# Yahoo! UI Library

### loader 3.1.1

Yahoo! UI Library > loader > rollup.js (source view)
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    /**
     * Optional automatic rollup logic for reducing http connections
     * when not using a combo service.
     * @module loader
     * @submodule rollup
     */

    /**
     * Look for rollup packages to determine if all of the modules a
     * rollup supersedes are required.  If so, include the rollup to
     * help reduce the total number of connections required.  Called
     * by calculate().  This is an optional feature, and requires the
     * appropriate submodule to function.
     * @method _rollup
     * @for Loader
     * @private
     */
    Y.Loader.prototype._rollup = function() {
        var i, j, m, s, rollups={}, r=this.required, roll,
            info = this.moduleInfo, rolled, c, smod;

        // find and cache rollup modules
        if (this.dirty || !this.rollups) {
            for (i in info) {
                if (info.hasOwnProperty(i)) {
                    m = this.getModule(i);
                    // if (m && m.rollup && m.supersedes) {
                    if (m && m.rollup) {
                        rollups[i] = m;
                    }
                }
            }

            this.rollups = rollups;
            this.forceMap = (this.force) ? Y.Array.hash(this.force) : {};
        }

        // make as many passes as needed to pick up rollup rollups
        for (;;) {
            rolled = false;

            // go through the rollup candidates
            for (i in rollups) {
                if (rollups.hasOwnProperty(i)) {
                    // there can be only one, unless forced
                    if (!r[i] && ((!this.loaded[i]) || this.forceMap[i])) {
                        m = this.getModule(i);
                        s = m.supersedes || [];
                        roll = false;

                        // @TODO remove continue
                        if (!m.rollup) {
                            continue;
                        }

                        c = 0;

                        // check the threshold
                        for (j=0;j<s.length;j=j+1) {
                            smod = info[s[j]];

                            // if the superseded module is loaded, we can't load the rollup
                            // unless it has been forced
                            if (this.loaded[s[j]] && !this.forceMap[s[j]]) {
                                roll = false;
                                break;
                            // increment the counter if this module is required.  if we are
                            // beyond the rollup threshold, we will use the rollup module
                            } else if (r[s[j]] && m.type == smod.type) {
                                c++;
                                // Y.log("adding to thresh: " + c + ", " + s[j]);
                                roll = (c >= m.rollup);
                                if (roll) {
                                    // Y.log("over thresh " + c + ", " + s[j]);
                                    break;
                                }
                            }
                        }

                        if (roll) {
                            // Y.log("adding rollup: " +  i);
                            // add the rollup
                            r[i] = true;
                            rolled = true;

                            // expand the rollup's dependencies
                            this.getRequires(m);
                        }
                    }
                }
            }

            // if we made it here w/o rolling up something, we are done
            if (!rolled) {
                break;
            }
        }
    };

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