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Add editable json_documents: set, push_back, insert, and erase
basic_json_document gets a second template parameter, Editable (false by default), plus the aliases json_editable_document, json_editable_view, ordered_json_editable_document and ordered_json_editable_view. Editable documents can change values and structure without rewriting the source text: set()/push_back() on values, keys, array indices and JSON pointers; insert() before an array element; erase() of an object key, array index or JSON pointer. New values and element sequences go into edit storage that the document owns and never moves, so views keep referring to their value across edits and a parsed node never moves. Read-only documents walk the plain node array and are unaffected. Strings are checked for UTF-8 on entry, so dump() of an editable document never throws type_error.316. Binary values cannot be stored (type_error.319). A seeded differential test applies random edits to an editable document and to the equivalent ordered_json and compares both after every step. Signed-off-by: Niels Lohmann <mail@nlohmann.me>
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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_view;
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```
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@@ -27,16 +27,30 @@ subtree on demand. [`operator[]`](operator%5B%5D.md), [`at`](at.md), [`contains`
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[`operator!=`](operator_ne.md) compare two views, or a view and a `BasicJsonType` value, without ever building a
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`BasicJsonType` value for a view; no ordering comparison (`#!cpp operator<`) is provided.
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`basic_json_view` itself is always read-only -- it never has a `set` or `push_back` of its own. A view of an
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**editable** document (`#!cpp Editable == true`) sees every edit made through
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[`basic_json_document::set`](../basic_json_document/set.md) and
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[`basic_json_document::push_back`](../basic_json_document/push_back.md): once a value is changed, every view that
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still refers to it -- including ones taken before the change -- reads the new value. See
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[Edits](../basic_json_document/index.md#edits).
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## Template parameters
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`BasicJsonType`
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: a specialization of [`basic_json`](../basic_json/index.md), matching the
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[`basic_json_document`](../basic_json_document/index.md) the view was taken from.
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`Editable`
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: whether the view is of an editable document, matching the [`basic_json_document`](../basic_json_document/index.md)
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it was taken from (optional, `#!cpp false` by default). See [Edits](../basic_json_document/index.md#edits).
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## Specializations
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- [**json_view**](../json_view.md) - views of a [`json_document`](../json_document.md)
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- [**ordered_json_view**](../ordered_json_view.md) - views of an [`ordered_json_document`](../ordered_json_document.md)
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- [**json_editable_view**](../json_editable_view.md) - views of a [`json_editable_document`](../json_editable_document.md)
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- [**ordered_json_editable_view**](../ordered_json_editable_view.md) - views of an
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[`ordered_json_editable_document`](../ordered_json_editable_document.md)
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## Member types
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