Implement the Clamp modifier (#740)

Fixes #750

src/rpc/common/MetaProcessors.cpp

@@ -0,0 +1,71 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of clio: https://github.com/XRPLF/clio
+    Copyright (c) 2023, the clio developers.
+
+    Permission to use, copy, modify, and distribute this software for any
+    purpose with or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL,  DIRECT,  INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#include <rpc/RPCHelpers.h>
+#include <rpc/common/MetaProcessors.h>
+
+#include <boost/json/value.hpp>
+
+#include <string_view>
+
+namespace RPC::meta {
+
+[[nodiscard]] MaybeError
+Section::verify(boost::json::value& value, std::string_view key) const
+{
+    if (not value.is_object() or not value.as_object().contains(key.data()))
+        return {};  // ignore. field does not exist, let 'required' fail instead
+
+    auto& res = value.as_object().at(key.data());
+
+    // if it is not a json object, let other validators fail
+    if (!res.is_object())
+        return {};
+
+    for (auto const& spec : specs)
+    {
+        if (auto const ret = spec.process(res); not ret)
+            return Error{ret.error()};
+    }
+
+    return {};
+}
+
+[[nodiscard]] MaybeError
+ValidateArrayAt::verify(boost::json::value& value, std::string_view key) const
+{
+    if (not value.is_object() or not value.as_object().contains(key.data()))
+        return {};  // ignore. field does not exist, let 'required' fail instead
+
+    if (not value.as_object().at(key.data()).is_array())
+        return Error{Status{RippledError::rpcINVALID_PARAMS}};
+
+    auto& arr = value.as_object().at(key.data()).as_array();
+    if (idx_ >= arr.size())
+        return Error{Status{RippledError::rpcINVALID_PARAMS}};
+
+    auto& res = arr.at(idx_);
+    for (auto const& spec : specs_)
+        if (auto const ret = spec.process(res); not ret)
+            return Error{ret.error()};
+
+    return {};
+}
+
+}  // namespace RPC::meta