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Document editable json_documents
- API pages for set and push_back of basic_json_document and for the editable aliases; the class overviews name the Editable parameter - type_error.319 on the exceptions page - the feature page explains editing, and the examples show when it helps: a configuration file changed without reformatting it Signed-off-by: Niels Lohmann <mail@nlohmann.me>
This commit is contained in:
@@ -137,8 +137,10 @@ INSERT INTO searchIndex(name, type, path) VALUES ('basic_json_document::node_cou
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INSERT INTO searchIndex(name, type, path) VALUES ('basic_json_document::owns_source', 'Method', 'api/basic_json_document/owns_source/index.html');
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INSERT INTO searchIndex(name, type, path) VALUES ('basic_json_document::parse', 'Function', 'api/basic_json_document/parse/index.html');
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INSERT INTO searchIndex(name, type, path) VALUES ('basic_json_document::parse_copy', 'Function', 'api/basic_json_document/parse_copy/index.html');
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INSERT INTO searchIndex(name, type, path) VALUES ('basic_json_document::push_back', 'Method', 'api/basic_json_document/push_back/index.html');
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INSERT INTO searchIndex(name, type, path) VALUES ('basic_json_document::read', 'Method', 'api/basic_json_document/read/index.html');
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INSERT INTO searchIndex(name, type, path) VALUES ('basic_json_document::root', 'Method', 'api/basic_json_document/root/index.html');
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INSERT INTO searchIndex(name, type, path) VALUES ('basic_json_document::set', 'Method', 'api/basic_json_document/set/index.html');
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INSERT INTO searchIndex(name, type, path) VALUES ('basic_json_document::shrink_to_fit', 'Method', 'api/basic_json_document/shrink_to_fit/index.html');
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INSERT INTO searchIndex(name, type, path) VALUES ('basic_json_document::source', 'Method', 'api/basic_json_document/source/index.html');
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INSERT INTO searchIndex(name, type, path) VALUES ('basic_json_view', 'Class', 'api/basic_json_view/index.html');
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@@ -187,6 +189,8 @@ INSERT INTO searchIndex(name, type, path) VALUES ('basic_json_view::type_name',
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INSERT INTO searchIndex(name, type, path) VALUES ('basic_json_view::value', 'Method', 'api/basic_json_view/value/index.html');
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INSERT INTO searchIndex(name, type, path) VALUES ('json', 'Class', 'api/json/index.html');
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INSERT INTO searchIndex(name, type, path) VALUES ('json_document', 'Class', 'api/json_document/index.html');
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INSERT INTO searchIndex(name, type, path) VALUES ('json_editable_document', 'Class', 'api/json_editable_document/index.html');
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INSERT INTO searchIndex(name, type, path) VALUES ('json_editable_view', 'Class', 'api/json_editable_view/index.html');
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INSERT INTO searchIndex(name, type, path) VALUES ('json_view', 'Class', 'api/json_view/index.html');
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INSERT INTO searchIndex(name, type, path) VALUES ('json_pointer', 'Class', 'api/json_pointer/index.html');
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INSERT INTO searchIndex(name, type, path) VALUES ('json_pointer::back', 'Method', 'api/json_pointer/back/index.html');
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@@ -222,6 +226,8 @@ INSERT INTO searchIndex(name, type, path) VALUES ('operator<<', 'Operator', 'api
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INSERT INTO searchIndex(name, type, path) VALUES ('operator>>', 'Operator', 'api/operator_gtgt/index.html');
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INSERT INTO searchIndex(name, type, path) VALUES ('ordered_json', 'Class', 'api/ordered_json/index.html');
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INSERT INTO searchIndex(name, type, path) VALUES ('ordered_json_document', 'Class', 'api/ordered_json_document/index.html');
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INSERT INTO searchIndex(name, type, path) VALUES ('ordered_json_editable_document', 'Class', 'api/ordered_json_editable_document/index.html');
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INSERT INTO searchIndex(name, type, path) VALUES ('ordered_json_editable_view', 'Class', 'api/ordered_json_editable_view/index.html');
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INSERT INTO searchIndex(name, type, path) VALUES ('ordered_json_view', 'Class', 'api/ordered_json_view/index.html');
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INSERT INTO searchIndex(name, type, path) VALUES ('ordered_map', 'Class', 'api/ordered_map/index.html');
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INSERT INTO searchIndex(name, type, path) VALUES ('std::hash<basic_json>', 'Class', 'api/basic_json/std_hash/index.html');
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@@ -3,7 +3,7 @@
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<small>Defined in header `<nlohmann/json_view.hpp>`</small>
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```cpp
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template<typename BasicJsonType>
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template<typename BasicJsonType, bool Editable = false>
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class basic_json_document;
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```
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@@ -19,6 +19,11 @@ it (a copy, or an rvalue `#!cpp std::string` that was moved in); see [`owns_sour
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is move-only: copying a document would either duplicate a potentially large index and text, or leave two documents
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claiming to borrow the same buffer, so it is disabled.
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With `#!cpp Editable == true`, the document also offers [`set`](set.md) and [`push_back`](push_back.md) to change
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values in place, see [Edits](#edits) below. The source text itself is never written; a read-only document
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(`#!cpp Editable == false`, the default) does not carry any of the bookkeeping edits need, and calling `set` or
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`push_back` on one fails to compile (`#!cpp static_assert`).
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## Template parameters
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`BasicJsonType`
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@@ -26,14 +31,22 @@ claiming to borrow the same buffer, so it is disabled.
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[`ordered_json`](../ordered_json.md). Only 64-bit `number_integer_t`/`number_unsigned_t` types are supported; this
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is checked with a `static_assert`.
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`Editable`
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: whether the document supports [`set`](set.md) and [`push_back`](push_back.md) (optional, `#!cpp false` by
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default). See [Edits](#edits) below.
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## Specializations
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- [**json_document**](../json_document.md) - documents of the default specialization [`json`](../json.md)
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- [**ordered_json_document**](../ordered_json_document.md) - documents of [`ordered_json`](../ordered_json.md)
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- [**json_document**](../json_document.md) - read-only documents of the default specialization [`json`](../json.md)
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- [**ordered_json_document**](../ordered_json_document.md) - read-only documents of
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[`ordered_json`](../ordered_json.md)
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- [**json_editable_document**](../json_editable_document.md) - editable documents of [`json`](../json.md)
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- [**ordered_json_editable_document**](../ordered_json_editable_document.md) - editable documents of
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[`ordered_json`](../ordered_json.md)
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## Member types
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- **view_type** - the type of view returned by [`root()`](root.md) (`#!cpp basic_json_view<BasicJsonType>`)
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- **view_type** - the type of view returned by [`root()`](root.md) (`#!cpp basic_json_view<BasicJsonType, Editable>`)
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- **value_t** - the JSON type enumeration, see [`basic_json::value_t`](../basic_json/value_t.md)
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## Member functions
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@@ -50,6 +63,37 @@ claiming to borrow the same buffer, so it is disabled.
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- [**node_count**](node_count.md) - the number of index entries (values plus object keys)
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- [**memory_usage**](memory_usage.md) - the number of bytes held by the document
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- [**shrink_to_fit**](shrink_to_fit.md) - release unused index capacity
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- [**set**](set.md) - replace a value, or set an object member, an array element, or the value a JSON pointer refers
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to (`#!cpp Editable` documents only)
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- [**push_back**](push_back.md) - append to an array (`#!cpp Editable` documents only)
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## Edits
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An editable document (`#!cpp Editable == true`) can be changed after parsing, with [`set`](set.md) and
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[`push_back`](push_back.md); [`json_editable_document`](../json_editable_document.md) and
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[`ordered_json_editable_document`](../ordered_json_editable_document.md) are the corresponding specializations. A few
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points apply to every edit:
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- **The source text is never written**, and the parsed index never moves: every value keeps the node it was parsed
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into, so [views](../basic_json_view/index.md) taken before an edit stay valid, including
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[`root()`](root.md). New values (and the element sequences of an edited array/object) go to storage owned by the
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document, allocated on demand.
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- **A view keeps referring to the same value.** After [`set`](set.md) replaces the value a view refers to, that view
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sees the new value; a view of a value that a later edit replaces or drops keeps showing what it last held. An edit
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of an array or object, however, **invalidates the iterators taken over it** (its members may now live in a
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different sequence), and a string obtained with [`get_string()`](../basic_json_view/get_string.md) stays valid even
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as further edits happen (earlier buffers of edited text are kept alive, not overwritten).
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- **Values are accepted three ways:** a [`basic_json_view`](../basic_json_view/index.md) of *any* document
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(read-only or editable; it is copied, nothing is shared with the source document), a `BasicJsonType` value, or
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anything `BasicJsonType` can be constructed from (numbers, strings, `#!cpp bool`, `#!cpp nullptr`, containers, ...).
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- [`dump()`](../basic_json_view/dump.md) writes an edited document with members in document order, new members at
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the end, and, with [`number_format::source`](../basic_json_view/number_format.md), keeps the spelling of every
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number that was not itself edited -- see [Editing a document](../../features/json_view.md#editing-a-document) for
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why this matters.
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- [`read()`](read.md) discards all edits, [`shrink_to_fit()`](shrink_to_fit.md) does not move the node index once
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there are edits, and [`memory_usage()`](memory_usage.md) includes the memory edits use.
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[`source_offset()`](../basic_json_view/source_offset.md) of a value introduced by an edit is
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`#!cpp static_cast<std::size_t>(-1)`, the same value it reports for a decoded string.
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## Version history
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@@ -0,0 +1,100 @@
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# <small>nlohmann::basic_json_document::</small>push_back
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```cpp
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template<typename V>
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view_type push_back(view_type array, V&& value);
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```
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Appends `value` as a new last element of `array`. A [null](../basic_json_view/is_null.md) `array` first becomes an
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empty array, the same way [`set`](set.md) turns a null `object` into an empty object.
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`value` is accepted three ways: a [`basic_json_view`](../basic_json_view/index.md) of *any* document -- read-only or
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editable, and it does not have to be `array`'s own document -- which is copied so that nothing is shared with the
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source document afterward; a `BasicJsonType` value; or anything `BasicJsonType` can be constructed from (numbers,
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strings, `#!cpp bool`, `#!cpp nullptr`, containers, ...).
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Only an **editable** document (`#!cpp Editable == true`, e.g. [`json_editable_document`](../json_editable_document.md))
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has `push_back`; calling it on a read-only `basic_json_document` fails to compile (`#!cpp static_assert`).
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## Template parameters
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`V`
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: the type of `value`, deduced; see above for what is accepted.
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## Parameters
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`array` (in)
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: the array (or null value) to append to
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`value` (in)
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: the value to append
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## Return value
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a view of the new last element of `array`, now holding `value`
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## Exception safety
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Basic exception safety: `value` is fully encoded -- including the checks below -- into storage owned by the document
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before anything already reachable from [`root()`](root.md) is touched, so a failure while encoding `value` (an
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invalid argument, or `#!cpp std::bad_alloc`) leaves the document completely unchanged, other than memory allocated
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for the encoding that is not reclaimed. A failure of a later allocation -- while `array` switches from its parsed
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layout to a growable block, or while that block grows, see [Notes](#notes) -- can still leave a partial effect, such
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as a null `array` argument already turned into an empty array even though `value` itself was not appended.
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## Exceptions
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Throws [`type_error.308`](../../home/exceptions.md#jsonexceptiontype_error308) if `array` is neither an array nor
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null -- the same message [`BasicJsonType::push_back`](../basic_json/push_back.md) throws for the same type. Throws
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[`invalid_iterator.202`](../../home/exceptions.md#jsonexceptioninvalid_iterator202) ("view does not belong to this
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document") if `array` is a [discarded](../basic_json_view/is_discarded.md) view or a view of a *different* document.
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Throws [`type_error.302`](../../home/exceptions.md#jsonexceptiontype_error302) if `value` is a
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[discarded](../basic_json_view/is_discarded.md) view or a [discarded](../basic_json/is_discarded.md) `BasicJsonType`
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value, and [`type_error.319`](../../home/exceptions.md#jsonexceptiontype_error319) if `value` is (or contains) a
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binary value -- `BasicJsonType` can hold one, but a `json_document` cannot. Throws
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[`type_error.316`](../../home/exceptions.md#jsonexceptiontype_error316) if `value` is (or contains) a string that is
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not valid UTF-8, with the same message [`BasicJsonType::dump()`](../basic_json/dump.md) gives for that string.
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## Complexity
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Amortized constant, plus time linear in the size of `value` to encode it into the document's storage (constant for
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a scalar, linear in the number of nested values for an array or object): the elements of `array` move to a growable
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block of links the first time it is appended to (or [`set`](set.md) on), and that block itself grows -- doubling its
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capacity, so the cost of growing it amortizes to constant per element -- only once it runs out of room. See
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[Notes](#notes).
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## Notes
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Like [`set`](set.md) on a member or an element, `push_back` never moves an existing element itself -- only where
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`array`'s *links* to its elements live -- so a view of an existing element of `array` stays valid across a
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`push_back`, but any iterator already taken over `array` is invalidated, since it was walking the old layout. See
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[Edits](index.md#edits) for what stays valid across an edit in general.
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## Examples
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??? example
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The example below appends records to an array one at a time, as they might arrive from a stream of events,
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without ever building a `BasicJsonType` value for the array or for the records already in it, and shows that a
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view taken from an earlier `push_back` still refers to the same element once later ones have run.
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```cpp
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--8<-- "examples/basic_json_document__push_back.cpp"
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```
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Output:
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```json
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--8<-- "examples/basic_json_document__push_back.output"
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```
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## See also
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- [set](set.md) - replace a value, or set an object member, an array element, or the value a JSON pointer refers to
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- [root](root.md) - the view of the root value
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- [`BasicJsonType::push_back`](../basic_json/push_back.md) - the corresponding function of `basic_json`
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- [Edits](index.md#edits) - what an edit guarantees, for every overload
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## Version history
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- Added in version 3.13.0.
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@@ -0,0 +1,192 @@
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# <small>nlohmann::basic_json_document::</small>set
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```cpp
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// (1)
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template<typename V>
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view_type set(view_type target, V&& value);
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// (2)
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template<typename V>
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view_type set(view_type object, string_view_t key, V&& value);
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// (3)
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template<typename I, typename V>
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view_type set(view_type array, I idx, V&& value);
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// (4)
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template<typename V>
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view_type set(const json_pointer& ptr, V&& value);
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```
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Only an **editable** document (`#!cpp Editable == true`, e.g. [`json_editable_document`](../json_editable_document.md))
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has `set`; calling it on a read-only `basic_json_document` fails to compile (`#!cpp static_assert`).
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1. Replaces the value `target` refers to with `value`.
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2. Sets the member `key` of the object `object` to `value`: assigns it if `object` already has a member with this
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key -- the first one, should the key occur more than once, and the later duplicates are then dropped (see the
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[Notes](#notes) below) -- or appends a new member at the end otherwise. A [null](../basic_json_view/is_null.md)
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`object` first becomes an empty object.
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3. Assigns `value` to the element at index `idx` of the array `array`, which must already exist (`#!cpp idx <
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array.size()`).
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4. Sets the value the JSON pointer `ptr` refers to, relative to [`root()`](root.md), to `value`. The *parent* of the
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target must already exist: an object member is set as in 2. (added if it does not exist yet), an array element is
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assigned as in 3., and a last reference token of `#!cpp "-"`, or equal to the size of the array, appends `value`
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instead, exactly as [`push_back`](push_back.md) would. An empty `ptr` sets [`root()`](root.md) itself, as in 1.
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||||
|
||||
In every overload, `value` is accepted three ways: a [`basic_json_view`](../basic_json_view/index.md) of *any*
|
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document -- read-only or editable, and it does not have to be `target`'s/`object`'s/`array`'s own document -- which
|
||||
is copied so that nothing is shared with the source document afterward; a `BasicJsonType` value; or anything
|
||||
`BasicJsonType` can be constructed from (numbers, strings, `#!cpp bool`, `#!cpp nullptr`, containers, ...).
|
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|
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## Template parameters
|
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|
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`V`
|
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: the type of `value`, deduced; see above for what is accepted.
|
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|
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`I`
|
||||
: an integral type other than `#!cpp bool`, deduced (overloads taking a `#!cpp bool` or a non-integral type for
|
||||
`idx` do not participate in overload resolution).
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|
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## Parameters
|
||||
|
||||
`target` (in)
|
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: the value to replace
|
||||
|
||||
`object` (in)
|
||||
: the object (or null value) whose member to set
|
||||
|
||||
`array` (in)
|
||||
: the array whose element to assign
|
||||
|
||||
`key` (in)
|
||||
: the key of the member to set
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||||
|
||||
`idx` (in)
|
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: the index of the element to assign; a negative value throws (see [Exceptions](#exceptions))
|
||||
|
||||
`ptr` (in)
|
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: a JSON pointer to the value to set, relative to `root()`
|
||||
|
||||
`value` (in)
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: the new value
|
||||
|
||||
## Return value
|
||||
|
||||
1. a view of `target`, now holding `value`
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||||
2. a view of the member `key` of `object`, now holding `value`
|
||||
3. a view of the element `idx` of `array`, now holding `value`
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||||
4. a view of the value `ptr` refers to, now holding `value`
|
||||
|
||||
## Exception safety
|
||||
|
||||
Basic exception safety: `value` is fully encoded -- including the checks below -- into storage owned by the document
|
||||
before anything already reachable from [`root()`](root.md) is touched, so a failure while encoding `value` (an
|
||||
invalid argument, or `#!cpp std::bad_alloc`) leaves the document completely unchanged, other than memory allocated
|
||||
for the encoding that is not reclaimed. A failure of a later allocation -- while an edited array or object switches
|
||||
from its parsed layout to a growable block, see [Notes](#notes) -- can still leave a partial effect, such as a
|
||||
[null](../basic_json_view/is_null.md) `object`/`array` argument already turned into an empty object/array even
|
||||
though `value` itself was not linked in.
|
||||
|
||||
## Exceptions
|
||||
|
||||
1. Throws [`type_error.302`](../../home/exceptions.md#jsonexceptiontype_error302) if `value` is a
|
||||
[discarded](../basic_json_view/is_discarded.md) view, or a [discarded](../basic_json/is_discarded.md)
|
||||
`BasicJsonType` value (e.g. `#!cpp BasicJsonType(value_t::discarded)`) -- an object or array `value`, of either
|
||||
kind, is fine and is encoded as a whole subtree.
|
||||
2. Throws [`type_error.305`](../../home/exceptions.md#jsonexceptiontype_error305) if `object` is neither an object
|
||||
nor null -- the same message [`operator[]`](../basic_json_view/operator%5B%5D.md) throws for a string argument on
|
||||
such a value. Throws [`type_error.316`](../../home/exceptions.md#jsonexceptiontype_error316) if `key` is not
|
||||
valid UTF-8, with the same message [`BasicJsonType::dump()`](../basic_json/dump.md) gives for that string.
|
||||
Also throws what 1. throws for `value`.
|
||||
3. Throws `type_error.305` if `array` is not an array -- the same message `operator[]` throws for a numeric argument
|
||||
on such a value. Throws [`out_of_range.401`](../../home/exceptions.md#jsonexceptionout_of_range401) if `idx` is
|
||||
negative, or if `#!cpp idx >= array.size()`. Also throws what 1. throws for `value`.
|
||||
4. Throws what [`at`](../basic_json_view/at.md) throws (overload 3) for resolving `ptr`'s parent, except that a
|
||||
missing object member or an array index equal to the array's size at the very last reference token is not an
|
||||
error there (it becomes a new member or an appended element) instead of
|
||||
[`out_of_range.403`](../../home/exceptions.md#jsonexceptionout_of_range403)/[`out_of_range.402`](../../home/exceptions.md#jsonexceptionout_of_range402).
|
||||
For the last reference token itself: if the parent is an object (or a primitive value, where it throws
|
||||
`type_error.305`), throws what 2. throws; if the parent is an array, throws what 3. throws for an index that is
|
||||
out of range, or, for a token that is not a valid array index,
|
||||
[`parse_error.106`](../../home/exceptions.md#jsonexceptionparse_error106) (a leading `#!cpp '0'`),
|
||||
[`parse_error.109`](../../home/exceptions.md#jsonexceptionparse_error109) (not a number),
|
||||
[`out_of_range.410`](../../home/exceptions.md#jsonexceptionout_of_range410) (too large for `size_type`), or
|
||||
[`out_of_range.404`](../../home/exceptions.md#jsonexceptionout_of_range404) (an empty token). Also throws what 1.
|
||||
throws for `value`.
|
||||
|
||||
Every overload also throws [`type_error.319`](../../home/exceptions.md#jsonexceptiontype_error319) if `value` is (or
|
||||
contains) a binary value -- `BasicJsonType` can hold one, but a `json_document` cannot -- and
|
||||
[`invalid_iterator.202`](../../home/exceptions.md#jsonexceptioninvalid_iterator202) ("view does not belong to this
|
||||
document") if `target`/`object`/`array` is a [discarded](../basic_json_view/is_discarded.md) view or a view of a
|
||||
*different* document (overloads 1-3 only; overload 4 always starts from this document's own [`root()`](root.md)).
|
||||
|
||||
## Complexity
|
||||
|
||||
1. Linear in the size of `value` (encoding it into the document's storage): constant for a scalar, linear in the
|
||||
number of nested values for an array or object. If `target` is itself an array or object that spans more than one
|
||||
node in its parent's original, unedited layout, and `value` is a scalar, replacing it additionally costs time
|
||||
linear in the number of elements of that parent, the *first* time -- see [Notes](#notes).
|
||||
2. Linear in the number of members of `object`, to find an existing member with `key`, plus the complexity of 1. for
|
||||
`value`.
|
||||
3. Constant, plus the complexity of 1. for `value`.
|
||||
4. Linear in the number of reference tokens of `ptr` and, for each token, in the number of members of the object at
|
||||
that level or the index into the array (as [`at`](../basic_json_view/at.md)), plus the complexity of 2. or 3. for
|
||||
the last token.
|
||||
|
||||
## Notes
|
||||
|
||||
!!! info "Duplicate keys"
|
||||
|
||||
If `object` already has more than one member with `key` (2.), the *first* one is assigned `value` and every
|
||||
later member with the same key is removed -- so that a lookup, an iteration, and
|
||||
[`materialize()`](../basic_json_view/materialize.md) of `object` afterward all agree on a single value for
|
||||
`key`, the same way [`operator[]`](../basic_json_view/operator%5B%5D.md) already picks the first occurrence of a
|
||||
duplicate key for reading. See the [Notes on duplicate keys](../basic_json_view/operator%5B%5D.md#notes) of
|
||||
`operator[]`.
|
||||
|
||||
Setting a member (2.) or an element (3., through 4.) of an array or object whose elements have not been edited
|
||||
before switches it from its parsed layout to a growable block holding links to its elements; a later
|
||||
[`push_back`](push_back.md) or `set` on the same container reuses that block, growing it (amortized constant time)
|
||||
only once it runs out of room. This never moves an element itself -- only where the container's *links* to its
|
||||
elements live -- so a view of an element stays valid, but any iterator already taken over the container is
|
||||
invalidated, since it was walking the old layout. See [Edits](index.md#edits) for what stays valid across an edit in
|
||||
general.
|
||||
|
||||
The same switch happens, for the same reason, when overload 1. replaces a multi-node array/object value with a
|
||||
scalar: the *parent's* element sequence is what has to switch to links, not `target` itself, because the parent
|
||||
originally stepped over `target`'s whole subtree by its node count, which no longer applies once `target` is a
|
||||
one-node scalar.
|
||||
|
||||
## Examples
|
||||
|
||||
??? example "Example: (1)/(2)/(3)/(4) replace a value, set a member, assign an element, set via a JSON pointer"
|
||||
|
||||
The example below edits a small configuration document -- replacing a value, adding an object member, assigning
|
||||
an array element, and reaching a field through a JSON pointer -- and shows what
|
||||
[`dump()`](../basic_json_view/dump.md) preserves that is lost once the same edits are made on a `BasicJsonType`
|
||||
value instead: the order object members were written in, and the exact spelling of a number that was never
|
||||
touched.
|
||||
|
||||
```cpp
|
||||
--8<-- "examples/basic_json_document__set.cpp"
|
||||
```
|
||||
|
||||
Output:
|
||||
|
||||
```json
|
||||
--8<-- "examples/basic_json_document__set.output"
|
||||
```
|
||||
|
||||
## See also
|
||||
|
||||
- [push_back](push_back.md) - append to an array
|
||||
- [root](root.md) - the view of the root value, the starting point of overload 4
|
||||
- [`basic_json_view::dump`](../basic_json_view/dump.md) - serialize the document, keeping an untouched number's
|
||||
spelling with `#!cpp number_format::source`
|
||||
- [Edits](index.md#edits) - what an edit guarantees, for every overload
|
||||
- [Editing a document](../../features/json_view.md#editing-a-document) - why editable documents keep the source
|
||||
text's order and number spelling
|
||||
|
||||
## Version history
|
||||
|
||||
- Added in version 3.13.0.
|
||||
@@ -3,7 +3,7 @@
|
||||
<small>Defined in header `<nlohmann/json_view.hpp>`</small>
|
||||
|
||||
```cpp
|
||||
template<typename BasicJsonType>
|
||||
template<typename BasicJsonType, bool Editable = false>
|
||||
class basic_json_view;
|
||||
```
|
||||
|
||||
@@ -27,16 +27,30 @@ subtree on demand. [`operator[]`](operator%5B%5D.md), [`at`](at.md), [`contains`
|
||||
[`operator!=`](operator_ne.md) compare two views, or a view and a `BasicJsonType` value, without ever building a
|
||||
`BasicJsonType` value for a view; no ordering comparison (`#!cpp operator<`) is provided.
|
||||
|
||||
`basic_json_view` itself is always read-only -- it never has a `set` or `push_back` of its own. A view of an
|
||||
**editable** document (`#!cpp Editable == true`) sees every edit made through
|
||||
[`basic_json_document::set`](../basic_json_document/set.md) and
|
||||
[`basic_json_document::push_back`](../basic_json_document/push_back.md): once a value is changed, every view that
|
||||
still refers to it -- including ones taken before the change -- reads the new value. See
|
||||
[Edits](../basic_json_document/index.md#edits).
|
||||
|
||||
## Template parameters
|
||||
|
||||
`BasicJsonType`
|
||||
: a specialization of [`basic_json`](../basic_json/index.md), matching the
|
||||
[`basic_json_document`](../basic_json_document/index.md) the view was taken from.
|
||||
|
||||
`Editable`
|
||||
: whether the view is of an editable document, matching the [`basic_json_document`](../basic_json_document/index.md)
|
||||
it was taken from (optional, `#!cpp false` by default). See [Edits](../basic_json_document/index.md#edits).
|
||||
|
||||
## Specializations
|
||||
|
||||
- [**json_view**](../json_view.md) - views of a [`json_document`](../json_document.md)
|
||||
- [**ordered_json_view**](../ordered_json_view.md) - views of an [`ordered_json_document`](../ordered_json_document.md)
|
||||
- [**json_editable_view**](../json_editable_view.md) - views of a [`json_editable_document`](../json_editable_document.md)
|
||||
- [**ordered_json_editable_view**](../ordered_json_editable_view.md) - views of an
|
||||
[`ordered_json_editable_document`](../ordered_json_editable_document.md)
|
||||
|
||||
## Member types
|
||||
|
||||
|
||||
@@ -0,0 +1,43 @@
|
||||
# <small>nlohmann::</small>json_editable_document
|
||||
|
||||
<small>Defined in header `<nlohmann/json_view.hpp>`</small>
|
||||
|
||||
```cpp
|
||||
using json_editable_document = basic_json_document<json, true>;
|
||||
```
|
||||
|
||||
This type is an **editable** [`basic_json_document`](basic_json_document/index.md) of the default
|
||||
[`json`](json.md) specialization: in addition to everything [`json_document`](json_document.md) offers,
|
||||
[`set`](basic_json_document/set.md) and [`push_back`](basic_json_document/push_back.md) change values after
|
||||
parsing, without ever rewriting the source text -- see [Edits](basic_json_document/index.md#edits) and
|
||||
[Editing a document](../features/json_view.md#editing-a-document).
|
||||
|
||||
## Examples
|
||||
|
||||
??? example
|
||||
|
||||
The example below patches two fields of a small configuration document -- changing one and adding another --
|
||||
and dumps it back out with the member order and the spelling of the untouched number preserved, something a
|
||||
plain [`json`](json.md) value cannot do.
|
||||
|
||||
```cpp
|
||||
--8<-- "examples/json_editable_document.cpp"
|
||||
```
|
||||
|
||||
Output:
|
||||
|
||||
```json
|
||||
--8<-- "examples/json_editable_document.output"
|
||||
```
|
||||
|
||||
## See also
|
||||
|
||||
- [json_editable_view](json_editable_view.md) - a view of a value of a `json_editable_document`
|
||||
- [json_document](json_document.md) - the read-only document this type adds edits to
|
||||
- [ordered_json_editable_document](ordered_json_editable_document.md) - the corresponding editable document for
|
||||
`ordered_json`
|
||||
- [Edits](basic_json_document/index.md#edits) - what an edit guarantees
|
||||
|
||||
## Version history
|
||||
|
||||
Since version 3.13.0.
|
||||
@@ -0,0 +1,41 @@
|
||||
# <small>nlohmann::</small>json_editable_view
|
||||
|
||||
<small>Defined in header `<nlohmann/json_view.hpp>`</small>
|
||||
|
||||
```cpp
|
||||
using json_editable_view = basic_json_view<json, true>;
|
||||
```
|
||||
|
||||
This type is a [`basic_json_view`](basic_json_view/index.md) of a value of a
|
||||
[`json_editable_document`](json_editable_document.md). It offers the same read-only interface as
|
||||
[`json_view`](json_view.md); what is different is what it can be a view *of* -- a value that
|
||||
[`set`](basic_json_document/set.md) and [`push_back`](basic_json_document/push_back.md) can change, with every view
|
||||
still referring to it seeing the change, see [Edits](basic_json_document/index.md#edits).
|
||||
|
||||
## Examples
|
||||
|
||||
??? example
|
||||
|
||||
The example below is the same as [`json_editable_document`'s](json_editable_document.md): every view read back
|
||||
out of the document -- `#!cpp doc.root()` and the views nested under it -- sees the edits made through `set`.
|
||||
|
||||
```cpp
|
||||
--8<-- "examples/json_editable_document.cpp"
|
||||
```
|
||||
|
||||
Output:
|
||||
|
||||
```json
|
||||
--8<-- "examples/json_editable_document.output"
|
||||
```
|
||||
|
||||
## See also
|
||||
|
||||
- [json_editable_document](json_editable_document.md) - the document type this view refers into
|
||||
- [json_view](json_view.md) - the corresponding read-only view
|
||||
- [ordered_json_editable_view](ordered_json_editable_view.md) - the corresponding view for
|
||||
`ordered_json_editable_document`
|
||||
|
||||
## Version history
|
||||
|
||||
Since version 3.13.0.
|
||||
@@ -0,0 +1,47 @@
|
||||
# <small>nlohmann::</small>ordered_json_editable_document
|
||||
|
||||
<small>Defined in header `<nlohmann/json_view.hpp>`</small>
|
||||
|
||||
```cpp
|
||||
using ordered_json_editable_document = basic_json_document<ordered_json, true>;
|
||||
```
|
||||
|
||||
This type is an **editable** [`basic_json_document`](basic_json_document/index.md) of the
|
||||
[`ordered_json`](ordered_json.md) specialization: [`set`](basic_json_document/set.md) and
|
||||
[`push_back`](basic_json_document/push_back.md) change values after parsing, as for
|
||||
[`json_editable_document`](json_editable_document.md), and
|
||||
[`materialize()`](basic_json_view/materialize.md) preserves the document order of object members -- including
|
||||
members [`set`](basic_json_document/set.md) added -- instead of sorting them like
|
||||
[`json_editable_document`](json_editable_document.md) does.
|
||||
|
||||
## Examples
|
||||
|
||||
??? example
|
||||
|
||||
The example below edits a document with `set`, then shows that `materialize()` keeps the member order of the
|
||||
source text (with the new member at the end) for `ordered_json_editable_document`, where it would sort the
|
||||
members alphabetically for [`json_editable_document`](json_editable_document.md).
|
||||
|
||||
```cpp
|
||||
--8<-- "examples/ordered_json_editable_document.cpp"
|
||||
```
|
||||
|
||||
Output:
|
||||
|
||||
```json
|
||||
--8<-- "examples/ordered_json_editable_document.output"
|
||||
```
|
||||
|
||||
## See also
|
||||
|
||||
- [ordered_json_editable_view](ordered_json_editable_view.md) - a view of a value of an
|
||||
`ordered_json_editable_document`
|
||||
- [ordered_json_document](ordered_json_document.md) - the read-only document this type adds edits to
|
||||
- [json_editable_document](json_editable_document.md) - the corresponding editable document for the default `json`
|
||||
specialization
|
||||
- [Object Order](../features/object_order.md)
|
||||
- [Edits](basic_json_document/index.md#edits) - what an edit guarantees
|
||||
|
||||
## Version history
|
||||
|
||||
Since version 3.13.0.
|
||||
@@ -0,0 +1,40 @@
|
||||
# <small>nlohmann::</small>ordered_json_editable_view
|
||||
|
||||
<small>Defined in header `<nlohmann/json_view.hpp>`</small>
|
||||
|
||||
```cpp
|
||||
using ordered_json_editable_view = basic_json_view<ordered_json, true>;
|
||||
```
|
||||
|
||||
This type is a [`basic_json_view`](basic_json_view/index.md) of a value of an
|
||||
[`ordered_json_editable_document`](ordered_json_editable_document.md), the corresponding view for
|
||||
[`ordered_json_view`](ordered_json_view.md) the way [`json_editable_view`](json_editable_view.md) is for
|
||||
[`json_view`](json_view.md).
|
||||
|
||||
## Examples
|
||||
|
||||
??? example
|
||||
|
||||
The example below is the same as [`ordered_json_editable_document`'s](ordered_json_editable_document.md): the
|
||||
views `set` returns see the document's member order preserved on `materialize()`, unlike for a
|
||||
[`json_editable_document`](json_editable_document.md).
|
||||
|
||||
```cpp
|
||||
--8<-- "examples/ordered_json_editable_document.cpp"
|
||||
```
|
||||
|
||||
Output:
|
||||
|
||||
```json
|
||||
--8<-- "examples/ordered_json_editable_document.output"
|
||||
```
|
||||
|
||||
## See also
|
||||
|
||||
- [ordered_json_editable_document](ordered_json_editable_document.md) - the document type this view refers into
|
||||
- [ordered_json_view](ordered_json_view.md) - the corresponding read-only view
|
||||
- [json_editable_view](json_editable_view.md) - the corresponding view for `json_editable_document`
|
||||
|
||||
## Version history
|
||||
|
||||
Since version 3.13.0.
|
||||
@@ -0,0 +1,24 @@
|
||||
#include <iostream>
|
||||
#include <nlohmann/json_view.hpp>
|
||||
|
||||
using json = nlohmann::json;
|
||||
using json_editable_document = nlohmann::json_editable_document;
|
||||
|
||||
int main()
|
||||
{
|
||||
// "events" starts out null -- the first push_back() turns it into an
|
||||
// array, exactly like set() turns a null object member into an object
|
||||
json_editable_document doc = json_editable_document::parse(R"({"source": "sensor-1", "events": null})");
|
||||
|
||||
const auto first = doc.push_back(doc.root()["events"], json{{"type", "start"}, {"t", 0}});
|
||||
for (int t = 1; t <= 3; ++t)
|
||||
{
|
||||
doc.push_back(doc.root()["events"], json{{"type", "tick"}, {"t", t}});
|
||||
}
|
||||
|
||||
// push_back() never moves an existing element: a view taken from an
|
||||
// earlier call still refers to the same element after later ones
|
||||
std::cout << first.dump() << '\n';
|
||||
std::cout << doc.root()["events"].size() << '\n';
|
||||
std::cout << doc.root().dump(2) << '\n';
|
||||
}
|
||||
@@ -0,0 +1,23 @@
|
||||
{"t":0,"type":"start"}
|
||||
4
|
||||
{
|
||||
"source": "sensor-1",
|
||||
"events": [
|
||||
{
|
||||
"t": 0,
|
||||
"type": "start"
|
||||
},
|
||||
{
|
||||
"t": 1,
|
||||
"type": "tick"
|
||||
},
|
||||
{
|
||||
"t": 2,
|
||||
"type": "tick"
|
||||
},
|
||||
{
|
||||
"t": 3,
|
||||
"type": "tick"
|
||||
}
|
||||
]
|
||||
}
|
||||
@@ -0,0 +1,41 @@
|
||||
#include <iostream>
|
||||
#include <nlohmann/json_view.hpp>
|
||||
|
||||
using json = nlohmann::json;
|
||||
using json_editable_document = nlohmann::json_editable_document;
|
||||
using json_editable_view = nlohmann::json_editable_view;
|
||||
|
||||
int main()
|
||||
{
|
||||
// a configuration file, as it might be read from disk -- "price" is
|
||||
// written with a trailing zero that has no effect on its value
|
||||
const std::string text = R"({
|
||||
"name": "cache",
|
||||
"host": "db1",
|
||||
"port": 6379,
|
||||
"price": 19.90,
|
||||
"replicas": ["db2", "db3"],
|
||||
"timeout": 30
|
||||
})";
|
||||
|
||||
json_editable_document doc = json_editable_document::parse(text);
|
||||
|
||||
doc.set(doc.root()["port"], 6380); // (1) replace a value
|
||||
doc.set(doc.root(), "region", "us-east"); // (2) add a member
|
||||
doc.set(doc.root()["replicas"], 0, "db4"); // (3) assign an element
|
||||
doc.set(json::json_pointer("/timeout"), 45); // (4) via a JSON pointer
|
||||
|
||||
// members stay in document order (the new one at the end), and a number
|
||||
// that was not itself edited keeps its exact spelling
|
||||
std::cout << doc.root().dump(2, ' ', false, json_editable_view::number_format::source) << "\n\n";
|
||||
|
||||
// the same edits on a plain json value: object_t is a std::map, so
|
||||
// parsing already sorted the keys, and dump() rewrites every number to
|
||||
// its shortest form, even "price", which was never touched
|
||||
json plain = json::parse(text);
|
||||
plain["port"] = 6380;
|
||||
plain["region"] = "us-east";
|
||||
plain["replicas"][0] = "db4";
|
||||
plain[json::json_pointer("/timeout")] = 45;
|
||||
std::cout << plain.dump(2) << '\n';
|
||||
}
|
||||
@@ -0,0 +1,25 @@
|
||||
{
|
||||
"name": "cache",
|
||||
"host": "db1",
|
||||
"port": 6380,
|
||||
"price": 19.90,
|
||||
"replicas": [
|
||||
"db4",
|
||||
"db3"
|
||||
],
|
||||
"timeout": 45,
|
||||
"region": "us-east"
|
||||
}
|
||||
|
||||
{
|
||||
"host": "db1",
|
||||
"name": "cache",
|
||||
"port": 6380,
|
||||
"price": 19.9,
|
||||
"region": "us-east",
|
||||
"replicas": [
|
||||
"db4",
|
||||
"db3"
|
||||
],
|
||||
"timeout": 45
|
||||
}
|
||||
@@ -0,0 +1,30 @@
|
||||
#include <iostream>
|
||||
#include <nlohmann/json_view.hpp>
|
||||
|
||||
using json = nlohmann::json;
|
||||
using json_editable_document = nlohmann::json_editable_document;
|
||||
using json_editable_view = nlohmann::json_editable_view;
|
||||
|
||||
int main()
|
||||
{
|
||||
// a configuration file, as it might be read from disk
|
||||
const std::string text = R"({"name": "cache", "host": "db1", "port": 6379, "price": 19.90})";
|
||||
std::cout << text << "\n\n";
|
||||
|
||||
// patch two fields -- "price" is never touched
|
||||
json_editable_document doc = json_editable_document::parse(text);
|
||||
doc.set(doc.root(), "host", "db2");
|
||||
doc.set(doc.root(), "retries", 3);
|
||||
|
||||
// member order (the new member at the end) and the untouched number's
|
||||
// exact spelling survive
|
||||
std::cout << doc.root().dump(-1, ' ', false, json_editable_view::number_format::source) << '\n';
|
||||
|
||||
// the same patch on a plain json value: keys are sorted (object_t is a
|
||||
// std::map), and "price" is rewritten even though the patch never
|
||||
// touched it
|
||||
json plain = json::parse(text);
|
||||
plain["host"] = "db2";
|
||||
plain["retries"] = 3;
|
||||
std::cout << plain.dump() << '\n';
|
||||
}
|
||||
@@ -0,0 +1,4 @@
|
||||
{"name": "cache", "host": "db1", "port": 6379, "price": 19.90}
|
||||
|
||||
{"name":"cache","host":"db2","port":6379,"price":19.90,"retries":3}
|
||||
{"host":"db2","name":"cache","port":6379,"price":19.9,"retries":3}
|
||||
@@ -0,0 +1,15 @@
|
||||
#include <iostream>
|
||||
#include <nlohmann/json_view.hpp>
|
||||
|
||||
using ordered_json_editable_document = nlohmann::ordered_json_editable_document;
|
||||
|
||||
int main()
|
||||
{
|
||||
// ordered_json_editable_document is basic_json_document<nlohmann::ordered_json, true>
|
||||
ordered_json_editable_document doc = ordered_json_editable_document::parse(R"({"z": 1, "a": 2, "m": 3})");
|
||||
doc.set(doc.root(), "b", 4); // set() always appends a new member at the end
|
||||
|
||||
// materialize() preserves the document order (with "b" at the end),
|
||||
// instead of sorting the keys the way json_editable_document does
|
||||
std::cout << doc.root().materialize().dump() << '\n';
|
||||
}
|
||||
@@ -0,0 +1 @@
|
||||
{"z":1,"a":2,"m":3,"b":4}
|
||||
@@ -13,6 +13,7 @@ C++ types, and finally serialize it again.
|
||||
[SAX interface](parsing/sax_interface.md), and [error handling](parsing/parse_exceptions.md).
|
||||
- [Zero-copy JSON views](json_view.md) — read a JSON text through a flat index instead of building a `json` tree;
|
||||
strings and numbers stay in the input and are only decoded when needed.
|
||||
[Editable documents](json_view.md#editing-a-document) can also be modified.
|
||||
- [Comments](comments.md) and [trailing commas](trailing_commas.md) — opt-in relaxations of the JSON grammar.
|
||||
|
||||
## Accessing and modifying values
|
||||
|
||||
@@ -187,14 +187,72 @@ a number to its parsed `#!cpp double`/`#!cpp int64_t` value.
|
||||
[`operator<<`](../api/basic_json_view/operator_ltlt.md) writes a view to a stream the way `basic_json`'s does, using
|
||||
the stream's `width`/`fill` for indentation.
|
||||
|
||||
## Editing a document
|
||||
|
||||
Everything above is read-only: a `json_document`/`json_view` lets you look at a parsed text without copying it, but
|
||||
not change it. [`basic_json_document<BasicJsonType, true>`](../api/basic_json_document/index.md) -- more conveniently
|
||||
spelled [`json_editable_document`](../api/json_editable_document.md) or
|
||||
[`ordered_json_editable_document`](../api/ordered_json_editable_document.md) -- also lets you
|
||||
[`set`](../api/basic_json_document/set.md) a value and [`push_back`](../api/basic_json_document/push_back.md) onto
|
||||
an array, still without ever building a `basic_json` tree for parts you do not touch.
|
||||
|
||||
`#!cpp Editable` defaults to `#!cpp false`, so `json_document`/`ordered_json_document` are unaffected -- they carry
|
||||
none of the bookkeeping edits need, and calling `set`/`push_back` on one is a compile error, not a runtime one.
|
||||
|
||||
### Why: editing without reformatting
|
||||
|
||||
The `#!cpp 19.90` price from [above](#writing-a-view-back) is exactly the kind of value that makes editing a `json`
|
||||
or `ordered_json` value in place lossy. Say you parse a configuration file, patch one field, and write it back:
|
||||
|
||||
- **`json`** re-sorts every key on the way in (`object_t` is a `#!cpp std::map`) and rewrites every number to its
|
||||
shortest round-trip form on the way out -- a one-field patch turns into a diff that reorders the whole file and
|
||||
rewrites `#!cpp 19.90` to `#!cpp 19.9`.
|
||||
- **`ordered_json`** keeps the key order, but still rewrites every number the same way: parsing has already reduced
|
||||
it to a `#!cpp double`/`#!cpp int64_t`, and there is no way back to how it was spelled in the source text.
|
||||
|
||||
An editable document keeps both. [`dump()`](../api/basic_json_view/dump.md) of an edited document writes members in
|
||||
document order -- a member [`set`](../api/basic_json_document/set.md) added goes at the end, exactly where it was
|
||||
inserted -- and [`number_format::source`](../api/basic_json_view/number_format.md) keeps the exact spelling of
|
||||
every number an edit did not itself touch; a number an edit *did* touch is written the way
|
||||
[`BasicJsonType::dump()`](../api/basic_json/dump.md) would write it, since there is no source spelling for a brand
|
||||
new value.
|
||||
|
||||
??? example "Example: patch a configuration, keeping member order and number spellings"
|
||||
|
||||
```cpp
|
||||
--8<-- "examples/json_editable_document.cpp"
|
||||
```
|
||||
|
||||
Output:
|
||||
|
||||
```json
|
||||
--8<-- "examples/json_editable_document.output"
|
||||
```
|
||||
|
||||
### What stays valid, and what an edit costs
|
||||
|
||||
The source text itself is **never written**, and the parsed index never moves -- a value keeps the node it was
|
||||
parsed into for as long as it is not itself replaced. So every [view](../api/basic_json_view/index.md) taken before
|
||||
an edit, including a previously obtained [`root()`](../api/basic_json_document/root.md), stays valid and, if it
|
||||
still refers to the edited value, sees the edit; a view of a value a later edit drops or replaces just keeps showing
|
||||
what it last held. New values go to storage the document allocates and owns on demand. The one thing an edit does
|
||||
invalidate is the **iterators** taken over an edited array or object: the first time one of its elements is set or
|
||||
appended to, its elements move from the parsed, fixed layout to a growable block of links so that
|
||||
[`push_back`](../api/basic_json_document/push_back.md) can later grow it in amortized constant time -- existing
|
||||
elements are not touched, but an iterator that was walking the old layout no longer matches. A string obtained with
|
||||
[`get_string()`](../api/basic_json_view/get_string.md) is unaffected either way and stays valid across further
|
||||
edits. See [`basic_json_document`'s Edits](../api/basic_json_document/index.md#edits) for the details, and
|
||||
[`set`'s Exception safety](../api/basic_json_document/set.md#exception-safety) for what an edit guarantees if it
|
||||
throws (the *basic* guarantee, not the strong one `dump()` and the read-only functions provide).
|
||||
|
||||
## Choosing between `json`, `ordered_json`, the SAX interface, and `json_view`
|
||||
|
||||
| | [`json`](../api/json.md) / [`ordered_json`](../api/ordered_json.md) | [SAX interface](parsing/sax_interface.md) | [`json_document`](../api/json_document.md) / [`json_view`](../api/json_view.md) |
|
||||
|---|---|---|---|
|
||||
| **Ownership** | owns every value | owns nothing; you decide what to keep, in your handler | borrows or owns the *text*; the index is always owned by the document |
|
||||
| **Mutability** | freely mutable | not applicable (a one-shot event stream) | read-only |
|
||||
| **What you get** | a full tree you can read, write, and keep as long as you like | a sequence of callbacks; whatever your handler builds from them | a flat index plus, on demand, [`materialize()`](../api/basic_json_view/materialize.md)d `json`/`ordered_json` values for the parts you actually use |
|
||||
| **Typical use** | general-purpose JSON handling: config, request/response bodies you build or modify, anything you hold onto | validating or projecting a text into your own data structure without ever holding the whole thing as JSON | large or high-volume input where you only need part of it, or need it repeatedly, and can keep the source text (or a copy) alive for as long as the document lives |
|
||||
| | [`json`](../api/json.md) / [`ordered_json`](../api/ordered_json.md) | [SAX interface](parsing/sax_interface.md) | [`json_document`](../api/json_document.md) / [`json_view`](../api/json_view.md) | [`json_editable_document`](../api/json_editable_document.md) / [`json_editable_view`](../api/json_editable_view.md) |
|
||||
|---|---|---|---|---|
|
||||
| **Ownership** | owns every value | owns nothing; you decide what to keep, in your handler | borrows or owns the *text*; the index is always owned by the document | same as `json_document`; edits go to storage the document owns |
|
||||
| **Mutability** | freely mutable | not applicable (a one-shot event stream) | read-only | [`set`](../api/basic_json_document/set.md)/[`push_back`](../api/basic_json_document/push_back.md) edit in place; the source text is never rewritten |
|
||||
| **What you get** | a full tree you can read, write, and keep as long as you like | a sequence of callbacks; whatever your handler builds from them | a flat index plus, on demand, [`materialize()`](../api/basic_json_view/materialize.md)d `json`/`ordered_json` values for the parts you actually use | the same, plus [`dump()`](../api/basic_json_view/dump.md) of an edited document that keeps the member order and, with [`number_format::source`](../api/basic_json_view/number_format.md), the spelling of every untouched number |
|
||||
| **Typical use** | general-purpose JSON handling: config, request/response bodies you build or modify, anything you hold onto | validating or projecting a text into your own data structure without ever holding the whole thing as JSON | large or high-volume input where you only need part of it, or need it repeatedly, and can keep the source text (or a copy) alive for as long as the document lives | a document you read, patch a few fields of, and write back -- a configuration file, for instance -- where the rest of it should come back exactly as it was |
|
||||
|
||||
## Version history
|
||||
|
||||
|
||||
@@ -782,6 +782,24 @@ The dynamic type of the object cannot be represented in the requested serializat
|
||||
|
||||
Encapsulate the JSON value in an object. That is, instead of serializing `#!json true`, serialize `#!json {"value": true}`
|
||||
|
||||
### json.exception.type_error.319
|
||||
|
||||
[`basic_json_document::set`](../api/basic_json_document/set.md) and
|
||||
[`basic_json_document::push_back`](../api/basic_json_document/push_back.md) can store any `basic_json` value except
|
||||
a binary one: a `json_document` has no representation for [binary values](../features/binary_values.md), which only
|
||||
ever arise from parsing a binary format or from an explicit [`json::binary`](../api/basic_json/binary.md) value, not
|
||||
from JSON text.
|
||||
|
||||
!!! failure "Example message"
|
||||
|
||||
```
|
||||
[json.exception.type_error.319] cannot store a binary value in a json_document
|
||||
```
|
||||
|
||||
!!! note
|
||||
|
||||
This exception was added in version 3.13.0, together with editable [`json_document`s](../features/json_view.md).
|
||||
|
||||
## Out of range
|
||||
|
||||
This exception is thrown in case a library function is called on an input parameter that exceeds the expected range, for instance, in the case of array indices or nonexisting object keys.
|
||||
@@ -1006,13 +1024,19 @@ MessagePack's ext type and BSON's binary subtype are each stored in a single byt
|
||||
|
||||
[`basic_json_document::parse()`](../api/basic_json_document/parse.md) and the other parsing functions of
|
||||
[`basic_json_document`](../api/basic_json_document/index.md) index a value's position in the source text in 32 bits,
|
||||
so they do not support an input of 4 GiB or more.
|
||||
so they do not support an input of 4 GiB or more. The same 32-bit limit applies to an **editable** document's own
|
||||
storage: [`set`](../api/basic_json_document/set.md) and [`push_back`](../api/basic_json_document/push_back.md) throw
|
||||
this exception once the strings and number tokens written by edits reach 4 GiB in total, or once more than
|
||||
4294967295 arrays/objects have had an element set or appended to them.
|
||||
|
||||
!!! failure "Example message"
|
||||
!!! failure "Example messages"
|
||||
|
||||
```
|
||||
[json.exception.out_of_range.416] input of 4 GiB or more is not supported by json_document
|
||||
```
|
||||
```
|
||||
[json.exception.out_of_range.416] edits of 4 GiB or more are not supported by json_document
|
||||
```
|
||||
|
||||
!!! note
|
||||
|
||||
|
||||
@@ -239,8 +239,10 @@ nav:
|
||||
- 'owns_source': api/basic_json_document/owns_source.md
|
||||
- 'parse': api/basic_json_document/parse.md
|
||||
- 'parse_copy': api/basic_json_document/parse_copy.md
|
||||
- 'push_back': api/basic_json_document/push_back.md
|
||||
- 'read': api/basic_json_document/read.md
|
||||
- 'root': api/basic_json_document/root.md
|
||||
- 'set': api/basic_json_document/set.md
|
||||
- 'shrink_to_fit': api/basic_json_document/shrink_to_fit.md
|
||||
- 'source': api/basic_json_document/source.md
|
||||
- basic_json_view:
|
||||
@@ -301,6 +303,8 @@ nav:
|
||||
- 'to_json': api/adl_serializer/to_json.md
|
||||
- 'json': api/json.md
|
||||
- 'json_document': api/json_document.md
|
||||
- 'json_editable_document': api/json_editable_document.md
|
||||
- 'json_editable_view': api/json_editable_view.md
|
||||
- json_pointer:
|
||||
- 'Overview': api/json_pointer/index.md
|
||||
- '(Constructor)': api/json_pointer/json_pointer.md
|
||||
@@ -341,6 +345,8 @@ nav:
|
||||
- 'operator""_json_pointer': api/operator_literal_json_pointer.md
|
||||
- 'ordered_json': api/ordered_json.md
|
||||
- 'ordered_json_document': api/ordered_json_document.md
|
||||
- 'ordered_json_editable_document': api/ordered_json_editable_document.md
|
||||
- 'ordered_json_editable_view': api/ordered_json_editable_view.md
|
||||
- 'ordered_json_view': api/ordered_json_view.md
|
||||
- 'ordered_map': api/ordered_map.md
|
||||
- macros:
|
||||
|
||||
Reference in New Issue
Block a user