json_view: view_mode enum instead of bool Editable, node_kind for node::kind (#5919)

* json_view: view_mode enum instead of bool Editable, node_kind for node::kind

basic_json_document and basic_json_view take a view_mode (read_only, the
default, or editable) instead of a bool: basic_json_document<json, true>
did not say what true means. The shortcut aliases are unchanged.

The kind of a node is a node_kind (the value_t values plus link, 10 as
before), which removes the static_cast<std::uint8_t>(value_t::...) of
every comparison. The node and image layouts are unchanged.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* json_view: node_kind in the node writers, spell out read_only, comment fixes

The builder and the edit functions take and store a node_kind instead of
casting a value_t; the numbering assertions and the comments now speak of
node_kind, and the link kind notes that it follows value_t::discarded.
The read-only aliases name view_mode::read_only like the editable ones.
view_mode.md says the mode is a compile-time property of the type.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* json_view: views of read-only documents convert to editable views

A read-only document has no edits, so a view of it reads correctly as a
view of an editable document before its first edit. The implicit
conversion lets a function taking a json_editable_view accept the views
of both modes. There is no conversion the other way: a read-only view of
an editable document would read wrong values after the next edit.

The mode comparisons in the cross-mode operator==/!= use an
is_other_mode trait, which astyle keeps compact.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
This commit is contained in:
Niels Lohmann authored and GitHub committed 2026-10-26 20:13:30 +01:00
1 parent 24078c862d
commit 731f1b5bfb
38 files changed
+704 -293

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+9 -9
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@@ -480,7 +480,7 @@ TEST_CASE("json_view images: edited documents")
{
CAPTURE(i)
CHECK((node_at(image, i).flags & nlohmann::detail::view::node_flags::linked) == 0);
CHECK(node_at(image, i).kind != nlohmann::detail::view::kind_link);
CHECK((node_at(image, i).kind != nlohmann::detail::view::node_kind::link));
}
for (const image_check check :
{
@@ -810,13 +810,13 @@ TEST_CASE("json_view images: check")
{
rejected(corrupted(image, 12, [&](node & n)
{
n.kind = kind;
n.kind = static_cast<nlohmann::detail::view::node_kind>(kind);
}), true);
}
// a key that is not a string
rejected(corrupted(image, 1, [](node & n)
{
n.kind = 0;
n.kind = nlohmann::detail::view::node_kind::null;
n.len = 0;
n.off = 0;
}), true);
@@ -960,11 +960,11 @@ TEST_CASE("json_view images: check")
}), true);
rejected(corrupted(image, 0, [](node & n)
{
n.kind = 2; // an array: the "keys" are values, and the counts do not match
n.kind = nlohmann::detail::view::node_kind::array; // an array: the "keys" are values, and the counts do not match
}), true);
const std::vector<std::uint8_t> as_array = corrupted(image, 16, [](node & n)
{
n.kind = 2; // {} as []: fine
n.kind = nlohmann::detail::view::node_kind::array; // {} as []: fine
});
CHECK(load_result(as_array, image_check::full).empty());
const std::string expected_dump = R"({"s":"x\"y","i":-12,"u":7,"f":1.5e+300,"b":true,"n":null,"a":["t",[]]})";
@@ -1013,13 +1013,13 @@ TEST_CASE("json_view images: check")
rejected(at_token(u6, 0, '8'), false); // 8 != 7
rejected(corrupted(image, 4, [](node & n)
{
n.kind = 6; // "-12" as unsigned: a sign
n.kind = nlohmann::detail::view::node_kind::number_unsigned; // "-12" as unsigned: a sign
n.extra = 3;
}), false);
// a non-negative number_integer (as edits write it): fine
const std::vector<std::uint8_t> positive = corrupted(image, 6, [](node & n)
{
n.kind = 5;
n.kind = nlohmann::detail::view::node_kind::number_integer;
n.extra = 0;
});
CHECK(load_result(positive, image_check::full).empty());
@@ -1027,7 +1027,7 @@ TEST_CASE("json_view images: check")
CHECK(pos.root()["u"].is_number_integer());
rejected(corrupted(image, 8, [](node & n)
{
n.kind = 6; // a float token as integer
n.kind = nlohmann::detail::view::node_kind::number_unsigned; // a float token as integer
n.extra = 7;
}), false);
}
@@ -1197,7 +1197,7 @@ TEST_CASE("json_view images: check")
{
std::vector<std::uint8_t> b = img;
node n = node_at(b, i);
n.kind = kind;
n.kind = static_cast<nlohmann::detail::view::node_kind>(kind);
n.extra = extra;
set_node(b, i, n);
return load_result(b, image_check::full);