break;
case op_and: result = eval_and(env, left, right); break;
case op_or: result = eval_or(env, left, right); break;
case op_gt: result = eval_gt(env, left, right); break;
case op_ge: result = eval_ge(env, left, right); break;
case op_lt: result = eval_lt(env, left, right); break;
case op_le: result = eval_le(env, left, right); break;
case op_eq: result = eval_eq(env, left, right); break;
case op_neq: result = eval_neq(env, left, right); break;
case op_cat: result = eval_cat(env, left, right); break;
case op_deref: {
ast_t* index = eval_expression(env, right);
if (index->type != at_integer) {
// TODO: error -> index must be an integer!
} else {
switch(left->type) {
case at_list: result = left->data.list.elements[index->data.i];
}
}
}
}
result->ref_count = 0;
dec_ref(left);
dec_ref(right);
return result;
}
/* no need to evaluate */
case at_integer:
case at_bool:
case at_double:
case at_string:
case at_function:
case at_statements:
case at_list:
return ast;
/* invalid */
case at_assignment:
case at_callargs:
case at_conditional:
case at_dowhile:
case at_elif:
case at_if:
case at_params:
case at_while:
case at_builtin:
error_expected(NULL,"expression",get_ast_type_name(ast->type));
}
return NULL; /* this should never happen */
}
///////////////////////////////////////////////////////////////////
//eval
//requires two arguments:exp & tail_context
///////////////////////////////////////////////////////////////////
cellpoint eval(void)
{
if (is_true(is_self_evaluating(args_ref(1)))){
reg = args_ref(1);
}else if (is_true(is_variable(args_ref(1)))){
reg = args_ref(1);
args_push(current_env);
args_push(reg);
reg = lookup_var_val();
}else if (is_true(is_quoted(args_ref(1)))){
args_push(args_ref(1));
reg = quotation_text();
}else if (is_true(is_assignment(args_ref(1)))){
args_push(args_ref(1));
reg = eval_assignment();
}else if (is_true(is_definition(args_ref(1)))){
args_push(args_ref(1));
reg = eval_definition();
}else if (is_true(is_if(args_ref(1)))){
//eval if expression with the second argument (tail_context)
reg = args_ref(1);
args_push(args_ref(2));
args_push(reg);
reg = eval_if();
}else if (is_true(is_lambda(args_ref(1)))){
args_push(args_ref(1));
reg = eval_lambda();
}else if (is_true(is_begin(args_ref(1)))){
args_push(args_ref(1));
reg = begin_actions();
//eval the actions of begin exp with the second argument (tail_context)
args_push(args_ref(2));
args_push(reg);
reg = eval_sequence();
}else if (is_true(is_cond(args_ref(1)))){
args_push(args_ref(1));
reg = cond_2_if();
//eval the exp with the second argument (tail_context)
args_push(args_ref(2));
args_push(reg);
reg = eval();
}else if (is_true(is_and(args_ref(1)))){
reg = args_ref(1);
args_push(args_ref(2));
args_push(reg);
reg = eval_and();
}else if (is_true(is_or(args_ref(1)))){
reg = args_ref(1);
args_push(args_ref(2));
args_push(reg);
reg = eval_or();
}else if (is_true(is_let(args_ref(1)))){
//convert let to combination
args_push(args_ref(1));
reg = let_2_combination();
//evals the combination
args_push(args_ref(2));
args_push(reg);
reg = eval();
}else if (is_true(is_letstar(args_ref(1)))){
//convert let* to nested lets
args_push(args_ref(1));
reg = letstar_2_nested_lets();
//evals the nested lets
args_push(args_ref(2));
args_push(reg);
reg = eval();
}else if (is_true(is_application(args_ref(1)))){
//computes operator
args_push(args_ref(1));
reg = operator();
args_push(a_false);
args_push(reg);
reg = eval();
stack_push(&vars_stack, reg);
//computes operands
args_push(args_ref(1));
reg = operands();
args_push(reg);
reg = list_of_values();
//calls apply with the second argument (tail_context)
args_push(args_ref(2));
args_push(reg);
args_push(stack_pop(&vars_stack));
reg = apply();
}else {
printf("Unknown expression type -- EVAL\n");
error_handler();
}
args_pop(2);
return reg;
}
