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#include <lcq/pit/runtime/macroexpand.h>
pit_value pit_macroexpand(pit_runtime *rt, pit_value top) {
i64 expr_stack_reset = rt->expr_stack->next;
i64 result_stack_reset = rt->result_stack->next;
i64 program_reset = rt->program->next;
if (pit_vec_push(pit_value)(rt->expr_stack, top) < 0)
pit_error(rt, "macro expansion stack overflow");
while (rt->expr_stack->next > expr_stack_reset) {
pit_value cur;
if (rt->error != PIT_NIL) goto end;
if (pit_vec_pop(pit_value)(rt->expr_stack, &cur) < 0)
pit_error(rt, "macro expansion stack underflow");
if (pit_value_is_cons(rt, cur)) {
pit_value fsym = pit_value_cons_car(rt, cur);
bool is_symbol = pit_value_is_symbol(rt, fsym);
pit_annotated_ref *ann = pit_annotation_get(rt, pit_value_as_ref(rt, cur));
if (is_symbol && pit_symtab_is_symbol_macro(rt, fsym)) {
pit_value f = pit_symtab_fget(rt, fsym);
pit_value args = pit_value_cons_cdr(rt, cur);
pit_value res = pit_value_apply(rt, f, args);
if (pit_vec_push(pit_value)(rt->expr_stack, res) < 0)
pit_error(rt, "macro expansion stack overflow");
} else if (is_symbol && pit_symtab_symbol_name_match_cstr(rt, fsym, "defer")) {
pit_value args = pit_value_cons_cdr(rt, cur);
pit_runtime_eval_program_push_literal(rt, rt->program, pit_value_cons_car(rt, args));
} else if (is_symbol && pit_symtab_symbol_name_match_cstr(rt, fsym, "quote")) {
pit_runtime_eval_program_push_literal(rt, rt->program, cur);
} else if (is_symbol && pit_symtab_symbol_name_match_cstr(rt, fsym, "lambda")) {
pit_value args = pit_value_cons_cdr(rt, cur);
pit_value bindings = pit_value_cons_car(rt, args);
pit_value body = pit_value_cons_cdr(rt, args);
i64 argcount = 0;
if (pit_vec_push(pit_value)(rt->expr_stack, pit_value_list(rt, 2, pit_symtab_intern_cstr(rt, "defer"), bindings)) < 0)
pit_error(rt, "macro expansion stack overflow");
while (body != PIT_NIL) {
pit_value a = pit_value_cons_car(rt, body);
if (pit_vec_push(pit_value)(rt->expr_stack, a) < 0)
pit_error(rt, "macro expansion stack overflow");
body = pit_value_cons_cdr(rt, body);
argcount += 1;
}
pit_runtime_eval_program_push_apply(rt, rt->program, argcount + 1, ann);
pit_runtime_eval_program_push_literal(rt, rt->program, fsym);
} else {
pit_value args = pit_value_cons_cdr(rt, cur);
i64 argcount = 0;
while (args != PIT_NIL) {
pit_value a = pit_value_cons_car(rt, args);
if (pit_vec_push(pit_value)(rt->expr_stack, a) < 0)
pit_error(rt, "macro expansion stack overflow");
args = pit_value_cons_cdr(rt, args);
argcount += 1;
}
if (!is_symbol) {
if (pit_vec_push(pit_value)(rt->expr_stack, fsym) < 0)
pit_error(rt, "macro expansion stack overflow");
}
pit_runtime_eval_program_push_apply(rt, rt->program, argcount, ann);
if (is_symbol) {
pit_runtime_eval_program_push_literal(rt, rt->program, fsym);
}
}
} else {
pit_runtime_eval_program_push_literal(rt, rt->program, cur);
}
}
for (i64 idx = rt->program->next - 1; idx >= program_reset; --idx) {
pit_runtime_eval_ins *ent = pit_vec_get(pit_runtime_eval_ins)(rt->program, idx);
if (ent == NULL) pit_error(rt, "macro expansion program invalid");
if (rt->error != PIT_NIL) goto end;
switch (ent->sort) {
case PIT_RUNTIME_EVAL_INS_LITERAL:
if (pit_vec_push(pit_value)(rt->result_stack, ent->in.literal) < 0)
pit_error(rt, "macro expansion stack overflow");
break;
case PIT_RUNTIME_EVAL_INS_APPLY: {
pit_value f = PIT_NIL;
pit_value args = PIT_NIL;
pit_value app = PIT_NIL;
if (pit_vec_pop(pit_value)(rt->result_stack, &f) < 0)
pit_error(rt, "macro expansion stack underflow");
for (i64 i = 0; i < ent->in.apply.arity; ++i) {
pit_value a;
if (pit_vec_pop(pit_value)(rt->result_stack, &a) < 0)
pit_error(rt, "macro expansion stack underflow");
args = pit_value_cons(rt, a, args);
}
app = pit_value_cons(rt, f, args);
if (ent->in.apply.annotation != NULL) {
pit_annotation_set(rt, pit_value_as_ref(rt, app), ent->in.apply.annotation->annotation);
}
if (pit_vec_push(pit_value)(rt->result_stack, app) < 0)
pit_error(rt, "macro expansion stack overflow");
break;
}
default:
pit_error(rt, "unknown program entry");
goto end;
}
}
end: {
pit_value ret = PIT_NIL;
if (pit_vec_pop(pit_value)(rt->result_stack, &ret) < 0)
pit_error(rt, "macro expansion stack underflow");
rt->expr_stack->next = expr_stack_reset;
rt->result_stack->next = result_stack_reset;
rt->program->next = program_reset;
return ret;
}
}
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