Fix C++17 support

include/chaiscript/dispatchkit/bootstrap_stl.hpp

@@ -580,8 +580,37 @@ namespace chaiscript::bootstrap::standard_library {
     m.add(fun([](const StringView *s, const StringView &f, size_t pos) { return s->find_last_not_of(f, pos); }), "find_last_not_of");
     m.add(fun([](const StringView *s, const StringView &f, size_t pos) { return s->find_first_not_of(f, pos); }), "find_first_not_of");
 
-    m.add(fun([](const StringView *s, const StringView &f) { return s->starts_with(f); }), "starts_with");
+    #if __cplusplus >= 202002L
-    m.add(fun([](const StringView *s, const StringView &f) { return s->ends_with(f); }), "ends_with");
+        m.add(fun([](const StringView *s, const StringView &f) { return s->starts_with(f); }), "starts_with");
+        m.add(fun([](const StringView *s, const StringView &f) { return s->ends_with(f); }), "ends_with");
+    #else
+        m.add(fun([](const StringView *s, const StringView &f) -> bool {
+                using size_type = typename StringView::size_type;
+                const size_type fsz = f.size();
+                if (fsz == 0) {
+                  return true;
+                }
+                if (fsz > s->size()) {
+                  return false;
+                }
+                return s->compare(size_type{0}, fsz, f) == 0;
+              }),
+              "starts_with");
+
+        m.add(fun([](const StringView *s, const StringView &f) -> bool {
+                using size_type = typename StringView::size_type;
+                const size_type fsz = f.size();
+                if (fsz == 0) {
+                  return true;
+                }
+                const size_type ssz = s->size();
+                if (fsz > ssz) {
+                  return false;
+                }
+                return s->compare(ssz - fsz, fsz, f) == 0;
+              }),
+              "ends_with");
+    #endif
 
     m.add(fun([](const StringView *s, size_t pos, size_t len) { return s->substr(pos, len); }), "substr");
 

include/chaiscript/dispatchkit/function_params.hpp

@@ -12,6 +12,9 @@
 
 #include "boxed_value.hpp"
 
+// std::span was introduced in >= C++20, so we implement a small
+// wrapper around it if it's not available.
+#if __cplusplus >= 202002L
 #include <span>
 
 namespace chaiscript {
@@ -20,4 +23,70 @@ namespace chaiscript {
 
 } // namespace chaiscript
 
+#else
+
+namespace chaiscript {
+  class Function_Params {
+  public:
+    constexpr Function_Params(const Boxed_Value *const t_begin, const Boxed_Value *const t_end)
+        : m_begin(t_begin)
+        , m_end(t_end) {
+    }
+
+    explicit Function_Params(const Boxed_Value &bv)
+        : m_begin(&bv)
+        , m_end(m_begin + 1) {
+    }
+
+    explicit Function_Params(const std::vector<Boxed_Value> &vec)
+        : m_begin(vec.empty() ? nullptr : vec.data())
+        , m_end(vec.empty() ? nullptr : vec.data() + vec.size()) {
+    }
+
+    template<size_t Size>
+    constexpr explicit Function_Params(const std::array<Boxed_Value, Size> &a)
+        : m_begin(a.data())
+        , m_end(a.data() + Size) {
+    }
+
+    [[nodiscard]] constexpr const Boxed_Value &operator[](const std::size_t t_i) const noexcept { return m_begin[t_i]; }
+
+    [[nodiscard]] constexpr const Boxed_Value *begin() const noexcept { return m_begin; }
+
+    [[nodiscard]] constexpr const Boxed_Value &front() const noexcept { return *m_begin; }
+
+    [[nodiscard]] constexpr const Boxed_Value &first() const noexcept { return *m_begin; }
+
+    [[nodiscard]] constexpr Function_Params first(std::size_t t_count) const noexcept { return Function_Params(m_begin, m_begin + t_count); }
+
+    [[nodiscard]] constexpr Function_Params subspan(std::size_t t_offset, std::size_t t_count = std::size_t(-1)) const noexcept {
+      const auto *begin = m_begin + t_offset;
+      const auto *end = (t_count == std::size_t(-1)) ? m_end : begin + t_count;
+      return Function_Params(begin, end);
+    }
+
+    [[nodiscard]] constexpr const Boxed_Value *end() const noexcept { return m_end; }
+
+    [[nodiscard]] constexpr std::size_t size() const noexcept { return static_cast<std::size_t>(m_end - m_begin); }
+
+    [[nodiscard]] std::vector<Boxed_Value> to_vector() const { return std::vector<Boxed_Value>{m_begin, m_end}; }
+
+    [[nodiscard]] constexpr bool empty() const noexcept { return m_begin == m_end; }
+
+  private:
+    const Boxed_Value *m_begin = nullptr;
+    const Boxed_Value *m_end = nullptr;
+  };
+
+  // Constructor specialization for array of size 0
+  template<>
+  constexpr Function_Params::Function_Params(const std::array<Boxed_Value, size_t{0}> & /* a */)
+      : m_begin(nullptr)
+      , m_end(nullptr) {
+  }
+
+} // namespace chaiscript
+
+#endif
+
 #endif

include/chaiscript/dispatchkit/register_function.hpp

@@ -12,6 +12,19 @@
 
 #include <type_traits>
 
+/**
+ * std::type_identity was introduced in >= C++20 so we put
+ * together a small shim for it if it doesn't exist.
+ */
+#if __cplusplus < 202002L
+namespace std {
+  template<typename T>
+  struct type_identity { using type = T; };
+  template<typename T>
+  using type_identity_t = typename type_identity<T>::type;
+}
+#endif
+
 #include "bind_first.hpp"
 #include "function_signature.hpp"
 #include "proxy_functions.hpp"

include/chaiscript/language/chaiscript_eval.hpp

@@ -1246,7 +1246,7 @@ namespace chaiscript {
         const auto &ns_name = this->children[0]->text;
 
         auto ns_name_bv = const_var(ns_name);
-        t_ss->call_function("namespace", m_ns_loc, Function_Params{&ns_name_bv, 1}, t_ss.conversions());
+        t_ss->call_function("namespace", m_ns_loc, Function_Params{&ns_name_bv, &ns_name_bv + 1}, t_ss.conversions());
 
         std::vector<std::string> parts;
         {
@@ -1350,7 +1350,7 @@ namespace chaiscript {
         };
 
         const auto call_function = [&t_ss](const auto &t_funcs, const Boxed_Value &t_param) {
-          return dispatch::dispatch(*t_funcs, Function_Params{&t_param, 1}, t_ss.conversions());
+          return dispatch::dispatch(*t_funcs, Function_Params{&t_param, &t_param + 1}, t_ss.conversions());
         };
 
         const std::string &loop_var_name = this->children[0]->text;
@@ -1646,8 +1646,8 @@ namespace chaiscript {
             return Boxed_Number::do_oper(m_oper, bv);
           } else {
             chaiscript::eval::detail::Function_Push_Pop fpp(t_ss);
-            fpp.save_params(Function_Params{&bv, 1});
+            fpp.save_params(Function_Params{&bv, &bv + 1});
-            return t_ss->call_function(this->text, m_loc, Function_Params{&bv, 1}, t_ss.conversions());
+            return t_ss->call_function(this->text, m_loc, Function_Params{&bv, &bv + 1}, t_ss.conversions());
           }
         } catch (const exception::dispatch_error &e) {
           throw exception::eval_error("Error with prefix operator evaluation: '" + this->text + "'", e.parameters, e.functions, false, *t_ss);
@@ -1755,7 +1755,7 @@ namespace chaiscript {
 
             if (dispatch::Param_Types(
                     std::vector<std::pair<std::string, Type_Info>>{Arg_List_AST_Node<T>::get_arg_type(*catch_block.children[0], t_ss)})
-                    .match(Function_Params{&t_except, 1}, t_ss.conversions())
+                    .match(Function_Params{&t_except, &t_except + 1}, t_ss.conversions())
                     .first) {
               t_ss.add_object(name, t_except);
 

include/chaiscript/language/chaiscript_parser.hpp

@@ -1029,7 +1029,7 @@ namespace chaiscript {
       template<typename string_type>
       struct Char_Parser {
         string_type &match;
-        using char_type = string_type::value_type;
+        using char_type = typename string_type::value_type;
         bool is_escaped = false;
         bool is_interpolated = false;
         bool saw_interpolation_marker = false;
@@ -2941,7 +2941,7 @@ namespace chaiscript {
       /// Parses the given input string, tagging parsed ast_nodes with the given m_filename.
       AST_NodePtr parse_internal(const std::string &t_input, std::string t_fname) {
         const auto begin = t_input.empty() ? nullptr : &t_input.front();
-        const auto end = begin == nullptr ? nullptr : std::next(begin, std::ssize(t_input));
+        const auto end = begin == nullptr ? nullptr : std::next(begin, (int)std::size(t_input)); // std::ssize() isn't available in C++17
         m_position = Position(begin, end);
         m_filename = std::make_shared<std::string>(std::move(t_fname));
 

include/chaiscript/utility/json.hpp

@@ -128,10 +128,10 @@ namespace chaiscript::json {
       }
       JSONWrapper(std::nullptr_t) {}
 
-      Container::iterator begin() { return object ? object->begin() : typename Container::iterator(); }
+      typename Container::iterator begin() { return object ? object->begin() : typename Container::iterator(); }
-      Container::iterator end() { return object ? object->end() : typename Container::iterator(); }
+      typename Container::iterator end() { return object ? object->end() : typename Container::iterator(); }
-      [[nodiscard]] Container::const_iterator begin() const { return object ? object->begin() : typename Container::iterator(); }
+      [[nodiscard]] typename Container::const_iterator begin() const { return object ? object->begin() : typename Container::const_iterator(); }
-      [[nodiscard]] Container::const_iterator end() const { return object ? object->end() : typename Container::iterator(); }
+      [[nodiscard]] typename Container::const_iterator end() const { return object ? object->end() : typename Container::const_iterator(); }
     };
 
     template<typename Container>
@@ -144,10 +144,10 @@ namespace chaiscript::json {
       }
       JSONConstWrapper(std::nullptr_t) {}
 
-      [[nodiscard]] Container::const_iterator begin() const noexcept {
+      [[nodiscard]] typename Container::const_iterator begin() const noexcept {
         return object ? object->begin() : typename Container::const_iterator();
       }
-      [[nodiscard]] Container::const_iterator end() const noexcept { return object ? object->end() : typename Container::const_iterator(); }
+      [[nodiscard]] typename Container::const_iterator end() const noexcept { return object ? object->end() : typename Container::const_iterator(); }
     };
 
     JSON() = default;

include/chaiscript/utility/static_string.hpp

@@ -33,7 +33,7 @@ namespace chaiscript::utility {
       return std::string_view(data, m_size) == other;
     }
 
-    constexpr bool operator==(const std::string &t_str) const noexcept { return std::equal(begin(), end(), std::cbegin(t_str), std::cend(t_str)); }
+    constexpr bool operator==(const std::string &t_str) const noexcept { return std::string_view(data, m_size) == std::string_view(t_str); }
 
     const size_t m_size;
     const char *data = nullptr;