1 files changed, 150 insertions, 0 deletions
diff --git a/src/interp.c b/src/interp.c
new file mode 100644
index 0000000..bf49dd5
--- /dev/null
+++ b/src/interp.c
@@ -0,0 +1,150 @@
+#include "interp.h"
+#include "algds/hash_table.h"
+#include "sexp.h"
+
+void Interp_init(Interp *self) {
+    SExpVector_init(&self->objs);
+    IntVector_init(&self->empty_space);
+    String2IntHashTable_init(&self->symbols);
+    self->gc_paused = false;
+    SExp sexp;
+    sexp.type = kNilSExp;
+    SExpVector_push_back(&self->objs, sexp);
+    self->nil = (SExpRef){0};
+
+    sexp.type = kEnvSExp;
+    sexp.env.parent= self->nil;
+    sexp.env.bindings = self->nil;
+    SExpVector_push_back(&self->objs, sexp);
+    self->top_level = (SExpRef){1};
+    sexp.type = kEmptySExp;
+    for (int i = 1; i < 1024; i++) {
+        SExpVector_push_back(&self->objs, sexp);
+        IntVector_push_back(&self->empty_space, i);
+    }
+
+    self->evaluating = self->nil;
+    self->stack = cons(self, self->top_level, self->nil);
+}
+
+void Interp_free(Interp *self) {
+    for (size_t i = 0; i < SExpVector_len(&self->objs); i++) {
+        SExp *obj = SExpVector_ref(&self->objs, i);
+        if (obj->type == kSymbolSExp || obj->type == kStringSExp) {
+            free((void*)obj->str);
+        }
+    }
+    String2IntHashTable_free(&self->symbols);
+    SExpVector_free(&self->objs);
+    IntVector_free(&self->empty_space);
+}
+
+SExp* Interp_ref(Interp *self, SExpRef ref) {
+    if (ref.idx > SExpVector_len(&self->objs)) return NULL;
+    SExp *res = SExpVector_ref(&self->objs, ref.idx);
+    return res;
+}
+
+void Interp_gc(Interp *interp) {
+    // TODO
+}
+
+SExpRef new_sexp(Interp *interp) {
+    if (IntVector_len(&interp->empty_space) == 0) {
+        if (interp->gc_paused) {
+            SExp sexp;
+            sexp.type = kEmptySExp;
+            SExpVector_push_back(&interp->objs, sexp);
+            return (SExpRef){ SExpVector_len(&interp->objs) - 1 };
+        } else Interp_gc(interp);
+    }
+    int idx = *IntVector_ref(&interp->empty_space, IntVector_len(&interp->empty_space) - 1);
+    IntVector_pop(&interp->empty_space);
+    return (SExpRef){idx};
+}
+
+SExpRef new_boolean(Interp *interp, bool val) {
+    SExpRef ret = new_sexp(interp);
+    SExp *psexp = Interp_ref(interp, ret);
+    psexp->type = kBooleanSExp;
+    psexp->boolean = val;
+    return ret;
+}
+
+SExpRef new_char(Interp *interp, char val) {
+    SExpRef ret = new_sexp(interp);
+    SExp *psexp = Interp_ref(interp, ret);
+    psexp->type = kCharSExp;
+    psexp->character = val;
+    return ret;
+}
+
+SExpRef new_integer(Interp *interp, int64_t val) {
+    SExpRef ret = new_sexp(interp);
+    SExp *psexp = Interp_ref(interp, ret);
+    psexp->type = kIntegerSExp;
+    psexp->integer = val;
+    return ret;
+}
+
+SExpRef new_real(Interp *interp, double val) {
+    SExpRef ret = new_sexp(interp);
+    SExp *psexp = Interp_ref(interp, ret);
+    psexp->type = kRealSExp;
+    psexp->real = val;
+    return ret;
+}
+
+SExpRef new_string(Interp *interp, const char *val) {
+    char *dup = strdup(val);
+    SExpRef ret = new_sexp(interp);
+    SExp *psexp = Interp_ref(interp, ret);
+    psexp->type = kStringSExp;
+    psexp->str = dup;
+    return ret;
+}
+
+SExpRef new_symbol(Interp *interp, const char *val) {
+    String2IntHashTableIter iter = String2IntHashTable_find(&interp->symbols, val);
+    if (iter == NULL) {
+        char *dup = strdup(val);
+        SExpRef ret = new_sexp(interp);
+        SExp *psexp = Interp_ref(interp, ret);
+        psexp->type = kSymbolSExp;
+        psexp->str = dup;
+        String2IntHashTable_insert(&interp->symbols, dup, ret.idx);
+        return ret;
+    } else {
+        return (SExpRef){ iter->val };
+    }
+}
+
+SExpRef cons(Interp *interp, SExpRef car, SExpRef cdr) {
+    SExpRef ret = new_sexp(interp);
+    SExp *psexp = Interp_ref(interp, ret);
+    psexp->type = kPairSExp;
+    psexp->pair.car = car;
+    psexp->pair.cdr = cdr;
+    return ret;
+}
+
+SExpRef new_list1(Interp *interp, SExpRef e1) {
+    return cons(interp, e1, interp->nil);
+}
+
+SExpRef new_list2(Interp *interp, SExpRef e1, SExpRef e2) {
+    return cons(interp, e1, new_list1(interp, e2));
+}
+
+SExpRef new_list3(Interp *interp, SExpRef e1, SExpRef e2, SExpRef e3) {
+    return cons(interp, e1, new_list2(interp, e2, e3));
+}
+
+SExpRef new_list4(Interp *interp, SExpRef e1, SExpRef e2, SExpRef e3, SExpRef e4) {
+    return cons(interp, e1, new_list3(interp, e2, e3, e4));
+}
+
+SExpRef new_list5(Interp *interp, SExpRef e1, SExpRef e2, SExpRef e3, SExpRef e4, SExpRef e5) {
+    return cons(interp, e1, new_list4(interp, e2, e3, e4, e5));
+}
+