add cs_charbuf (mutable buffer controlled by our allocator)

also use it in a few places

src/cs_util.cc

@@ -519,9 +519,9 @@ OSTD_EXPORT std::size_t list_count(cs_list_parse_state &ps, cs_state &cs) {
 
 OSTD_EXPORT cs_strref list_get_item(cs_list_parse_state &ps, cs_state &cs) {
     if (!ps.quoted_item.empty() && (*ps.quoted_item == '"')) {
-        auto app = ostd::appender<cs_string>();
+        auto app = ostd::appender<cs_charbuf>(cs);
         util::unescape_string(app, ps.item);
-        return cs_strref{cs, app.get()};
+        return cs_strref{cs, app.get().str()};
     }
     return cs_strref{cs, ps.item};
 }

src/cs_util.hh

@@ -82,6 +82,21 @@ struct cs_shared_state {
         v->~T();
         alloc(v, len * sizeof(T), 0);
     }
+
+    template<typename T>
+    struct allocator {
+        using value_type = T;
+
+        T *allocate(std::size_t n) {
+            return static_cast<T *>(state->alloc(nullptr, 0, n * sizeof(T)));
+        }
+
+        void deallocate(T *p, std::size_t n) {
+            state->alloc(p, n, 0);
+        }
+
+        cs_shared_state *state;
+    };
 };
 
 inline cs_shared_state *cs_get_sstate(cs_state &cs) {
@@ -164,6 +179,31 @@ struct cs_strman {
     std::unordered_map<ostd::string_range, cs_strref_state *> counts{};
 };
 
+struct cs_charbuf {
+    cs_charbuf(cs_shared_state &cs):
+        buf{cs_shared_state::allocator<char>{&cs}}
+    {}
+
+    cs_charbuf(cs_state &cs):
+        buf{cs_shared_state::allocator<char>{cs_get_sstate(cs)}}
+    {}
+
+    using size_type = std::size_t;
+    using value_type = char;
+    using reference = char &;
+    using const_reference = char const &;
+
+    void reserve(std::size_t s) { buf.reserve(s); }
+
+    void push_back(char c) { buf.push_back(c); }
+
+    ostd::string_range str() {
+        return ostd::string_range{buf.data(), buf.data() + buf.size()};
+    }
+
+    std::vector<char, cs_shared_state::allocator<char>> buf;
+};
+
 } /* namespace cscript */
 
 #endif /* LIBCUBESCRIPT_CS_UTIL_HH */

src/lib_str.cc

@@ -82,16 +82,16 @@ void cs_init_lib_string(cs_state &cs) {
         res.set_str(sr);
     });
 
-    cs.new_command("escape", "s", [](auto &, auto args, auto &res) {
-        auto s = ostd::appender<cs_string>();
+    cs.new_command("escape", "s", [](auto &ccs, auto args, auto &res) {
+        auto s = ostd::appender<cs_charbuf>(ccs);
         util::escape_string(s, args[0].get_str());
-        res.set_str(s.get());
+        res.set_str(s.get().str());
     });
 
-    cs.new_command("unescape", "s", [](auto &, auto args, auto &res) {
-        auto s = ostd::appender<cs_string>();
+    cs.new_command("unescape", "s", [](auto &ccs, auto args, auto &res) {
+        auto s = ostd::appender<cs_charbuf>(ccs);
         util::unescape_string(s, args[0].get_str());
-        res.set_str(s.get());
+        res.set_str(s.get().str());
     });
 
     cs.new_command("concat", "V", [](auto &ccs, auto args, auto &res) {