refactor: add validator for json-pointer and relative-json-pointer

include/jvalidate/format.h

@@ -3,14 +3,20 @@
 #include <cctype>
 #include <cstddef>
 #include <ctime>
-#include <iostream>
 #include <string>
 #include <unordered_map>
 #include <utility>
 
+#include <jvalidate/detail/pointer.h>
+#include <jvalidate/detail/relative_pointer.h>
 #include <jvalidate/forward.h>
 
 namespace jvalidate::format::detail {
+struct result {
+  ptrdiff_t consumed;
+  bool valid;
+};
+
 inline bool is_leapyear(int y) { return (y % 400) == 0 || ((y % 4) == 0 && (y % 100) != 0); }
 
 inline bool illegal_date(int y, int m, int d) {
@@ -21,22 +27,22 @@ inline bool illegal_date(int y, int m, int d) {
   return d > days[m];
 }
 
-inline auto date(std::string_view dt) {
+inline result date(std::string_view dt) {
   struct tm tm;
   if (auto end = strptime(dt.data(), "%Y-%m-%d", &tm); end) {
     if ((end - dt.data()) != 10 || illegal_date(tm.tm_year + 1900, tm.tm_mon, tm.tm_mday)) {
-      return std::make_pair(0L, false);
+      return {.consumed = 0, .valid = false};
     }
-    return std::make_pair(end - dt.data(), true);
+    return {.consumed = end - dt.data(), .valid = true};
   }
-  return std::make_pair(0L, false);
+  return {.consumed = 0L, .valid = false};
 }
 }
 
 namespace jvalidate::format {
 inline bool date(std::string_view dt) {
-  auto [size, good] = detail::date(dt);
-  return good && size == dt.size();
+  auto [consumed, valid] = detail::date(dt);
+  return valid && consumed == dt.size();
 }
 
 inline bool time(std::string_view dt) {
@@ -260,6 +266,13 @@ inline bool email(std::string_view em) {
   }
   return hostname(em);
 }
+
+template <typename T> inline bool ctor_as_valid(std::string_view str) {
+  try {
+    [[maybe_unused]] auto _ = T(str);
+    return true;
+  } catch (std::exception const &) { return false; }
+}
 }
 
 namespace jvalidate {
@@ -281,8 +294,8 @@ private:
       {"ipv6", &format::ipv6},
       {"iri", nullptr},
       {"iri-reference", nullptr},
-      {"json-pointer", nullptr},
-      {"relative-json-pointer", nullptr},
+      {"json-pointer", &format::ctor_as_valid<detail::Pointer>},
+      {"relative-json-pointer", &format::ctor_as_valid<detail::RelativePointer>},
       /* {"regex", &detail::StdRegexEngine::is_valid}, */
       {"time", &format::time},
       {"uri", nullptr},