str_t impl: added alloc bare

str_t impl: started `str_free()`

TODO: Walk derived string slice"s parent list, and free orphaned top-parent. (`str_free()` for derived string slices is more complex and is currently unimplemented, requiring list walking functions and full-offset computation during the walk.)

Fortune for naka's current commit: Future blessing − 末吉

include/macros.h

@@ -55,7 +55,13 @@
 #define _cconv__hot _hot
 #define _cconv__entry __attribute__((constructor))
 #define _cconv__exit __attribute__((destructor))
+
+// Allocates
 #define _cconv__alloc __attribute__((malloc))
+// Infallible alloc
+#define _cconv__ialloc __attribute__((malloc)) __attribute__((returns_nonnull))
+#define _cconv__nonnull __attribute__((returns_nonnull))
+
 #define _callcv(name) _cconv__ ## name
 #define _callconv(name) _callcv(name)
 
@@ -130,7 +136,7 @@ _mixin void _drain_val(void* x, ...) { IGNORE(x); } // This compiles to no-op on
 
 #define box(t) aligned_alloc(_Alignof(t), sizeof(t))
 #define box_value(v) ({ let _box = box(var(v)); *_box = (v); _box; })
-#define unbox_value(v) ({ let _v = (v); let _res = *_v; free(_v); _res; }
+#define unbox_value(v) ({ let _v = (v); let _res = *_v; free(_v); _res; })
 #define stackalloc(t) __builtin_alloca_with_align(sizeof(t), _Alignof(t))
 
 // Function macros
@@ -257,4 +263,9 @@ static_assert_eq(bswap(bswap(128lu)), 128, "bswap128 (lu) failed (3)");
 #define VERSION_REV(ver) _AS_u32(_AS_u32(ver) & 0xffu)
 _Static_assert( (VERSION_COMP(VERSION(1,2,3,4), VER_COMP_MIN) >> VER_COMP_MIN) == 2u, "invalid native version spec");
 
+// Misc.
+
+#define PTR_ASSIGN(ptr, val) ( (ptr) ? (*(ptr) = (val), (ptr)) : (ptr) )
+#define PTR_ASSIGNx(ptr, val) ({ let _ptr = (ptr); let _val = (val); PTR_ASSIGN(_ptr, _val); })
+
 #endif /* _MACROS_H */

include/str.h

@@ -6,7 +6,7 @@
 #include <ints.h>
 
 #define STRF_OWNED	AS(1ul << 5, int)
-#define STRF_DERRIVED 	AS(1ul << 6, int)
+#define STRF_DERIVED 	AS(1ul << 6, int)
 enum str_ownership {
 	STR_NULL = 0,
 
@@ -15,10 +15,10 @@ enum str_ownership {
 	STR_OWNED_MALLOC,
 	STR_OWNED_STACK,
 
-	STR_DERRIVED = STRF_DERRIVED,
+	STR_DERIVED = STRF_DERIVED,
-	STR_DERRIVED_STATIC,
+	STR_DERIVED_STATIC,
-	STR_DERRIVED_MALLOC,
+	STR_DERIVED_MALLOC,
-	STR_DERRIVED_STACK,
+	STR_DERIVED_STACK,
 };
 
 typedef struct string str_t;

src/str.c

@@ -11,17 +11,18 @@ struct string {
 		enum str_ownership owned;
 		union _str_meta_inner {
 			// `STRF_OWNED` 
-			struct {
+			struct str_meta_owned {
 				_Atomic usize refs; // Number of derrivations from this 
 				void (*m_free)(void*); // How to free (when `_MALLOC`).
+				_Atomic bool orphan; // If a `derive` references this parent somehow, but this string has been `str_free()`d. Tell the derived string that sets the `refs` to 0 to free it.
 			} owned;
-			// `STRF_DERRIVED`
+			// `STRF_DERIVED`
-			struct {
+			struct str_meta_derived {
-				// String this is derrived from, can be either owned or derrived.
+				// String this is derived from, can be either owned or derived.
 				struct string* _shared parent;
 				// `str`'s offset from `parent->str`.
 				usize offset;
-			} derrived;
+			} derived;
 		} _inner;
 	} meta;
 	// The start of this string slice. Regardless of slicing
@@ -30,32 +31,88 @@ struct string {
 
 //TODO: We can use offsetof() to reverse the result of `str_new()` from char* (str field) to str_t*.
 
+
+
 inline static bool _str_meta_is_owned(enum str_ownership owned)
 {
 	return AS(owned, u32) & AS(STRF_OWNED, u32);
 }
 
+// Returns true for owned, false for derived
+inline static  bool _str_meta_parts_from(enum str_ownership o, union _str_meta_inner *pIN inner, struct str_meta_owned* *pOUT own, struct str_meta_derived* *pOUT derive)
+{
+	if(_str_meta_is_owned(o))
+		return (PTR_ASSIGN(own, &inner->owned), true);
+	else	return (PTR_ASSIGN(derive, &inner->derived), false);
+}
+
 inline static bool _str_is_owned(const str_t*pIN str)
 {
 	return _str_meta_is_owned(str->meta.owned);
 }
 
-static union _str_meta_inner _str_default_meta(enum str_ownership oship)
+inline static bool _str_is_owned_parts(str_t*pIN str, struct str_meta_owned* *pOUT own, struct str_meta_derived* *pOUT derive)
 {
-	bool owned = _str_meta_is_owned(oship);
+	return _str_meta_parts_from(str->meta.owned, &str->meta._inner, own, derive);
+}
+
+static union _str_meta_inner _str_default_meta(enum str_ownership oship, bool *pOUT owned)
+{
+	union _str_meta_inner output;
+	
+	struct str_meta_owned* o_own = NULL;
+	struct str_meta_derived* o_der = NULL;
+
+	// PTR_ASSIGNx always evaluates both args, so this is fine
+	PTR_ASSIGNx(owned,
+			_str_meta_parts_from(oship, &output, 
+				&o_own,
+				&o_der)
+	);
 	switch(oship)
 	{
-		
+		case STR_OWNED_STACK:
+		case STR_OWNED_STATIC:
+			debug_assert(o_own);
+			*o_own = (struct str_meta_owned){ 
+				.refs = 0,
+				.m_free = NULL,	
+				.orphan = false,
+			};
+			break;
+		case STR_OWNED_MALLOC:
+			debug_assert(o_own);
+			*o_own = (struct str_meta_owned){
+				.refs = 0,
+				.m_free = &free,
+				.orphan = false,
+			};
+			break;
+
+		case STR_DERIVED_STATIC:
+		case STR_DERIVED_STACK:
+		case STR_DERIVED_MALLOC:
+			debug_assert(o_der);
+			*o_der = (struct str_meta_derived){
+				.parent = NULL,
+				.offset = 0,
+			};
+			break;
+		default:
+			ERROR("Cannot assign metadata from ownership type 0x%x, returning 0'd metadata", AS(oship, u32));	
+			memset(&output, 0, sizeof(output));
 	}
-	TODO("default str metadata");
+	return output;
 }
 
+/// Allocates a bare new str_t. The metadata will be incomplete for `derived` string slices, and `str` will be `NULL`. For `owned` strings, `str` will be `calloc()`ed to `cap+1`.
 static str_t _str_alloc_bare(usize cap, enum str_ownership owned)
 {
-	bool is_owned = _str_meta_is_owned(owned);
+	bool is_owned;
+	let meta_inner = _str_default_meta(owned, &is_owned);
 	struct str_meta meta = {
 		.owned = owned,
-		._inner = _str_default_meta(owned),
+		._inner = meta_inner,
 	};
 	str_t str = {
 		.len = 0,
@@ -65,3 +122,33 @@ static str_t _str_alloc_bare(usize cap, enum str_ownership owned)
 	str.str = is_owned ? calloc(cap+1, 1) : NULL;
 	return str;
 }
+
+static void _str_force_free(struct str_meta_owned*pIN o_own, void* ptr)
+{
+	(o_own->m_free ?: &free)(ptr);
+}
+
+void str_free(str_t* restrict strp)
+{
+	str_t str = unbox_value(strp);
+	
+	struct str_meta_owned* o_own = NULL;
+	struct str_meta_derived* o_der = NULL;
+
+	if(_str_is_owned_parts(&str, &o_own, &o_der))
+	{
+		debug_assert(o_own);
+		if(o_own->refs > 0) o_own->orphan = true;
+		else if(str.meta.owned == STR_OWNED_MALLOC && str.str)
+			_str_force_free(o_own, str.str);
+	}
+	else {
+		debug_assert(o_der);
+		TODO(" \
+		//TODO: Find top-level parent (traverse list of potentially derived `o_der->parent`s. \
+		//TODO: While doing so, compute the full offset that this slice has from the top owned parent. \
+		//TODO: Then, decrement its `refs` \
+		//TODO: Then, if it is marked as `orphan`, and we have decremented its `refs` to 0, free its `ptr`. \
+		");
+	}
+}