1 files changed, 73 insertions, 0 deletions
diff --git a/stdlib/optionals.c b/stdlib/optionals.c
new file mode 100644
index 00000000..b6ca8dfb
--- /dev/null
+++ b/stdlib/optionals.c
@@ -0,0 +1,73 @@
+// Optional types
+
+#include <pthread.h>
+
+#include "bools.h"
+#include "datatypes.h"
+#include "integers.h"
+#include "metamethods.h"
+#include "threads.h"
+#include "text.h"
+#include "util.h"
+
+public const Array_t NULL_ARRAY = {.length=-1};
+public const OptionalBool_t NULL_BOOL = 2;
+public const Int_t NULL_INT = {.small=0};
+public const Table_t NULL_TABLE = {.entries.length=-1};
+public const Closure_t NULL_CLOSURE = {.fn=NULL};
+public const Text_t NULL_TEXT = {.length=-1};
+
+public PUREFUNC bool is_null(const void *obj, const TypeInfo *non_optional_type)
+{
+    if (non_optional_type == &Int$info)
+        return ((Int_t*)obj)->small == 0;
+    else if (non_optional_type == &Bool$info)
+        return *((OptionalBool_t*)obj) == NULL_BOOL;
+    else if (non_optional_type == &Num$info)
+        return isnan(*((Num_t*)obj));
+    else if (non_optional_type == &Int64$info)
+        return ((OptionalInt64_t*)obj)->is_null;
+    else if (non_optional_type == &Int32$info)
+        return ((OptionalInt32_t*)obj)->is_null;
+    else if (non_optional_type == &Int16$info)
+        return ((OptionalInt16_t*)obj)->is_null;
+    else if (non_optional_type == &Int8$info)
+        return ((OptionalInt8_t*)obj)->is_null;
+    else if (non_optional_type == &Thread)
+        return *(pthread_t**)obj == NULL;
+
+    switch (non_optional_type->tag) {
+        case ChannelInfo: return *(Channel_t**)obj == NULL;
+        case PointerInfo: return *(void**)obj == NULL;
+        case TextInfo: return ((Text_t*)obj)->length < 0;
+        case ArrayInfo: return ((Array_t*)obj)->length < 0;
+        case TableInfo: return ((Table_t*)obj)->entries.length < 0;
+        case FunctionInfo: return *(void**)obj == NULL;
+        case StructInfo: {
+            int64_t offset = non_optional_type->size;
+            if (offset % non_optional_type->align)
+                offset += non_optional_type->align - (offset % non_optional_type->align);
+            return *(bool*)(obj + offset);
+        }
+        case EnumInfo: return (*(int*)obj) == 0; // NULL tag
+        case CStringInfo: return (*(char**)obj) == NULL;
+        default: {
+            Text_t t = generic_as_text(NULL, false, non_optional_type);
+            errx(1, "is_null() not implemented for: %k", &t);
+        }
+    }
+}
+
+#pragma GCC diagnostic ignored "-Wstack-protector"
+public Text_t Optional$as_text(const void *obj, bool colorize, const TypeInfo *type)
+{
+    if (!obj)
+        return Text$concat(generic_as_text(obj, colorize, type->OptionalInfo.type), Text("?"));
+
+    if (is_null(obj, type->OptionalInfo.type))
+        return Text$concat(colorize ? Text("\x1b[31m!") : Text("!"), generic_as_text(NULL, false, type->OptionalInfo.type),
+                           colorize ? Text("\x1b[m") : Text(""));
+    return Text$concat(generic_as_text(obj, colorize, type->OptionalInfo.type), colorize ? Text("\x1b[33m?\x1b[m") : Text("?"));
+}
+
+// vim: ts=4 sw=0 et cino=L2,l1,(0,W4,m1