minheap/build/heap.js

Simple implementation of min-heap

// Generated by CoffeeScript 1.10.0
(function() {
  var Heap, MIN_LEN;

  MIN_LEN = 1 << 5;

  Heap = (function() {
    function Heap(compare) {
      this.compare = compare;
      if (this.compare == null) {
        this.compare = function(a, b) {
          if (a < b) {
            return -1;
          } else if (a > b) {
            return 1;
          } else {
            return 0;
          }
        };
      }
      this.array = [null];
      this.len = 0;
    }

    Heap.prototype.top = function() {
      return this.array[1];
    };

    Heap.prototype.pop = function() {
      var res;
      res = this.array[1];
      if (this.len === 0) {
        return res;
      }
      this.array[1] = this.array[this.len];
      this.array[this.len] = null;
      this.len--;
      if (this.len > 0) {
        if (this.array.length > MIN_LEN && this.array.length >= this.len * 2) {
          this.array.splice(this.len + 1);
        }
        this._traceDown(1);
      }
      return res;
    };

    Heap.prototype.push = function(val) {
      if (this.len < this.array.length - 1) {
        this.array[++this.len] = val;
      } else {
        this.array.push(val);
        this.len++;
      }
      return this._traceUp(this.len);
    };

    Heap.prototype._swap = function(a, b) {
      var t;
      t = this.array[a];
      this.array[a] = this.array[b];
      this.array[b] = t;
    };

    Heap.prototype._traceUp = function(pos) {
      var com, parent;
      while (pos > 1) {
        parent = Math.floor(pos / 2);
        com = this.compare(this.array[pos], this.array[parent]);
        if (com < 0) {
          this._swap(pos, parent);
          pos = parent;
        } else {
          break;
        }
      }
    };

    Heap.prototype._traceDown = function(pos) {
      var child, com, left, right;
      while (true) {
        child = 0;
        left = pos * 2;
        if (left > this.len) {
          return;
        }
        com = this.compare(this.array[left], this.array[pos]);
        if (com < 0) {
          child = left;
        }
        right = left + 1;
        if (right <= this.len) {
          if (child > 0) {
            com = this.compare(this.array[right], this.array[left]);
            if (com < 0) {
              child = right;
            }
          } else {
            com = this.compare(this.array[right], this.array[pos]);
            if (com < 0) {
              child = right;
            }
          }
        }
        if (child > 0) {
          this._swap(child, pos);
          pos = child;
        } else {
          break;
        }
      }
    };

    return Heap;

  })();

  if ((typeof GLOBAL !== "undefined" && GLOBAL !== null) && (typeof window === "undefined" || window === null)) {
    module.exports = Heap;
  } else {
    window.Heap = Heap;
  }

}).call(this);