diffusion/src/node_modules/topics/selector-set.js

Diffusion JavaScript client

var inherits = require('inherits');
var utils = require('topics/topic-path-utils');
var TopicSelector = require('../../selectors/topic-selector');

var DELIMITER = "////";

function extractCommonPrefix(selectors) {
    if (selectors.length === 0) {
        return "";
    }
    
    // Set initial value to Integer.MAX_VALUE
    var minimum = 2147483647;
    
    var prefixes = [], i = 0;
    
    selectors.forEach(function(selector) {      
        var part = utils.split(selector.prefix);
        
        minimum = Math.min(minimum, part.length);
        prefixes[i++] = part;
    });
    
    var composite = [];
    
    assembly:
    for (var j = 0; j < minimum; ++j) {
        var part = prefixes[0][j];
        
        for (var k = 0; k < prefixes.length; ++k) {
            if (part !== prefixes[k][j]) {
                break assembly;
            }
        }
        
        composite.push(part);
        composite.push(utils.PATH_SEPARATOR);
    }
    
    return utils.canonicalise(composite.join(''));
}

function SelectorSet(selectors) {
    var expanded = [];
    
    selectors.forEach(function(selector) {
        if (selector instanceof SelectorSet) {
            selector.selectors.forEach(function(nested) {
                expanded.push(nested);
            });
        } else {
            expanded.push(selector);
        }
    });
    
    this.selectors = expanded;
    
    var remainder = expanded.join(DELIMITER);
    var prefix = extractCommonPrefix(expanded);
    
    TopicSelector.call(
        this, 
        TopicSelector.Type.SELECTOR_SET, 
        prefix, 
        TopicSelector.Prefix.SELECTOR_SET + remainder);
}

SelectorSet.DELIMITER = DELIMITER;

inherits(SelectorSet, TopicSelector);

SelectorSet.prototype.selects = function(topicPath) {
    for (var i = 0; i < this.selectors.length; ++i) {
        if (this.selectors[i].selects(topicPath)) {
            return true;
        }
    }
    
    return false;
};

module.exports = SelectorSet;