cmake-js/ref

Name: ref

Owner: CMake.js

Description: Turn Buffer instances into "pointers"

Created: 2016-09-15 20:41:38.0

Updated: 2016-09-15 20:41:39.0

Pushed: 2016-11-11 21:40:47.0

Homepage: http://tootallnate.github.com/ref

Size: 537

Language: JavaScript

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README

ref

Turn Buffer instances into “pointers”

This module is inspired by the old Pointer class from node-ffi, but with the intent of using Node's fast Buffer instances instead of a slow C++ Pointer class. These two concepts were previously very similar, but now this module brings over the functionality that Pointers had and Buffers are missing, so now Buffers are a lot more powerful.

Features:

• Get the memory address of any Buffer instance
• Read/write references to JavaScript Objects into Buffer instances
• Read/write Buffer instances' memory addresses to other Buffer instances
• Read/write int64_t and uint64_t data values (Numbers or Strings)
• A “type” convention, so that you can specify a buffer as an int *, and reference/dereference at will.
• Offers a buffer instance representing the NULL pointer

Installation

Install with npm:

m install ref

Examples

referencing and derefencing

ref = require('ref')

o we can all agree that a buffer with the int value written
o it could be represented as an "int *"
buf = new Buffer(4)
writeInt32LE(12345, 0)

irst, what is the memory address of the buffer?
ole.log(buf.address())  // ? 140362165284824

sing `ref`, you can set the "type", and gain magic abilities!
type = ref.types.int

ow we can dereference to get the "meaningful" value
ole.log(buf.deref())  // ? 12345


ou can also get references to the original buffer if you need it.
his buffer could be thought of as an "int **"
one = buf.ref()

nd you can dereference all the way back down to an int
ole.log(one.deref().deref())  // ? 12345

See the full API Docs for more examples.

The “type” interface

You can easily define your own “type” objects at attach to Buffer instances. It just needs to be a regular JavaScript Object that contains the following properties:

| Name | Data Type | Description |:————–|:———————————|:———————————- | size | Number | The size in bytes required to hold this type. | indirection | Number | The current level of indirection of the buffer. Usually this would be 1, and gets incremented on Buffers from ref() calls. A value of less than or equal to 0 is invalid. | get | Function (buffer, offset) | The function to invoke when dereferencing this type when the indirection level is 1. | set | Function (buffer, offset, value) | The function to invoke when setting a value to a buffer instance. | name | String | (optional) The name to use during debugging for this type. | alignment | Number | (optional) The alignment of this type when placed in a struct. Defaults to the type's size.

Be sure to check out the Wiki page of “Known Types”, for the list of built-in ref types, as well as known external type implementations.

For example, you could define a “bigint” type that dereferences into a bigint instance:

ref = require('ref')
bigint = require('bigint')

efine the "type" instance according to the spec
BigintType = {
size: ref.sizeof.int64
indirection: 1
get: function (buffer, offset) {
  // return a bigint instance from the buffer
  return bigint.fromBuffer(buffer)
}
set: function (buffer, offset, value) {
  // 'value' would be a bigint instance
  var val = value.toString()
  return ref.writeInt64(buffer, offset || 0, val)
}


ow we can create instances of the type from existing buffers.
buf" is some Buffer instance returned from some external data
ource, which should contain "bigint" binary data.
type = BigintType

nd now you can create "bigint" instances using this generic "types" API
val = buf.deref()
        .add('1234')
        .sqrt()
        .shiftLeft(5)

Build the docs

Install the dev dependencies:

m install

Generate the docs:

m run docs

License

(The MIT License)

Copyright (c) 2012 Nathan Rajlich <nathan@tootallnate.net>

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.