untested string.contains(haystack, needle)

sysdata/libraries/stn/src/string.hb

@@ -82,3 +82,40 @@ equals := fn(lhs: ^u8, rhs: ^u8): bool {
 		i += 1
 	}
 }
+
+contains := fn(haystack: ^u8, needle: ^u8): bool {
+	haystack_len := @inline(length, haystack)
+	needle_len := @inline(length, needle)
+
+	if needle_len == 0 {
+		return true
+	}
+	if haystack_len < needle_len {
+		return false
+	}
+
+	max_start := haystack_len - needle_len
+
+	pos := 0
+	loop if pos > max_start break else {
+		is_match := true
+		offset := 0
+
+		loop if offset >= needle_len break else {
+			if *(haystack + pos + offset) != *(needle + offset) {
+				is_match = false
+			}
+			if is_match == false {
+				break
+			}
+			offset += 1
+		}
+
+		if is_match {
+			return true
+		}
+		pos += 1
+	}
+
+	return false
+}