nv-data-fixed-queue

• nv-data-fixed-queue
• wrap of https://github.com/nodejs/node/blob/178e52a7ead2ef9ffb6eb5e17be167f17beb45a8/lib/internal/fixed_queue.js

install

• npm install nv-data-fixed-queue

usage

• the code is from nodejs lib/internal/fixed_queue.js
• this structure is used in nodejs as a task-queue
• its useful when you modify nodejs

example

var {FixedCircularBuffer} = require("nv-data-fixed-queue")
var cir = new FixedCircularBuffer(4)

/*
> cir
FixedCircularBuffer {
  bottom: 0,
  top: 0,
  list: [ <4 empty items> ],
  next: null
}
> cir.push('a')
undefined
> cir
FixedCircularBuffer {
  bottom: 0,
  top: 1,
  list: [ 'a', <3 empty items> ],
           |     |
          bot   top
  next: null
}
>
> cir.push('b')
undefined
> cir
FixedCircularBuffer {
  bottom: 0,
  top: 2,
  list: [ 'a', 'b', <2 empty items> ],
           |         |
          bot       top
  next: null
}
> cir.shift()
'a'
>
> cir
FixedCircularBuffer {
  bottom: 1,
  top: 2,
  list: [ undefined, 'b', <2 empty items> ],
                      |    |
                      bot top
  next: null
}
>
> cir.shift()
'b'
>
> cir
FixedCircularBuffer {
  bottom: 2,
  top: 2,
  list: [ undefined, undefined, <2 empty items> ],
  next: null
}
>
> cir.isEmpty()
true
>

*/

/*
var cir = new FixedCircularBuffer(4)
> cir
FixedCircularBuffer {
  bottom: 0,
  top: 3,
  list: [ 'a', 'b', 'c', <1 empty item> ],
                             |
                            4 -1 =3  means full
  next: null
}
> cir.isFull()  ----------> extra-slot
true
>

*/

var {FixedQueue} = require("nv-data-fixed-queue")
var queue = new FixedQueue(4)
/*
> queue
FixedQueue {
  tail: FixedCircularBuffer {
    bottom: 0,
    top: 0,
    list: [ <4 empty items> ],
    next: null
  },
  head: FixedCircularBuffer {
    bottom: 0,
    top: 0,
    list: [ <4 empty items> ],
    next: null
  }
}
> queue.push('a')
undefined
> queue.push('b')
undefined
> queue.push('c')
undefined
> queue
FixedQueue {
  tail: FixedCircularBuffer {
    bottom: 0,
    top: 3,
    list: [ 'a', 'b', 'c', <1 empty item> ],
    next: null
  },
  head: FixedCircularBuffer {
    bottom: 0,
    top: 3,
    list: [ 'a', 'b', 'c', <1 empty item> ],
    next: null
  }
}
> queue.push('d')
undefined
> queue
FixedQueue {
  tail: FixedCircularBuffer {
    bottom: 0,
    top: 3,
    list: [ 'a', 'b', 'c', <1 empty item> ],
    next: FixedCircularBuffer {
      bottom: 0,
      top: 1,
      list: [Array],
      next: null
    }
  },
  head: FixedCircularBuffer {
    bottom: 0,
    top: 1,
    list: [ 'd', <3 empty items> ],
    next: null
  }
}
> queue.push('e')
undefined
> queue
FixedQueue {
  tail: FixedCircularBuffer {
    bottom: 0,
    top: 3,
    list: [ 'a', 'b', 'c', <1 empty item> ],
    next: FixedCircularBuffer {
      bottom: 0,
      top: 2,
      list: [Array],
      next: null
    }
  },
  head: FixedCircularBuffer {
    bottom: 0,
    top: 2,
    list: [ 'd', 'e', <2 empty items> ],
    next: null
  }
}
> queue.shift()
'a'
> queue.shift()
'b'
> queue
FixedQueue {
  tail: FixedCircularBuffer {
    bottom: 2,
    top: 3,
    list: [ undefined, undefined, 'c', <1 empty item> ],
    next: FixedCircularBuffer {
      bottom: 0,
      top: 2,
      list: [Array],
      next: null
    }
  },
  head: FixedCircularBuffer {
    bottom: 0,
    top: 2,
    list: [ 'd', 'e', <2 empty items> ],
    next: null
  }
}
> queue.shift()
'c'
> queue
FixedQueue {
  tail: FixedCircularBuffer {
    bottom: 0,
    top: 2,
    list: [ 'd', 'e', <2 empty items> ],
    next: null
  },
  head: FixedCircularBuffer {
    bottom: 0,
    top: 2,
    list: [ 'd', 'e', <2 empty items> ],
    next: null
  }
}
> queue.shift()
'd'
> queue.shift()
'e'
> queue
FixedQueue {
  tail: FixedCircularBuffer {
    bottom: 2,
    top: 2,
    list: [ undefined, undefined, <2 empty items> ],
    next: null
  },
  head: FixedCircularBuffer {
    bottom: 2,
    top: 2,
    list: [ undefined, undefined, <2 empty items> ],
    next: null
  }
}
>

*/

API

• FixedCircularBuffer(kSize =2048)
• FixedQueue(kSize =2048)

LICENSE

• ISC