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json_view: exceptions name the path and the bytes of the value

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With JSON_DIAGNOSTICS and JSON_DIAGNOSTIC_POSITIONS, the exceptions of views
now carry the same context as those of basic_json: "(/path) " and
"(bytes a-b) " in front of the message, in basic_json's format (with
JSON_DIAGNOSTICS, no context for the root). Before, views threw without any
context, and since get<T>() reads the view directly, conversions had lost
even the relative path they used to get through materialize().

The throw helpers of detail/view/errors.hpp take an error_site (document
and node; empty without the two macros). Only on the error path, the path is
found by descending from the root (pruned by subtree extent before the first
edit, a full walk through edited sequences after), and the bytes as
materialize() sets them (position_source; a container's end by following the
chain of last elements and scanning to the closing brackets). from_json() for
views and the strict enum macro put the same context in front through
exception_prefix(). Iterators keep their container only under the two
macros, for key(). Without the macros, the accessors compile to the same
code as before.

Tests compare every value's exceptions with those of the parsed or
materialized basic_json value, including edited documents; the checks that
were disabled under the two macros run again.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
This commit is contained in:
Niels Lohmann committed 2026-10-30 21:51:23 +01:00
1 parent 755bb16d7a
commit 8ac510b8d3
25 files changed
+1571 -710
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include/nlohmann/json_view.hpp
+38 -31
View File
@@ -285,7 +285,7 @@ class basic_json_view
{
return {};
}
detail::view::throw_type_error(detail::exception_id::subscript_wrong_type, "cannot use operator[] with a string argument with ", type_name());
detail::view::throw_type_error(site(), detail::exception_id::subscript_wrong_type, "cannot use operator[] with a string argument with ", type_name());
}
return lookup(key);
}
@@ -311,7 +311,7 @@ class basic_json_view
{
return {};
}
detail::view::throw_type_error(detail::exception_id::subscript_wrong_type, "cannot use operator[] with a numeric argument with ", type_name());
detail::view::throw_type_error(site(), detail::exception_id::subscript_wrong_type, "cannot use operator[] with a numeric argument with ", type_name());
}
return idx < m_node->len ? element(idx) : basic_json_view();
}
@@ -344,12 +344,12 @@ class basic_json_view
{
if (NLOHMANN_VIEW_UNLIKELY(!is_object()))
{
detail::view::throw_type_error(detail::exception_id::at_wrong_type, "cannot use at() with ", type_name());
detail::view::throw_type_error(site(), detail::exception_id::at_wrong_type, "cannot use at() with ", type_name());
}
const basic_json_view r = lookup(key);
if (NLOHMANN_VIEW_UNLIKELY(r.is_discarded()))
{
detail::view::throw_key_not_found(std::string(key.data(), key.size()));
detail::view::throw_key_not_found(site(), std::string(key.data(), key.size()));
}
return r;
}
@@ -370,11 +370,11 @@ class basic_json_view
{
if (NLOHMANN_VIEW_UNLIKELY(!is_array()))
{
detail::view::throw_type_error(detail::exception_id::at_wrong_type, "cannot use at() with ", type_name());
detail::view::throw_type_error(site(), detail::exception_id::at_wrong_type, "cannot use at() with ", type_name());
}
if (NLOHMANN_VIEW_UNLIKELY(idx >= m_node->len))
{
detail::view::throw_array_index_out_of_range(idx);
detail::view::throw_array_index_out_of_range(site(), idx);
}
return element(idx);
}
@@ -402,7 +402,7 @@ class basic_json_view
{
if (NLOHMANN_VIEW_UNLIKELY(!is_object()))
{
detail::view::throw_type_error(detail::exception_id::value_wrong_type, "cannot use value() with ", type_name());
detail::view::throw_type_error(site(), detail::exception_id::value_wrong_type, "cannot use value() with ", type_name());
}
const basic_json_view r = lookup(key);
return r.is_discarded() ? default_value : r.template get<T>();
@@ -412,7 +412,7 @@ class basic_json_view
{
if (NLOHMANN_VIEW_UNLIKELY(!is_object()))
{
detail::view::throw_type_error(detail::exception_id::value_wrong_type, "cannot use value() with ", type_name());
detail::view::throw_type_error(site(), detail::exception_id::value_wrong_type, "cannot use value() with ", type_name());
}
// (the default is made only if there is no such member)
const basic_json_view r = lookup(key);
@@ -427,7 +427,7 @@ class basic_json_view
{
if (NLOHMANN_VIEW_UNLIKELY(!is_structured()))
{
detail::view::throw_type_error(detail::exception_id::value_wrong_type, "cannot use value() with ", type_name());
detail::view::throw_type_error(site(), detail::exception_id::value_wrong_type, "cannot use value() with ", type_name());
}
const basic_json_view r = detail::view::resolve_pointer(*this, detail::json_pointer_access::reference_tokens(ptr), detail::view::pointer_mode::value);
return r.is_discarded() ? default_value : r.template get<T>();
@@ -437,7 +437,7 @@ class basic_json_view
{
if (NLOHMANN_VIEW_UNLIKELY(!is_structured()))
{
detail::view::throw_type_error(detail::exception_id::value_wrong_type, "cannot use value() with ", type_name());
detail::view::throw_type_error(site(), detail::exception_id::value_wrong_type, "cannot use value() with ", type_name());
}
const basic_json_view r = detail::view::resolve_pointer(*this, detail::json_pointer_access::reference_tokens(ptr), detail::view::pointer_mode::value);
return r.is_discarded() ? string_t(default_value) : r.template get<string_t>();
@@ -450,7 +450,7 @@ class basic_json_view
const iterator it = begin();
if (NLOHMANN_VIEW_UNLIKELY(it == end()))
{
detail::view::throw_invalid_iterator(detail::exception_id::iterator_value_unavailable, "cannot get value");
detail::view::throw_invalid_iterator(site(), detail::exception_id::iterator_value_unavailable, "cannot get value");
}
return *it;
}
@@ -481,7 +481,7 @@ class basic_json_view
return end();
}
const node* const k = find_key(key);
return k != nullptr ? iterator(m_doc, k, true) : end();
return k != nullptr ? iterator(m_doc, k, true, m_node) : end();
}
iterator find(const char* key) const
@@ -544,18 +544,18 @@ class basic_json_view
{
if (NLOHMANN_VIEW_LIKELY(is_structured()))
{
return iterator(m_doc, navigation::first(*m_doc, m_node), is_object());
return iterator(m_doc, navigation::first(*m_doc, m_node), is_object(), m_node);
}
return iterator(m_doc, m_node, false);
return iterator(m_doc, m_node, false, m_node);
}
NLOHMANN_VIEW_ALWAYS_INLINE iterator end() const noexcept
{
if (NLOHMANN_VIEW_LIKELY(is_structured()))
{
return iterator(m_doc, navigation::end(*m_doc, m_node), is_object());
return iterator(m_doc, navigation::end(*m_doc, m_node), is_object(), m_node);
}
return iterator(m_doc, (is_null() || is_discarded()) ? m_node : m_node + 1, false);
return iterator(m_doc, (is_null() || is_discarded()) ? m_node : m_node + 1, false, m_node);
}
iterator cbegin() const noexcept
@@ -606,7 +606,7 @@ class basic_json_view
{
if (NLOHMANN_VIEW_UNLIKELY(!is_string()))
{
detail::view::throw_type_error(detail::exception_id::type_mismatch, "type must be string, but is ", type_name());
detail::view::throw_type_error(site(), detail::exception_id::type_mismatch, "type must be string, but is ", type_name());
}
return {m_doc->str(*m_node), m_node->len};
}
@@ -618,7 +618,7 @@ class basic_json_view
{
if (NLOHMANN_VIEW_UNLIKELY(!is_number()))
{
detail::view::throw_type_error(detail::exception_id::type_mismatch, "type must be number, but is ", type_name());
detail::view::throw_type_error(site(), detail::exception_id::type_mismatch, "type must be number, but is ", type_name());
}
return {m_doc->str(*m_node), detail::view::number_length(*m_node)};
}
@@ -764,12 +764,19 @@ class basic_json_view
template<typename, view_mode> friend class basic_json_view;
template<typename, typename> friend class detail::view::editor;
template<typename, typename> friend class detail::view::view_side;
friend struct detail::view::view_access;
friend iterator;
basic_json_view(const document_data* d, const node* n) noexcept
: m_doc(d), m_node(n)
{}
/// this value as the context of an exception
detail::view::error_site site() const noexcept
{
return detail::view::error_site(m_doc, m_node);
}
using json_side_t = detail::view::json_side<BasicJsonType, string_view_t>;
static detail::view::view_side<BasicJsonType, basic_json_view> side(const basic_json_view& v) noexcept
@@ -876,7 +883,7 @@ class basic_json_view
{
if (NLOHMANN_VIEW_UNLIKELY(!is_boolean()))
{
detail::view::throw_type_error(detail::exception_id::type_mismatch, "type must be boolean, but is ", type_name());
detail::view::throw_type_error(site(), detail::exception_id::type_mismatch, "type must be boolean, but is ", type_name());
}
return (m_node->flags & detail::view::node_flags::is_true) != 0;
}
@@ -886,7 +893,7 @@ class basic_json_view
{
if (NLOHMANN_VIEW_UNLIKELY(m_node == nullptr))
{
detail::view::throw_type_error(detail::exception_id::type_mismatch, "type must be number, but is ", type_name());
detail::view::throw_type_error(site(), detail::exception_id::type_mismatch, "type must be number, but is ", type_name());
}
return detail::view::arithmetic_value<T, BasicJsonType>(*m_doc, *m_node);
}
@@ -895,7 +902,7 @@ class basic_json_view
{
if (NLOHMANN_VIEW_UNLIKELY(!is_null()))
{
detail::view::throw_type_error(detail::exception_id::type_mismatch, "type must be null, but is ", type_name());
detail::view::throw_type_error(site(), detail::exception_id::type_mismatch, "type must be null, but is ", type_name());
}
return nullptr;
}
@@ -1309,7 +1316,7 @@ class basic_json_document
template<typename I, typename V, typename std::enable_if<detail::view::is_non_bool_integral<I>::value, int>::type = 0>
view_type set(view_type array, I idx, V && value)
{
return editor().set(array, index(idx), std::forward<V>(value));
return editor().set(array, index(array, idx), std::forward<V>(value));
}
/// set the value at a JSON pointer: its parent must exist; an object
@@ -1346,7 +1353,7 @@ class basic_json_document
const std::size_t idx = pointer_index(token);
if (idx >= 0xFFFFFFFFu)
{
detail::view::throw_array_index_out_of_range(idx);
detail::view::throw_array_index_out_of_range(detail::view::site_of(parent), idx);
}
for (std::size_t i = 0; i < idx; ++i)
{
@@ -1380,7 +1387,7 @@ class basic_json_document
template<typename I, typename V, typename std::enable_if<detail::view::is_non_bool_integral<I>::value, int>::type = 0>
view_type insert(view_type array, I idx, V && value)
{
return editor().insert(array, index(idx), std::forward<V>(value));
return editor().insert(array, index(array, idx), std::forward<V>(value));
}
/// remove all members with this key; returns their number
@@ -1393,7 +1400,7 @@ class basic_json_document
template<typename I, typename std::enable_if<detail::view::is_non_bool_integral<I>::value, int>::type = 0>
void erase(view_type array, I idx)
{
editor().erase(array, index(idx));
editor().erase(array, index(array, idx));
}
/// remove the value at a JSON pointer; returns the number of removed
@@ -1427,25 +1434,25 @@ class basic_json_document
return detail::view::editor<BasicJsonType, view_type>(*m_data);
}
/// an index (out_of_range.401 if negative)
/// an index into @a array (out_of_range.401 if negative)
template<typename I>
static std::size_t index(I idx)
static std::size_t index(const view_type& array, I idx)
{
return index(idx, std::is_signed<I> {});
return index(array, idx, std::is_signed<I> {});
}
template<typename I>
static std::size_t index(I idx, std::true_type /*signed*/)
static std::size_t index(const view_type& array, I idx, std::true_type /*signed*/)
{
if (idx < 0)
{
detail::view::throw_array_index_out_of_range(idx);
detail::view::throw_array_index_out_of_range(detail::view::site_of(array), idx);
}
return static_cast<std::size_t>(idx);
}
template<typename I>
static std::size_t index(I idx, std::false_type /*unsigned*/)
static std::size_t index(const view_type& /*array*/, I idx, std::false_type /*unsigned*/)
{
return static_cast<std::size_t>(idx);
}