mirror of https://github.com/jkjoy/sunpeiwen.git
55 lines
2.1 KiB
Markdown
55 lines
2.1 KiB
Markdown
## Buffers
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NAN's `node::Buffer` helpers exist as the API has changed across supported Node versions. Use these methods to ensure compatibility.
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- <a href="#api_nan_new_buffer"><b><code>Nan::NewBuffer()</code></b></a>
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- <a href="#api_nan_copy_buffer"><b><code>Nan::CopyBuffer()</code></b></a>
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- <a href="#api_nan_free_callback"><b><code>Nan::FreeCallback()</code></b></a>
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<a name="api_nan_new_buffer"></a>
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### Nan::NewBuffer()
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Allocate a new `node::Buffer` object with the specified size and optional data. Calls `node::Buffer::New()`.
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Note that when creating a `Buffer` using `Nan::NewBuffer()` and an existing `char*`, it is assumed that the ownership of the pointer is being transferred to the new `Buffer` for management.
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When a `node::Buffer` instance is garbage collected and a `FreeCallback` has not been specified, `data` will be disposed of via a call to `free()`.
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You _must not_ free the memory space manually once you have created a `Buffer` in this way.
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Signature:
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```c++
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Nan::MaybeLocal<v8::Object> Nan::NewBuffer(uint32_t size)
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Nan::MaybeLocal<v8::Object> Nan::NewBuffer(char* data, uint32_t size)
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Nan::MaybeLocal<v8::Object> Nan::NewBuffer(char *data,
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size_t length,
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Nan::FreeCallback callback,
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void *hint)
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```
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<a name="api_nan_copy_buffer"></a>
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### Nan::CopyBuffer()
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Similar to [`Nan::NewBuffer()`](#api_nan_new_buffer) except that an implicit memcpy will occur within Node. Calls `node::Buffer::Copy()`.
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Management of the `char*` is left to the user, you should manually free the memory space if necessary as the new `Buffer` will have its own copy.
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Signature:
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```c++
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Nan::MaybeLocal<v8::Object> Nan::CopyBuffer(const char *data, uint32_t size)
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```
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<a name="api_nan_free_callback"></a>
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### Nan::FreeCallback()
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A free callback that can be provided to [`Nan::NewBuffer()`](#api_nan_new_buffer).
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The supplied callback will be invoked when the `Buffer` undergoes garbage collection.
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Signature:
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```c++
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typedef void (*FreeCallback)(char *data, void *hint);
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```
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