Yahoo! UI Library

/**
 * 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                        // if the superseded module is loaded, we can't load the rollup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;
        }
    }
};