remove list_index, add parse() that takes number of items

include/cubescript/cubescript.hh

@@ -768,6 +768,7 @@ namespace util {
 
         void skip();
         bool parse();
+        ostd::Size parse(ostd::Size n);
         ostd::Size count();
 
         CsString element() const;
@@ -776,10 +777,6 @@ private:
         CsState &p_state;
     };
 
-    OSTD_EXPORT ostd::Maybe<CsString> list_index(
-        CsState &cs, ostd::ConstCharRange s, ostd::Size idx
-    );
-
     template<typename R>
     inline ostd::Ptrdiff format_int(R &&writer, CsInt val) {
         return ostd::format(ostd::forward<R>(writer), IntFormat, val);

src/cs_util.cc

@@ -372,6 +372,17 @@ endblock:
         return true;
     }
 
+    ostd::Size ListParser::parse(ostd::Size n) {
+        ostd::Size ret = 0;
+        for (ostd::Size i = 0; i < n; ++i) {
+            if (!parse()) {
+                return ret;
+            }
+            ++ret;
+        }
+        return ret;
+    }
+
     ostd::Size ListParser::count() {
         ostd::Size ret = 0;
         while (parse()) {
@@ -394,21 +405,6 @@ endblock:
         s.advance(item.size());
         return s;
     }
-
-    OSTD_EXPORT ostd::Maybe<CsString> list_index(
-        CsState &cs, ostd::ConstCharRange s, ostd::Size idx
-    ) {
-        ListParser p(cs, s);
-        for (ostd::Size i = 0; i < idx; ++i) {
-            if (!p.parse()) {
-                return ostd::nothing;
-            }
-        }
-        if (!p.parse()) {
-            return ostd::nothing;
-        }
-        return ostd::move(p.element());
-    }
 } /* namespace util */
 
 } /* namespace cscript */