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63 lines
1.2 KiB
Markdown
63 lines
1.2 KiB
Markdown
# <small>nlohmann::basic_json::</small>diff
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```cpp
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static basic_json diff(const basic_json& source,
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const basic_json& target);
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```
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Creates a [JSON Patch](http://jsonpatch.com) so that value `source` can be changed into the value `target` by calling
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[`patch`](patch.md) function.
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For two JSON values `source` and `target`, the following code yields always `#!cpp true`:
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```cpp
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source.patch(diff(source, target)) == target;
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```
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## Parameters
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`source` (in)
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: JSON value to compare from
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`target` (in)
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: JSON value to compare against
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## Return value
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a JSON patch to convert the `source` to `target`
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## Exception safety
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Strong guarantee: if an exception is thrown, there are no changes in the JSON value.
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## Complexity
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Linear in the lengths of `source` and `target`.
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## Notes
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Currently, only `remove`, `add`, and `replace` operations are generated.
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## Examples
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??? example
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The following code shows how a JSON patch is created as a diff for two JSON values.
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```cpp
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--8<-- "examples/diff.cpp"
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```
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Output:
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```json
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--8<-- "examples/diff.output"
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```
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## See also
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- [RFC 6902 (JSON Patch)](https://tools.ietf.org/html/rfc6902)
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## Version history
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- Added in version 2.0.0.
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