string: rename _capacity field to _size

include/neo/_types.h

@@ -56,7 +56,8 @@ struct _neo_string {
 	/* The *amount of Unicode code points*, NOT amount of bytes */
 	NLEN_FIELD(_len);
 	NREF_FIELD;
-	usize _capacity;
+	/* physical size in bytes, including the four NUL terminators */
+	usize _size;
 	char *_data;
 };
 typedef struct _neo_string string;

src/string/leftpad.c

@@ -25,7 +25,7 @@ static inline string *leftpad_unsafe(const string *s, usize len, nchar fillchr,
 	 * but that's okay because if we don't even have enough memory for three
 	 * extra bytes we are screwed anyway.
 	 */
-	usize size_now = s->_capacity;
+	usize size_now = s->_size;
 	usize size_after = size_now + (extra_chars * fillchr_size);
 	char *dest = nalloc(size_after, err);
 	catch(err) {

src/string/nstr.c

@@ -51,7 +51,7 @@ static string *nstr_unsafe(const char *restrict s, usize size_without_nul, error
 	}
 
 	str->_len = len;
-	str->_capacity = size_without_nul + 4;
+	str->_size = size_without_nul + 4;
 	nref_init(str, nstr_destroy);
 
 	memcpy(str->_data, s, size_without_nul);

src/string/nstrcmp.c

@@ -23,10 +23,10 @@ int nstrcmp(const string *s1, const string *s2, error *err)
 	int ret;
 
 	usize maxbytes;
-	if (s1->_capacity > s2->_capacity)
+	if (s1->_size > s2->_size)
-		maxbytes = s2->_capacity;
+		maxbytes = s2->_size;
 	else
-		maxbytes = s1->_capacity;
+		maxbytes = s1->_size;
 
 	ret = strncmp(s1->_data, s2->_data, maxbytes);
 	neat(err);