scratch-vm/src/engine/runtime.js

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var EventEmitter = require('events');
var Sequencer = require('./sequencer');
var Thread = require('./thread');
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var util = require('util');
var defaultBlockPackages = {
'scratch3_control': require('../blocks/scratch3_control'),
'scratch3_event': require('../blocks/scratch3_event'),
'scratch3_looks': require('../blocks/scratch3_looks'),
'scratch3_motion': require('../blocks/scratch3_motion'),
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'scratch3_operators': require('../blocks/scratch3_operators')
};
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/**
* Manages targets, stacks, and the sequencer.
* @param {!Array.<Target>} targets List of targets for this runtime.
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*/
function Runtime (targets) {
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// Bind event emitter
EventEmitter.call(this);
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// State for the runtime
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/**
* Target management and storage.
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*/
this.targets = targets;
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/**
* A list of threads that are currently running in the VM.
* Threads are added when execution starts and pruned when execution ends.
* @type {Array.<Thread>}
*/
this.threads = [];
/** @type {!Sequencer} */
this.sequencer = new Sequencer(this);
/**
* Map to look up a block primitive's implementation function by its opcode.
* This is a two-step lookup: package name first, then primitive name.
* @type {Object.<string, Function>}
*/
this._primitives = {};
this._registerBlockPackages();
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}
/**
* Event name for glowing a stack
* @const {string}
*/
Runtime.STACK_GLOW_ON = 'STACK_GLOW_ON';
/**
* Event name for unglowing a stack
* @const {string}
*/
Runtime.STACK_GLOW_OFF = 'STACK_GLOW_OFF';
/**
* Event name for glowing a block
* @const {string}
*/
Runtime.BLOCK_GLOW_ON = 'BLOCK_GLOW_ON';
/**
* Event name for unglowing a block
* @const {string}
*/
Runtime.BLOCK_GLOW_OFF = 'BLOCK_GLOW_OFF';
/**
* Event name for visual value report.
* @const {string}
*/
Runtime.VISUAL_REPORT = 'VISUAL_REPORT';
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/**
* Inherit from EventEmitter
*/
util.inherits(Runtime, EventEmitter);
/**
* How rapidly we try to step threads, in ms.
*/
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Runtime.THREAD_STEP_INTERVAL = 1000 / 60;
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// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
/**
* Register default block packages with this runtime.
* @todo Prefix opcodes with package name.
* @private
*/
Runtime.prototype._registerBlockPackages = function () {
for (var packageName in defaultBlockPackages) {
if (defaultBlockPackages.hasOwnProperty(packageName)) {
// @todo pass a different runtime depending on package privilege?
var packageObject = new (defaultBlockPackages[packageName])(this);
var packageContents = packageObject.getPrimitives();
for (var op in packageContents) {
if (packageContents.hasOwnProperty(op)) {
this._primitives[op] =
packageContents[op].bind(packageObject);
}
}
}
}
};
/**
* Retrieve the function associated with the given opcode.
* @param {!string} opcode The opcode to look up.
* @return {Function} The function which implements the opcode.
*/
Runtime.prototype.getOpcodeFunction = function (opcode) {
return this._primitives[opcode];
};
// -----------------------------------------------------------------------------
// -----------------------------------------------------------------------------
/**
* Create a thread and push it to the list of threads.
* @param {!string} id ID of block that starts the stack
*/
Runtime.prototype._pushThread = function (id) {
this.emit(Runtime.STACK_GLOW_ON, id);
var thread = new Thread(id);
thread.pushStack(id);
this.threads.push(thread);
};
/**
* Remove a thread from the list of threads.
* @param {?Thread} thread Thread object to remove from actives
*/
Runtime.prototype._removeThread = function (thread) {
var i = this.threads.indexOf(thread);
if (i > -1) {
this.emit(Runtime.STACK_GLOW_OFF, thread.topBlock);
this.threads.splice(i, 1);
}
};
/**
* Toggle a stack
* @param {!string} stackId ID of block that starts the stack
*/
Runtime.prototype.toggleStack = function (stackId) {
// Remove any existing thread
for (var i = 0; i < this.threads.length; i++) {
if (this.threads[i].topBlock == stackId) {
this._removeThread(this.threads[i]);
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return;
}
}
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// Otherwise add it
this._pushThread(stackId);
};
/**
* Green flag, which stops currently running threads
* and adds all top-level stacks that start with the green flag
*/
Runtime.prototype.greenFlag = function () {
// Remove all existing threads
for (var i = 0; i < this.threads.length; i++) {
this._removeThread(this.threads[i]);
}
// Add all top stacks with green flag
for (var t = 0; t < this.targets.length; t++) {
var target = this.targets[t];
var stacks = target.blocks.getStacks();
for (var j = 0; j < stacks.length; j++) {
var topBlock = stacks[j];
if (target.blocks.getBlock(topBlock).opcode ===
'event_whenflagclicked') {
this._pushThread(stacks[j]);
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}
}
}
};
/**
* Stop "everything"
*/
Runtime.prototype.stopAll = function () {
var threadsCopy = this.threads.slice();
while (threadsCopy.length > 0) {
var poppedThread = threadsCopy.pop();
// Unglow any blocks on this thread's stack.
for (var i = 0; i < poppedThread.stack.length; i++) {
this.glowBlock(poppedThread.stack[i], false);
}
// Actually remove the thread.
this._removeThread(poppedThread);
}
};
/**
* Repeatedly run `sequencer.stepThreads` and filter out
* inactive threads after each iteration.
*/
Runtime.prototype._step = function () {
var inactiveThreads = this.sequencer.stepThreads(this.threads);
for (var i = 0; i < inactiveThreads.length; i++) {
this._removeThread(inactiveThreads[i]);
}
};
/**
* Emit feedback for block glowing (used in the sequencer).
* @param {?string} blockId ID for the block to update glow
* @param {boolean} isGlowing True to turn on glow; false to turn off.
*/
Runtime.prototype.glowBlock = function (blockId, isGlowing) {
if (isGlowing) {
this.emit(Runtime.BLOCK_GLOW_ON, blockId);
} else {
this.emit(Runtime.BLOCK_GLOW_OFF, blockId);
}
};
/**
* Emit value for reporter to show in the blocks.
* @param {string} blockId ID for the block.
* @param {string} value Value to show associated with the block.
*/
Runtime.prototype.visualReport = function (blockId, value) {
this.emit(Runtime.VISUAL_REPORT, blockId, String(value));
};
/**
* Return the Target for a particular thread.
* @param {!Thread} thread Thread to determine target for.
* @return {?Target} Target object, if one exists.
*/
Runtime.prototype.targetForThread = function (thread) {
// @todo This is a messy solution,
// but prevents having circular data references.
// Have a map or some other way to associate target with threads.
for (var t = 0; t < this.targets.length; t++) {
var target = this.targets[t];
if (target.blocks.getBlock(thread.topBlock)) {
return target;
}
}
};
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/**
* Handle an animation frame from the main thread.
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*/
Runtime.prototype.animationFrame = function () {
if (self.renderer) {
self.renderer.draw();
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}
};
/**
* Set up timers to repeatedly step in a browser
*/
Runtime.prototype.start = function () {
self.setInterval(function() {
this._step();
}.bind(this), Runtime.THREAD_STEP_INTERVAL);
};
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module.exports = Runtime;