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Add support for nested quasiquotation.

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This brings Janet more in line with Scheme,
Common Lisp, and Clojure.
This commit is contained in:
Calvin Rose 2019-12-04 16:40:53 -06:00
parent f39cf702db
commit 4199c42fe2
2 changed files with 24 additions and 8 deletions
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27
src/core/specials.c
View File

@ -55,7 +55,11 @@ static JanetSlot qq_slots(JanetFopts opts, JanetSlot *slots, int makeop) {
return target;
}
static JanetSlot quasiquote(JanetFopts opts, Janet x) {
static JanetSlot quasiquote(JanetFopts opts, Janet x, int depth, int level) {
if (depth == 0) {
janetc_cerror(opts.compiler, "quasiquote too deeply nested");
return janetc_cslot(janet_wrap_nil());
}
JanetSlot *slots = NULL;
switch (janet_type(x)) {
default:
@ -66,11 +70,18 @@ static JanetSlot quasiquote(JanetFopts opts, Janet x) {
len = janet_tuple_length(tup);
if (len > 1 && janet_checktype(tup[0], JANET_SYMBOL)) {
const uint8_t *head = janet_unwrap_symbol(tup[0]);
if (!janet_cstrcmp(head, "unquote"))
return janetc_value(janetc_fopts_default(opts.compiler), tup[1]);
if (!janet_cstrcmp(head, "unquote")) {
if (level == 0) {
return janetc_value(janetc_fopts_default(opts.compiler), tup[1]);
} else {
level--;
}
} else if (!janet_cstrcmp(head, "quasiquote")) {
level++;
}
}
for (i = 0; i < len; i++)
janet_v_push(slots, quasiquote(opts, tup[i]));
janet_v_push(slots, quasiquote(opts, tup[i], depth - 1, level));
return qq_slots(opts, slots, (janet_tuple_flag(tup) & JANET_TUPLE_FLAG_BRACKETCTOR)
? JOP_MAKE_BRACKET_TUPLE
: JOP_MAKE_TUPLE);
@ -79,7 +90,7 @@ static JanetSlot quasiquote(JanetFopts opts, Janet x) {
int32_t i;
JanetArray *array = janet_unwrap_array(x);
for (i = 0; i < array->count; i++)
janet_v_push(slots, quasiquote(opts, array->data[i]));
janet_v_push(slots, quasiquote(opts, array->data[i], depth - 1, level));
return qq_slots(opts, slots, JOP_MAKE_ARRAY);
}
case JANET_TABLE:
@ -88,8 +99,8 @@ static JanetSlot quasiquote(JanetFopts opts, Janet x) {
int32_t len, cap = 0;
janet_dictionary_view(x, &kvs, &len, &cap);
while ((kv = janet_dictionary_next(kvs, cap, kv))) {
JanetSlot key = quasiquote(opts, kv->key);
JanetSlot value = quasiquote(opts, kv->value);
JanetSlot key = quasiquote(opts, kv->key, depth - 1, level);
JanetSlot value = quasiquote(opts, kv->value, depth - 1, level);
key.flags &= ~JANET_SLOT_SPLICED;
value.flags &= ~JANET_SLOT_SPLICED;
janet_v_push(slots, key);
@ -106,7 +117,7 @@ static JanetSlot janetc_quasiquote(JanetFopts opts, int32_t argn, const Janet *a
janetc_cerror(opts.compiler, "expected 1 argument");
return janetc_cslot(janet_wrap_nil());
}
return quasiquote(opts, argv[0]);
return quasiquote(opts, argv[0], JANET_RECURSION_GUARD, 0);
}
static JanetSlot janetc_unquote(JanetFopts opts, int32_t argn, const Janet *argv) {

5
test/suite7.janet
View File

@ -265,4 +265,9 @@
(assert (= (in buf 0) 0) "cryptorand doesn't overwrite buffer")
(assert (= (length buf) 2) "cryptorand appends to buffer"))
# Nested quasiquotation
(def nested ~(a ~(b ,(+ 1 2) ,(foo ,(+ 1 3) d) e) f))
(assert (deep= nested '(a ~(b ,(+ 1 2) ,(foo 4 d) e) f)) "nested quasiquote")
(end-suite)