fix build with clang-6.0.1 (Neargye#34)

Author: Naratzul

include/semver.hpp

@@ -527,28 +527,20 @@ using namespace semver::detail;
 
 class range {
  public:
-  constexpr explicit range(std::string_view str) noexcept : str_{str} {}
-
-  constexpr bool satisfies(const version& ver, bool include_prerelease) const {
-    range_parser parser{str_};
-
-    auto is_logical_or = [&parser]() constexpr noexcept -> bool { return parser.current_token.type == range_token_type::logical_or; };
-
-    auto is_operator = [&parser]() constexpr noexcept -> bool { return parser.current_token.type == range_token_type::range_operator; };
-
-    auto is_number = [&parser]() constexpr noexcept -> bool { return parser.current_token.type == range_token_type::number; };
+  constexpr explicit range(std::string_view str) noexcept : parser{str} {}
 
+  constexpr bool satisfies(const version& ver, bool include_prerelease) {
     const bool has_prerelease = ver.prerelease_type != prerelease::none;
 
     do {
-      if (is_logical_or()) {
+      if (is_logical_or_token()) {
         parser.advance_token(range_token_type::logical_or);
       }
 
       bool contains = true;
       bool allow_compare = include_prerelease;
 
-      while (is_operator() || is_number()) {
+      while (is_operator_token() || is_number_token()) {
         const auto range = parser.parse_range();
         const bool equal_without_tags = equal_to(range.ver, ver, comparators_option::exclude_prerelease);
 
@@ -570,7 +562,7 @@ class range {
         return true;
       }
 
-    } while (is_logical_or());
+    } while (is_logical_or_token());
 
     return false;
   }
@@ -797,7 +789,18 @@ class range {
     }
   };
 
-  std::string_view str_;
+  [[nodiscard]] constexpr bool is_logical_or_token() const noexcept {
+    return parser.current_token.type == range_token_type::logical_or;
+  }
+  [[nodiscard]] constexpr bool is_operator_token() const noexcept {
+    return parser.current_token.type == range_token_type::range_operator;
+  }
+
+  [[nodiscard]] constexpr bool is_number_token() const noexcept {
+    return parser.current_token.type == range_token_type::number;
+  }
+
+  range_parser parser;
 };
 
 } // namespace semver::range::detail