1 files changed, 68 insertions, 0 deletions
diff --git a/builtins/pointer.c b/builtins/pointer.c
new file mode 100644
index 00000000..69d11c07
--- /dev/null
+++ b/builtins/pointer.c
@@ -0,0 +1,68 @@
+
+#include <gc.h>
+#include <gc/cord.h>
+#include <stdalign.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <ctype.h>
+#include <sys/param.h>
+#include <err.h>
+
+#include "types.h"
+#include "../util.h"
+#include "../SipHash/halfsiphash.h"
+
+extern const void *SSS_HASH_VECTOR;
+
+typedef struct recursion_s {
+    const void *ptr;
+    struct recursion_s *next;
+} recursion_t;
+
+public CORD Pointer__cord(const void *x, bool colorize, const TypeInfo *type) {
+    auto ptr_info = type->PointerInfo;
+    const void *ptr = *(const void**)x;
+    if (!ptr)
+        return colorize ? CORD_asprintf("\x1b[34;1m!%s\x1b[m", ptr_info.pointed->name) : CORD_cat(ptr_info.sigil, ptr_info.pointed->name);
+
+    // Check for recursive references, so if `x.foo = x`, then it prints as
+    // `@Foo{foo=@..1}` instead of overflowing the stack:
+    static recursion_t *recursion = NULL;
+    int32_t depth = 0;
+    for (recursion_t *r = recursion; r; r = r->next) {
+        ++depth;
+        if (r->ptr == ptr)
+            return CORD_asprintf(colorize ? "\x1b[34;1m%s..%d\x1b[m" : "%s..%d", ptr_info.sigil, depth);
+    }
+
+    CORD pointed;
+    { // Stringify with this pointer flagged as a recursive one:
+        recursion_t my_recursion = {.ptr=ptr, .next=recursion};
+        recursion = &my_recursion;
+        pointed = generic_cord(ptr, colorize, ptr_info.pointed);
+        recursion = recursion->next;
+    }
+    return colorize ? CORD_asprintf("\x1b[34;1m%s%r\x1b[m", ptr_info.sigil, pointed) : CORD_cat(ptr_info.sigil, pointed);
+}
+
+public int32_t Pointer__compare(const void *x, const void *y, const TypeInfo *type) {
+    (void)type;
+    const void *xp = *(const void**)x, *yp = *(const void**)y;
+    return (xp > yp) - (xp < yp);
+}
+
+public bool Pointer__equal(const void *x, const void *y, const TypeInfo *type) {
+    (void)type;
+    const void *xp = *(const void**)x, *yp = *(const void**)y;
+    return xp == yp;
+}
+
+public uint32_t Pointer__hash(const void *x, const TypeInfo *type) {
+    (void)type;
+    uint32_t hash;
+    halfsiphash(x, sizeof(void*), SSS_HASH_VECTOR, (uint8_t*)&hash, sizeof(hash));
+    return hash;
+}
+
+// vim: ts=4 sw=0 et cino=L2,l1,(0,W4,m1,\:0