Constructors and context -> sys

We can register memory we've allocated onto the heap into a ~sys_t~
instance for examination (read: garbage collection) later.  We can
also add items to the symbol table it has internally.

6 files changed, 157 insertions, 18 deletions

diff --git a/base.h b/base.h
index a114ce0..6d1f034 100644
--- a/base.h
+++ b/base.h
@@ -102,22 +102,26 @@ typedef struct
 {
   lisp_t *memory;
   sym_table_t symtable;
-} context_t;
+} sys_t;
 
-void context_init(context_t *);
-void context_cleanup(context_t *);
+void sys_init(sys_t *);
+void sys_register(sys_t *sys, lisp_t *ptr);
+void sys_cleanup(sys_t *);
 
 /// Constructors and destructors
 lisp_t *make_int(i64 i);
-lisp_t *intern(context_t *context, char *str);
-lisp_t *cons(context_t *context, lisp_t *car, lisp_t *cdr);
-lisp_t *make_vec(context_t *context, u64 capacity);
+lisp_t *make_vec(sys_t *sys, u64 capacity);
+lisp_t *intern(sys_t *sys, sv_t sv);
+lisp_t *cons(sys_t *sys, lisp_t *car, lisp_t *cdr);
 
 i64 as_int(lisp_t *);
 char *as_sym(lisp_t *);
 cons_t *as_cons(lisp_t *);
 void *as_vec(lisp_t *);
 
+#define CAR(L) (as_cons(L)->car)
+#define CDR(L) (as_cons(L)->cdr)
+
 /// Pointer tagging scheme for lisps
 
 typedef enum Tag
@@ -153,6 +157,8 @@ enum Mask
 #define INT_MAX ((1L << 62) - 1)
 #define INT_MIN (-(1L << 62))
 
+tag_t get_tag(lisp_t *lisp);
+
 lisp_t *tag_int(i64 i);
 lisp_t *tag_sym(char *str);
 lisp_t *tag_cons(cons_t *cons);
diff --git a/build.sh b/build.sh
index 9f749ed..878c28c 100644
--- a/build.sh
+++ b/build.sh
@@ -1,7 +1,7 @@
 #!/usr/bin/env sh
 
 CFLAGS="-Wall -Wextra -std=c11 -ggdb -fsanitize=address -fsanitize=undefined"
-SRC="vec.c tag.c symtable.c main.c"
+SRC="vec.c symtable.c tag.c constructor.c sys.c main.c"
 OUT="alisp.out"
 
 set -xe
diff --git a/constructor.c b/constructor.c
new file mode 100644
index 0000000..e500430
--- /dev/null
+++ b/constructor.c
@@ -0,0 +1,48 @@
+/* Copyright (C) 2025 Aryadev Chavali
+
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE.  See the Unlicense for details.
+
+ * You may distribute and modify this code under the terms of the Unlicense,
+ * which you should have received a copy of along with this program.  If not,
+ * please go to <https://unlicense.org/>.
+
+ * Created: 2025-08-20
+ * Description: Lisp constructors/destructors
+ */
+
+#include <malloc.h>
+
+#include "./base.h"
+
+lisp_t *make_int(i64 i)
+{
+  return tag_int(i);
+}
+
+lisp_t *cons(sys_t *sys, lisp_t *car, lisp_t *cdr)
+{
+  cons_t *cons = calloc(1, sizeof(*cons));
+  cons->car    = car;
+  cons->cdr    = cdr;
+
+  lisp_t *lcons = tag_cons(cons);
+  sys_register(sys, lcons);
+  return lcons;
+}
+
+lisp_t *make_vec(sys_t *sys, u64 capacity)
+{
+  lvec_t *lvec = calloc(1, sizeof(*lvec));
+  vec_make(&lvec->data, capacity);
+  lisp_t *ptr = tag_vec(lvec);
+  sys_register(sys, ptr);
+  return ptr;
+}
+
+lisp_t *intern(sys_t *sys, sv_t sv)
+{
+  char *s = sym_table_find(&sys->symtable, sv);
+  return tag_sym(s);
+}
diff --git a/main.c b/main.c
index 75750ad..7ce10a5 100644
--- a/main.c
+++ b/main.c
@@ -27,16 +27,8 @@ sv_t sv_copy(sv_t old)
 
 int main(void)
 {
-  i64 numbers[] = {
-      1, 1024, -200, 1LU << 32, INT_MAX, INT_MIN,
-  };
-
-  for (u64 i = 0; i < ARRSIZE(numbers); ++i)
-  {
-    i64 num      = numbers[i];
-    lisp_t *lisp = tag_int(num);
-    i64 ret      = as_int(lisp);
-    printf("%#16lx => %#16lx => %#16lx\n", num, lisp, ret);
-  }
+  sys_t sys;
+  sys_init(&sys);
+  sys_cleanup(&sys);
   return 0;
 }
diff --git a/sys.c b/sys.c
new file mode 100644
index 0000000..e266de3
--- /dev/null
+++ b/sys.c
@@ -0,0 +1,77 @@
+/* Copyright (C) 2025 Aryadev Chavali
+
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE.  See the Unlicense for details.
+
+ * You may distribute and modify this code under the terms of the Unlicense,
+ * which you should have received a copy of along with this program.  If not,
+ * please go to <https://unlicense.org/>.
+
+ * Created: 2025-08-20
+ * Description: System management
+ */
+
+#include "./base.h"
+
+#include <assert.h>
+#include <malloc.h>
+#include <string.h>
+
+void sys_init(sys_t *sys)
+{
+  sys->memory = NIL;
+  sym_table_init(&sys->symtable);
+}
+
+void sys_register(sys_t *sys, lisp_t *ptr)
+{
+  // Generate an unmanaged cons
+  cons_t *cons = calloc(1, sizeof(*cons));
+  cons->car    = ptr;
+  cons->cdr    = sys->memory;
+  sys->memory  = tag_cons(cons);
+}
+
+void sys_cleanup(sys_t *sys)
+{
+  static_assert(NUM_TAGS == 5);
+
+  sym_table_cleanup(&sys->symtable);
+
+  if (!sys->memory)
+    return;
+
+  // Iterate through each element of memory
+  for (lisp_t *cell = sys->memory, *next = CDR(cell); cell;
+       cell = next, next = CDR(cell))
+  {
+    // Only reason allocated exists is because we had to allocate memory on the
+    // heap for it.  It's therefore
+    lisp_t *allocated = CAR(cell);
+    switch (get_tag(allocated))
+    {
+    case TAG_CONS:
+      // Delete the cons
+      free(as_cons(allocated));
+      break;
+    case TAG_VEC:
+    {
+      lvec_t *lvec = as_vec(allocated);
+      vec_free(&lvec->data);
+      free(lvec);
+      break;
+    }
+    case TAG_NIL:
+    case TAG_INT:
+    case TAG_SYM:
+    case NUM_TAGS:
+      // shouldn't be dealt with (either constant or dealt with elsewhere)
+      break;
+    }
+
+    // Then free the current cell
+    free(as_cons(cell));
+  }
+  memset(sys, 0, sizeof(*sys));
+}
diff --git a/tag.c b/tag.c
index dbc47ba..ebed8cb 100644
--- a/tag.c
+++ b/tag.c
@@ -27,11 +27,27 @@ lisp_t *tag_sym(char *str)
   return TAG((u64)str, SYM);
 }
 
+lisp_t *tag_vec(lvec_t *lvec)
+{
+  return TAG((u64)lvec, VEC);
+}
+
 lisp_t *tag_cons(cons_t *cons)
 {
   return TAG((u64)cons, CONS);
 }
 
+tag_t get_tag(lisp_t *lisp)
+{
+  static_assert(NUM_TAGS == 5);
+  if (!lisp)
+    return TAG_NIL;
+  else if (IS_TAG(lisp, INT))
+    return TAG_INT;
+
+  return (u64)lisp & 0xFF;
+}
+
 i64 as_int(lisp_t *obj)
 {
   assert(IS_TAG(obj, INT));