js-marketplace-2014/src/actor.js

var Reflect = require("./reflect.js");
var Minimart = require("./minimart.js");
var World = Minimart.World;
var Route = Minimart.Route;

Actor._chunks = null;

function Actor(bootfn) {
  return {
    boot: function () {
      delete this.boot;
      var oldChunks = Actor._chunks;
      try {
	Actor._chunks = [];
	bootfn.call(this);
	finalizeActor(this, Actor._chunks);
	Actor._chunks = oldChunks;
      } catch (e) {
	Actor._chunks = oldChunks;
	throw e;
      }
    }
  };
}

function checkChunks(type) {
    if (!Actor._chunks) {
	throw new Error("Call to Actor."+type+" outside of Actor constructor");
    }
}

function extractChunk(type, kind, defaultOptions, args) {
    var rawProjectionFn = args[0]
    var options = null;
    var handler = null;
    if (typeof rawProjectionFn !== 'function') {
	throw new Error("Actor."+type+" expects a function producing a pattern as first argument");
    }
    for (var i = 1; i < args.length; i++) { // NB: skip the first arg - it's rawProjectionFn
	if (typeof args[i] === 'function') {
	    if (handler !== null) { throw new Error("Too many handler functions in Actor."+type); }
	    handler = args[i];
	} else if (typeof args[i] === 'object') {
	    if (options !== null) { throw new Error("Too many options arguments in Actor."+type); }
	    options = args[i];
	} else {
	    throw new Error("Unrecognised argument in Actor."+type);
	}
    }
    options = options || {};
    for (var k in options) {
	if (!(k in defaultOptions)) {
	    throw new Error("Unrecognised option '"+k+"' in Actor."+type);
	}
    }
    for (var k in defaultOptions) {
	if (!(k in options)) {
	    options[k] = defaultOptions[k];
	}
    }
    return {
	type: type,
	kind: kind,
	rawProjectionFn: rawProjectionFn,
	options: options,
	handler: handler
    };
}

function recordChunk(chunk) {
    Actor._chunks.push(chunk);
}

function chunkExtractor(type, kind, defaultOptions) {
    return function (/* ... */) {
	checkChunks(type);
	recordChunk(extractChunk(type,
				 kind,
				 defaultOptions,
				 Array.prototype.slice.call(arguments)));
    };
}

var participantDefaults = {
    metaLevel: 0,
    when: function () { return true; }
};

var observerDefaults = {
    metaLevel: 0,
    level: 0,
    when: function () { return true; },
    presence: null,
    name: null,
    singleton: null,
    set: null,
    added: null,
    removed: null
};

Actor.advertise = chunkExtractor('advertise', 'participant', participantDefaults);
Actor.subscribe = chunkExtractor('subscribe', 'participant', participantDefaults);

Actor.observeAdvertisers = chunkExtractor('observeAdvertisers', 'observer', observerDefaults);
Actor.observeSubscribers = chunkExtractor('observeSubscribers', 'observer', observerDefaults);

Actor.observeGestalt = function (gestaltFn, eventHandlerFn) {
    checkChunks('observeGestalt');
    recordChunk({
	type: 'observeGestalt',
	kind: 'raw',
	gestaltFn: gestaltFn,
	options: {
	    when: function () { return true; }
	},
	eventHandlerFn: eventHandlerFn
    });
};

function finalizeActor(behavior, chunks) {
    var oldHandleEvent = behavior.handleEvent;
    var projections = {};
    var compiledProjections = {};
    var previousObjs = {};

    behavior.updateRoutes = function () {
	var newRoutes = Route.emptyGestalt;
	for (var i = 0; i < chunks.length; i++) {
	    var chunk = chunks[i];
	    if (chunk.options.when.call(this)) {
		switch (chunk.kind) {
		case 'raw':
		    newRoutes = newRoutes.union(chunk.gestaltFn.call(this));
		    break;
		case 'participant':
		    var proj = chunk.rawProjectionFn.call(this);
		    projections[i] = proj;
		    var g = Route.simpleGestalt(chunk.type === 'advertise',
						Route.projectionToPattern(proj),
						chunk.options.metaLevel,
						0);
		    newRoutes = newRoutes.union(g);
		    break;
		case 'observer':
		    var proj = chunk.rawProjectionFn.call(this);
		    projections[i] = proj;
		    compiledProjections[i] = Route.compileProjection(proj);
		    var g = Route.simpleGestalt(chunk.type === 'observeSubscribers',
						Route.projectionToPattern(proj),
						chunk.options.metaLevel,
						chunk.options.level + 1);
		    newRoutes = newRoutes.union(g);
		    if (chunk.options.added || chunk.options.removed) {
			previousObjs[i] = Route.arrayToSet([]);
		    }
		    break;
		default:
		    throw new Error("Unsupported chunk type/kind: "+chunk.type+"/"+chunk.kind);
		}
	    }
	}
	World.updateRoutes([newRoutes]);
    };

    behavior.handleEvent = function (e) {
	if (oldHandleEvent) { oldHandleEvent.call(this, e); }
	for (var i = 0; i < chunks.length; i++) {
	    var chunk = chunks[i];
	    switch (chunk.kind) {
	    case 'raw':
		chunk.eventHandlerFn.call(this, e);
		break;
	    case 'participant':
		if (chunk.handler
		    && (e.type === 'message')
		    && (e.metaLevel === chunk.options.metaLevel)
		    && (e.isFeedback === (chunk.type === 'advertise')))
		{
		    var matchResult = Route.matchPattern(e.message, projections[i]);
		    if (matchResult) {
			kwApply(chunk.handler, this, matchResult);
		    }
		}
		break;
	    case 'observer':
		if (e.type === 'routes') {
		    var projectionResult = e.gestalt.project(compiledProjections[i],
							     chunk.type !== 'observeSubscribers',
							     chunk.options.metaLevel,
							     chunk.options.level);

		    var isPresent = !Route.is_emptyMatcher(projectionResult);
		    if (chunk.options.presence) {
			this[chunk.options.presence] = isPresent;
		    }

		    var objs = [];
		    if (isPresent) {
			var keys = Route.matcherKeys(projectionResult);
			if (keys === null) {
			    console.warn("Wildcard detected while projecting ("
					 +JSON.stringify(chunk.options)+")");
			} else {
			    objs = Route.matcherKeysToObjects(keys, compiledProjections[i]);
			    if (chunk.options.set) {
				for (var j = 0; j < objs.length; j++) {
				    objs[j] = chunk.options.set.call(this, objs[j]);
				}
			    }
			}
		    }
		    if (chunk.options.name) {
			this[chunk.options.name] = objs;
		    }
		    if (chunk.options.singleton) {
			this[chunk.options.singleton] = objs.length === 1 ? objs[0] : undefined;
		    }

		    if (chunk.options.added || chunk.options.removed) {
			var objSet = Route.arrayToSet(objs);

			if (chunk.options.added) {
			    this[chunk.options.added] =
				Route.setToArray(Route.setSubtract(objSet, previousObjs[i]));
			}

			if (chunk.options.removed) {
			    this[chunk.options.removed] =
				Route.setToArray(Route.setSubtract(previousObjs[i], objSet));
			}

			previousObjs[i] = objSet;
		    }

		    if (chunk.handler) {
			chunk.handler.call(this);
		    }
		}
		break;
	    default:
		throw new Error("Unsupported chunk type/kind: "+chunk.type+"/"+chunk.kind);
	    }
	}
    };

    if (behavior.boot) { behavior.boot(); }
    for (var i = 0; i < chunks.length; i++) {
      var chunk = chunks[i];
      if (chunk.kind === 'observer') {
	if (chunk.options.presence) { behavior[chunk.options.presence] = false; }
	if (chunk.options.name) { behavior[chunk.options.name] = []; }
	if (chunk.options.singleton) { behavior[chunk.options.singleton] = undefined; }
	if (chunk.options.added) { behavior[chunk.options.added] = []; }
	if (chunk.options.removed) { behavior[chunk.options.removed] = []; }
      }
    }
    behavior.updateRoutes();
}

function kwApply(f, thisArg, args) {
    var formals = Reflect.formalParameters(f);
    var actuals = []
    for (var i = 0; i < formals.length; i++) {
	var formal = formals[i];
	if (!(formal in args)) {
	    throw new Error("Function parameter '"+formal+"' not present in args");
	}
	actuals.push(args[formal]);
    }
    return f.apply(thisArg, actuals);
}

///////////////////////////////////////////////////////////////////////////

module.exports.Actor = Actor;
module.exports.kwApply = kwApply;